bluuebunny/crossref_metadata_2025 huggingface dataset:
Triazine isocyanates: Part II: Reaction of 2,4‐diamino‐s‐triazines with ethyl chlorocarbonate
Authors: Duynstee E. F. J. , Veerkamp Th.
Published: September 2010

Benzoguanamine (2,4‐diamino‐6‐phenyl‐s‐triazine) and acetoguanamine (2,4‐diamino‐6‐methyl‐s‐triazine) both react with an excess of ethyl chlorocarbonate; in this reaction two hydrogen atoms from the guanamines are replaced by two carbethoxy groups. The I.R. spectrum reveals that this double substitution takes place on one amino group; in consequence, the resulting compounds are derivatives of iminodicarboxylic acid diethyl ester. Upon heating above the melting point, the compounds decompose, during which process a very short occurrence of isocyanate absorption can be observed in the I.R. spectrum.
The structure of AuCl.PCl3
Authors: Arai Gerda J.
Published: September 2010

So far no members of the group of coordination compounds in which PCl3 acts as a donor molecule have been investigated crystallographically, although many such compounds are known to exist. We have studied the structure of a relatively simple representative of this group, AuCl·PCl3. Univalent gold is always found to have a linear coordination, even when the analogous copper and silver complexes show a tetrahedral coordination of the metal atom. AuCl·PCl3 is no exception and also shows a linear configuration at the gold atom.
Mechanism of reactions of unsaturated ethers and thioethers. V: Dipole moments of acetylenic ethers and thioethers
Authors: Drenth W. , Hekkert G. L. , Zwanenburg B. G.
Published: September 2010

Electric dipole moments of the following compounds have been measured in benzene solution:

HC≡COCH(CH3)2, HC≡COC(CH3)3, H3CC≡COC(CH3)3

H5C2C≡COC(CH3)3, (H3CC≡C)2S, (H5C2C≡C)2S, H3CC≡CSC2H5

HC≡CSC2H5 and H2C≡CHSC2H5.

Probably, hyperconjugation between R′ and the triple bond occurs in R′C≡COR. The charge shift due to the resonance structure R′C−=C=S⊕R, is smaller in the sulphur compounds than in the analogous oxygen compounds, but its quantitative value could not be estimated.
Addition of water to tertiary butyl carbylamine
Authors: Drenth W.
Published: September 2010

Tertiary butyl carbylamine was hydrated in aqueous solution under the catalytic influence of phosphoric acid buffers and of perchloric acid at 25°. The reaction is general acid catalyzed.
Über Aromaten‐Komplexe mit Titan‐Auminiumchloriden
Authors: de Vries Harmen
Published: September 2010

Martin und Vohwinkel1 haben gezeigt, dass sich die von Natta und Mitarbb.2 als Al2T1IICl8·C6H5 angesprochene Verbindung aus TiCl2, 2 AlCl3 und C6H6 zusammensetzt. Es werden noch zwei Argumente zur Unterstützung dieser Formulierung angeführt.
Hydrolysis of 2‐substituted 4,6 dichloro‐1,3,5‐triazines
Authors: Koopman H.
Published: September 2010

The hydrolysis of the 2‐substituted 4,6‐dichloro‐1,3,5‐triazines was investigated in a mixture of water and acetone. The reaction constant of the hydrolysis of the first chlorine atom was determined, and is discussed in relation to the structure of the triazine derivatives.
Chemistry of acetylenic ethers LVI Di‐(alk‐1‐ynyl) ethers and thioethers
Authors: Brandsma L. , Arens J. F.
Published: September 2010

A number of di‐(alk‐1‐ynyl) thioethers VIII have been synthesized using reaction scheme 1. Except for diethynyl ether VI the compounds are relatively stable.

Reaction scheme 2 has been used to synthesize di‐(prop‐1‐ynyl) ether, a substance exploding at room temperature. An attempt to prepare (HC≡C)2O failed; this substance seems to be unstable even at −70°.
Chemistry of acetylenic ethers LVIII: Alkylthiolation of chloroethyne and ethoxyethyne (with a note on alkylthiolations in liquid ammonia)
Authors: Nooi J. R. , Arens J. F.
Published: September 2010

Conversions of chloroethynyllithium into 1‐chloro‐2‐(ethylthio)ethyne and of ethoxyethynyllithium into 1‐ethoxy‐2‐(ethylthio)ethyne have been effected with the thiolsulphonate C2H5SSO2C2H5 in liquid ammonia. 1‐Ethoxy‐2‐(ethylthio)ethyne is unstable and decomposes even at 0°. Attention is drawn to the fact that ammonia can also be alkylthiolated.
Chemistry of acetylenic ethers. LIX: Alk‐1‐enyl alk‐1‐ynyl ethers, thioethers and selenoethers
Authors: Brandsma L. , Arens J. F.
Published: September 2010

The compounds listed in tables I and II have been prepared by the reaction schemes A, B and C.

Acid hydrolysis of vinyloxyethyne produces vinyl acetate. Rearrangement of 3‐hydroxy‐3‐methyl‐1‐vinyloxy‐1‐butyne XIV by acid gives the vinyl ester of 2,2‐dimethylacrylic acid XV.
Practical notes on the preparation of p‐anisyltrithione
Authors: Rekker R. F. , Reiding D. J. , Mulder D. , Nauta W. Th.
Published: September 2010

When large quantities of p‐anisyltrithione are to be synthesized, the purification of the product presents great difficulties and consequently the yield of purified product is very disappointing. The present article suggests a few changes which can easily be incorporated into the original method of Böttcher and Lüttringhaus.
Mechanism of reactions of unsaturated ethers and thioethers.: VI. Nuclear magnetic resonance studies of acetylenic ethers and thioethers
Authors: Drenth W. , Loewenstein A.
Published: September 2010

The position of the acetylenic hydrogen in the n.m.r. spectra of several acetylenic ethers and thioethers was measured in carbon tetrachloride, benzene and dioxan. 1‐Hexyne and 1,5‐hexadiyne were taken as reference compounds. The results prove the existence of a large charge shift in acetylenic ethers, due to resonance. There is no appreciable charge shift in acetylenic thioethers.

