bluuebunny/crossref_metadata_2025 huggingface dataset:
The structure of the compound diphosphotrioxytetrachloride, P2O3Cl4
Authors: Gerding H. , Gijben H. , Nieuwenhuijse B. , van Raaphorst J. G.
Published: September 2010

The frequencies of and the polarization of most of the Raman lines of liquid P2O3Cl4 have been determined.

The molecule contains an oxygen bridge connecting two magnified image groups.

From the polarization measurements it is deduced that at least one symmetry element is still present in the molecule.
The Raman spectrum of an equimolar liquid mixture of sodium chloride and gallium trichloride
Authors: Gerding H. , Koningstein J. A.
Published: September 2010

The Raman spectrum of a liquid mixture consisting of one mole of sodium chloride with a half mole of Ga2Cl6 (one GaCl3), melting temperature 103.7°, gives indications for the presence of an equilibrium between the molecular species NaCl, Ga2Cl6 and NaGaCl4.
The action of ethyl diazoacetate on acetic anhydride
Authors: de Graaff G. B. R. , van de Kolk G.
Published: September 2010

From the reaction mixture, obtained by reacting ethyl diazoacetate and acetic anhydride in the manner described in previous communications1, we have isolated ethyl acetoxyacetate, ethyl (α‐acetoxy)‐acetoacetate and 1‐acetyl‐3,4,5‐tri(ethoxycarbonyl)‐2‐pyrazoline. The reaction mechanism is discussed.
A study of the ziegler‐type combinations TiCl4‐n‐C5H11Na and TiCl4‐(C2H5)2AlBr
Authors: Havinga R. , Tan Y. Y.
Published: September 2010

The reaction between catalyst components has been studied and polymerization experiments carried out on ethylene using the systems pentyl‐sodium – TiCl4 (I) and diethylaluminium bromide – TiCl4 (II). Results of reduction of TiCl4 can be interpreted on the basis of the following equations: AmNa + TiCl4 → TiCl3 + NaCl + Am•, in the case of I, Et2AlBr + TiCl4 → TiX3 + EtAlX3 + Et• and EtAlX2 + TiCl4 → TiX3 + + AlX3 + Et• (X = Cl, Br), in the case of II. The occurrence of the second reaction in II was confirmed by analyses of the precipitates formed in the reaction and by reacting TiCl4 with EtAlBr2. The reducing power of the organometallic compounds examined decreases in the range: AmNa > Et2AlBr > EtAlBr2.

Polymerization results with system I showed that active catalysts are obtained only with AmNa/TiCl4 mole ratios > unity. The polymer yield appeared to increase with increasing catalyst ratio. This may reasonably be explained by postulating the existence of an AmNa‐TiCl3 complex as the actual catalytic species. In this range of catalyst ratios, the intrinsic viscosities of the polyethylenes remain approximately constant.

In the case of system II, polymerization results could also be interpreted by assuming the existence of one complex or a mixture of a number of complexes as the catalyst. With Et2AlBr/TiCl4 mole ratios > ∼ 2, a complex between Et2AlBr and TiCl3 (Et2AlX‐TiX3) is postulated. With catalyst ratios in the vicinity of unity and lower, ambiguous results were obtained due to the occurrence of reactions between the catalyst components during polymerization.
Investigations on herbicides III: 2,4‐Disubstituted 6‐chloro‐1,3,5‐triazines
Authors: Koopman H. , Daams J.
Published: September 2010

In view of their herbicidal properties a number of similarly or differently 2,4‐substituted 6‐chloro‐1,3,5‐triazines was synthesized. Their herbicidal properties are briefly discussed.
Synthesis of a tyrosine “homologue” of oxytocin
Authors: Beyerman H. C. , Bontekoe J. S. , Koch A. C.
Published: September 2010

A synthesis is described of the “protected” decapeptide N‐benzyloxycarbonyl‐S‐benzyl‐L‐cysteinyl‐L‐tyrosyl‐L‐tyrosyl‐L‐isoleucyl‐L‐glutaminyl‐L‐asparaginyl‐S‐benzyl‐L‐cysteinyl‐L‐prolyl‐L‐leucylglycineamide (V).

