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To a solution of 1,3-dihydro-1,3-bis(chloromethyl)benzo[c] thiophene 2,2-dioxide (0.584 g, 2.2 mmol) in 50 ml of dry benzene was added 0.80 mL (2.8 mmol) of a 70% benzene solution of NaAlH(OCHCHOCH) via syringe, and the solution was refluxed for 12 hours. The mixture was cooled to 0° and decomposed with 20% sulfuric acid. The benzene layer was separated, washed with 10 mL of water, dried over potassium carbonate, and concentrated to give the product as a yellow oil in 91% yield (0.480 g); IR (film) 770, 1140, and 1320 cm–1; NMR (CDCl) δ 4.22 (q, 2 H), 1.61 and 1.59 (2 d, 6 H, J = 7 Hz), 7.3 (s, 4 H); m/e (rel. intensity) 196 (M+) (14), 132 (M-SO2) (100); MS analysis 196.055796 (calc.), 196.057587 (obs.). | 0 | Organic Reactions |
A number of salts containing the tetrachlorozincate anion, , are known. "Caulton's reagent", , which is used in organic chemistry, is an example of a salt containing . The compound contains tetrahedral and Chloride| anions, so, the compound is not caesium pentachlorozincate, but caesium tetrachlorozincate chloride. No compounds containing the ion (hexachlorozincate ion) have been characterized.
The compound may be prepared by careful precipitation from a solution of acidified with HCl. It contains a polymeric anion with balancing monohydrated hydronium ions, ions.
The coordination complex (zinc dichloride di(hydroxylamine)), known as Crismer's salt, releases hydroxylamine upon heating. | 1 | Inorganic Reactions + Inorganic Compounds |
With increasing temperature, the reaction rate increases, but hydrogen production becomes less favorable thermodynamically since the water gas shift reaction is moderately exothermic; this shift in chemical equilibrium can be explained according to Le Chatelier's principle. Over the temperature range of 600–2000 K, the equilibrium constant for the WGSR has the following relationship:
</div> | 1 | Inorganic Reactions + Inorganic Compounds |
Removal of a halogen atom from an organohalide generates a radical. Such reactions are difficult to achieve and, when they can be achieved, these processes often lead to complicated mixtures. When a pair of halides are mutually adjacent (vicinal), their removal is favored. Such reactions give alkenes in the case of vicinal alkyl dihalides:
Most desirable from the perspective of remediation are dehalogenations by hydrogenolysis, i.e. the replacement of a bond by a bond. Such reactions are amenable to catalysis:
The rate of dehalogenation depends on the strength of the bond between the carbon and halogen atom. The bond dissociation energies of carbon-halogen bonds are described as: (234 kJ/mol), (293 kJ/mol), (351 kJ/mol), and (452 kJ/mol). Thus, for the same structures the bond dissociation rate for dehalogenation will be: . Additionally, the rate of dehalogenation for alkyl halide also varies with steric environment and follows this trend: halides. | 0 | Organic Reactions |
Many decarboxylative cross coupling reactions involve the breaking of C–COOH bonds, therefore subsequent studies have attempted to enable cross coupling with </sub>C carboxylic acids. One such reaction by Shang et al. described a palladium catalyzed cross coupling that enables the formation of functionalized pyridines, pyrazines, quinolines, benzothiazoles, and benzoxazoles. The position of the nitrogen atom in the 2 position relative to the linkage is found to be required, therefore implying its binding to Pd in a transition state. | 0 | Organic Reactions |
Four crystalline forms (polymorphs) of are known: α, β, γ, and δ. Each case features tetrahedral centers.
Here a, b, and c are lattice constants, Z is the number of structure units per unit cell, and ρ is the density calculated from the structure parameters.
The orthorhombic form (δ) rapidly changes to one of the other forms on exposure to the atmosphere. A possible explanation is that the ions originating from the absorbed water facilitate the rearrangement. Rapid cooling of molten gives a glass.
Molten has a high viscosity at its melting point and a comparatively low electrical conductivity, which increases markedly with temperature. As indicated by a Raman scattering study, the viscosity is explained by the presence of polymers,. Neutron scattering study indicated the presence of tetrahedral centers, which requires aggregation of monomers as well..
In the gas phase, molecules are linear with a bond length of 205 pm. | 1 | Inorganic Reactions + Inorganic Compounds |
Boric acid, more specifically orthoboric acid, is a compound of boron, oxygen, and hydrogen with formula . It may also be called hydrogen orthoborate, trihydroxidoboron or boracic acid. It is usually encountered as colorless crystals or a white powder, that dissolves in water, and occurs in nature as the mineral sassolite. It is a weak acid that yields various borate anions and salts, and can react with alcohols to form borate esters.
Boric acid is often used as an antiseptic, insecticide, flame retardant, neutron absorber, or precursor to other boron compounds.
The term "boric acid" is also used generically for any oxoacid of boron, such as metaboric acid and tetraboric acid . | 1 | Inorganic Reactions + Inorganic Compounds |
While water acts as a catalyst in the reaction, other catalysts can be added to the reaction vessel to optimize the conversion. Previously used catalysts include water-soluble inorganic compounds and salts, including KOH and NaCO, as well as transition metal catalysts using nickel, palladium, platinum and ruthenium supported on either carbon, silica or alumina. The addition of these catalysts can lead to an oil yield increase of 20% or greater, due to the catalysts converting the protein, cellulose, and hemicellulose into oil. This ability for catalysts to convert biomaterials other than fats and oils to bio-oil allows for a wider range of feedstock to be used. | 0 | Organic Reactions |
The reaction substrate has also been extended to allenes. In this specific ring expansion the AAA reaction is also accompanied by a Wagner–Meerwein rearrangement: | 0 | Organic Reactions |
Chloropentammineplatinum chloride is the inorganic compound with the formula . It is the chloride salt of the coordination complex . It is a white, water soluble solid.
The compound is prepared by treating potassium hexachloroplatinate with aqueous ammonia: | 1 | Inorganic Reactions + Inorganic Compounds |
Halides are X-type ligands in coordination chemistry. They are both σ- and π-donors. Chloride is commonly found as both a terminal ligand and a bridging ligand. The halide ligands are weak field ligands. Due to a smaller crystal field splitting energy, the homoleptic halide complexes of the first transition series are all high spin. Only [CrCl] is exchange inert.
Homoleptic metal halide complexes are known with several stoichiometries, but the main ones are the hexahalometallates and the tetrahalometallates. The hexahalides adopt octahedral coordination geometry, whereas the tetrahalides are usually tetrahedral. Square planar tetrahalides are known for Pd(II), Pt(II), and Au(III). Examples with 2- and 3-coordination are common for Au(I), Cu(I), and Ag(I).
Due to the presence of filled p orbitals, halide ligands on transition metals are able to reinforce π-backbonding onto a π-acid. They are also known to labilize cis-ligands. | 1 | Inorganic Reactions + Inorganic Compounds |
Zinc chloride is the name of inorganic chemical compounds with the formula ZnCl·nHO, with x ranging from 0 to 4.5, forming hydrates. Zinc chloride, anhydrous and its hydrates are colorless or white crystalline solids, and are highly soluble in water. Five hydrates of zinc chloride are known, as well as four forms of anhydrous zinc chloride. This salt is hygroscopic and even deliquescent. Zinc chloride finds wide application in textile processing, metallurgical fluxes, and chemical synthesis. No mineral with this chemical composition is known aside from the very rare mineral simonkolleite, . | 1 | Inorganic Reactions + Inorganic Compounds |
The bromodomain is a motif that is responsible for acetylated lysine recognition on histones by nucleosome remodelling proteins. Posttranslational modifications of N- and C-terminal histone tails attracts various transcription initiation factors that contain bromodomains, including human transcriptional coactivator PCAF, TAF1, GCN5 and CREB-binding protein (CBP), to the promoter and have a significance in regulating gene expression. Structural analysis of transcription factors has shown that highly conserved bromodomains are essential for protein to bind to acetylated lysine. This suggests that specific histone site acetylation has a regulatory role in gene transcriptional activation. | 0 | Organic Reactions |
In aqueous solution, boric acid can act as a weak Brønsted acid, that is, a proton donor, with pK ~ 9. However, it more often acts as a Lewis acid, accepting an electron pair from a hydroxyl ion produced by the water autoprotolysis:
: + 2 + (pK = 8.98)
This reaction is very fast, with characteristic time less than 10 μs. Polymeric boron oxoanions are formed in aqueous solution of boric acid at pH 7–10 if the boron concentration is higher than about 0.025 mol/L. The best known of these is the tetraborate ion , found in the mineral borax:
Other anions observed in solution are triborate(1−) and pentaborate(1−), in equilibrium with boric acid and tetrahydroxyborate according to the following overall reactions:
: 2 + + 3 (fast, pK = —1.92)
: 4 + + 6 (slow, pK = —2.05)
In the pH range 6.8 to 8.0, any alkali salts of "boric oxide" anions with general formula where 3x+q = 2y + z will eventually equilibrate in solution to a mixture of , , , and .