The rates of acetylenic hydrogen exchange in some of these compounds and in tert. butylacetylene, were also measured as a function of base concentration. The rates are highest in the sulphur compounds and lowest in tert. butylacetylene. They decrease with increasing dielectric constant of the solvent. The results are interpreted in terms of inductive effects and resonance structures of the anions.
Acetylation of anthracene by the Friedel‐crafts reaction using chloroform as the solvent
Authors: Bassilios H. F. , Shawky M. , Salem A. Y.
Published: September 2010

Acetylation of anthracene by the Friedel‐Crafts Reaction using chloroform as the solvent leads to a high yield of 9‐acetyl or 1,5‐diacetylanthracene.
Studies in antibacterials ‐ Part III. Synthesis of some halogenochalkones
Authors: Vernekar S. S. , Rajagopal S.
Published: September 2010

The synthesis of some halogenochalkones having appreciable antibacterial activity is recorded. These chalkones have been characterised by the preparation of appropriate derivatives and conversion into the corresponding flavonols.
The resolution of DL‐4‐oxalysine
Authors: Tesser G. I. , Nivard R. J. F. , Gruber M.
Published: September 2010

Both enantiomorphs have been isolated from racemic Nα, Nδ‐diphthaloyl‐4‐oxalysine in optically pure form via brucine salts and converted into (+)‐and (‐)‐4‐oxalysine by acid hydrolysis.

(‐)‐4‐Oxalysine has a negative Cotton‐effect from which we conclude that this stereoisomer possesses the D‐configuration. This conclusion is corroborated by the formation of a quasi‐racemic compound between (+)‐Nα, Nδ‐diphthaloyl‐4‐oxalysine, stereochemically corresponding to (‐)‐oxalysine, and Nα, Nδ‐diphthaloyl‐L‐4‐thialysine.
Syntheses of 2,6‐DI‐t‐Butylpyridine‐3‐and −4–sulphonic acids
Authors: van der Plas H. C. , den Hertog H. J.
Published: September 2010

Syntheses of 2,6‐di‐t‐butylpyridine‐3‐ and −4‐sulphonic acids proving the structure of these compounds are described. They were carried out in order to confirm that during the sulphonation of 2,6‐di‐t‐butylpyridine at low temperature the sulphonic acid group enters the 3‐position.
Binary systems with water as second component. I. The system calcium cyclamate (cyclohexylsulphamate)‐ water
Authors: Broers P. M. A. , van Oeveren W. J.
Published: September 2010

A large part of the phase diagram of this system has been determined, and the following compounds occur: Calcium cyclamate 5 aq, 2 aq and 2/3 aq.

The dihydrate occurs in two modifications, α‐ and β‐, which change into one another at 79.6 ± 0.2°.
The lowering of the three‐phase equilibrium temperature in a binary system upon addition of a third component
Authors: Pieroen A. P. , Korvezee A. E.
Published: September 2010

In a binary system A‐B, wherein a solid compound ABn occurs beside a liquid phase consisting mainly of B and a gaseous phase consisting mainly of A, the three‐phase equilibrium temperature and pressure are interdependent. At a given pressure the addition of a third component C causes a lowering of the equilibrium temperature, already discussed in a previous article on gas hydrates1 and for which the general equation (VI) is now derived. Under specified conditions this equation may be simplified. The calculation of the standard heat of formation ΔH° to be used in this general equation is given in another previous paper 2. When the compound is formed from two immiscible liquid layers, instead of from a gaseous phase and a liquid one, similar considerations are valid.
X‐Ray diffraction studies on the structure of water
Authors: Heemskerk J.
Published: September 2010

The X‐ray diffraction of water was measured at 0°, 25° and 45°. An improved method has been used for the calculation of the distribution functions from the experimental data. This method was checked on the data for vitreous SiO2

The interpretation of the distribution curves for water leads to a model for the “structure” of water in which the average configuration around the molecules is described in terms of a short‐range octahedral arrangement.
The thermal decarboxylation of alkali trichloroacetates in aprotic solvents VThe decarboxylation and its catalytic effect on the decomposition of trichloroacetic anhydride
Authors: Wagner W. M. , Kloosterziel H. , van der Ven S. , Bickel A. F.
Published: September 2010

Thermal decarboxylation of sodium trichloroacetate in 1,2‐dimethoxyethane yields NaCl, CO2, CO, CCl4, perchloroisopropenyl acetate (I) and perchloro‐1,2‐dimethylenecyclobutane (II). Strong evidence is presented for the intermediate formation of trichloroacetic anhydride. This compound was found to be decomposed to CO2, CCl4, I and II by heating with CCl3COONa in 1,2‐dimethoxyethane.

The mechanisms of these reactions are discussed.
Chemistry of α‐diazosulphones: Part I. Preliminary Communication
Authors: Strating J. , van Leusen A. M.
Published: September 2010

The preparation of the first representative of the hitherto unknown α‐diazosulphones, RSO2CHN2, is described.
Determination of the order of a reaction and calculation of the initial rate by absorption spectroscopy
Authors: Koning H. N. , van Senden K. G.
Published: September 2010

The determination of the order of a chemical reaction using linear functions obtained from absorption spectroscopic data is described. The calculation of the initial rate by this method is given.
Crystallization chromatography of glycerides
Authors: van den Tempel M. , de Bruyne P. , Mank A. P. J.
Published: September 2010

Mixtures of high‐melting glycerides can be separated into their constituents by means of a chromatographic process resembling repeated fractional crystallization. Use is made of a column in which a temperature gradient is established, and of solvent mixtures with gradually increasing solvent power. The principle of the method is briefly discussed, and examples are given of the analysis and purification of synthetic glycerides, and the isolation of “pure” triglycerides from natural products.
A study of some biphenylamines: Part I. The electronic spectra in acidic solvents of some biphenylamines
Authors: Dieteren H. M. L. , Koningsberger C.
Published: September 2010

The K‐bands in the ultraviolet absorption spectra of meta and para substituted biphenylamines, dissolved in acidic media, appear to be essentially identical with each other and with that of their parent compound, biphenyl. Apparently the electronic interaction of the two aromatic rings is not markedly disturbed by the mere presence of positively charged ammonium groups, provided the molecules are able to assume a planar structure. As can be expected, however, appreciable hypsochromic shifts of the K‐bands become manifest when one or more of these groups are located at the ortho positions. Moreover, a buttressing effect is observed in the case where ammonium groups are present simultaneously in adjoining meta positions.

