bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diels‐alder reactions of o‐nitronitrosobenzene and 3‐nitro‐4‐nitrosotoluene
Authors: Hamer Jan , Bernard Robert E. 
Published: September 2010

Abstracto‐Nitro‐nitrosobenzene and 3‐nitro‐4‐nitrosotoluene were reacted with 1,3‐butadiene and 2,3‐dimethyl‐1,3‐butadiene to form 3,6‐dihydro‐1,2‐oxazines, in high yields.Infrared spectra, measured in KBr pellets, of starting materials and adducts indicate coplanarity of the nitrogroup and the benzene ring for the starting materials, and considerable steric inhibition of the mesomeric interaction between the nitro group and the benzene ring for the adducts.
Polysaccharides, lipids and poly‐β‐hydroxybutyrate in microorganisms
Authors: Mulder E. G. , Deinema Mia H. , van Veen W. L. , Zevenhuizen L. P. T. M. 
Published: September 2010

AbstractThe occurrence, formation and utilization of polysaccharides, lipids and poly‐β‐hydroxybutyrate in micro‐organisms have been investigated. Bacteria belonging to the genus Arthrobacter were found to accumulate within their cells large amounts (up to 70% of their dry weight) of carbohydrates consisting mainly of polysaccharides.Yeast cells belonging to the Rhodotorulaceae synthesized large amounts of intra‐cellular lipids (up to 50%). Some species in addition produced considerable quantities of extra‐cellular lipids. The composition of intra‐ and extra‐cellular lipids differed in their component fatty acids and alcohols.Poly‐β‐hydroxybutyrate was found to occur, in an amount of 30% of the dry cell weight, in the sewage bacterium Sphaerotilus natans; it was also detected in related sheath‐forming bacteria.These polymeric compounds were synthesized under more or less similar cultural conditions viz. excess of glucose and deficiency of nitrogen.Lipids and presumably poly‐β‐hydroxybutyrate may be reserve materials, serving as substrates for endogenous metabolism. The function of polysaccharides is less clear.
Electrochemical properties of a new glass electrode containing beryllium oxide II. The responsiveness of the glass electrode to other ions than the protons
Authors: Mans A. E. , Kateman Miss I. 
Published: September 2010

AbstractA previously published research 2 with membranes of a BeO‐containing glass was continued. Electrodes of the glass in question show increasing responsiveness to monovalent cations according to the series:C3H7(NH3)+ < Li+ < Na+ < NH4+ < K+ < Rb+ < Ag+ < H+.In alkaline solutions, which may contain considerable amounts of Na+ by the side of K+, the glass electrodes are very suitable for the determination of the pK. The responsiveness of the electrodes to K+ and to the other monovalent cations can be expressed as a characteristic constant.
The thermal decarboxylation of alkali trichloroacetates in aprotic solvents III
Authors: Wagner W. M. , Kloosterziel H. , Bickel A. F. 
Published: September 2010

AbstractThermal decomposition of sodium trichloroacetate in 1,2‐dimethoxyethane in the presence of various perchloro compounds leads to α,β‐elimination of chlorine from these compounds and formation of CCl4. Hexachlorocyclopentadiene yields decachlorobi‐(2,4‐cyclopentadien‐1‐yl)These results point to a mechanism involving Cl+‐abstraction by the CCl3−ion.
Aromatic sulphonation IV Kinetics and mechanism of the sulphonation of benzene in aqueous sulphuric acid
Authors: Kaandorp A. W. , Cerfontain H. , Sixma F. L. J. 
Published: September 2010

AbstractThe kinetics of the sulphonation of benzene have been measured at 5.0°, 25.0° and 45.0° in aqueous sulphuric acid solutions, varying from 77.6 to 99.2 wt‐% H2SO4In addition, sulphonation rate measurements have been made at 5.0° in 98.8 wt‐% H2SO4containing various concentrations of sodium bisulphate. All reactions were found to be first order with respect to benzene. The kinetics are discussed in terms of the mechanism:magnified imageIt is suggested that sulphur trioxide or, though less probable, the sulphuric acid solvate of sulphur trioxide SO3(H2SO4) or disulphuric acid (H2S2O7), is the sulphonating entity X and thatk1 <k2|B|+k3No kinetic distinction can be made between the deprotonation by reaction [2] and the less probable intramolecular proton shift (reaction [3]).A comparison between the mechanisms of sulphonation in aqueous and fuming sulphuric acid furnishes additional evidence that SO3, instead of SO3(H2SO4) or H2S2O7, should be regarded as the sulphonating entity.
Syntheses with metallated thioacetals and orthothioformates
Authors: Fröling A. , Arens J. F. 
Published: September 2010

