bluuebunny/crossref_metadata_2025_split huggingface dataset:
The interaction of chloranil with aliphatic amines
Authors: Foster R. 
Published: September 2010

AbstractAlthough substitution of chlorine usually occurs in the interaction of chloranil with aliphatic amines, solutions of chloranil in pure triethylamine yield a product which appears to be a salt, the anion of which is the free radical semiquinone ion derived from chloranil. In acetone solution this salt decomposes to yield 2,3,5‐trichloro‐6‐(2′‐diethylaminovinyl)‐p‐benzoquinone.
The η‐ and ε‐phase of the system copper‐silicon as solid reactants in the synthesis of dimethyldichlorosilane
Authors: Kolster B. H. , Vlugter J. C. , Voorhoeve R. J. H. 
Published: September 2010

AbstractThe investigation was performed partly at the Laboratory for Physical Chemistry of the solid state.To investigate the actual form of the copper catalysing the direct synthesis of methylchlorosilanes, intermetallic compounds of silicon and copper are used as contact masses. Apparently copper must be present as an intermetallic compound with silicon in order to yield selectively dimethyldichlorosilane.It appears that the selectivity of the direct synthesis can be maintained as long as free silicon is available to fill up the silicon sites in the intermetallic compound, which are emptied due to the reaction with methyl chloride.
Vapour pressure of selenium trioxide
Authors: Mijlhoff F. C. , Block R. 
Published: September 2010

AbstractThe vapour pressure of solid and liquid SeO3 was measured in the temperature range between 80°C and 120°C. Measurements are easily affected by the presence of residual SO3. The triple point is situated at 120.9°C and 5.5 mm Hg. The plot of log p against 1/T shows that the heat of vaporisation depends greatly on temperature. Sublimation pressure data can be explained in terms of a tetramer‐monomer dissociation in the gaseous phase. Calculated sublimation and dissociation enthalpies are 9.0 and 119 kcal/mole (SeO3)4.
Condensation of tri‐n‐propylbromogermane with propylene oxide
Authors: Pike R. M. , Lavigne A. A. 
Published: September 2010

AbstractThe rate of reaction of tri‐n‐propylbromogermane with propylene oxide has been measured under a variety of conditions. The effect on the reaction rate of temperature, concentration of reacting species, and the observed second‐order kinetics indicate a bimolecular type mechanism. The reaction offers a route to the synthesis of 2‐halo‐1‐hydroxy substituted alkanes.
The radical induced oxidation of acetaldehyde
Authors: Cerfontain H. 
Published: September 2010

AbstractThe radical induced oxidation of acetaldehyde in the photo‐oxidation of azoethane was studied at 28°, 118° and 152°. In most experiments the acetaldehyde built up was substantially less than 0.8 mm, the observed limiting value at high conversion. Major products in the radical induced oxidation of acetaldehyde are carbon dioxide and methanol; minor products are carbon monoxide and (per)acetic acid. Formaldehyde was positively identified as a reaction product. It is proposed that the formation of the reaction products proceeds via the acetyl radical:CH3CHO + RCH2O· → CH3CO· + RCH2OH [8]CH3CO· → ·CH3 + CO [9]CH3CO· + O2 → CH3O· + CO2 [11]CH3CO· + O2 → CH3CO3· [12]CH3CO3· + AH → CH3CO3H + A· [16]where AH stands for acetaldehyde and azoethane. The methoxy radicals will form methanol and formaldehyde.Reaction [11] does not necessarily proceed in one step. At 28° k9/k11 = (4±2) · 1013 molec · cm −3.
Reactions of aliphatic halides with solutions of alkali metals in liquid ammonia IV. Experiments with optically active 1‐phenylethyl halides
Authors: Verkade P. E. , de Vries K. S. , Wepster B. M. 
Published: September 2010

AbstractOptically active 1‐phenylethyl chloride or bromide when treated with a solution of lithium, sodium, or potassium in liquid ammonia yields optically active 2,3‐diphenylbutane. It is concluded that the formation of the “biaralkyl” proceeds via carbanions.The absolute configurations of (+)‐ and (‐)‐2,3‐diphenylbutane are deduced.
Autoxidation of cyclohexanecarboxylic Acid‐l‐14C
Authors: Bigot J. A. , Duynstee E. F. J. , Hennekens J. L. J. P. 
Published: September 2010