A discussion of results takes into account both steric and electrostatic factors operating between the groups involved.
Über die basischen Inhaltsstoffe des Fliegenpilzes: XI. Mitteilung über das Muscaridin und Seine Stereoisomeren
Authors: Salemink C. A. , Schuller P. L.
Published: September 2010

This communication contains a description of the isolation of muscaridine from Amanita muscaria L. The constitution of muscaridin is established as erythro‐4,5‐dihydroxy‐n‐hexyltrimethylammoniumchloride. The synthesis, starting from 2,3‐dihydropyran, leads to racemic muscaridine. The resolution of racemic muscaridine succeeded with di‐p. toluyl‐L‐ tartaric acid and with di‐p. toluyl‐D‐tartaric acid. The synthetic product has the same RF‐value, a fully identical infrared spectrum and equal optical rotation as the natural base. The syntheses of threo‐4,5‐dihydroxy‐n‐hexyltrimethylammoniumchloride and of 5‐hydroxy‐n‐hexyltrimethylammoniumchloride are described as well.
Microbiological conversion of 19‐nortestosterone: (V) 6β‐ and 14α‐hydroxylation
Authors: de Flines J. , van der Waard W. F. , Mijs W. J. , van Dijck L. A. , Szpilfogel S. A.
Published: September 2010

The microbiological reactions of 19‐nortestosterone with Helminthosporium kusanoi leading to the 6β‐hydroxy‐derivative and with Helminthosporium buchloes leading to the 14α‐hydroxy‐derivative are described.
Synthesis of some α,β‐unsaturated sulphones with potential acaricidal properties
Authors: Gerstenfeld M. , van Zwieten P. A. , Huisman H. O.
Published: September 2010

The preparation of two α, β‐unsaturated sulphones with potential acaricidal properties is described.
Acetylation of anthracene by the Friedel‐crafts reaction using ethylene chloride as the solvent
Authors: Bassilios H. F. , Shawky M. , Salem A. Y.
Published: September 2010

Acetylation of anthracene by the Friedel‐Crafts Reaction using ethylene chloride as the solvent leads to a high yield of 1‐acetylanthracene. Diacetylation gives a mixture of 1,5‐ and 1,8‐diacetylanthtacene. Oxidation to the corresponding acetylanthraquinones and carboxylic acids is described.
The conversion of acylglycol‐iodohydrins into monoacylglycols with the aid of metal salts in a mixture of acetone and water
Authors: Boeree C. H. , Hoefnagel M. A. , Verkade P. E.
Published: September 2010

It was already known that monoacylglycols can be obtained readily and in very good yields by boiling a solution of the corresponding acylglycol‐iodohydrin and an appropriate silver salt (nitrite or nitrate) in a mixture of ethanol and water. We have now found that mercury(II) salts and palladium(II) salts are equally suitable for this purpose. When salts were used of a great many other metals, distributed as widely as possible over the whole periodic table, under identical experimental conditions the reaction did not take place, or at least not to an extent that could be clearly demonstrated by us. A discussion is devoted to these facts.
Preparation of adipic acid by oxidation of cyclohexanol and cyclohexanone with nitric acid: Part II. Reaction kinetics of the decomposition of 6‐hydroxyimino‐6‐nitro hexanoic acid
Authors: van Asselt W. J. , van Krevelen D. W.
Published: September 2010

The stablest intermediate product formed in the oxidation of cyclohexanol and cyclohexanone is 6‐hydroxyimino‐6‐nitro hexanoic acid (nitrolic acid). In the temperature range investigated it yields over 90% of adipic acid and N2O. In addition, a small amount of a still unidentified by‐product is formed at low temperatures; upon heating, the latter gives also adipic acid.

The decomposition reaction appeared to be first‐order in nitrolic acid. Nitric acid greatly influences the reaction rate; in the range of concentrations up to 50% HNO3, the first‐order rate constant was found to be linearly dependent on the hydrogen‐ion activity. The activation energy of the reaction amounts about 24,000 cal/gmol.
Preparation of some 3‐benzylthiophenes from alkylbenzenes
Authors: Kooyman E. C. , Kroon J. B. H.
Published: September 2010

3‐Benzyl, 3‐α‐methylbenzyl, and 3‐α‐dimethylbenzylthiophene were prepared from the sodium salts of the corresponding benzylsuccinic acids and phosphorus trisulphide in 20–40% yields. The succinic acids were obtained through side‐chain addition of toluene, ethylbenzene, and isopropylbenzene, respectively to maleic anhydride.
The chemistry of sulfenyl halides: Part II: Photochlorination of alkanes with trichloromethylsulfenyl chloride
Authors: Kloosterziel H.
Published: September 2010

When solutions of trichloromethylsulfenyl chloride, Cl3CSCl, in alkanes are exposed to sunlight, alkyl chlorides, hydrogen chloride and hexachlorodimethyl disulfide are formed:

An advantage of this novel chlorination method is the high selectivity, which is even further increased in the presence of benzene. The disulfide may be reconverted to the sulfenyl chloride by molecular chlorine in a separate step.

A radical chain mechanism is proposed for the reaction in which trichloromethylthiyl and alkyl are the chain‐carrying radicals.
Spiranes: II. The synthesis of carbocyclic polyspiranes with six‐membered rings. Preliminary communication
Authors: de Jongh H. A. P. , Wynberg Hans
Published: September 2010

Using the double Michael condensation technique with divinyl ketone recently described1, as well as the dialkylation method2, we have prepared the compounds I, II and III. No syntheses of linear dispiro‐ and trispiro‐hydrocarbons embodying the 6‐membered carbocyclic ring only, have yet been reported 3, 4, 5.
Reactions of ortho‐esters of germanium: Part IV Reactions of alkyl orthogermanates with acetyl chloride
Authors: Mehrotra R. C. , Chandra G.
Published: September 2010