AbstractThioacetals and orthothioformates, compounds having the general formula HC(R)(SR′)2 with R = H, SR′, CH3, or C6H5 and R′ = C2H5 or C6H5, were metallated by means of alkali amides in liquid ammonia. The metallated derivatives were A) alkylated, B) converted with ketones (successfully only when R = H and R′ = C6H5), and C) ethylthiolated by means of diethyldisulphide (only when R = H, SR′, or C6H5). The results of the reactions are summarized in Tables I‐VI, VIII, and IX. Similar conversions were impossible with common acetals or orthoformates (notably CH2(OC2H5)2, C6H5‐CH(OC2H5)2, and CH(OC2H5)3). The easy metallation of the thiocompounds is attributed to d‐orbital participation of sulphur, which probably lowers the activation energy of the metallation reaction and enhances the stability of the carbanions.The new reactions in principle enable the synthesis of aldehydes from formaldehyde, of methyl ketones from acetaldehyde, of phenyl ketones from benzaldehyde, and of carboxylic acids from formic acid.Upon standing, solutions of NaC(SC2H5)3 and NaC(SC6H5)3 in liquid ammonia slowly decompose, yielding compounds of the type (R′S)2C = C(SR′)2. The transient occurrence of a carbene: C(SR′)2, formed by splitting‐off of thiolate from the carbanion ⊖ C(SR′)3, is discussed.
Dihydroquinolones I: Reactions of substituted 4‐oxo‐1,2,3,4‐tetrahydroquinoline
Authors: Speckamp W. N. , Pandit U. K. , Huisman H. O. 
Published: September 2010

AbstractThe main product of cyclisation of N‐(m‐methoxyphenyl)‐N‐tosyl‐2‐aminopropionyl chloride is shown to be N‐tosyl‐7‐methoxy‐4‐oxo‐1,2,3,4‐tetrahydroquinoline. The 3‐cyano‐3‐methyl derivative of this quinolone, which was obtained from the latter in two steps, underwent a base catalyzed ring cleavage during an attempted Stobbe condensation. A mechanism for this cleavage reaction has been suggested.
A simple laboratory scale preparative method for dialkyl sulphides, selenides, tellurides, thiols and selenols
Authors: Brandsma L. , Wijers H. E. 
Published: September 2010

AbstractThe preparation of dialkyl sulphides, selenides and tellurides by alkylating sodium sulphide, selenide or telluride, obtained from sodium and sulphur, selenium or tellurium in liquid ammonia, is very easily carried out and gives good yields. It is also possible to prepare and alkylate sodium disulphide and diselenide in liquid ammonia. The resulting dialkyl disulphides and diselenides in the reaction mixture can be converted simply and in good yields into the corresponding thiols and selenols.
On the impedance of galvanic cells: V. The impedance of a galvanic cell with two plane parallel electrodes at short distance
Authors: Sluyters J. H. 
Published: September 2010

AbstractIt is shown both by calculation and experimentally that in a galvanic cell with two plane electrodes, through which an alternating current flows, the concentration waves interfere if the distance of the electrodes is of the order of a wave length.
Foam‐fractionation applied to the nonionic detergent nonidet P 40
Authors: Prins A. 
Published: September 2010

AbstractThe nonionic detergent Nonidet P 40 as made from iso‐octylphenol and ethylene oxide is a mixture of polymers with a divergent ethylene oxide content. It is possible to separate it into components with differing ethylene oxide contents by foam‐fractionation.A solution of a nonionic detergent like Nonidet P 40 in water separates into two phases when the temperature is raised. This cloud point is a measure of the ethylene oxide content of the soap. Use is made of this fact in the analysis of the foam‐fractions.
On the superimposability of the electronic spectra of disubstituted benzene derivatives in the interpretation of the principal absorption bands of certain trisubstituted derivatives
Authors: Rekker R. F. , Nauta W. Th. 
Published: September 2010