AbstractOxidation of cyclohexanecarboxylic acid‐1‐14C by molecular oxygen at 205°C in the presence of cupric salt of cyclohexanecarboxylic acid and magnesium oxide yielded nearly equal amounts of cyclohexanone and cyclohexene. When cupric salt and magnesium oxide were omitted, only cyclohexanone was obtained. In both cases the label distribution in the cyclohexanone was determined. This showed that in the presence of cupric salt and magnesium oxide and at a temperature of about 205°C, cyclohexanone formation comes about by attachment of oxygen to either the tertiary carbon atom (54%) or to one of the neighbouring secondary carbon atoms (44%) of the cyclohexanecarboxylic acid molecule. In the absence of cupric salt and magnesium oxide over 90% of the cyclohexanone is formed by attachment of oxygen to the tertiary carbon atom of the cyclohexanecarboxylic acid.When the oxidation is carried out in the presence of cupric salt and magnesium oxide, but at a lower temperature (165°C), cyclohexanone formation is very slow; the label distribution indicated formation through oxidative attack at the tertiary carbon atom only.The fact that at 205°C and in the presence of cupric salt and magnesium oxide, oxidative attack at the β‐carbon atoms of cyclohexanecarboxylic acid takes place, is tentatively explained by assuming the formation of the 2‐carboxycyclohexyl radical (II) from the cupric salt of cyclohexanecarboxylic acid.
Non‐hydrolyzable synthetic analogs of phosphatidic acids
Authors: Rosenthal Arthur F. , Kosolapoff Gennady M. , Geyer Robert P. 
Published: September 2010

AbstractDiether‐phosphonate analogs of phosphatidic acids of the type ROCH2‐CH(OR′)CH2P(O)(OH)2(RC2H5,R′CH3;RC18H37,R′C16H33;RC18H37,R′CH3) have been prepared by reaction of the corresponding iodides with triethyl phosphite, followed by hydrolysis. The iodides were prepared in one step from the allyl alkyl ether, alcohol, iodine, and zinc oxide. It was found that a reagent recently described for the detection of phosphatides on thin‐layer chromatograms also detects many but not all phosphonic acids and esters. The synthesis of propargyl octadecyl ether and of barium ethyl 2‐benzyloxyethylphosphonate is also described.
Chemistry of acetylenic ethers: 76 Preparation of compounds with a 1,3‐enyne system
Authors: Montijn P. P. , Schmidt H. M. , van Boom J. H. , Bos H. J. T. , Brandsma L. , Arens J. F. 
Published: September 2010

AbstractEthers with the systems , CH3CCCH(OR)2, CH3CCCH(OR)3 or ‐CH2‐CH2‐CCOR undergo an elimination of ROH [R = alkyl, 2‐alkynyl (‐CH2CC‐R′) phenyl, or 2‐tetrahydropyranyl] with formation of 1,3‐enyne derivatives, , on treatment with alkali amides in liquid ammonia.The cyclic ethers: and are isomerized under these conditions to the 1,3‐enyne carbinols HCC‐CHC(CH3)CH2OH and HCC‐CHCH(CH2)4OH.
Saturated five‐membered heterocyclics, III.: Conversion of 1,3,4‐oxadiazolidines into 1,2,4‐triazolidines
Authors: Zwanenburg B. , Weening W. E. , Strating J. 
Published: September 2010

Abstract2,3,4,5‐Alkyl substituted 1,3,4‐oxadiazolidines have been converted into 1,2,3,4,5‐substituted 1,2,4‐triazolidines by reaction with a primary amine and a trace of acid as a catalyst. 2,3‐Diethyl‐1,3‐oxazolidine gave on treatment with n‐butylamine and acid, instead of the corresponding imidazolidine, ring cleavage to N‐ethylaminoethanol and the Schiff base VII. The mechanism of these aminolyses is discussed.
The formation of 2,2‐di(4‐hydroxyphenyl)propane (bisphenol‐a) from phenol and acetone
Authors: de Jong J. I. , Dethmers F. H. D. 
Published: September 2010