Reacting alkyl orthogermanates with acetyl chloride in different stoichiometric ratios results in almost quantitative yields of compounds of the type (RO)xGeCl4‐X, where x is 2 or 3 and R=C2H5‐, iso‐C3H7‐ or n‐C4H9‐. Monoalkoxy trichloro derivatives, (RO)GeCl3 can be conveniently prepared by refluxing appropriate alkyl orthogermanates with excess germanium tetrachloride.
The cryoscopic behaviour of phenols in ethanolamine
Authors: Baliah V. , Ramakrishnan V.
Published: September 2010

The cryoscopic behaviour of some phenols in ethanolamine has been studied. The experimental data indicate that phenols react with ethanolamine forming ion‐pairs which dissociate only partially in ethanolamine.
The chemistry of cycloheptatriene: Part VII: Thermal isomerization of 7‐deuterocycloheptatriene by trans‐annular 1‐5 shifts of hydrogen
Authors: ter Borg A. P. , Kloosterziel H. , van Meurs N.
Published: September 2010

7‐Deuterocycloheptatriene ‐ prepared from tropylium bromide and lithium aluminium deuteride in 94% isotopic purity ‐ rearranges on heating at 100‐140°. Mass spectrometry and proton magnetic resonance (NMR) spectroscopy showed that by an intramolecular process a mixture of the 7‐, α‐, β‐ and γ‐monodeuterocycloheptatrienes is formed. The changes in shape and intensity of the NMR signals proved that these isomers arise in successive steps, each of which involves a trans‐annular 1‐5 shift of hydrogen, combined with a shift of two double bonds. The Arrhenius parameters of the shift are E = 31‐32 kcal/mole and log A (s−1) = 10.9‐11.5. In transition‐state theory this corresponds with an appreciable negative entropy of activation, indicating a rigid transition state.

A number of known isomerizations in 7‐membered ring systems, particularly those of the Buchner esters and acids, can be explained by a trans‐annular 1‐5 shift.
Studies in the zinc reduction series: The reduction of certain 2‐benzoylbenzoic acids and esters
Authors: Risinger Gerald E. , Thompson James A.
Published: September 2010

The reaction mechanism of the reduction o certain 2‐benzoylbenzoic acids and esters is discussed. It is suggested that the carboxyl group directs product formation either by neighboring group participation or by facilitating the hydrogenolysis of the carbinol group. Furthermore, it is concluded that the intermediate in the reduction of the esters does not contain a carbinol group.
A study of the polarographic reduction of the acridizinium and phenanthridizinium ions
Authors: Frost Jackie G. , Saylor John H.
Published: September 2010

The properties of acridizinium and phenanthridizinium at the dropping mercury electrode have been investigated, and a mechanism for reduction is proposed. Acridizinium is reduced in two one‐electron stages at potentials of −0.807 volts and −1.022 volts in acid and neutral solutions, these values being independent of pH. In basic solution, these two reduction steps disappear and two other waves appear at potentials of approximately −1.5 volts and −2.1 volts (vs. saturated calomel electrode). This change in polarographic behavior has been linked with “pseudo‐base” formation. Phenanthridizinium is reduced in a single two‐electron step with a measured half‐wave potential of −1.202 volts. The reduction potential is independent of pH.
Addition of carbonyl compounds to alkynes under the influence of boron trifluoride
Authors: Bos H. J. T. , Arens J. F.
Published: September 2010

α,β‐Unsaturated ketones are formed by reaction of aldehydes and ketones with phenylethyne under the influence of boron trifluoride. When using aromatic aldehydes 2,4,6‐triarylpyrylium tetrafluoroborates are formed as by‐products. trans‐2,3‐Diphenylindane‐1‐one is obtained from 1,2‐diphenylethyne and benzal‐dehyde.
Mechanism of reactions of unsaturated ethers and thioethers XIII: Reaction of 1‐ethoxy‐1‐alkynes with carboxylic acids in non‐aqueous solvents
Authors: Zwanenburg B. , Drenth W.
Published: September 2010

The reaction between 1‐ethoxy‐1‐alkynes and carboxylic acids has been studied in non‐aqueous solvents. The first stage of this reaction, the formation of 1‐ethoxyvinyl esters, is described in this paper. The kinetics of the reaction in benzene follow the rate equation

v = k03·C1‐alkynyl ether·C2acid

whereas in dioxan and sulpholane the equation

v = (k03·C2acid + k4·C3acid) C1‐alkynyl ether

is obeyed. A considerable rate increase was observed on varying the solvent from dioxan to sulpholane, while the rate in benzene is approximately equal to that in sulpholane. From measurements on the reaction of ethoxyethyne and either normal or O‐deuteroacetic acid in benzene a kinetic isotope effect, kH/kD, of 3.1 was observed. In sulpholane as solvent kH/kD was equal to 2.8. Infrared spectra of reaction mixtures of ethoxyethyne and O‐deuteroacetic acid showed that no incorporation of deuterium into ethoxyethyne occurred during reaction in benzene and sulpholane, whereas it did occur in dioxan. The effect of added tetrabutylammonium perchlorate on the rate of reaction of ethoxyethyne and chloroacetic acid in dioxan was also studied. The rates of a number of 1‐alkynyl ethers were correlated with a Taft‐equation.

It was concluded that proton transfer occurs in the rate determining step in which an ion pair is formed. Before protonation the substrate is solvated by acid molecules in a number of pre‐equilibria.
Total synthesis of aza‐steroids I: d,l‐N‐Tosyl‐6‐aza‐8,14‐bisdehydroestrone methyl ether and d,l‐N‐tosyl‐6‐aza‐8,14‐bisdehydro‐D‐homoestrone methyl ether
Authors: Huisman H. O. , Speckamp W. N. , Pandit U. K.
Published: September 2010

A three step synthesis of the key intermediate (IV) for the total synthesis of 6‐aza‐19‐norsteroids is described.
Physical properties of organic thiones: Part V. Effect of substituents with thiocarbonyl functions on acid strength
Authors: Janssen M. J.
Published: September 2010