These ions, similarly to the complexed borates mentioned above, are more acidic than boric acid itself. As a result of this, the pH of a concentrated polyborate solution will increase more than expected when diluted with water. | 1 | Inorganic Reactions + Inorganic Compounds |
Neutral alanes are not nucleophilic enough to deliver organic groups to electrophilic substrates. However, upon activation by a nucleophile, the resulting aluminates are highly nucleophilic and add to electrophiles with retention of configuration at the migration carbon. Thus, stereospecific hydroalumination followed by nucleophilic attack provides a method for the stereospecific synthesis of olefins from alkynes. | 0 | Organic Reactions |
Nucleophilic alkylating agents deliver the equivalent of an alkyl anion (carbanion). The formal "alkyl anion" attacks an electrophile, forming a new covalent bond between the alkyl group and the electrophile. The counterion, which is a cation such as lithium, can be removed and washed away in the work-up. Examples include the use of organometallic compounds such as Grignard (organomagnesium), organolithium, organocopper, and organosodium reagents. These compounds typically can add to an electron-deficient carbon atom such as at a carbonyl group. Nucleophilic alkylating agents can displace halide substituents on a carbon atom through the SN2 mechanism. With a catalyst, they also alkylate alkyl and aryl halides, as exemplified by Suzuki couplings.
The SN2 mechanism is not available for aryl substituents, where the trajectory to attack the carbon atom would be inside the ring. Thus, only reactions catalyzed by organometallic catalysts are possible. | 0 | Organic Reactions |
Reihlen and Flohr demonstrated that Wolffram’s salt could be prepared directly by mixing aqueous solutions of the colorless [[Pt(etn)4Cl2|[Pt(etn)]Cl]] and its yellow analogue, [Pt(etn)Cl]Cl, where etn = NHCHCH, leading to the most probable conclusion of the double salt formula, [Pt(CHNH)Cl] [Pt(CHNH)]Cl·4HO, compared with concurrently postulated explanations of tervalent platinum. | 1 | Inorganic Reactions + Inorganic Compounds |
The Baeyer–Drewsen indigo synthesis (1882) is an organic reaction in which indigo is prepared from 2-nitrobenzaldehyde and acetone The reaction was developed by von Baeyer in 1880 to produce the first synthetic indigo at laboratory scale. This procedure is not used at industrial scale.
The reaction is classified as an aldol condensation. As a practical route to indigo, this method was displaced by routes from aniline. | 0 | Organic Reactions |
Examples of hydrated minerals include:
* silicates (, )
** phyllosilicates, clay minerals "commonly found on Earth as weathering products of rocks or in hydrothermal systems"
***chlorite
*** muscovite
* non-silicates
** oxides (, , , etc.) and oxy-hydroxides
*** brucite,
*** goethite, FeO(OH)
** carbonates (, etc.)
*** hydromagnesite,
*** ikaite, , the unstable hexahydrate form of calcium carbonate
** hydroxylated minerals
*** saponite
*** talc
** hydroxysulfides (mixed sulfides-hydroxides)
*** tochilinite, a hydroxysulfide or hydrated sulfide mineral of iron(II) and magnesium of chemical formula: <br />, also written , in IMA notation
*** valleriite, an uncommon sulfide-hydroxide mineral of iron(II) and copper of chemical formula: <br />, or | 1 | Inorganic Reactions + Inorganic Compounds |
Carboxylic acids, amides, esters, and carboxylate salts convert to the trifluoromethyl derivatives, although conditions vary widely:
For carboxlic acids, the first step gives the acyl fluorides, in keeping with the tendency of SF to fluorinate acidic hydroxyl groups:
Similarly SF converts sulfonic acids to sulfonyl fluorides:
Aldehydes and ketones convert to geminal difluorides:
Alcohols convert to alkyl fluorides, although this conversion works best with acidic alcohols, such as fluorinated alcohols: | 0 | Organic Reactions |
It adopts "antifluorite structure," which means that the small K ions occupy the tetrahedral (F) sites in fluorite, and the larger S centers occupy the eight-coordinate sites. LiS, NaS, and RbS crystallize similarly. | 1 | Inorganic Reactions + Inorganic Compounds |
Many alkyl amines are produced industrially by the amination of alcohols using ammonia in the presence of solid acid catalysts. Illustrative is the production of tert-butylamine:
:NH + CH=C(CH) → HNC(CH)
The Ritter reaction of isobutene with hydrogen cyanide is not useful in this case because it produces too much waste. | 0 | Organic Reactions |
Aryl alkynes are typically made utilizing the Sonogashira reaction which is the palladium catalyzed cross-coupling reaction of terminal alkynes and aryl halides. Instead of the terminal alkynes, alkyne carboxylic acids has advantages, easy handling and storage. The first decarboxylative coupling of alkyne carboxylic acids was reported in 2008 by S. Lee. They employed propiolic acid as an alkyne source. One year later, S. Lee applied the decarboxylative coupling reactions toward 2-octynoic acid and phenylpropiolic acid. In 2010, Xue et al. reported the coupling of an aryl halide and alkynyl carboxylic acid under mild reactions conditions and a copper-only catalyst to obtain aryl alkynes. | 0 | Organic Reactions |
In biological systems, methylation is accomplished by enzymes. Methylation can modify heavy metals and can regulate gene expression, RNA processing, and protein function. It is a key process underlying epigenetics. Sources of methyl groups include S-methylmethionine, methyl folate, methyl B12. | 0 | Organic Reactions |
Azanes with more than three nitrogen atoms can be arranged in various different ways, forming structural isomers. The simplest isomer of an azane is the one in which the nitrogen atoms are arranged in a single chain with no branches. This isomer is sometimes called the n-isomer (n for "normal", although it is not necessarily the most common). However the chain of nitrogen atoms may also be branched at one or more points. The number of possible isomers increases rapidly with the number of nitrogen atoms.
Due to the low energy of inversion, unsubstituted branched azanes cannot be chiral. In addition to these isomers, the chain of nitrogen atoms may form one or more loops. Such compounds are called cycloazanes. | 1 | Inorganic Reactions + Inorganic Compounds |
Various hydrates of zinc chloride are known: with n = 1, 1.33, 2.5, 3, and 4.5. However, only the 1.33-hydrate, hemipentahydrate, trihydrate, and the heminonahydrate has been structurally elucidated.
The 1.33-hydrate, previously thought to be the hemitrihydrate, consists of trans-Zn(HO)Cl centers with the chlorine atoms connected to repeating ZnCl chains. The hemipentahydrate, structurally formulated [Zn(HO)][ZnCl], consists of Zn(HO)Cl octahedrons where the chlorine atom is part of a [ZnCl] tetrahedera. The trihydrate consists of distinct hexaaquozinc(II) cations and tetrachlorozincate anions; formulated [Zn(HO)][ZnCl]. Finally, the heminonahydrate, structurally formulated [Zn(HO)][ZnCl]·3HO also consists of distinct hexaaquozinc(II) cations and tetrachlorozincate anions like the trihydrate but has three extra water molecules. | 1 | Inorganic Reactions + Inorganic Compounds |
In 1937, Hans Adolf Krebs, who discovered the citric acid cycle bearing his name, confirmed the anaerobic dismutation of pyruvic acid into lactic acid, acetic acid and CO by certain bacteria according to the global reaction:
The dismutation of pyruvic acid in other small organic molecules (ethanol + CO, or lactate and acetate, depending on the environmental conditions) is also an important step in fermentation reactions. Fermentation reactions can also be considered as disproportionation or dismutation biochemical reactions. Indeed, the donor and acceptor of electrons in the redox reactions supplying the chemical energy in these complex biochemical systems are the same organic molecules simultaneously acting as reductant or oxidant.
Another example of biochemical dismutation reaction is the disproportionation of acetaldehyde into ethanol and acetic acid.