Removal of the blocking groups from V followed by oxidation yielded biologically active preparations believed to contain a “homologue” of oxytocin with two consecutive molecules of tyrosine instead of one (VI). Oxytocin‐inhibiting activities of VI have been described by other investigators.
Phosphatidic acids and derivatives. IX. A new synthesis of glycolkephalins and glycerol‐α‐kephalins
Authors: Hoefnagel M. A. , Stegerhoek L. J. , Verkade P. E.
Published: September 2010

A new synthesis of glycerol‐α‐kephalins and glycolkephalins is described. The corresponding silver benzyl diacylglycerol‐α‐phosphate or silver benzyl glycolphosphate is boiled in benzene solution with 2‐(dibenzylamino)ethyl bromide, and the O,N,N‐tribenzyl derivative of the kephalin thus obtained is converted into the kephalin by hydrogenolysis. The overall yields are 80‐90 %.
Tautomerism of hydroxypyridines (II). Bromination of 2,4‐dihydroxypyridine and its ethyl derivatives
Authors: Kolder C. R. , den Hertog H. J.
Published: September 2010

2,4‐Dihydroxypyridine, 2‐ethoxy‐4‐hydroxypyridine, 4‐ethoxy‐2‐hydroxypyridine and 2,4‐diethoxypyridine were brominated in pyridine as solvent. It appeared that bromine enters the 3‐position during the bromination of the three first mentioned substances whereas from 2,4‐diethoxypyridine the 5‐bromo derivative is formed.

Ultraviolet absorption spectra of substrates and reaction products in 50% aqueous ethanolic solution were measured. Comparison of these spectra with the known spectra of the mono‐ and dimethoxy derivatives of 2,4‐dihydroxypyridine enabled the tautomeric structures of the substances to be investigated. The course of the brominations is connected with the structure of the substrates.
Etude de L'Amphotérisme de L'Hydroxyde Germaneux par Spectrographie Infrarouge
Authors: Dupuis Mme Thérése
Published: September 2010

L'étude de la courbe de thermolyse de l'hydroxyde germaneux préparé et isolé à l'abri de l'oxygène de l'air, confirme la composition globale GeO.1H2O. D'autre part, la comparaison des spectres d'absorption infrarouge de GeO.H2O, de GeO et de GeO2.xH2O montre que l'hydroxyde germaneux présente la structure Ge(OH)2 avec des groupements OH associés par ponts hydrogènes.
The pH of some standard solutions in methanol and methanol‐water mixtures at 25° II. Experimental Part
Authors: de Ligny C. L. , Luykx P. F. M. , Rehbach M. , Wieneke A. A.
Published: September 2010

By application of a method which was developed in Part I of this series the pH* of an oxalate and a succinate buffer in water, methanol‐water mixtures and methanol and that of a salicylate buffer in methanol was measured. The pH* in methanol was measured by application of both silver chloride and silver bromide electrodes: the values obtained agreed closely.
Experiments on the synthesis of hexadehydroyohimbanes
Authors: Ribbens C. , Nauta W. Th.
Published: September 2010

The reaction of tryptamine with some isocoumarins has been studied. From the reaction products hexadehydroyohimbane and a new dimethoxy derivative can be synthesized.
Synthesis of a tyrosine “homologue” of lysine‐vasopressin
Authors: Beyerman H. C. , Bontekoe J. S. , Koch A. C.
Published: September 2010

The synthesis is described of the protected linear decapeptide: N‐benzyloxycarbonyl‐S‐benzyl‐L‐cysteinyl‐L‐tyrosyl‐L‐tyrosyl‐L‐phenylalanyl‐L‐glutaminyl‐L‐asparaginyl‐S‐benzyl‐L‐cysteinyl‐L‐prolyl‐N6‐tosyl‐L‐lysylglycineamide (II, Fig. 2).