The acid dissociation constants of a number of substituted acetic acids were determined. Compounds were of the general type AC = X—BCH2COOH with A methyl, alkoxy, alkylthio or dimethylamino, X oxygen or sulphur, B oxygen, sulphur or nitrogen. The influence of the substituent AC(X)B upon the acidity is related to electronic (mesomeric and inductive) effects. In one instance complication by steric effects arises. The main results support the model, previously conceived for thiones with heteroatoms attached to the thiocarbonyl group: extensive mesomeric electron displacements together with appreciable contributions from inductive shifts, the latter especially noteworthy, where sulphur is concerned. In the molecules studied the thiocarbonyl group is more electron‐attracting than the carbonyl group.
Synthesis of arachidonic acid and related higher unsaturated compounds
Authors: van der Steen D. , Pabon H. J. J. , van Dorp D. A.
Published: September 2010

The usefulness of hexa‐2,5‐diyn‐1‐ol as an intermediate in the synthesis of arachidonic acid, poly‐yn alcohols and docosa‐4,7,10,13,16,19‐hexaynoic acid is demonstrated. Difficulties in the partial reduction of the latter product to the corresponding all cis‐hexaenoic acid are described.
The conformation of the red form of 2,2′‐methylenediquinoline
Authors: van Thuijl J. , Romers C. , Havinga E.
Published: September 2010

The studies by Scheibe and his coworkers revealed that the conformation of the red form of 2,2′‐methylenediquinoline (I) is di‐cis. This paper reports a direct proof of the conformation of the red form of 8‐bromo‐2,2′‐methylenediquinoline (III) by X‐ray analysis.
Chemistry of acetylenic ethers, 67: Allenyl thioethers from alkynyl thioethers
Authors: Brandsma L. , Wijers H. E. , Arens J. F.
Published: September 2010

The isomeric allenyl thioethers, III, are produced in good yield by treating 1‐ethylthio‐1‐alkynes, I, with an equivalent amount of sodamide in liquid ammonia, followed by hydrolysis of the reaction mixture.

The corresponding allenyl thioethers alkylated in the 1‐position, IV, are obtained, also in good yield, by adding primary or secondary alkyl halides to the reaction product of sodamide and 1‐ethylthio‐1‐alkynes, I.
Investigations into the conformation of non‐aromatic ring‐compounds X: The crystal structure of trans‐2,3‐dibromo‐1,4‐dioxan at −100°
Authors: Altona C. , Knobler Carolyn , Romers C.
Published: September 2010

trans‐2,3‐Dibromo‐1,4‐dioxan crystallizes in the orthorhombic system, space group P212121, Z = 4, with cell dimensions: a = 5.685, b = 7.59, c = 15.82 Å at −100°.

The structure was refined in two centrosymmetric projections by means of reflexion data obtained at −100° using copper radiation. The dioxan ring has the chair conformation; the bromine atoms occupy axial positions.
Chemistry of acetylenic ethers 69: A new synthesis of di‐(alk‐1‐ynyl) thioethers
Authors: Brandsma L.
Published: September 2010

Di‐(alk‐1‐ynyl) thioethers IV have been prepared from 2,2′‐dichlorodivinyl thioether II by converting this compound into metallated diethynyl thioether by means of four equivalents of sodamide in liquid ammonia, followed by alkylation. The starting material II was obtained in a high yield by partial dehydrochlorination of the adduct I from vinyl chloride and sulphur dichloride. The overall yields are very satisfactory.
Gas phase pyrolysis of alkyl acetates
Authors: Scheer J. C. , Kooyman E. C. , Sixma F. L. J.
Published: September 2010

An investigation was made into the thermal decomposition of twenty‐seven aliphatic acetates, using a micro‐scale flow reactor connected to a gas chromatograph. The rate of elimination increases markedly as the degree of alkylation of the α‐carbon atom becomes higher. The accelerating effect of β‐alkyl substituents on the rate of elimination is small, as compared with that of α‐alkyl substituents. The reactivity of the aliphatic acetates approaches a limiting value as the carbon chain is extended. The reactivity decreases on the introduction at the β‐carbon atom of an electron‐attracting group and increases on the introduction of an electron‐releasing group. A tentative mechanism is proposed which is based on the reversible formation of an ion‐pair.
The chemistry of cycloheptatriene: Part IX: Thermal interconversion of 2,7‐ and 2,3‐dihydrotropone by transannular 1‐5 shifts of hydrogen
Authors: ter Borg A. P. , Kloosterziel H.
Published: September 2010

2,7‐Dihydrotropone upon heating at 60‐100deg; isomerizes (partly) to the 2,3‐isomer. Kinetic data: order of the reaction, influence of solvent and entropy of activation, point to a mechanism involving an intramolecular 1‐5 shift of hydrogen in this cycloheptadiene derivative.
Investigations on syntheses “under physiological conditions”: I. Comparison of the behaviour of ammonia and methylamine as one of the reaction components
Authors: Beyerman H. C. , Enthoven P. H. , Verkade P. E.
Published: September 2010

The behaviour of the following six combinations of compounds has been studied “under physiological conditions”: glutaraldehyde or succinaldehyde, methylamine or ammonia, acetonedicarboxylic acid or diethyl acetonedicarboxylate. The pH was maintained at 3, 5, 7, 10 or 13; the other experimental conditions were the same in the series with acetonedicarboxylic acid and in those with diethyl acetonedicarboxylate as reaction component. The yield of reaction product was in each case determined carefully.

Ammonia proved to be well suited as reaction component in these Schöpf syntheses. The relation between the pH and the yield of reaction product in the six cases was discussed in detail; ammonia and methylamine proved to behave in the same way.
Pyrones et Pyronones. I. Carboxy‐3 phényl‐6 pyrone‐2 et carboxy‐6 phényl‐3 pyrone‐2
Authors: van Dam Mathieu J. D.
Published: September 2010

6‐Phenyl‐2‐pyrone‐3‐carboxylic acid has been prepared by acid hydrolysis of its ethyl ester and by the action of sulfuric acid on its isomer, 2‐carboxy‐5‐phenyl‐2‐penten‐4‐yn‐1‐oic acid. The distinction between these two isomers and a third, 2‐carboxy‐5‐phenyl‐2,4‐pentadien‐(1,4)olide, is set forth. A fourth isomer, 3‐phenyl‐2‐pyrone‐6‐carboxylic acid, has been synthesized by acid hydrolysis and cyclization of diethyl 2‐hydroxy‐5‐phenylmuconate.
Pyrones et Pyronones. II Synthèse d'alcoyl‐6 pyrones‐2 par réduction d'alcoyl‐6 pyronones
Authors: van Dam M. J. D. , Kögl F.
Published: September 2010

By reaction of triacetic lactone with phosphoryl chloride 4‐chloro‐6‐methyl‐2‐pyrone was prepared; this happened to be identical with a compound of uncertain structure, previously obtained from acetyl chloride and 1,1‐dichloroethene. Reductive dechlorination yielded 6‐methyl‐2‐pyrone.