While in respiration electrons are transferred from substrate (electron donor) to an electron acceptor, in fermentation part of the substrate molecule itself accepts the electrons. Fermentation is therefore a type of disproportionation, and does not involve an overall change in oxidation state of the substrate. Most of the fermentative substrates are organic molecules. However, a rare type of fermentation may also involve the disproportionation of inorganic sulfur compounds in certain sulfate-reducing bacteria. | 0 | Organic Reactions |
Perhaps the single most important reaction of enolate ions is their alkylation by treatment with an alkyl halide or tosylate, thereby forming a new C-C bond and joining two smaller pieces into one larger molecule. Alkylation occurs when the nucleophilic enolate ion reacts with the electrophilic alkyl halide in an SN reaction and displaces the leaving group by backside attack.
Alkylation reactions are subject to the same constraints that affect all SN reactions. Thus, the leaving group X in the alkylating agent R-X can be chloride, bromide, iodide, or tosylate . Tile alkyl group R should be primary or methyl, and preferably should be allylic or benzylic. Secondary halides react poorly, and tertiary halides don't react at all because a competing E2 elimination of HX occurs instead. Vinylic and aryl halides are also unreactive because backside approach is sterically prevented. | 0 | Organic Reactions |
Chiral oxocarbenium ions have been exploited to carry out highly diastereoselective and enantioselective acetate aldol
addition reactions. The oxocarbenium ion is used as an electrophile in the reaction. When the methyl group increases in size, the diastereoselevtivity increases. | 0 | Organic Reactions |
Electrophilic alkylation uses Lewis acids and Brønsted acids, sometimes both. Classically, Lewis acids, e.g., aluminium trichloride, are employed when the alkyl halide are used. Brønsted acids are used when alkylating with olefins. Typical catalysts are zeolites, i.e. solid acid catalysts, and sulfuric acid. Silicotungstic acid is used to manufacture ethyl acetate by the alkylation of acetic acid by ethylene: | 0 | Organic Reactions |
Preconcentrated waste acid from the preconcentrator (III / IV) is injected into the reactor (I) by means of one or more spray booms (VIII) bearing one or more injection nozzles each. Injection takes place at reactor top at a pressure between 4 and 10 bar. The reactor is directly fired by tangentially mounted burners that create a hot swirl. Temperatures inside the reactor vary between 700 °C (burner level) and 370 °C (roast gas exit duct).
In the reactor the conversion of droplets of preconcentrated waste acid into iron oxide powder and hydrogen chloride gas takes place. Hydrogen Chloride leaves the reactor through the top, while iron oxide powder is removed from the reactor bottom by means of mechanical extraction devices. A cyclone (II) in the roast gas duct ensures separation and feed back of larger oxide particles carried by the roast gas. | 1 | Inorganic Reactions + Inorganic Compounds |
Generally this topic is discussed when covering mass spectrometry and occurs generally by the same mechanisms.
To neutralize the positive charge on the ionization site a single two-electron transfer must be made. Neutralization of the positive charge at the ionization site is performed at the expense of the atom adjacent to the ionization site, transferring the positive charge to this atom as a result of the bond cleavage. | 0 | Organic Reactions |
Pyridines are highly variable substrates for asymmetric reduction (even compared to other heteroaromatics), in that five carbon centers are available for differential substitution on the initial ring. As of October 2012 no method seems to exist that can control all five, although at least one reasonably general method exists.
The most-general method of asymmetric pyridine hydrogenation is actually a heterogeneous method, where asymmetry is generated from a chiral oxazolidinone bound to the C2 position of the pyridine. Hydrogenating such functionalized pyridines over a number of different heterogeneous metal catalysts gave the corresponding piperidine with the substituents at C3, C4, and C5 positions in an all-cis geometry, in high yield and excellent enantioselectivity. The oxazolidinone auxiliary is also conveniently cleaved under the hydrogenation conditions.
<br />
Methods designed specifically for 2-substituted pyridine hydrogenation can involve asymmetric systems developed for related substrates like 2-substituted quinolines and quinoxalines. For example, an iridium(I)\chiral phosphine\I system is effective in the asymmetric hydrogenation of activated (alkylated) 2-pyridiniums or certain cyclohexanone-fused pyridines. Similarly, chiral Brønsted acid catalysis with a Hantzsh ester as a hydride source is effective for some 2-alkyl pyridines with additional activating substitution. | 0 | Organic Reactions |
The nitrogen centres of hexachlorophosphazene are weakly basic, and this Lewis base behaviour has been suggested to play a role in the polymerisation mechanism. Specifically, hexachlorophosphazene has been reported to form adducts of various stoichiometries with Lewis acids Aluminium chloride|, Aluminium bromide|, Gallium trichloride|, Sulfur trioxide|, Tantalum(V) chloride|, Vanadium oxytrichloride|, but no isolable product with Boron trichloride|.
Among these, the best structurally characterised are the 1:1 adducts with aluminium trichloride or with gallium trichloride; they are found with the Al/Ga atom bound to a N and assume a more prominently distorted chair conformation compared to the free hexachlorophosphazene. The adducts also exhibit fluxional behaviour in solution for temperatures down to −60 °C, which can be monitored with N and P-NMR. | 1 | Inorganic Reactions + Inorganic Compounds |
* Invisible ink: when suspended in solution, cobalt(II) chloride can be made to appear invisible on a surface; when that same surface is subsequently exposed to significant heat (such as from a handheld heat gun or lighter) the ink reversibly changes to blue.
* Cobalt chloride is an established chemical inducer of hypoxia-like responses such as erythropoiesis. Cobalt supplementation is not banned and therefore would not be detected by current anti-doping testing. Cobalt chloride is a banned substance under the Australian Thoroughbred Racing Board.
* Cobalt chloride is one method used to induce pulmonary arterial hypertension in animals for research and evaluation of treatment efficacy. | 1 | Inorganic Reactions + Inorganic Compounds |
Sodium hydroxide is a popular strong base used in industry. Sodium hydroxide is used in the manufacture of sodium salts and detergents, pH regulation, and organic synthesis. In bulk, it is most often handled as an aqueous solution, since solutions are cheaper and easier to handle.
Sodium hydroxide is used in many scenarios where it is desirable to increase the alkalinity of a mixture, or to neutralize acids. For example, in the petroleum industry, sodium hydroxide is used as an additive in drilling mud to increase alkalinity in bentonite mud systems, to increase the mud viscosity, and to neutralize any acid gas (such as hydrogen sulfide and carbon dioxide) which may be encountered in the geological formation as drilling progresses. Another use is in salt spray testing where pH needs to be regulated. Sodium hydroxide is used with hydrochloric acid to balance pH. The resultant salt, NaCl, is the corrosive agent used in the standard neutral pH salt spray test.
Poor quality crude oil can be treated with sodium hydroxide to remove sulfurous impurities in a process known as caustic washing. Sodium hydroxide reacts with weak acids such as hydrogen sulfide and mercaptans to yield non-volatile sodium salts, which can be removed. The waste which is formed is toxic and difficult to deal with, and the process is banned in many countries because of this. In 2006, Trafigura used the process and then dumped the waste in Ivory Coast.
Other common uses of sodium hydroxide include:
* for making soaps and detergents. Sodium hydroxide is used for hard bar soap, while potassium hydroxide is used for liquid soaps. Sodium hydroxide is used more often than potassium hydroxide because it is cheaper and a smaller quantity is needed.
* as drain cleaners that convert pipe-clogging fats and grease into soap, which dissolves in water
* for making artificial textile fibres such as rayon
* in the manufacture of paper. Around 56% of sodium hydroxide produced is used by industry, 25% of which is used in the paper industry.
* in purifying bauxite ore from which aluminium metal is extracted. This is known as the Bayer process.