AbstractThe validity of a superimposability principle for the electronic spectra of disubstituted benzene derivatives, proposed byDoubandVandenbelt5to interpret the principal absorption bands of some trisubstituted benzene derivatives is discussed forp‐aminosalicylic acid, β‐resorcylic acid and 2‐amino‐5‐chlorobenzoic acid.
Mechanism of reactions of unsaturated ethers and thioethers. VII: Linear free energy relationships and inverse secondary deuterium isotope effect in the addition of water to 1‐alkynyl thioethers
Authors: Hogeveen H. , Drenth W. 
Published: September 2010

AbstractThe effect of structure on the rates of hydration was analyzed with the Taft equation log k = ϱ*σ* + constant, for the following two series:
HCCSR′, with R′ = C2H5, CH(CH3)2> and C(CH3)3, log kR′ = −0.73σR′* −0.75;
RC  CSC2H5, with R = CH3, C2H5, CH2CH2CH3> and CH(CH3)2, log kR = −3.76σR* −2.07.
The values of the polar reaction constants are in agreement with the established mechanism of this reaction.The kinetic experiments with HCCSC2H5 and DCCSC2H5 revealed an inverse secondary deuterium isotope effect: kD/kH = 1.03. This value, was compared with those calculated either from the alterations of the vibrations during the reaction or from the difference in inductive effect of H and D.
Mechanism of reactions of unsaturated ethers and thioethers. IX: Acid‐catalyzed alkyl oxygen fission of alkyl ethynyl ethers
Authors: Stamhuis E. J. , Drenth W. 
Published: September 2010

AbstractAs in the formation of esters from alkyl ethynyl ethers with primary alkyl groups by addition of water, isopropyl and tert.‐butyl acetate are produced from isopropoxy‐ and tert.‐butoxyethyne. In addition, the latter ethers show formation of an acidic product and an olefin.A mechanism is proposed in which the first step is a rate determining proton‐transfer to the triple bond:

The carbonium ion formed initially reacts in two ways. One is by addition of water leading to the production of ester. The other is an alkyl oxygen fission from which keten and an alkyl carbonium ion result. The keten is rapidly converted into acetic acid. The alkyl carbonium ion is stabilized among other things by olefin formation.Rate constants for HCCOR, as R is varied, obey the Taft equation: log kR = ϱ*σR* + constant. The polar reaction constants, ϱ*, have exceptionally large values of approximately −7.
Preparation of adipic acid by oxidation of cyclohexanol and cyclohexanone with nitric acid: Part III. Reaction kinetics of the oxidation
Authors: van Asselt W. J. , van Krevelen D. W. 
Published: September 2010

AbstractThe reaction velocity of the oxidation of cyclohexanol and cyclohexanone with nitric acid (without a catalyst) can be calculated from the chromato‐graphically measured change in the concentration of some of the reaction products: nitrolic acid and adipic acid.The oxidation reaction appeared to be first order in cyclohexanone, which rapidly forms in the oxidation of cyclohexanol. The oxidation rate can be calculated by means of a simple empiric formula.The catalysts NH4VO3 and Cu(NO3)2 do not affect the oxidation rate proper. The rate at which Dione decomposes into adipic acid (kv) in the presence of vanadate can be calculated from the increase of the adipic acid concentration. If vanadate is absent, an impression of the rate at which Dione is further oxidized into by‐products (kH) can be obtained from the increase of the glutaric acid and succinic acid concentrations.
The constitution of the Grignard reagent
Authors: Vreugdenhil A. D. , Blomberg C. 
Published: September 2010

AbstractExperiments are reported on the association number of magnesium bromide, diethylmagnesium, mixtures of these two compounds, the Grignard reagent prepared from magnesium and ethyl bromide and mixtures of this Grignard reagent with magnesium bromide, all dissolved in pure diethyl ether at concentrations from 10−3 to 10−2 molar and measured at the same temperature.No trace of the equilibrium:

was observed.Only one magnesium atom is incorporated in the molecules of the Grignard reagent, even in the presence of a large amount of magnesium bromide.
On the synthesis of isomeric lysophosphatides
Authors: Slotboom A. J. , de Haas G. H. , van Deenen L. L. M. 
Published: September 2010