Removal of the blocking groups from II, followed by oxidation, yielded a preparation believed to contain a “homologue” of lysine‐vasopressin with two consecutive molecules of tyrosine instead of one (Fig. 1, n = 2).
Synthesis of tyrosine3‐lysine8‐vasopressin
Authors: Beyerman H. C. , Bontekoe J. S.
Published: September 2010

The synthesis is described of the protected linear nonapeptide: N‐benzyloxycarbonyl‐S‐benzyl‐L‐cysteinyl‐L‐tyrosyl‐L‐tyrosyl‐L‐glutammyl‐L‐asparaginyl‐S‐benzyl‐L‐cysteinyl‐L‐prolyl‐Ne‐p‐toluenesulfonyl‐L‐lysylglycineamide (II, Fig. 2) in analytically pure form.

Removal of the blocking groups from II, followed by cyclization through oxidation, yielded a preparation assumed to contain an analogue of lysine8‐vasopressin with L‐phenylalanine replaced by L‐tyrosine (Fig. 1).
Investigations on pesticidal phosphorus compounds III: The structure of the reaction product of 3‐amino‐5‐phenyl‐1,2,4‐triazole and bis(dimethylamido)phosphoryl chloride (WP 155)
Authors: van den Bos B. G.
Published: September 2010

The structure of the reaction product (WP 155) of 3‐amino‐5‐phenyl‐1,2,4‐triazole and bis‐(dimethylamido)phosphoryl chloride is discussed. By comparing the U. V. absorption spectra of the bromo compound (X) obtained from WP 155 and the three N‐ethyl‐3‐bromo‐5‐phenyl‐1,2,4‐triazoles (VII, VIII, IX) with those of the three known N‐methyl‐3‐methyl‐5‐phenyl‐1,2,4‐triazoles (XI, XII, XIII) it may be concluded that WP 155 is 5‐amino‐1‐[bis(dimethylamido)phosphoryl]‐3‐phenyl‐1,2,4‐triazole.
Syntheses and physical constants of eleven monobranched hexadecanes
Authors: Wibaut J. P. , Brand H.
Published: September 2010

The syntheses of seven methylpentadecanes, 3‐ethyltetradecane, 4‐n‐propyltridecane, 5‐n‐butyldodecane and 6‐n‐pentylundecane are described. The degree of purity, determined from the melting curves, was over 99.7%. Densities and refractive indices of the hydrocarbons and the intermediate tertiary alcohols have been determined at 20 and 25°. Further, melting points and boiling points of the hydrocarbons have been measured and their infra‐red and mass spectra have been recorded.
Studies on the hypohalogenation of isomeric 6,7‐octadecenoic acids: Petroselinic and petroselaidic acids
Authors: Farooq M. O. , Osman S. M. , Siddiqui M. Saleem
Published: September 2010

The 6(7)‐chloro‐7(6)‐hydroxystearic acids of petroselinic and petroselaidic acids have been successfully prepared by the action of hypochlorous acid on the parent acids and by the hydrochlorination of their corresponding epoxides. The chlorohydrins on dehydrohalogenation furnished the original epoxides. The bromohydrins and iodohydrins have been prepared and were found to behave in a similar manner. The mutual transformation of the erythro‐ and threo‐6, 7‐dihydroxystearic acids through the chlorohydrins and the epoxides has been achieved.

The results of these experiments lead to the conclusion that inversions of configuration occur during the replacement of the hydroxyl group by a halogen atom and also at the time of the opening and closing of the epoxide ring.
Adsorption of nitrogen on alumina at high pressure
Authors: Michels A. M. J. F. , Menon P. G. , ten Seldam C. A.
Published: September 2010

A method is described for determining adsorption isotherms of gases on solids under elevated pressures. Results are given for nitrogen as adsorbate and alumina as adsorbent. The range covered extends to 3000 atm at temperatures between ‐ 7.6° and 100°.

The volume in which the experimentally determined equation of state is valid is defined as the total volume v minus a volume v0 of the adsorbent sample inaccessible to the gas as determined with helium at low pressures.

A quantity ΔG is taken as a measure of the amount of gas adsorbed. It is defined as the difference between the total amount of gas exposed to the adsorbent and the quantity which would be present in the volume v ‐ v0 at the experimental temperature and pressure if no adsorption occurred.