AbstractThe addition of phenol to acetone appeared to be the rate‐determining step in the formation of bisphenol‐A in the presence of sulfuric acid. The kinetic picture was further supplemented by the synthesis of two possible intermediates and by measuring their equilibrium.
The synthesis of [6,7‐T]‐tropine
Authors: Hespe W. , Klopper W. J. F. , Nauta W. Th. 
Published: September 2010

AbstractThe synthesis of [6,7‐T]‐tropine has been effected by reacting 2,5‐dimethoxy‐2,5‐dihydrofuran with tritium gas and subsequently hydrolysing the product to [2,3‐T]‐succindialdehyde. A Robinson‐Schöpf reaction afforded [6,7‐T]‐tropinone, which was finally reduced with the aid of Raney nickel and hydrogen.
Mass spectrometry of nitro compounds: Part I: Mass spectra of α‐, β‐ and γ‐deuterated 1‐nitropropane
Authors: Nibbering N. M. M. , de Boer Th. J. , Hofman H. J. 
Published: September 2010

AbstractA fragmentation pattern is suggested for 1‐nitropropane by comparing its mass spectrum with that of its α‐, β‐ and γ‐deuterated analogues.
Some aspects of the interaction of β‐rays with matter
Authors: de Ligny C. L. , Levering T. , de Hoyer H. 
Published: September 2010

AbstractThe backscattering and absorption of β‐rays by compounds have been measured and interpreted on the basis of elemental reflecting and stopping powers. A straightforward method has been devised for the determination of the elemental stopping powers. The elemental reflecting powers have been compared with the backscattering from elements and appear to be in good agreement. A simple relationship has been shown to exist between the elemental reflecting and stopping powers.
A simple method for the preparation of some methylphenylsulfonium nitrates
Authors: van der Veen J. 
Published: September 2010

AbstractA simple method for the preparation of dimethylphenyl‐, dimethyl‐p‐chlorophenyl‐ and methyldiphenylsulfonium nitrate is described.By condensing equimolar amounts of mercuric iodide and a phenyl sulfide with methyl iodide a sulfonium triiodomercurate is formed. The triiodomercurate is converted into the nitrate by using an anion exchange resin.
The influence of non‐planarity in styrene and stilbene derivatives VI: Dipole moments and conformations of cis‐ and trans‐benzal ketones
Authors: Kronenberg M. E. , Havinga E. 
Published: September 2010

AbstractOpen chain α,β‐unsaturated ketones in solution show rotational isomerism. The infrared spectra of cis‐benzal ketones indicate that one conformation is predominant. To obtain more insight into the nature of this conformation the dipole moments of a number of cis‐ and trans‐benzal ketones were determined. The data suggest that in the cis‐isomer the carbonyl group is considerably twisted out of the plane of the double bond.
Selective alkylation of chelated hydroxyls in condensed benzopyrones ‐ Part II
Authors: Puranik Gurubasav S. , Rajagopal S. 
Published: September 2010

AbstractSelective alkylation of 1 or 8 hydroxyl as 1,3‐dihydroxy‐ or 3,8‐dihydroxyxanthone is recorded.
The copper‐catalysed oxidation of unsaturated carbonyl compounds Part III: Oxidation of α,β‐ and β,γ‐unsaturated aldehydes and ketones by oxygen in the presence of cupric complexes
Authors: Volger H. C. , Brackman W. , Lemmers J. W. F. M. 
Published: September 2010

AbstractUnsaturated (α,β‐ and β,γ‐) aldehydes and ketones, capable of forming a conjugated dienol can be oxidized under mild reaction conditions in the presence of catalytic amounts of cupric‐amine complexes in alkaline methanolic solution.Specific oxidation in the γ‐position is thought to occur with formation of a γ‐hydroperoxy α,β‐unsaturated carbonyl compound as a primary intermediate. The decomposition products of the γ‐hydroperoxide depend upon the number of hydrogen atoms attached to the γ‐carbon atom. A hydroperoxide group attached to a primary carbon atom is converted into an aldehyde function; likewise a secondary and a tertiary γ‐carbon atom lead to a keto and an alcohol function, respectively.The alcohols can be isolated as such, whereas products containing an aldehyde and a keto function form either cyclization products like unsaturated lactones, polyacetals or cyclic ethers or are cleft into esters and aldehydes.The mechanism of the oxidation reaction is discussed briefly.
The oxidative coupling of aromatic compounds with palladium salts
Authors: van Helden R. , Verberg G. 
Published: September 2010