Both 6‐cyclopentyl‐3‐cyclopentylcarbonyl‐4‐hydroxy‐2‐pyrone and 6‐cyclopentyl‐4‐hydroxy‐2‐pyrone were prepared by conventional methods; they have bacteriostatic properties. By chlorination and reduction of the latter compound 6‐cyclopentyl‐2‐pyrone was obtained.

The mechanism of these substitution reactions is discussed.
Investigations on selective bromination of tertiary hydrogen atoms in alicyclic compounds
Authors: Siegmann R. H. , Beers M. J. , Huisman H. O.
Published: September 2010

Investigations are described on selective bromination of tertiary hydrogen atoms in alicyclic compounds by radical halogenation with molecular bromine.

Isopropylcyclopentane, isopropylcyclohexane, bicyclopentyl and bicyclohexyl have been chosen as simple model systems.

From the first two compounds the corresponding di‐tertiary 1,6‐dibromoisopropylcyclopentane and 1,7‐dibromoisopropylcyclohexane, respectively, were obtained in good yields.

The structure of both these substances has been elucidated by degradation reactions as well as by independent syntheses; N.M.R.‐spectra also provide confirmatory evidence for the structures assigned to the di‐tertiary dibromo compounds.

The tertiary hydrogen atoms in bicyclopentyl and bicyclohexyl cannot be brominated selectively; in both cases higher brominated compounds are obtained as the main products.
The mechanism of the formation of 10‐D‐Chlorosulphoxide‐camphor
Authors: Strating J.
Published: September 2010

A mechanism for the formation of 10‐D‐chlorosulphoxide‐camphor is proposed and its meaning for a possible preparation of thioaldehyde and thioketone oxides put forward.
Alkaloids in Pausinystalia yohimbe (K.Schum.) ex pierre: Part I. The paper‐chromatographic identification of alkaloids occurring in some yohimbine‐containing barks
Authors: van der Meulen Th. Hajonides , van der Kerk G. J. M.
Published: September 2010

The simultaneous use of two solvent systems allows of an easy chromatographical identification of yohimbine and a number of related alkaloids in extracts from several yohimbine‐containing barks. By using these solvent systems the occurrence of two unknown alkaloids was demonstrated.
Alkaloids in Pausinystalia yohimbe (K.Schum.) ex pierre: Part III. The structure of a new alkaloid
Authors: van der Meulen Th. Hajonides , van der Kerk G. J. M.
Published: September 2010

The structure has been determined of a new alkaloid isolated from barks of Pausinystalia yohimbe. The compound is tetrahydro‐desmethyl‐corynantheine. Stereochemically it can be related to tetrahydro‐desmethoxy‐corynantheine alcohol, a compound described earlier by Karrer et al.
Applications of proton resonance spectroscopy to structural problems: Part X. Disulphonyl derivatives of 2‐Aminopyridine
Authors: Bedford G. R. , Dorn H. , Hilgetag G. , Katritzky A. R.
Published: September 2010

Proton resonance distinguishes clearly disulphonyl derivatives of 2‐aminopyridine which are derived from (a) the amino and (b) the imino form.
Aromatic sulphonation IXheterogeneous sulphonation of toluene with aqueous sulphuric acid
Authors: Cerfontain H. , Sixma F. L. J. , Vollbracht L.
Published: September 2010

The heterogeneous sulphonation of toluene with 81.9 and 95.9 wt‐% aqueous sulphuric acid has been studied at 25°. The isomer distribution which deviates from that observed in homogeneous sulphonation, varies with toluene conversion and with toluene to sulphuric acid volume ratio. The content of p‐toluenesulphonic acid is higher under heterogeneous conditions than under homogeneous conditions. It is suggested that the variation in isomer distribution is due chiefly to the presence of increasing amounts of sulphonic acids in the sulphuric acid phase.

The heterogeneous sulphonation of toluene proceeds mainly in the sulphuric acid phase. Some sulphonation in the toluene phase by sulphur trioxide may take place as well. However, the latter process is of little ‐ if any ‐ importance.
The mechanism of the aluminium bromide catalyzed isomerization of n‐propyl bromide
Authors: Douwes H. S. A. , Kooyman E. C.
Published: September 2010

n‐Propyl bromide is readily isomerized to isopropyl bromide in carbon disulphide solution under the influence of aluminium bromide at ‐20°. The reaction may be followed by infrared spectroscopy or by gas‐liquid chromatography. Rate data can be accommodated only by using two kinetic equations, obtaining at high and low molar intake ratios of the reactants, respectively.

No incorporation of deuterium takes place when carrying out the reaction in the presence of deuterium bromide, indicating that the isomerization does not involve reversible dehydrobromination.

Runs with 2‐deuterated n‐propyl bromide show a significant isotope effect, a hydrogen atom shifting about 3.4 times more rapidly than a deuterium atom.

These and other results obtained may be interpreted in terms of reversible (partial) ionization, followed by a 1,2‐hydrogen shift.
Reactions of aliphatic halides with solutions of alkali metals in liquid ammonia: III. The reduction of optically active 6‐chloro‐2,6‐dimethyloctane to the corresponding hydrocarbon
Authors: Verkade P. E. , de Vries K. S. , Wepster B. M.
Published: September 2010

The reduction of optically active 6‐chloro‐2,6‐dimethyloctane to 2,6‐dimethyloctane by a solution of an alkali metal in liquid ammonia proceeds with predominating retention of configuration. It is concluded that the reaction proceeds via carbanions. The mechanism of the reaction is discussed.