With increase of pressure ΔG increases till a gas density ρg of about 175 amagat is reached, then it falls off (practically linearly with ρg), but rises again steeply at densities above 500 amagat. No hysteresis has been found; the alumina showed no permanent change after completion of the experiments.

In the first and second range δΔG/δT is negative but in the third section it changes sign. Apparently the adsorption then changes from an exothermic to an endothermic process. An attempt is made to interpret the linear section in terms of a simple two‐phase model.
Synthesis of β‐phenylethylamine derivatives VII: The enantiomers of erythro‐1‐(4′‐hydroxyphenyl)‐2‐(1″‐methyl‐2″‐phenoxyethylamino)‐propanol‐1
Authors: van Dijk J. , Moed H. D.
Published: September 2010

The resolution of racemic erythro‐i‐(4′‐hydroxyphenyl)‐2‐(1″‐methyl‐2″‐phenoxyethylamino)propanol‐1 (Caa 40

Name used in the pharmacological tests. Commercial name “Duvadilan”, N.V. Philips‐Duphar.

) is described. The absolute configuration of the three asymmetric centres of the enantiomers is established.
Syntheses, infrared spectra and molecular refractions of some sterically hindered p,p′‐dimethoxystilbenes: The influence of non‐planarity in styrene and stilbene derivatives IV
Authors: Laarhoven W. H. , Nivard R. J. F. , Havinga E.
Published: September 2010

Syntheses of a series of 4,4′‐dimethoxystilbenes, substituted with methyl or ethyl groups in ortho and α‐positions, including the new compounds 2,2′,6,6′‐tetramethyl‐ ; α,2‐dimethyl‐ ; α,2′‐dimethyl‐ ; α,2,2′‐trimethyl‐ and α,α′,2‐trimethyl‐4,4′‐dimethoxystilbene, are described.

In most cases demethylation with pyridine hydrochloride gave the 4,4′‐dihydroxystilbenes in good yield.

Attempts to synthesize 2,2′,6,6′,α,α′‐hexamethyl‐4,4′‐dimethoxystilbene in reasonable amount were unsuccessful.

The infrared absorption spectra of the dimethoxystilbenes were measured. An increase in the out‐of‐plane Cα‐H frequency was observed in the series: 4,4′‐dimethoxystilbene, 2,2′‐dimethyl‐, 2,2′‐diethyl‐, 2,2′,6,6′‐tetramethyl‐4,4′‐dimethoxystilbene. This increase, seemingly, parallels the increase in steric inhibition of molecular coplanarity, the same sequence being observed in the positions of the ultraviolet N → V absorption bands.

For the α‐substituted stilbenes, the Cα‐H frequencies are located in the same region as the absorptions due to the substituted benzene rings and conclusions are uncertain.

The molecular refractions of the compounds, corrected for the alkyl substituents, decrease with increasing steric hindrance. For most compounds the decrements in molecular refraction are linearly related with the oscillator strengths of the N → V transition in the stilbene chromophore.
Chemistry of the silylamines. III. Condensation of silylamines with silylesters
Authors: Pike R. M.
Published: September 2010

The conditions under which a series of trimethylsilylesters of the type magnified image, where R=H, CH3, CF3, and C6H5, condense with a number of trimethylsilylamines to form hexamethyl‐disiloxane and an organic amide were investigated. The nature of the R group in the silylester appreciably affected the relative ease of condensation. Addition of an acid catalyst to the reaction system was observed to increase the relative rate of the reaction.
A study of the biological activity of iodinated insulin
Authors: de Zoeten L. W. , van Strik R.
Published: September 2010

Bioassays were carried out with two iodinated insulin preparations containing 0.8 and 3.0 atoms of iodine per molecule of insulin. In these preparations 80% and 30% of the original biological activity was retained.