* de-greasing metals
* oil refining
* making dyes and bleaches
* in water treatment plants for pH regulation
* to treat bagels and pretzel dough, giving the distinctive shiny finish | 1 | Inorganic Reactions + Inorganic Compounds |
Molten anhydrous at 500–700 °C dissolves zinc metal, and, on rapid cooling of the melt, a yellow diamagnetic glass is formed, which Raman studies indicate contains the ion. | 1 | Inorganic Reactions + Inorganic Compounds |
The NS radical was detected by LIF spectrum as the product of photolysis of tetranitrogen tetrasulfide (NS) gas by a 248 nm laser. | 1 | Inorganic Reactions + Inorganic Compounds |
Sodium hydroxide also reacts with acidic oxides, such as sulfur dioxide. Such reactions are often used to "scrub" harmful acidic gases (like and ) produced in the burning of coal and thus prevent their release into the atmosphere. For example, | 1 | Inorganic Reactions + Inorganic Compounds |
As a ligand, NS acts as a σ-donor and π-acceptor, forming metal-thionitrosyl complexes. Transition-metal thionitrosyl complexes have been prepared by the following procedures:
* Sulfur transfer to metal nitrido complexes
** Example: Reflux of (PhP)[OsNCl] and (PhP)NCS yields green-brown solid [PhP][Os(NS)(NCS)]
* Reaction of trithiazyltrichloride with transition metal complexes
** NSCl + OsCl > [Os(NS)Cl]
* Halide abstraction from coordinated thiazyl complexes
** Abstraction of sulfur-bonded fluorine from [(ηCH)Cr(NO)(NSF)]-[AsF] by AsF > [(η-CH)Cr(NO)(NS)]-[AsF]
* Reaction of NS salts with transition metal complexes
** NSSbF + [M(CO)Br] > [M(CO)(NS)], M=Mn, Re
** NSAsF + [(η-CH)Fe(CO)(SO)] > [(η-CH)Fe(CO)(NS)] [AsF]
* Reaction of tetrasulfur tetranitride with metal halides or nitrides
From X-ray crystallography of many of such metal-thionitrosyl complexes, one can observe that the M-N-S bond angle is nearly linear, suggesting sp hybridization about N. Short M-N distances and long N-S distances reflect the resonance structure of M=N=S having greater contribution than M-N≡S.
Typical v(NS) IR stretching frequencies are approximately 1065 cm for low-valent transition metal complexes and around 1390 cm in the high valent cases, whereas the free gas-phase radical exhibits a 1204 cm signal. | 1 | Inorganic Reactions + Inorganic Compounds |
Substrates can be classified according to their polarity. Nonpolar substrates are dominated by alkenes. Polar substrates include ketones, enamines ketimines. | 0 | Organic Reactions |
Praseodymium(III) nitride is a binary inorganic compound of praseodymium and nitrogen. Its chemical formula is . The compound forms black crystals, and reacts with water. | 1 | Inorganic Reactions + Inorganic Compounds |
The majority of benzylic functionalization reactions of tricarbonyl(arene)chromium complexes proceed by mechanisms analogous to those followed by the free arenes. The aromatic ring and benzylic position are activated towards solvolysis, deprotonation, and nucleophilic attack (at the ortho and para positions of the arene) upon complexation to chromium, which is able to stabilize developing charges in the arene ligand. As a result, these reactions of chromium arene complexes are often faster than analogous reactions of free arenes.
Second, in benzylic cations and anions of chromium arene complexes, rotation about the bond connecting the benzylic carbon and aromatic ring is severely restricted. This bond possesses a significant amount of double bond character due to the delocalization of charge into the aromatic ring (and the stabilization of that charge by chromium).
Finally, the chromium tri(carbonyl) moiety serves as a sterically bulky group in reactions of arene chromium complexes, preventing the approach of a reagent endo to chromium. In addition, ortho-substituted aromatic aldehydes and styrenes prefer to adopt a conformation in which the doubly bound oxygen or carbon is pointed away from the ortho substituent. As a result, only one face of the double bond is exposed on the exo face of the aromatic ring. If this were not the case, addition to styrenes and aromatic aldehydes would not be diastereoselective, despite the presence of the chromium tri(carbonyl) group. The ortho substituent is necessary for high stereoselectivity; meta-substituted arenes exhibit very low diastereoselectivity. | 0 | Organic Reactions |
They are also utilized in military electronics such as active electronically scanned array radars.
Thales Group introduced the Ground Master 400 radar in 2010 utilizing GaN technology. In 2021 Thales put in operation more than 50,000 GaN Transmitters on radar systems.
The U.S. Army funded Lockheed Martin to incorporate GaN active-device technology into the AN/TPQ-53 radar system to replace two medium-range radar systems, the AN/TPQ-36 and the AN/TPQ-37. The AN/TPQ-53 radar system was designed to detect, classify, track, and locate enemy indirect fire systems, as well as unmanned aerial systems. The AN/TPQ-53 radar system provided enhanced performance, greater mobility, increased reliability and supportability, lower life-cycle cost, and reduced crew size compared to the AN/TPQ-36 and the AN/TPQ-37 systems.
Lockheed Martin fielded other tactical operational radars with GaN technology in 2018, including TPS-77 Multi Role Radar System deployed to Latvia and Romania. In 2019, Lockheed Martin's partner ELTA Systems Limited, developed a GaN-based ELM-2084 Multi Mission Radar that was able to detect and track air craft and ballistic targets, while providing fire control guidance for missile interception or air defense artillery.
On April 8, 2020, Saab flight tested its new GaN designed AESA X-band radar in a JAS-39 Gripen fighter. Saab already offers products with GaN based radars, like the Giraffe radar, Erieye, GlobalEye, and Arexis EW. Saab also delivers major subsystems, assemblies and software for the AN/TPS-80 (G/ATOR) | 1 | Inorganic Reactions + Inorganic Compounds |
The aza-Payne rearrangement may be effected in either the "forward" (epoxide to aziridine) or "reverse" (aziridine to epoxide) direction depending on the conditions employed. Electron-poor aziridines undergo the reverse rearrangement in the presence of hydride base, while the corresponding epoxy amines undergo the forward rearrangement in the presence of boron trifluoride etherate.
The thia-Payne rearrangement has only been observed in the forward direction (epoxide to thiiranium) with in situ opening of the thiiranium. Invertive nucleophilic opening at C-2 is possible through the use of trialkylaluminum reagents. | 0 | Organic Reactions |
A dyotropic reaction (from the Greek dyo, meaning two) in organic chemistry is a type of organic reaction and more specifically a pericyclic valence isomerization in which two sigma bonds simultaneously migrate intramolecularly. The reaction type is of some relevance to organic chemistry because it can explain how certain reactions occur and because it is a synthetic tool in the synthesis of organic molecules for example in total synthesis. It was first described by Manfred T. Reetz in 1971
In a type I reaction two migrating groups interchange their relative positions and a type II reaction involves migration to new bonding sites without positional interchange. | 0 | Organic Reactions |
In asymmetric trifluoromethylation the trifluoromethyl group is added to the substrate in an enantioselective way. Ruppert's reagent has been used for this purpose in an asymmetric induction approach to functionalise chiral amino acid derivates, saccharides, and steroids.
Because Ruppert's reagent requires a tetraalkylammonium fluoride, chiral ammonium fluorides have been employed in asymmetric catalysis.
In the field of electrophilic trifluoromethylation an early contribution involved reaction of a metal enolate with a trifluoromethyl chalcogen salt in presence of a chiral boron catalyst.
More recent examples of highly enantioselective methods for the α-trifluoromethylation of carbonyls are available through enamine catalysis of aldehydes (photoredox or iodonium), copper catalysis of β-ketoesters, and radical addition to zirconium enolates. | 0 | Organic Reactions |
The armed/disarmed approach to glycosylation is an effective way to prevent sugar molecules from self-glycosylation when synthesizing disaccharides. This approach was first recognized when acetylated sugars only acted as glycosyl acceptors when reacted with benzylated sugars. The acetylated sugars were termed “disarmed” while the benzylated sugars were termed “armed”. | 0 | Organic Reactions |
CdS is used as pigment in plastics, showing good thermal stability, light and weather fastness, chemical resistance and high opacity. As a pigment, CdS is known as cadmium yellow (CI pigment yellow 37). About 2000 tons are produced annually as of 1982, representing about 25% of the cadmium processed commercially. | 1 | Inorganic Reactions + Inorganic Compounds |
Phenyl isothiocyanate is reacted with an uncharged N-terminal amino group, under mildly alkaline conditions, to form a cyclical phenylthiocarbamoyl derivative. Then, under acidic conditions, this derivative of the terminal amino acid is cleaved as a thiazolinone derivative. The thiazolinone amino acid is then selectively extracted into an organic solvent and treated with acid to form the more stable phenylthiohydantoin (PTH)- amino acid derivative that can be identified by using chromatography or electrophoresis. This procedure can then be repeated again to identify the next amino acid. A major drawback to this technique is that the peptides being sequenced in this manner cannot have more than 50 to 60 residues (and in practice, under 30). The peptide length is limited due to the cyclical derivatization not always going to completion. The derivatization problem can be resolved by cleaving large peptides into smaller peptides before proceeding with the reaction. It is able to accurately sequence up to 30 amino acids with modern machines capable of over 99% efficiency per amino acid. An advantage of the Edman degradation is that it only uses 10 - 100 pico-moles of peptide for the sequencing process. The Edman degradation reaction was automated in 1967 by Edman and Beggs to speed up the process and 100 automated devices were in use worldwide by 1973. | 0 | Organic Reactions |
The outcomes of manganese-mediated coupling reactions depend on both the structure of the substrate(s) and the reaction conditions. This section describes the scope and limitations of inter- and intramolecular manganese-mediated radical coupling reactions and is organized according to the carbonyl compound employed as the substrate.