AbstractReaction of benzene, palladium chloride and sodium acetate in acetic acid solvent produces biphenyl in a high yield. In the absence of sodium acetate no reaction occurs. The reaction is first‐order with respect to benzene and PdCl2. With monosubstituted benzenes in general a mixture of isomeric biphenyls (X‐C6H4‐C6H4‐X,X = alkyl, aryl, OR, Cl, COOR) is obtained. The substitution pattern corresponds with that observed in electrophilic aromatic substitution. The substituents exert a weak polar effect: electron‐donating groups increase the rate, while the opposite holds for electron‐attracting groups.With disubstituted benzenes steric effects play an important role. From o‐xylene 3,4,3′,4′‐ and 2,3,3′,4′‐tetramethylbiphenyl have been obtained as the only products in a molar ratio of 2.7 : 1.The results are most satisfactorily described by a mechanism involving complex formation between the aromatic compound and PdCl2 as the rate‐determining step. The complex formed is assumed to yield a π‐cyclohexadienyl‐PdCl complex by a fast reaction with acetate anions. The complex formed, being unstable, decomposes to yield biphenyl and palladium metal.
Synthesis of α‐esters of N‐acylaspartic acid
Authors: Nefkens G. H. L. , Nivard R. J. F. 
Published: September 2010

AbstractSeveral pure α‐esters of N‐benzyloxycarbonyl‐l‐aspartic acid have been obtained in high yields by esterification of N‐benzyloxycarbonyl‐L‐aspargine, followed by deamidation with nitrosonium hydrogen sulfate (NO · HSO4) in glacial acetic acid.
Hydroperoxides of partially reduced quinoxalines, pteridines and (iso)alloxazines: Intermediates in oxidation processes
Authors: Mager H. I. X. , Berends W. 
Published: September 2010

AbstractTransient peroxides have now been found in the oxidation of condensed pyrazines. Tetrahydropteridines and dihydro(iso)alloxazines proved to have a catalytic effect on the nonenzymatic oxidation of other compounds. This could be explained by regarding the partially reduced condensed pyrazines as acceptors for molecular oxygen. A general structure has been proposed for hydroperoxides occurring as key‐intermediates. The new theory may provide a more complete explanation for some enzymatic oxidation proccesses like the enzymatic hydroxylation of phenylalanine to tyrosine.
The complete configuration of sedridine and of pelletierine
Authors: Beyerman H. C. , Maat L. , van Veen A. , Zweistra A. , von Philipsborn W. 
Published: September 2010

Abstract(+)‐Sedridine fromSedum acreL. is shown to be (2S)‐1‐[(2′S)‐2′‐piperidyl]‐propan‐2‐ol.Oxidation of unnatural (‐)‐sedridine yieldedD‐pipecolic acid, from which follows the absolute configuration of the piperidine asymmetric centre. Oxidation of unnatural (+)‐pelletierine sulfate gaveL‐pipecolic acid.This also confirms a previous deduction of the absolute configuration of (‐)‐pelletierine fromPunica granatumL.; this is R‐1‐(2‐piperidyl)propan‐2‐one.Racemic sedridine and allosedridine were condensed withp‐substituted benzaldehydes to 1‐(4‐substituted‐phenyl)‐3‐methylhexahydro‐1H,3H‐pyrido‐[1,2‐c]oxazines. The relative configurations followed from conformational analysis and proton magnetic resonance spectra: sedridine isthreoidand allosedridine iserythroid.
The phase diagram K2Wo4 ‐ Wo3
Authors: Gelsing R. J. H. , Stein H. N. , Stevels J. M. 
Published: September 2010

AbstractThe phase diagram K2WO4‐WO3 in the vicinity of the eutectic point is presented and X‐ray powder diffraction data of the solid compounds involved are tabulated. In addition to the stable compounds K2WO4, K2O · 2WO3, K2O · 3WO3 and K2O · 4WO3, two metastable compounds of as yet unknown composition may be formed.
Photoconductivity of crystals of anthracene doped with tetracene and acridine
Authors: Mulder B. J. , de Jonge J. 
Published: September 2010