With the help of the experimentally found reactivities of the tyrosine residues of insulin a statistical calculation is made of the iodine distribution over the insulin molecules at a certain (average) incorporation. On account of these distribution data it is reasonably certain that the substitution of one atom of iodine has no effect upon the biological activity. It seems likely that insulin molecules which contain two atoms of iodine also possess biological activity.
A study of the “david” reaction
Authors: Axelson Eeva , Diczfalusy Egon
Published: September 2010

Some of the variables influencing the David reaction have been studied. An improved method is described.

Among the oestrogens studied only compounds with a 17β and a 16α, or 16β‐hydroxyl group gave a positive David reaction; the approximate relative chromogenicities were oestriol:100, 16‐epioestriol: 60, 6‐hydroxyoestriol: 16 and 2‐hydroxyoestriol: 7%.

The presence of highly purified methylated and chromatographed urinary residues greatly diminished the David chromogenicity of oestriol. This decrease was linearly related to log concentration of urinary residue.
Determination of molecular weights with a semi‐micro‐ebulliometer
Authors: van Pelt J. G.
Published: September 2010

The semi‐micro‐ebulliometer consists of two units in a solvent vapour thermostat. The temperature difference is measured by two thermistors (readings of 3.10−4°. accurate to 1%). One determination takes 20 minutes. Light‐sensitive compounds are protected by a clear varnish. Decomposition, if not completed within 2 minutes, is indicated by a bent curve.
Investigations on sterols XX. The synthesis and properties of 8α,10α‐progesterone and 8α,10α‐testosterone
Authors: Westerhof P. , Smit A.
Published: September 2010

The 8α, 10α‐isomers of progesterone and of testosterone have been prepared using pyrocalciferol as the starting material.
Acylation of aromatic ring systems with mixed anhydrides of phosphoric acid
Authors: Schoot C. J. , Ponjee J. J. , Klaassens K. H.
Published: September 2010

The reactions between a number of orthophosphates, especially silver orthophosphate, and acid chlorides are described as well as a synthesis and the properties of tribenzoyl phosphate. Nucleophilic aromatic ring systems are acylated by triacyl phosphates.
Study of the reactions between titanium tetrachloride and ethylaluminium compounds in hydrocarbon solution: III. Solid reaction products and the formantion of catalyst systems for olefin polymerization
Authors: Arlman E. J. , de Jong J. R. , Beintema J. , van Reijen L. L.
Published: September 2010

The brown precipitate obtained at 80°C, and the purple precipitate prepared at 170°C from AlEt3 and TiCl4 at an Al/Ti ratio 1/3, both consist essentially of TiCl3 in which about one sixth of the Ti is replaced by Al and a few percent of the chlorine by ethyl. The brown precipitate gives the X‐ray diagram of β‐TiCl3, whereas the purple one gives that of γ‐TiCl3.

Magnetic measurements showed that already at ambient temperature precipitates of the β‐TiCl3 structure gradually change into products with the γ‐TiCl3 structure.

On treating the brown precipitates with AlEt3 they change into nearly amorphous black products with an atom ratio of chlorine to (Al + Ti) considerably lower than two. The composition and structure of the purple precipitates are much less affected by this treatment, the effect of AlEt3 being stronger than that of AlEt2Cl.

It seems that the catalyst systems so obtained only polymerize propene to a highly isotactic polymer if the crystalline substrate is not more than slightly converted at its surface.
A direct determination of nitrogen in sulphuric acid digestion mixtures
Authors: Böttcher C. J. F. , van Gent C. M. , Pries C.
Published: September 2010

The micro‐determination of nitrogen described is based on a preliminary digestion with sulphuric acid, potassium sulphate and selenium, followed by a direct assay of ammonia in the resultant solution by a phenol‐hypochlorite colorimetric method, without previous liberation and distillation of the ammonia.
Acid anilides: VIII. Determination of esterified acetic and butyric acids in butterfat
Authors: De Jonge A. P. , Verhage A. , van Der Ven B.
Published: September 2010

In this paper some applications of the qualitative and quantitative paper chromatography of fatty acid anilides are described, viz.:

identification of a very small sample of an unknown fat as butter‐fat;

determination of esterified acetic acid in butterfat and in fats containing aceto‐fats.
The 4‐(p‐phenylazophenyl)semicarbazones of some carbonylic pyridine derivatives
Authors: Allan F. J. , Allan G. G.
Published: September 2010