Intermolecular reactions between ketones/aldehydes and alkenes tend to result in low yields. In the absence of copper(II) acetate, hydrogen atom abstraction occurs, yielding saturated ketones or aldehydes.
When Cu(OAc) is present, further oxidation to carbocations followed by elimination takes place, leading to the formation of β,γ-unsaturated carbonyl compounds in moderate yields.
Aromatic compounds are also useful radical acceptors in manganese(III)-mediated coupling reactions. Furan reacts selectively at the α position to afford substituted products in high yield.
Lactonization of alkenes in the presence of acetic acid and acetate salts is a synthetically useful method for the synthesis of γ-lactones. Selectivity is high for the radical addition that leads to the more stable adduct radical, and trans lactones are selectively formed from either cis or trans acyclic alkenes.
β-Dicarbonyl compounds are useful substrates for the formation of dihydrofurans. Copper(II) acetate is not necessary in this case because of the high resonance stabilization of the intermediate diphenylmethyl radical.
When alkenes or carbonyl compounds containing pendant unsaturated moiety are treated with manganese(III) acetate, tandem intramolecular cyclization reactions may occur. Generally, exo cyclization of terminal double bonds is favored, as shown in equation (10). A variety of substitution patterns may be employed for this transformation, and yields are generally higher than intermolecular coupling reactions.
The stereochemical course of tandem reactions can be understood in some cases by invoking a chairlike transition state with as many substituents as possible in pseudoequatorial positions; however, a number of examples exhibiting unpredictable stereochemistry are known.
Nitriles are useful as radical acceptors in tandem cyclizations. Hydrolysis of the resulting imine leads to polycyclic ketones in moderate yields with good stereoselectivity. | 0 | Organic Reactions |
Reaction of diplutonium triselenide and plutonium trihydride:
Fusion of stoichiometric amounts of pure substances: | 1 | Inorganic Reactions + Inorganic Compounds |
Methods for the stereoselective synthesis of cyclopropanes from diazocarbonyl compounds and olefins have relied on either the use of pre-formed chiral rhodium catalysts or chiral auxiliaries on the diazocarbonyl compound. For example, Rh[S-DOSP] is a highly effective catalyst for the enantioselective cyclopropanation of alkenes.
Chiral auxiliaries derived from readily available chiral alcohols (such as pantolactone) may be used for diastereoselective cyclopropanations with diazo esters. | 0 | Organic Reactions |
Synthetic zeolites have complex structures and examples (with structural formulae) are:
* NaAlSiO·27HO, zeolite A (Linde type A sodium form, NaA), used in laundry detergents
* NaAlSiO·16HO, Analcime, IUPAC code ANA
* NaAlSiO·q HO, Losod
* NaAlSiO·518HO, Linde type N | 1 | Inorganic Reactions + Inorganic Compounds |
Manganese-mediated couplings have been used for the synthesis of hydrocarbon natural products, such as pheromones. A synthesis of queen bee pheromone uses the intermolecular coupling of acetone and an ω-alkenyl acetate en route to the target.
Lactonization is a key step in the synthesis of tomato pinworm sex pheromone. Subsequent Lindlar hydrogenation, reduction and acetylation provided the target compound. | 0 | Organic Reactions |
After the deprotonation, the hydrazone turns into an azaenolate with lithium cation chelating both the nitrogen and oxygen. There are two possible options for lithium chelation. One is that lithium is antiperiplanar to the C=C bond (blue colored), leading to the conformation of Z; the other one is that lithium and the C=C bond are at the same side of the C-N bond (red colored), leading to the E conformer. There are also two available orientations for the chelating nitrogen and R group, being either E or Z. This leads to four possible azaenolate intermediates (A, B, C and D) for the Enders' SAMP/RAMP hydrazone alkylation reaction.
Experiments and calculations show that one specific stereoisomer of the azaenolate is favored over the other three possible candidates. Therefore, although four isomers are possible for the azaenolate, only the one (azaenolate A) with the stereochemistry of its C=C double bonds being E and that of its C-N bond being Z stereochemistry is dominant (EZ) for both cyclic and acyclic ketones. | 0 | Organic Reactions |
The structures of acceptors play a critical role in the rate and stereoselectivity of glycosylations. Generally, the unprotected hydroxyl groups are less reactive when they are between bulky protecting groups. That is the reason why the hydroxyl group at OH-4 in pyranosides is unreactive. Hyperconjugation is involved when OH-4 is anti-periplanar to the ring oxygen, which can also reduce its reactivity. (Scheme 3) Furthermore, acyl protecting groups can reduce the reactivity of the acceptors compared with alkyl protecting groups because of their electron-withdrawing ability. Hydroxyl group at OH-4 of N-acetylglucosamine derivatives is particularly unreactive.
The glycosidic bond is formed from a glycosyl donor and a glycosyl acceptor. There are four types of glycosidic linkages: 1, 2-trans-α, 1, 2-trans-beta, 1, 2-cis-α, and 1, 2-cis-beta linkages. 1, 2-trans glycosidic linkages can be easily achieved by using 2-O-acylated glycosyl donors (neighboring group participation). To prevent the accumulation of the orthoester intermediates, the glycosylation condition should be slightly acidic. | 0 | Organic Reactions |
Epigenetic modifications of histone tails in specific regions of the brain are of central importance in addictions, and much of the work on addiction has focused on histone acetylation. Once particular epigenetic alterations occur, they appear to be long lasting "molecular scars" that may account for the persistence of addictions.
Cigarette smokers (about 21% of the US population) are usually addicted to nicotine. After 7 days of nicotine treatment of mice, acetylation of both histone H3 and histone H4 was increased at the FosB promoter in the nucleus accumbens of the brain, causing 61% increase in FosB expression. This would also increase expression of the splice variant Delta FosB. In the nucleus accumbens of the brain, Delta FosB functions as a "sustained molecular switch" and "master control protein" in the development of an addiction.
About 7% of the US population is addicted to alcohol. In rats exposed to alcohol for up to 5 days, there was an increase in histone 3 lysine 9 acetylation in the pronociceptin promoter in the brain amygdala complex. This acetylation is an activating mark for pronociceptin. The nociceptin/nociceptin opioid receptor system is involved in the reinforcing or conditioning effects of alcohol.
Cocaine addiction occurs in about 0.5% of the US population. Repeated cocaine administration in mice induces hyperacetylation of histone 3 (H3) or histone 4 (H4) at 1,696 genes in one brain "reward" region [the nucleus accumbens (NAc)] and deacetylation at 206 genes. At least 45 genes, shown in previous studies to be upregulated in the NAc of mice after chronic cocaine exposure, were found to be associated with hyperacetylation of H3 or H4. Many of these individual genes are directly related to aspects of addiction associated with cocaine exposure.
In rodent models, many agents causing addiction, including tobacco smoke products, alcohol, cocaine, heroin and methamphetamine, cause DNA damage in the brain. During repair of DNA damages some individual repair events may alter the acetylations of histones at the sites of damage, or cause other epigenetic alterations, and thus leave an epigenetic scar on chromatin. Such epigenetic scars likely contribute to the persistent epigenetic changes found in addictions.
In 2013, 22.7 million persons aged 12 or older needed treatment for an illicit drug or alcohol use problem (8.6 percent of persons aged 12 or older). | 0 | Organic Reactions |
The compound crystallizes in the monoclinic system, cell parameters a = 3.400 Å, b = 5.156 Å, c = 9.055 Å, β = 95.60°, Z = 4.
Lithium oxalate decomposes when heated at : | 1 | Inorganic Reactions + Inorganic Compounds |
When a spin-trapping agent, such as Fe(SCNEt) is present during the photolysis of Cr(CHCN)(NS), new S=1/2 EPR bands are observed, attributed to the formation of Fe(SCNEt)(NS), and the signal from Cr(CHCN)(NS) disappears. This suggests that the NS radical has transferred from the chromium complex to the iron complex.