AbstractThe synthesis is described of two isomeric lysophosphatidylethanolamines, containing the fatty acid residue in the γ‐ and β‐ester position, respectively. The preparation of the (β‐stearoyl)‐DL‐α‐lysophosphatidylethanolamine was accomplished by two procedures. According to the first method developed, a silver iodide interchange reaction was carried out between γ‐O‐benzyl‐β‐stearoylglycerol‐α‐iodohydrin and silver benzyl 2‐phthalimidoethyl phosphate. This procedure was also applied for the synthesis of (γ‐stearoyl)‐DL‐α‐lysophosphatidyl‐ethanolamine by starting from γ‐stearoyl‐β‐O‐benzylglycerol‐α‐iodohydrin. A second method involved the preparation of silver benzyl γ‐O‐benzyl‐β‐stearoyl‐α‐glycerol phosphate which was coupled with 2‐iodoethylphthalimide. This pathway also furnishes several intermediates which are suitable for the preparation of other types of lysophosphatides. A distinction between both structurally isomeric lysophosphatidyl‐ethanolamines by enzymic means proved to be possible. Phospholipase A from snake venom was shown to release the fatty acid constituent from the β‐acyl isomer, whereas the γ‐acyl isomer was not susceptible to the action of this enzyme.
On the impedance of galvanic cells: VI Alternating current polarography in the complex impedance plane: General treatment
Authors: Sluyters‐Rehbach M. , Sluyters J. H. 
Published: September 2010

AbstractThe views developed in parts III and IV of this series are applied to alternating current polarography in the impedance plane. It is shown that from such polarograms a quantity q can be determined which is inversely proportional to concentration. The method covers a concentration range of 5.10−9/n2<C*<3.10−6/n2 for reversible processes and of 10−10/n2ksh <C*<10−7/n2ksh for irreversible processes.
Tin and lead as selective catalysts in the direct synthesis of methylchlorosilanes
Authors: Voorhoeve R. J. H. , Vlugter J. C. 
Published: September 2010

AbstractIn this paper experiments are described in which tin and lead are used as selective catalysts for the synthesis of methyltrichlorosilane (80‐90% yield) and methyldichlorosilane (72% yield), respectively. For the methyltrichlorosilane synthesis, the reaction velocity is given as a function of temperature and conversion of methyl chloride at atmospheric pressure.
Aromatic sulphonation VII: Orientation in the homogeneous sulphonation of toluene in aqueous and fuming sulphuric acid
Authors: Cerfontain H. , Sixma F. L. J. , Vollbracht L. 
Published: September 2010

AbstractThe isomer distribution in the homogeneous monosulphonation of toluene in 77.6‐98.8 wt‐ % aqueous sulphuric acid has been determined at various temperatures between 5 and 65°. Sulphone formation and disulphonation are negligible. The isomer distribution is independent of toluene conversion. The degree of meta‐substitution is low under all conditions. At 25.0° the ratio of o‐ to p‐toluene‐sulphonic acid changes from 0.276 to 1.08 on varying the concentration of sulphuric acid from 77.6 to 98.8 wt‐%; the meta‐isomer shows only a small increase over this acid range. The decrease in the partial rate factor ratio, fp/fm, with increasing sulphuric acid concentration results mainly from an increase in the activation enthalpy difference between para‐ and meta‐substitution. This decrease in fp/fm, is taken as an indication of increasing reactivity of the sulphonating entity.The entropy of activation is greater for para‐substitution than for ortho‐substitution. On varying the sulphuric acid concentration from 77.6 to 95.8 wt‐%, the entropy difference decreases from 8.8 ± 0.2 to 4.8 ± 0.7 cal · degree‐1 · mole‐1 probably because the solvation of the transition state leading to ortho‐substitution decreases with increasing acid concentration. The difference in activation enthalpy between para‐ and ortho‐substitution is 1.3 ± 0.2 kcal · mole‐1, whatever the acid concentration. This enthalpy difference is explained by an intramolecular hyperconjugative proximity effect in the transition state leading to ortho‐substitution.
The autoxidation of mercaptans in non‐aqueous alkaline media
Authors: Berger H. 
Published: September 2010