The absolute configuration of (+)‐2.6‐dimethyloctane was determined by synthesis from (S)‐(−)‐2‐methylbutanol‐1.
Studies on elimination VII. Syntheses of D,L‐Piperitone (D,L‐Δ1‐p‐Menthen‐3‐one) and Related Compounds from t‐butyl β‐keto‐esters
Authors: Lawesson Sven‐Olov , Larsen Erik Holger , Jakobsen Hans Jørgen , Frisell Christer
Published: September 2010

Methyl vinyl ketone has been condensed with t‐butyl acetoacetate (and its 2‐alkyl and aralkyl derivatives) in the molar ratio of one to one and the infrared spectra have been examined. It is concluded that by a spontaneous cyclization the products are hydroxycyclohexanones. By heating them with catalytic amounts of p‐toluenesulfonic acid both water and the t‐butoxycarbonylgroup are eliminated smoothly giving piperitone and related cyclohexenones.
Spectropolarimetry III. Determination of the absolute configuration of some phenylethylamino derivatives
Authors: Dirkx I. P. , de Boer Th. J.
Published: September 2010

The absolute configurations of phenylethylamino derivatives I, II and III with two or three asymmetric centres were determined spectropolarimetrically by comparison with optical rotatory dispersions of related amino‐alcohols and amines and their dithiocarbamates and N‐nitroso derivatives.
Hetarynes VII. Evidence for the occurrence of 2,3‐pyridyne and some of its derivatives as intermediates in various reactions
Authors: Martens R. J. , den Hertog H. J.
Published: September 2010

Reactions of halogenopyridines, halogenopyridine‐N‐oxides and ethoxy derivatives of these compounds are described proceeding presumably via 2,3‐pyridyne, 2,3‐pyridyne‐N‐oxide, 4‐ethoxy‐2,3‐pyridyne and 4‐ethoxy‐2,3‐pyridyne‐N‐oxide as intermediates.
Cyclisation of ψ‐ionone with deuterated sulfuric acid
Authors: de Boer Th. J. , van't Hof H. A. , Veenland J. U.
Published: September 2010

Cyclisation of ψ‐ionone with deuterated sulfuric acid at 10° yields β‐ionone, deuterated in such positions as to indicate a predominant reaction via α‐ionone.
Trityl derivatives of amines: II. C‐trityl derivatives of aromatic secondary amines
Authors: Verkade P. E. , van der Goot H. , Tollenaar F. D.
Published: September 2010

Aromatic secondary amines give C‐trityl derivatives under conditions under which aromatic primary amines give N‐trityl derivatives.
Valency‐bond studies of some conjugated hydrocarbons ‐ III: Calculations on heptalene
Authors: den Boer P. C. , den Boer D. H. W. , Goodwin T. H.
Published: September 2010

Valency‐bond calculations on heptalene suggest that bond length alternation occurs in the ground state. Penney‐Dirac bond orders have been determined.
Measuring air‐liquid surface tensions: A rapid method requiring small amounts of liquid (Short communication)
Authors: Rijke A. M.
Published: September 2010

The measurement of surface tensions of liquids is in general a time‐consuming procedure requiring relatively large amounts, i.e. severals mls of liquid. The method to be introduced here is very rapid, using only about two drops of liquid, thereby combining some of the specific advantages of the respective standard methods.

The principle is very simple. The pressure required to expel the liquid, of which the surface tension is to be determined, from a narrow pore in a thin glass plate is read on a manometer. According to Laplace's equation this pressure is proportional to the surface tension of the liquid

P = γ (1/R1 + 1/R2) (1)

where P is the pressure in dynes/cm2, γ the surface tension (dynes/cm) and R1 and R2 the two principal radii of curvature of the liquid surface in the pore (cm.

Most organic liquids have contact angles with clean glass which are zero or very nearly so, and if the pore is cylindrical, R1 and R2 will both be equal to r, the radius of the pore, so that equation (1) reduces to

P = 2 γ/r (2)

Now if the glass plate is sufficiently thin, so that the hydrostatic head in the pore can be neglected, and if r is known, γ can be determined using equation (2) with the same degree of accuracy as P can be measured.
Electron‐diffraction by gases apparatus and calculation techniques
Authors: Corbet H. C. , Dallinga G. , Oltmans F. , Toneman L. H.
Published: September 2010

An apparatus for electron‐diffraction by gases has been constructed. It incorporates a peripherally driven rotating sector; the specimen‐film distance is variable through vertical movement of the camera‐sector assembly.

Calculation techniques are discussed and a least‐squares calculation with constraints is described, based on comparison of experimental and theoretical intensity data.
The reactions of cis‐cis‐tetrachloromuconic acid in solution
Authors: Shulgin A. T.
Published: September 2010

Tetrachloromuconic acid dehydrohalogenates spontaneously in an inert solvent to form either of two five‐membered lactone acids. In an alcoholic medium, however, there is the further loss of CO2 with concurrent incorporation of a molecule of solvent to yield the novel neutral lactone, IV.
Synthesis of the racemic mixtures of the diastereomeric nicotine‐2‐carboxylic acids
Authors: de Graaff G. B. R. , Ch. Melger W. , van Bragt J. , Schukking S.
Published: September 2010

The preparation of the racemic mixtures of the 4 stereomers of 1‐methyl‐5‐(3′‐pyridyl)proline (nicotine‐2‐carboxylic acid) has been studied; one pathway, starting from ethyl nicotinate and proceeding via 6‐(3′‐pyridyl)‐2‐piperidone proved successful.
The halogenation of aromatics: Part IX. Vapour‐phase chlorination and bromination of benzotrifluoride
Authors: Albers Robert J. , Kooyman E. C.
Published: September 2010

Vapour‐phase bromination (375‐475°) as well as chlorination (350‐450°) of benzotrifluoride led to halogenobenzotrifluorides containing 53‐54% meta, 30‐32% para and 13‐17% ortho isomers. Dihalogeno compounds were only formed to a small extent, except at high conversions. Liquid‐phase nitration of benzotrifluoride produced about 91% meta, 3% para and 6% ortho isomer.

Competitive chlorinations at 400° indicated that benzotrifluoride has about the same reactivity as benzonitrile, chloro‐ and fluoro‐benzene and is 3‐4 times less reactive than benzene.