This was particularly significant as it was the first controlled and well-characterized reactivity of NS in solution. Further, it showed the potential for similar reactivity in known reactions with NO, such as use of this iron dithiocarbamate complex. | 1 | Inorganic Reactions + Inorganic Compounds |
[Ni(NH)], like all octahedral nickel(II) complexes, is paramagnetic with two unpaired electrons localized on each Ni center. [Ni(NH)]Cl is prepared by treating aqueous nickel(II) chloride with ammonia. It is useful as a molecular source of anhydrous nickel(II). | 1 | Inorganic Reactions + Inorganic Compounds |
Hydroacylation as an asymmetric reaction was demonstrated in the form of a kinetic resolution. A true asymmetric synthesis was also described. Both conversions employed rhodium catalysts and a chiral diphosphine ligand. In one application the ligand is Me-DuPhos: | 0 | Organic Reactions |
Metal halides are compounds between metals and halogens. Some, such as sodium chloride are ionic, while others are covalently bonded. A few metal halides are discrete molecules, such as uranium hexafluoride, but most adopt polymeric structures, such as palladium chloride. | 1 | Inorganic Reactions + Inorganic Compounds |
Vanadium(III) bromide and molybdenum(IV) bromide were prepared by treatment of the higher chlorides with HBr. These reactions proceed via redox reactions: | 1 | Inorganic Reactions + Inorganic Compounds |
Boric acid in equilibrium with its conjugate base the borate ion is widely used (in the concentration range 50–100 ppm boron equivalents) as a primary or adjunct pH buffer system in swimming pools. Boric acid is a weak acid, with pK (the pH at which buffering is strongest because the free acid and borate ion are in equal concentrations) of 9.24 in pure water at 25 °C. But apparent pK is substantially lower in swimming pool or ocean waters because of interactions with various other molecules in solution. It will be around 9.0 in a salt-water pool. No matter which form of soluble boron is added, within the acceptable range of pH and boron concentration for swimming pools, boric acid is the predominant form in aqueous solution, as shown in the accompanying figure. The boric acid – borate system can be useful as a primary buffer system (substituting for the bicarbonate system with pK = 6.0 and pK = 9.4 under typical salt-water pool conditions) in pools with salt-water chlorine generators that tend to show upward drift in pH from a working range of pH 7.5–8.2. Buffer capacity is greater against rising pH (towards the pKa around 9.0), as illustrated in the accompanying graph. The use of boric acid in this concentration range does not allow any reduction in free HOCl concentration needed for pool sanitation, but it may add marginally to the photo-protective effects of cyanuric acid and confer other benefits through anti-corrosive activity or perceived water softness, depending on overall pool solute composition. | 1 | Inorganic Reactions + Inorganic Compounds |
The agriculture industry uses 1 million pounds per year as a fertilizer. In particular, its use has been suggested for treatment of whiptail in broccoli and cauliflower in molybdenum-deficient soils. However, care must be taken because at a level of 0.3 ppm sodium molybdate can cause copper deficiencies in animals, particularly cattle.
It is used in industry for corrosion inhibition, as it is a non-oxidizing anodic inhibitor. The addition of sodium molybdate significantly reduces the nitrite requirement of fluids inhibited with nitrite-amine, and improves the corrosion protection of carboxylate salt fluids. In industrial water treatment applications where galvanic corrosion is a potential due to bimetallic construction, the application of sodium molybdate is preferred over sodium nitrite. Sodium molybdate has the advantage in that the dosing of lower ppm's of molybdate allow for lower conductivity of the circulating water. Sodium molybdate at levels of 50-100 ppm offer the same levels of corrosion inhibition as sodium nitrite at levels of 800+ ppm. By utilizing lower concentrations of sodium molybdate, conductivity is kept at a minimum and thus galvanic corrosion potentials are decreased. | 1 | Inorganic Reactions + Inorganic Compounds |
Hexaamminecobalt(III) chloride is the chemical compound with the formula [Co(NH)]Cl. It is the chloride salt of the coordination complex [Co(NH)], which is considered an archetypal "Werner complex", named after the pioneer of coordination chemistry, Alfred Werner. The cation itself is a metal ammine complex with six ammonia ligands attached to the cobalt(III) ion. | 1 | Inorganic Reactions + Inorganic Compounds |
The Riemschneider thiocarbamate synthesis for aromatic compounds does not work efficiently for ortho-substituted compounds such as ortho-carboxy, ortho-methoxy or ortho-nitro derivative compounds. The reaction is also not as efficient for compounds that are sensitive to concentrated acid, such as thiocyanophenols. The reaction works well for other compounds. Various thiocyanate compounds underwent the Riemschneider synthesis to form thiocarbamates, and all had melting points similar to the predicted value. | 0 | Organic Reactions |
A benzene solution of 1 eq of diethylaluminum chloride was added dropwise at 0° to a solution of 1 eq of lithium 2,2,6,6-tetramethylpiperidide prepared in the usual fashion in benzene. The resulting slurry was stirred for 30 minutes and used immediately.
To a stirred mixture of 0.004 mol of diethylaluminum 2,2,6,6-tetramethylpiperidide in 10 mL of benzene at 0 °C was added dropwise over 5 minutes a solution of 0.18 g (0.001 mol) of epoxide in 3 mL of benzene. The mixture was stirred at 0 °C until analysis indicated the absence of starting material. The reaction was quenched by the addition of ice-cold 1 N hydrochloric acid. The organic layer was separated, and the aqueous layer was extracted with ether. The organic layers were combined, washed with brine, dried, and concentrated. The residue was purified by preparative TLC (R 0.22 in 1:2 ether–hexane) to give 99% of (E)-2-cyclododecenol: IR (neat) 3330–3370, 1465, 1450, 970 cm; NMR (CCl) δ 3.73–4.20 (1, m), 4.97–5.82 (2, m); mass spectrum (m/z) 182 (16), 164 (13), 139 (32), 125 (46), and 98 (100). | 0 | Organic Reactions |
Oxychlorination is employed in the conversion of ethylene into vinyl chloride. In the first step in this process, ethylene undergoes oxychlorination to give ethylene chloride:
:CH=CH + 2 HCl + ½ O → ClCHCHCl + HO
Oxychlorination is of special importance in the making of 1,2-dichloroethane, which is then converted into vinyl chloride. As can be seen in the following reaction, 1,2-dichloroethane is cracked:
:ClCHCHCl → CH=CHCl + HCl
The HCl from this cracking process is recycled by oxychlorination in order to reduce the consumption of raw material HCl (or Cl, if direct chlorination of ethylene is chosen as main way to produce 1,2-dichloroethane).
Iron(III) chloride is produced commercially by oxychlorination (and other methods). For example, dissolution of iron ores in hydrochloric acid gives a mixture of ferrous and ferric chlorides:
The iron(II) chloride is converted to the iron(III) derivative by treatment with oxygen and hydrochloric acid: | 0 | Organic Reactions |
Neutralizing a solution containing an salt such as indium nitrate () or a solution of indium trichloride () gives a white precipitate that on aging forms indium(III) hydroxide. A thermal decomposition of freshly prepared shows the first step is the conversion of to cubic indium(III) hydroxide. The precipitation of indium hydroxide was a step in the separation of indium from zincblende ore by Reich and Richter, the discoverers of indium.
Indium(III) hydroxide is amphoteric, like gallium(III) hydroxide () and aluminium hydroxide (), but is much less acidic than gallium hydroxide (), having a lower solubility in alkaline solutions than in acid solutions. It is for all intents and purposes a basic hydroxide.
Dissolving indium(III) hydroxide in strong alkali gives solutions that probably contain either four coordinate or .
Reaction with acetic acid or carboxylic acids is likely to give the basic acetate or carboxylate salt, e.g. .
At 10 MPa pressure and 250-400 °C, indium(III) hydroxide converts to indium oxide hydroxide (InO(OH)), which has a distorted rutile structure.
Rapid decompression of samples of indium(III) hydroxide compressed at 34 GPa causes decomposition, yielding some indium metal.
Laser ablation of indium(III) hydroxide gives indium(I) hydroxide (InOH), a bent molecule with an In-O-H angle of around 132° and an In-O bond length of 201.7 pm. | 1 | Inorganic Reactions + Inorganic Compounds |
AGEs are responsible for many things. These molecules play an important role especially in nutrition, they are responsible for the brownish color and the aromas and flavors of some foods. It is demonstrated that cooking at high temperature results in various food products having high levels of AGEs.
Having elevated levels of AGEs in the body has a direct impact on the development of many diseases. It has a direct implication in diabetes mellitus type 2 that can lead to many complications such as: cataracts, renal failure, heart damage... And, if they are present at a decreased level, skin elasticity is reduced which is an important symptom of aging.