AbstractThe autoxidation of n‐octyl mercaptan and thiophenol in tert‐butanol containing varying amounts of potassium tert. butoxide, yields as the only products disulfide and/or acids (sulfinic and sulfonic). It appears that disulfide is formed from unionized mercaptan, whereas the acids originate in the mercaptide ion. A mechanism for the formation of the acids is presented, in which the sulfenate anion (RSO−) is an important intermediate. The primary species formed in the reaction of mercaptide ion with oxygen is thought to react preferentially with unionized mercaptan to give the disulfide.
The binary system sulphur trioxide‐selenium trioxide
Authors: Mijlhoff F. C. , Gerding H. 
Published: September 2010

AbstractThe solid‐liquid equilibria present in mixtures of sulphur trioxide and selenium trioxide have been investigated. Homogeneous mixed crystals exist in a wide range of SeO3‐ concentrations up to 100% SeO3. T he system has a eutectic at 15° with a composition of 0.03 mole % SeO3 and 99.97 mole % SO3.The melting point (120.9 ± 0.5°) and the heat of fusion (1.7 kcal/mole SeO3) of pure SeO3 were determined.
Separation of unsaturated dinitrophenylhydrazones into classes
Authors: de Jong K. , Mostert K. , Sloot D. 
Published: September 2010

AbstractUnsaturated dinitrophenylhydrazones with one or more isolated double bonds may, as a class, be separated from saturated, α‐β‐unsaturated or α‐β, γ‐δ‐unsaturated DNPHs by using silicagel impregnated with AgNO3 (column chromatography) or alumina impregnated with AgNO3 (thin layer chromatography).
Efficiency of chromatographic procedures. I. Theory
Authors: de Ligny C. L. , Schmidt H. M. , de Vries W. 
Published: September 2010

AbstractEquations for the efficiency of chromatographic procedures are derived. In contrast to the equation, obtained by Haarhoff and Pretorius, these equations are not restricted to column chromatography and in the derivation the theoretical‐plate concept is not introduced.
Investigations into the conformation of non‐aromatic ring‐compounds IX: The crystal structure of trans‐2,3‐dichloro‐1,4‐dioxan at −145°
Authors: Altona C. , Romers C. 
Published: September 2010

Abstracttrans‐2,3‐Dichloro‐1,4‐dioxan crystallizes in the monoclinic system, space group P21/c, Z = 4, with cell dimensions:a = 7.203 Å, b = 5.704 Å, c = 15.79 Å, β = 107.3° at −145°.The structure was refined in two projections by means of reflexion data obtained at −145° using molybdenum radiation. The dioxan ring has the chair conformation; the chlorine atoms occupy axial positions.
Chemistry of acetylenic ethers 68: Preparation of enynes by elimination of alcohol from acetylenic ethers
Authors: Brandsma L. , Montijn P. P. , Arens J. F. 
Published: September 2010

AbstractAcetylenic ethers of the types RCH2CCCH2OR′ and RCH2CH2CCOR′ have been converted into alkenynylides RCHCHCCNa and alkoxides R′ONa by treatment with two moles of sodamide in liquid ammonia.
Cardiolipin and derivatives: I. Synthesis of an acyl derivative of diphosphatidylglycerol
Authors: de Haas G. H. , van Deenen L. L. M. 
Published: September 2010

AbstractThis paper describes the synthesis of a long‐chain fatty acyl ester of diphosphatidylglycerol. The properties of this compound were compared with those of natural cardiolipin isolated from ox‐heart. Although both substances display a very similar behaviour, they are not identical.
On Criegee's mechanism of ozonisation: The isolation of the six possible ozonides from methyl oleate
Authors: Riezebos G. , Grimmelikhuysen J. C. , van Dorp D. A. 
Published: September 2010