These and earlier data

Part VI: J. W. Engelsma and E. C. Kooyman, Rec. Trav. Chim. 80, 537 (1961. Parts VII and VIII of this series deal with liquid‐phase halogenations: E. C. Kooyman and R. Louw, Rec. Trav. Chim. 81, 365 (1962) and 82, 616 (1963.

can be accommodated by a mechanism

E. C. Kooyman, Pure and Applied Chemistry 7,193 (1963), (IUPAC Congress Lecture, London, July 1963.

involving hydrogen‐loss as the isomer‐pattern determining step in gas‐phase halogenations of aromatic compounds, possibly through a positively charged aromatic species.
Chemical shifts of ethylenic protons in CIS and TRANS β‐Arylthio‐, β‐arylsulfinyl‐and β‐arylsulfonyl‐acrylic acids
Authors: Hogeveen H. , Maccagnani G. , Taddei F.
Published: September 2010

Chemical shifts of the ethylenic protons Hα and Hβ in cis and trans β‐arylthio‐,β‐arylsulfinyl‐ and β‐arylsulfonyl‐acrylic acids have been determined in acetone and in Na2CO3/D2O solution. The absorption signals were assigned unambiguously by β‐deuteration. An increase of electron‐withdrawing power of the β‐substituent (ArSO2 > ArSO > ArS) causes an increase in shielding of Hβ proton and a decrease in that of Hα proton. The τ‐values of the Hβ protons are lower in the trans than in the corresponding cis acids, which may be explained in terms of magnetic anisotropy effects of the carboxyl group in the trans acids. Generally, the τ‐values of the Hβ protons are lower, and those of the Hα protons higher, in acetone than in Na2CO3/D2O solution; this is probably due to differences in electron‐withdrawing power of the COOH and COO⊙ groups. In all trans derivatives the average values of the coupling constants Jαβ are 15.3 c./sec., and lie between 10.1‐11.4 c./sec. for the cis derivatives. The effects of para‐substituents (CH3O, CH3, H, Cl, NO2) on the chemical shifts of the Hα and Hβ protons in cis and trans β‐arylthio‐, β‐arylsulfinyl‐, and β‐arylsulfonyl‐acrylic acids are correlated with the Hammett σ‐constants.
On the impedance of galvanic cells: XI. The impedance of the Hg/Hg2++ electrode in 1 M and 0.1 M HClO4
Authors: Sluyters‐Rehbach M. , Sluyters J. H.
Published: September 2010

The accuracy of the double layer capacity measurements at high potentials described in part IX 1 is critically examined, especially with a view to the correct determination of the ohmic resistance of the cell. A limit for the exchange current density of the redox couple, which can be detected by the method of frequency variation, is determined. The systematic error in the calculated double layer capacity values, if this limit is just reached, is estimated. From impedance measurements in 0.1 M‐HClO4 solution it appears that the capacity‐potential curve is identical with that in 1 M‐HClO4 solution.
Detection of γ‐ and δ‐keto acids in butterfat
Authors: van der Ven B.
Published: September 2010

A mixture of keto acids (other then β) in an amount of about 100 p.p.m. has been isolated from steam‐deodorized butterfat by means of Girard‐T‐reagent. The methylated keto acids were fractionated and after saponification, the lower boiling fraction was reduced with sodium tetrahydridoborate. After heating of the hydroxy acids obtained, a small amount (about 2.5. p.p.m.) of γ‐ and δ‐lactones could be isolated. G.L.C.‐analysis demonstrated that the main components were δ‐octa, δ‐deca, δ‐dodecalactones and the minor components γ‐deca, γ‐undeca and γ‐dodecalactones, thus proving the presence of the corresponding keto acids in butterfat.
The reaction of hydroxy‐esters and amino‐esters with isocyanates
Authors: Rekker R. F. , Nauta W. Th.
Published: September 2010

Addition of an organic isocyanate to hydroxy‐esters or amino‐esters results in attachment of the active H of the OH or NH2 group to the N atom of the isocyanate, the rest of the adding molecule being linked to the C atom of the N = C bond. Though stable in themselves, the resulting products undergo cyclisation in inert media under the catalytic influence of sodium, or in some cases, by simply heating without any medium. The final ring compounds obtained in this way are oxazolidinediones, hydantoins, oxazines, uracils and quinazolidinediones starting with α‐hydroxy‐esters, α‐amino‐esters, ortho‐hydroxybenzoates, β‐amino‐esters, and ortho‐aminobenzoates, respectively, as the original addition partners. β‐Hydroxy‐esters with a free H in the α‐position give unsaturated amides as final reaction products.
Substituierte Amide des Cystins als Inhibitoren des Oxytocinabbaues durch die Oxytocinase des Schwangerenserums
Authors: Wintersberger E. , Stoklaska E. , Moed H. D. , van Dijk Und J.
Published: September 2010

Die Synthesen einiger einfach gebauter substituierter Cystinylamide werden beschrieben. Die durch diese Substanzen verursachte Hemmung des Abbaues von L‐Cystin‐di‐β‐naphthylamid und von Oxytocin durch die Oxytocinase des Schwangerenserums wird bestimmt und diskutiert.
Investigations on sterols XXIII: Synthesis and properties of 9β‐progesterone and 9β‐testosterone
Authors: Westerhof P.
Published: September 2010

A description is given of a synthesis of 9β‐progesterone (X) and 9β‐testosterone (XVII) with 9β‐ergosterol (I) as the starting material.
Asymmetric syntheses by Grignard compounds prepared in optically active solvents: Part I. Optically active monofunctional ethers
Authors: Blomberg C. , Coops J.
Published: September 2010

Grignard compounds, prepared in benzene in the presence of one molar equivalent of an ether derived from (‐) (S)‐2‐methylbutan‐1‐ol, yield optically active alcohols on reaction with aldehydes. A comparison is made with the optical activities of the products obtained when an optically active bifunctional ether ((+) (2 R:3 R)‐2,3‐dimethoxybutane) is used. A discussion is given of the reacting system.
Bicyclanes: V. New syntheses of cis‐bicyclo[3.3.0]octane and cis‐bicyclo[3.3.0]oct‐2‐ene
Authors: Knotnerus J. , Schilling H.
Published: September 2010

New three‐step syntheses of cis‐bicyclo[3.3.0]octane and cis‐bicyclo[3.3.0]oct‐2‐ene are described; overall yields of about 20% based on cyclopentadiene are obtained.