They are also the precursors of many hormones and regulate and modify their receptor mechanisms at the DNA level. | 0 | Organic Reactions |
Donovan's solution is an inorganic compound prepared from arsenic triiodide and mercuric iodide. Despite its name, it is a compound and not a solution.
__TOC__ | 1 | Inorganic Reactions + Inorganic Compounds |
The following processes for the regeneration of HCl from spent pickle liquors have been adopted by the ferrous metals processing industry: | 1 | Inorganic Reactions + Inorganic Compounds |
Sodium hexanitritocobaltate(III) is inorganic compound with the formula . The anion of this yellow-coloured salt consists of the transition metal nitrite complex . It was a reagent for the qualitative test for potassium and ammonium ions. | 1 | Inorganic Reactions + Inorganic Compounds |
Unsaturated esters may be epoxidized using either electrophilic or nucleophilic methods. Lanthanide-mediated epoxidation has been successfully applied to cinnamates and β-heteroaryl unsaturated esters. Amides are also epoxidized under lanthanide-mediated conditions.
Epoxidations of other electron-deficient double bonds (substituted by electron-withdrawing groups other than carbonyls) are limited in scope, although a few examples have been reported. The ability of the carbonyl group to coordinate Lewis acidic functionality is critical for most existing methods. | 0 | Organic Reactions |
Under basic, protic conditions, 2,3-epoxy alcohols undergo a rearrangement in which the alcohol oxygen opens the epoxide with inversion of configuration, forming an isomeric 1,2-epoxy alcohol. Overall, the Payne rearrangement represents a migration of the epoxide. Although the migration itself is fully reversible, nucleophilic opening under Curtin–Hammett conditions provides good yields of functionalized diols derived from a single epoxy alcohol isomer. Intramolecular electrophilic trapping of the new alkoxide generated upon rearrangement may also be used to drive the reaction to completion. In some cases, the thermodynamic difference between epoxide isomers is large enough to obtain a single isomer in synthetically useful yield without relying on kinetic differences associated with trapping.
Strongly basic conditions are required to induce equilibration, which limits the synthetic utility of the transformation to substrates lacking base-labile functionality. Many epoxy alcohol equilibria are very finely balanced; however, taking advantage of the trapping strategies described above may lead to high yields of single isomers. | 0 | Organic Reactions |
Ferrous oxalate (iron(II) oxalate) are inorganic compound with the formula FeCO(HO) where x is 0 or 2. These are orange compounds, poorly soluble in water. | 1 | Inorganic Reactions + Inorganic Compounds |
A nitrogen bound to both a good electrofuge and a good nucleofuge is known as a nitrenoid (for its resemblance to a nitrene). Nitrenes lack a full octet of electrons are thus highly electrophilic; nitrenoids exhibit analogous behavior and are often good substrates for electrophilic amination reactions. Nitrenoids can be generated from O-alkylhydroxylamines containing an N−H bond via deprotonation or from O-alkyloximes via nucleophilic addition. These intermediates react with carbanions to give substituted amines. Other electron-deficient, sp amination reagents react by similar mechanisms to give substitution products.
In aminations involving oxaziridines, nucleophilic attack takes place on the nitrogen atom of the three-membered ring. For some substrates (α-cyano ketones, for example), the resulting alkoxide reacts further to afford unexpected products. Straightforward β-elimination of the alkoxide leads to the formation of an amine.
Additions across pi bonds appear to proceed by typical nucleophilic addition pathways in most cases. Alkyl-, aryl-, and heteroaryllithium reagents add to azides to afford triazene salts. Reduction of these salts leads to amines, although they also may be converted to azides upon acidic workup with overall elimination of sulfinic acid. | 0 | Organic Reactions |
Using either Pd–Cu or Cu catalysts Yang et al. reported the first example of decarboxylative C–P cross-coupling. | 0 | Organic Reactions |
dimesitylborane is a dimer (CHMe)BH). It reacts only slowly with simple terminal alkenes. On the other hand, alkynes undergo monohydroboration with MesBH easily to produce alkenylboranes. | 0 | Organic Reactions |
Allyl- and vinylsilanes react with a variety of electrophiles under conditions of nucleophilic catalysis or Lewis acid promotion (often stoichiometric). The primary advantage of using Lewis acids versus fluoride catalysis is site selectivity—fluoride activation tends to generate allyl anions, which can then react at either the α or γ position. Use of Lewis-acid-activated electrophiles leads to reaction at only the γ position of allylsilanes. | 0 | Organic Reactions |
It is common in E1 and S1 reactions for a poor leaving group to be transformed into a good one by protonation or complexation with a Lewis acid. Thus, it is by protonation before departure that a molecule can formally lose such poor leaving groups as hydroxide.
The same principle is at work in the Friedel-Crafts reaction. Here, a strong Lewis acid is required to generate either a carbocation from an alkyl halide in the Friedel-Crafts alkylation reaction or an acylium ion from an acyl halide.
In the vast majority of cases, reactions that involve leaving group activation generate a cation in a separate step, before either nucleophilic attack or elimination. For example, S1 and E1 reactions may involve an activation step, whereas S2 and E2 reactions generally do not. | 0 | Organic Reactions |
The scope of leaving groups has also been expanded to include a number of different leaving groups, although carbonates, phenols, phosphates, halides and carboxylates are the most widely used. | 0 | Organic Reactions |
Intramolecular reactions of diazocarbonyl compounds include addition to carbon–carbon double bonds to form fused cyclopropanes and insertion into carbon–hydrogen bonds or carbon–carbon bonds. | 0 | Organic Reactions |
In general, radical cyclization to produce small rings is difficult. However, it is possible to trap the cyclized radical before re-opening. This process can be facilitated by fragmentation (see the three-membered case below) or by stabilization of the cyclized radical (see the four-membered case). Five- and six-membered rings are the most common sizes produced by radical cyclization.
Polycycles and macrocycles can also be formed using radical cyclization reactions. In the former case, rings can be pre-formed and a single ring closed with radical cyclization, or multiple rings can be formed in a tandem process (as below). Macrocyclizations, which lack the FMO requirement of cyclizations of smaller substrates, have the unique property of exhibiting endo selectivity. | 0 | Organic Reactions |
The reaction between tricarbonylchromium complexes Cr(CO)L and electron-rich or electron-neutral aromatic rings produces tricarbonyl(arene)chromium complexes (arene)Cr(CO). Complexation to chromium(0) activates the side chain of the arene, facilitating dissociation of a benzylic proton, leaving group, or nucleophilic addition to the homobenzylic position of styrenes. Further transformations of the resulting conformationally restricted, benzylic anion or cation involve the approach of reagents exo to the chromium fragment. Thus, benzylic functionalization reactions of planar chiral chromium arene complexes are highly diastereoselective. Additionally, the chromium tri(carbonyl) fragment can be used as a blocking element in addition reactions to ortho-substituted aromatic aldehydes and alkenes. An ortho substituent is necessary in these reactions to restrict conformations available to the aldehyde or alkene. Removal of the chromium fragment to afford the metal-free functionalized aromatic compound is possible photolytically or with an oxidant. | 0 | Organic Reactions |
Methanation is the conversion of carbon monoxide and carbon dioxide (CO) to methane (CH) through hydrogenation. The methanation reactions of CO were first discovered by Sabatier and Senderens in 1902.
CO methanation has many practical applications. It is a means of carbon oxide removal from process gases and is also being discussed as an alternative to PROX in fuel processors for mobile fuel cell applications.
Methanation as a means of producing synthetic natural gas has been considered since the 1970s. More recently it has been considered as a way to store energy produced from solar or wind power using power-to-gas systems in conjunction with existing natural gas storage. | 0 | Organic Reactions |
The first reported decarboxylative cross coupling reaction was an Ullmann reaction, in 1966 by Nilsson et al. Thermal decarboxylation of copper benzoates, in the presence of an aryl halide, was found to produce (both symmetric and unsymmetric) biaryls through aryl-Cu intermediates.
This monometallic copper system required drastic conditions for complete cross-coupling, and had various intrinsic limitations, both of which prevented development of a catalytic, preparatory version of this reaction.
It was not until 2009 that Liu and Shang et al. found that decarboxylative cross-coupling of aryl bromides and iodides with potassium polyfluorobenzoates could be achieved using monometallic copper iodide as a catalyst. The oxidative addition step was determined to be the rate-limiting step in the copper-only catalyst cycle (a contrast with Pd-catalyzed decarboxylative cross-coupling).