AbstractA study was made of the photoconductivity of anthracene crystals containing small amounts of tetracene and acridine in the crystal lattice and with aqueous solutions as the electrode material. Doping of anthracene with tetracene markedly reduced the photoconductivity but increased the variation of the photocurrent with the wavelength of the exciting light. The photoconductivity spectrum of heavily doped crystals accurately duplicated the absorption spectrum of anthracene. The theory according to which charge carriers in anthracene are generated only at the positive crystal‐water interface and the role of tetracene as a trap for excitation energy in anthracene can adequately explain the effects of tetracene on the photoconductivity. The effects of acridine on the photoconductivity of anthracene were opposite to those of tetracene. In order to understand the latter results another or an additional mechanism for the generation of charge carriers must be assumed to exist in the crystals doped with acridine.
The influence of sugars on the U.V. absorption spectrum of proteins
Authors: Berrens L. , Bleumink E. 
Published: September 2010

AbstractN‐Glycosidic coupling of aldoses and the free amino groups of protein is accompanied by profound modification of the ultraviolet absorption spectrum of the protein partner in the Maillard reaction. The increased extinction coefficient at 250 mμ of protein‐carbohydrate complexes incorporating sites of N‐glycosidic linkage is largely attributable to effects of denaturation, while absorbancy changes at 325 and 350 mμ are accounted for by side reactions involving the sugar partner only. Specifically, the Maillard reaction between protein and sugar results in the formation of a chromophor at the site of coupling absorbing at 305 mμ. The identification of this chromophor as the 1,2‐enol form of an N‐substituted 1‐amino‐1‐deoxy‐2‐ketose is substantiated by studies of ultraviolet absorption in model systems containing low‐molecular weight primary amines and aldoses.
Studies in homogeneous catalysis.: Radicals of the \documentclass{article}\pagestyle{empty}\begin{document}\[{\rm R}_{\rm 2}{\rm NO}^{-\bullet}\]\end{document} type as catalysts for the oxidation of methanol by cupric complexes and as promoters for various oxidations catalysed by copper
Authors: Brackman W. , Gaasbeek C. J. 
Published: September 2010

AbstractThe stable radical di‐tert‐butyl nitroxide is found to catalyse various oxidation reactions effected by cupric complexes, and to promote various oxidations with oxygen catalysed by copper complexes. Examples of its activity are found in the formation of hydrogen cyanide from methanol, ammonia and oxygen, the synthesis of nitriles from aldehydes, ammonia and oxygen, and various catalytic oxidations of methanol to formaldehyde.The kinetics and mechanism of the oxidation of methanol by cupric‐phenanthroline, catalysed by di‐tert‐butyl nitroxide, have been studied in detail. The essential step in this reaction appears to be a simultaneous hydrogen abstraction (by the nitroxide radical) and electron abstraction (by the cupric ion) from coordinated methanol. The activation of C‐H bonds with respect to hydrogen abstraction in methanol and other compounds coordinated to cupric ions is discussed.The reactive cupric complexes are coordinatively unsaturated with respect to phenanthroline. The likewise unsaturated cuprous complexes formed during the oxidation regenerate the reactive cupric complexes by a fast electrontransfer reaction. This reaction gives rise to the peculiar phenomenon that the reaction rate is not a single‐valued function of the concentration of the starting‐materials, but is co‐determined by the history of the system.
Aromatic sulfonation XV: Isomerization and dealkylation of t‐butylbenzenesulfonic acids in aqueous sulfuric acid
Authors: Cerfontain H. , Arends J. M. 
Published: September 2010

AbstractThe kinetics of the isomerization of p‐ and m‐t‐butylbenzenesulfonic acid have been studied in 74.0 wt‐% sulfuric acid at elevated temperatures. The isomerization is accompanied by dealkylation. Evidence was obtained that the formation of benzenesulfonic acid from p‐t‐butylbenzenesulfonic acid proceeds mainly by a three‐step process, viz., desulfonation, dealkylation and sulfonation of the benzene produced. With m‐t‐butylbenzenesulfonic acid, however, there is an indication of additional dealkylation of the sulfonic acid itself. Desulfonation rate constants were calculated. The activation energies for desulfonation are of the order of 27‐30 kcal · mole−1.
α‐Nitrosocyclohexanecarboxylic acid as a possible intermediate in the nitrosodecarboxylation of cyclohexanecarboxylic acid
Authors: Duynstee E. F. J. , Mevis M. E. A. H. 
Published: September 2010