AbstractOzonisation of methyl oleate in light petroleum at 10° yielded six ozonides. They were characterised as the three possible pairs of “cis‐” and “trans‐” isomers, which can be predicted on the basis of Criegee's theory. Our results indicate that a complete breakdown occurs of the oleate molecule into “zwitter‐ionic” and aldehydic fragments. Hence we exclude a mechanism proposed by Milas, where a complete breakdown of the molecule does not take place.
Polysubstituted monocyclic boroxazolidines
Authors: Zimmerman Howard K. , Jones David A. 
Published: September 2010

AbstractSix new substituted aminoethyl esters of hydroxydiphenylborane are described.In contrast to the behaviour of triptych boroxazolidines, in which subsituents in the amino‐alcohol carbon atoms are associated with increased resistance of the boroxazolidine towards acidic hydrolysis, increased substitution among the monocyclic boroxazolidines is associated with increased lability in acidic solutions.
Hydrazine derivatives of pyridylacetic acids
Authors: Bojarska‐Dahlig H. N. 
Published: September 2010

AbstractA series of hydrazine derivatives of 2‐, 3‐ and 4‐pyridylacetic acids has been prepared by catalytic hydrogenation of aldehyde or ketone pyridylacetyl‐hydrazones and tested in vitro for MAO inhibition. Compounds derived from benzylhydrazine were the most active MAO inhibitors in vitro.
Nitration of α‐chloronaphthalene‐α‐sulphonic acids
Authors: Bassilios H. F. , Shawky M. , Salem A. Y. , Mohtasseb I. F. 
Published: September 2010

AbstractNitration of α‐chloronaphthalene‐α‐sulphonic acids using mixed acids or fuming nitric acid gives α‐substituted nitro derivatives. The deactivation of the aromatic nucleus by the two electrophilic groups is increased as the sulphonic group passes from the 4‐ to the 5‐ and finally to the 8‐position.
Phosphatidic acids and derivatives: XIII. Synthesis and alkaline hydrolysis of tris(2‐stearoyloxyethyl) phosphate
Authors: van Gijzen J. , Hoefnagel M. A. , Verkade P. E. 
Published: September 2010

AbstractWe describe the preparation of tris(2‐stearoyloxyethyl) phosphate, starting from monostearoylglycol (2‐stearoyloxyethanol) and phosphorus oxychloride and from silver bis(2‐stearoyloxyethyl) phosphate and stearoylglycol iodohydrin. The alkaline hydrolysis of the first‐mentioned compound is investigated.
Chemistry of acetylenic ethers 71: Acetylenic benzyl ethers and their rearrangement into 2‐indanones
Authors: Olsman H. , Graveland A. , Arens J. F. 
Published: September 2010

AbstractAcetylenic benzyl ethers, IV, with R  CH3 or C2H5 and R′  H or CH3 have been prepared according to the scheme below. These compounds rearrange very easily into 1,3‐dialkyl‐2‐indanones, V, on refluxing in tetrachloromethane and into 1‐hydroxy‐1‐phenyl‐2‐alkynes with sodamide in liquid ammonia.
Chemistry of acetylenic ethers 72: Nucleophilic substitutions at sulphur and selenium in some alkynyl thioethers and alkynyl selenoethers
Authors: Brandsma L. 
Published: September 2010

AbstractUnder the catalytic influence of bases, such as sodamide and sodium acetylide dissolved in liquid ammonia, ethylselenoacetylene, HCC‐SeC2H5, disproportionates into bis(ethylseleno)acetylene, C2H5SeCCSeC2H5, while ethylthioacetylene remains unchanged under the same conditions. Bis(ethylseleno)acetylene and bis(ethylthio)acetylene react with phenyl‐lithium in ether. The selenoether gives lithium ethylselenoacetylide, LiCCSeC2H5 or dilithium acetylide LiCCLi and ethyl phenyl selenide, C6H5SeC2H5, while the thioether is converted into lithium ethylthioacetylide, LiCCSC2H5 or dilithium acetylide and ethyl phenyl sulphide, C6H5SC2H5, and some phenylacetylene. Ethers of the type RCCSC2H5, in which R represents a tertiary butyl group or a phenyl group, are smoothly cleaved by a solution of potassium amide in liquid ammonia, RCCK being produced.