Cu(I)-only systems have also been found to promote coupling of alkynyl carboxylic acids with aryl halides (see aryl alkynes below), as well as decarboxylative dehydrogenative cross-coupling of amino acids with alkynes (or similar nucleophiles).
Catalysts for decarboxylative cross-coupling are of the general form ML2, with a wide variety of ligand types optimized for different substrates. Copper (and silver) centers are often complexed with phenanthrolines, and activity is reported to increase with electron-rich substituents on the ligands. | 0 | Organic Reactions |
Usually called molybdenum pentachloride, it is in fact partly a dimer with the molecular formula . In the dimer, each molybdenum has local octahedral symmetry and two chlorides bridge between the molybdenum centers. A similar structure is also found for the pentachlorides of W, Nb and Ta. In the gas phase and partly in solution, the dimers partially dissociate to give a monomeric . The monomer is paramagnetic, with one unpaired electron per Mo center, reflecting the fact that the formal oxidation state is +5, leaving one valence electron on the metal center. | 1 | Inorganic Reactions + Inorganic Compounds |
C-Nitroso compounds, such as nitrosobenzene, are typically prepared by oxidation of hydroxylamines:
:RNHOH + [O] → RNO + HO | 0 | Organic Reactions |
In the Gallagher–Hollander degradation (1946) pyruvic acid is removed from a linear aliphatic carboxylic acid yielding a new acid with two carbon atoms fewer. The original publication concerns the conversion of bile acid in a series of reactions: acid chloride (2) formation with thionyl chloride, diazoketone formation (3) with diazomethane, chloromethyl ketone formation (4) with hydrochloric acid, organic reduction of chlorine to methylketone (5), ketone halogenation to 6, elimination reaction with pyridine to enone 7 and finally oxidation with chromium trioxide to bisnorcholanic acid 8. | 0 | Organic Reactions |
Since the LUMOs of nontrigonal pnictogen compounds consist mainly of the vacant p orbitals of the pnictogen nuclei, they could undergo one-electron reduction to afford radical anions if the energy levels of LUMOs are appropriate. For a less sterically hindered compound, the generated radical anion readily dimerizes to form a dianion with a P-P bond. When a sterically encumbered tris-amide ligand is used, stable radical anions bearing T-shaped pnictogen nuclei can be isolated and characterized.
The oxidation of nontrigonal phosphorus compounds and transfer of halogen molecules to the phosphorus atoms to generate phosphoranes with phosphorus atoms in an oxidation state of +5 was achieved by various synthetic procedures. These dihalides are promising starting materials and potentially applicable for the generation of numerous secondary products, but only few reactions have been reported so far in the literature. Nontrigonal phosphorus compounds can also be oxidized by organic azide to yield phosphazenes. | 1 | Inorganic Reactions + Inorganic Compounds |
The Eschweiler–Clarke reaction is a method for methylation of amines. This method avoids the risk of quaternization, which occurs when amines are methylated with methyl halides. | 0 | Organic Reactions |
Nucleophilic epoxidation is the formation of epoxides from electron-deficient double bonds through the action of nucleophilic oxidants. Nucleophilic epoxidation methods represent a viable alternative to electrophilic methods, many of which do not epoxidize electron-poor double bonds efficiently.
Although the most commonly used asymmetric epoxidation methods (the Sharpless-Katsuki, and Jacobsen epoxidations) rely on the catalytic reactivity of electrophilic oxidants, nucleophilic oxygen sources substituted with a suitable leaving group can also act as epoxidation reagents. The classic example, the Weitz-Scheffer reaction employs hydrogen peroxide under basic conditions (Z = OH below). Other notable examples have employed hypochlorites (Z = Cl) and chiral peroxides (Z = OR*).
Asymmetric versions of the above reaction have taken advantage of a number of strategies for achieving asymmetric induction. The highest yielding and most enantioselective methods include:
* Use of stoichiometric chiral oxidant
* Use of stoichiometric metal peroxides substituted with chiral ligands
* Use of stoichiometric chiral base
* Use of polypeptides
Although the mechanisms of each of these reactions differ somewhat, in each case the chiral catalyst or reagent must be involved in the [https://en.wiktionary.org/wiki/enantio- enantio] determining conjugate addition step. Cis-epoxides are difficult to access using nucleophilic epoxidation methods. Nearly all nucleophilic epoxidations of cis olefins afford trans epoxides. | 0 | Organic Reactions |
The Boord olefin synthesis is an organic reaction forming alkenes from ethers carrying a halogen atom 2 carbons removed from the oxygen atom (β-halo-ethers) using a metal such as magnesium or zinc. The reaction, discovered by Cecil E. Boord in 1930 is a classic named reaction with high yields and broad scope.
The reaction type is an elimination reaction with magnesium forming an intermediate Grignard reagent. The alkoxy group is a poor leaving group and therefore an E1cB elimination reaction mechanism is proposed. The original publication describes the organic synthesis of the compound isoheptene in several steps.
In a 1931 publication the scope is extended to 1,4-dienes with magnesium replaced by zinc (see also: Barbier reaction). In the first part of the reaction the allyl Grignard acts as a nucleophile in nucleophilic aliphatic substitution. | 0 | Organic Reactions |
The crystal structure of APR resembles that of scheelite, with atomic cation is replaced by ammonium. The pertechnetate (NHTcO), periodate (NHIO), tetrachlorothallate (NHTlCl), and tetrachloroindate (NHInCl) follow this motif. It undergoes a molecular orientational ordering transition on cooling without change of space group, but with a highly anisotropic change in the shape of the unit cell, resulting in the unusual property of having a positive temperature and pressure Re NQR coefficient. APR does not give hydrates. | 1 | Inorganic Reactions + Inorganic Compounds |
Tetraoxidane is an inorganic compound of hydrogen and oxygen with the chemical formula . This is one of the unstable hydrogen polyoxides. | 1 | Inorganic Reactions + Inorganic Compounds |
Source:
A solution of the olefinic acid (0.499 g, 2.25 mmol) dissolved in benzene (20 ml, freshly distilled from calcium hydride) was stirred at 0 °C (ice bath) under nitrogen while oxalyl chloride (1.35 ml, 2.0 g, 15.75 mmol) was added dropwise. The ice bath
was removed and the solution was stirred at room temperature for 2 hr. The solvent and excess reagent were removed in vacuo. The resulting orange oil was dissolved in benzene (2 x 5.0 mi, freshly distilled from calcium hydride) under nitrogen.
This solution was added dropwise at 0 °C (ice bath) to an anhydrous ethereal solution of diazomethane (50 ml, −20 mmol, predried over sodium metal) with vigorous stirring under nitrogen. The resulting solution was stirred at 0 °C for 1 hr and then at room temperature for 1.5 hr. The solvents and excess reagent were removed in vacuo.
Tetrahydrofuran (40 ml, freshly distilled from lithium aluminum hydride) and finely divided metallic copper powder (0.67 g) were added to the crude diazo ketone, sequentially. This suspension was vigorously stirred at reflux under nitrogen for 2 hr. The resulting suspension was allowed to stir at room temperature for an additional 14 hr. The solution was filtered into water (100 ml). The mixture was shaken vigorously for 5 min and then extracted with ether (3 x 50 ml). The combined ethereal extracts were washed with saturated sodium bicarbonate solution (4 X 40 ml), water (40 ml), and saturated sodium chloride solution (40 ml), dried (NaSO), and concentrated in vacuo to give 0.673 g of a crude brown oil. This crude oil was chromatographed on silica gel (67 g) in a 2-cm diameter column using 10% ether-90% petroleum ether to develop the column, taking 37-ml sized fractions. Fractions 11–16 gave 0.164 g (33%) of pure ketone product: mp 64-64.5° (from pentane); IR (CCl) 3095 (cyclopropyl CH)
and 1755 cm (CO); NMR (CCl) δ 1.18 (s, 3H, CH) 1.03 (9, 3H, CH),
0.97 (s, 3H, CH), and 0.90 ppm (s, 3H, CH). Anal. Calcd for CHO: C, 82.52; H, 10.16. Found: C, 82.61; H, 10.01. | 0 | Organic Reactions |
K. C. Nicolaou and coworkers at Scripps Research Institute generated the chiral hydrazone through Enders hydrazone alkylation reaction with high stereoselectivity (de' > 95%). The subsequent ozonolysis and Wittig reaction led to the side chain fragment of zaragozic acid A, which is a potent medicine for coronary heart disease. | 0 | Organic Reactions |