AbstractA description is given of the synthesis of dimeric α‐nitrosocyclohexanecarboxylic acid (III). This acid provides the first example of the hitherto unknown class of α‐nitrosocarboxylic acids. It is shown that III is not an intermediate in the nitrosodecarboxylation of cyclohexanecarboxylic acid to caprolactam.
The enzymic conversion of all‐cis 8,11,14‐eicosatrienoic acid into prostaglandin E1
Authors: Nugteren D. H. , Beerthuis R. K. , van Dorp D. A. 
Published: September 2010

AbstractIn the biosynthesis of prostaglandin E1 (PGE1) with an enzyme fraction of sheep vesicular glands glutathione and a moderate amount of antioxidant are required to obtain maximum yield; two oxygen molecules are consumed per mole PGE1 formed. By altering the incubation conditions, besides PGE1 various other products can be obtained.A scheme for the mechanism of the conversion is proposed in which the formation of PGE1 as well as that of the byproducts is assumed to occur on the enzyme in concerted reactions via peroxy‐radicals and a cyclic peroxide.
The bromination of 1,4‐Di‐tert.Butylbenzene: Synthesis of 1,4‐di‐tert.butyl‐2‐bromobenzene and some tert.butyl‐dibromobenzenes
Authors: Baas J. M. A. , Wepster B. M. 
Published: September 2010

AbstractThe reaction of 1,4‐di‐tert.butylbenzene in carbon tetrachloride with bromine and with iron as catalyst yields 1,4‐di‐tert.butyl‐2‐bromobenzene, 1‐tert.butyl‐3‐bromobenzene, 1‐tert.butyl‐4‐bromobenzene, and 1‐tert.butyl‐3,4‐dibromobenzene. Besides these compounds, 1‐tert.butyl‐2,4‐dibromobenzene and 1‐tert.‐butyl‐2,5‐dibromobenzene were also synthesized in an unambiguous way.
The conformation of non‐aromatic ring compounds. XX: The dipole moments and NMR spectra of some 2‐substituted 1,3‐dithianes
Authors: Kalff H. T. , Havinga E. 
Published: September 2010

AbstractThe conformation of several 2‐substituted 1,3‐dithianes is studied by means of dipole moments and NMR spectra. The value of the dipole moments of all compounds having only hydrocarbon substituents is 2.0 ± 0.1 D., indicating that in all these compounds the six‐membered ring is in the same conformation. From the dipole moments of the 1,3‐dithianes studied it may be concluded that in solution the dithiane ring has the same geometry (chair conformation) as that found by X‐ray analysis of 2‐phenyl‐1,3‐dithiane2. The NMR spectra of 2‐methyl‐2‐phenyl‐, 2,2‐diphenyl‐ and 2‐p‐chlorophenyl‐2‐methyl‐1,3‐dithiane show that a phenyl group at atom 2 in axial position gives rise to two absorption peaks, one due to the ortho protons and one to the meta (and para) protons. The same effect is seen with the axial phenyl group in α‐trithiobenzaldehyde. The protons of an equatorial phenyl substituent give only one band. These phenomena are discussed.
The crystal structure of bis(1,3‐Diphenyl‐1,3‐Propanedionato)copper (II)
Authors: Blackstone Marijke , van Thuijl J. , Romers C. 
Published: September 2010

AbstractThe crystal structure of bis(1,3‐diphenyl‐1,3‐propanedionato)copper(II), Cu(C6H5CO.CH · COC6H5)2, has been determined with the aid of three‐dimensional X‐ray diffraction data. The dimensions of the monoclinic cell are a = 26.18, b = 6.07, c = 16.64 Å, β = 115.3°, Z = 4, and the space group is C2/c.The copper ion has the square configuration with Cu‐O = 1.91 Å and with valency angles close to 90°. The chelate ring is entirely planar, the phenyl rings make small angles (9.3° and 4.6°) to this plane.There is no indication of extensive conjugation between the phenyl groups and the chelate ring system.