The preparation and characterisation of the 4‐(p‐phenylazophenyl)‐semicarbazones of pyridine‐2,3 and 4‐aldehyde, 2,3 and 4‐acetylpyridine, 6‐methylpyridine‐2‐aldehyde and pyridine‐2,6‐dialdehyde are described. These semicarbazones proved most useful for the isolation and characterisation of carbonylic pyridines. The preparation of the semicarbazones was carried out in dry ethanol and crystalline coloured products were obtained in good yield.
Investigations on chemical kinetics by means of absorption spectroscopy and calculations of immeasurable spectra by this method
Authors: van Senden K. G. , Koning H. N.
Published: September 2010

The determination of reaction‐rate constants of unimolecular, pseudo‐unimolecular and bimolecular reactions by means of absorption spectroscopy is described. The calculation of immeasurable absorption spectra by this method is given.
Studies in organosilicon chemistry. XLII. Reactions of certain silylbenzaldehydes in concentrated base
Authors: Maass Thomas J. , Post Howard W.
Published: September 2010

A crossed Cannizzaro reaction using formaldehyde with m‐trimethylsilylbenzaldehyde and p‐trimethylsilylbenzaldehyde yields mostly the benzyl alcohol derivative. No formic acid was detectable but a small amount of the substituted benzoic acid was isolated. The corresponding triphenylsilylbenzaldehydes, meta and para, without formaldehyde gave good yields of hexaphenyldisiloxane or triphenylsilanol along with the substituted benzoic acid.
The isolation of citronin from the peel of argentine oranges (naranja dulce),: citrus sinensis, Linn
Authors: Rahman Aziz‐Ur , Khan Ausat A.
Published: September 2010

The isolation of ‘citronin’ from the peel of Argentine oranges, Citrus sinensis, Linn. has been described and its structure established as a 7‐rhamnoglucoside of 5,7‐dihydroxy‐2′‐methoxyflavanone. A higher m.p. (240–241°) as against 235° reported in the literature for the glycoside, and 225–226° as against 204° reported in the literature for the natural product, for the aglycone viz. citronetin, have been confirmed. The acetyl derivative of the glycoside and the acetyl and the methyl derivatives of the aglycone — have been prepared. The ultra‐violet and infra‐red spectra of the glycoside are discussed.
The iodination of monohydroxypyridines to monohydroxyiodopyridines
Authors: Broekman F. W. , Tendeloo H. J. C.
Published: September 2010

The method of Schickh, Binz and Schulz for the iodination of 3‐hydroxypyridine to give a hydroxymonoiodopyridine is also suitable for iodinating 2‐ and 4‐hydroxypyridine; 2‐ (or 4‐)hydroxy‐3,5‐diiodopyridine is produced as a by‐product from 2‐ and 4‐hydroxypyridine, respectively.

Above ˜ 255° 4‐hydroxy‐3‐iodopyridine is converted into a mixture containing 4‐hydroxy‐3,5‐diiodopyridine.
The halogenation of aromatics: Part VII. Isomerizations, disproportionations and transbrominations involving bromobenzenes in the presence of aluminium bromide
Authors: Kooyman E. C. , Louw R.
Published: September 2010

The dibromobenzenes isomerize under the influence of aluminium bromide at room temperature to form an equilibrium mixture of dibromo compounds (60 % meta, 35 % para, 5 % ortho), bromobenzene and tribromobenzenes. p‐Dibromobenzene first forms ortho‐isomer, meta‐isomer being formed at a later stage. Small amounts of water have an accelerating effect (formation of HBr); carbon disulphide or naphthalene are inhibitors, probably as a result of complex formation involving aluminium bromide.

The intermolecular nature of these reactions is demonstrated by the fact that in the presence of an excess of acceptors such as chlorobenzene or toluene, transbromination (ArBr + ArZ → ArH + ArZBr) is the main reaction observed.

This phenomenon is used for the determination of relative rates of debromination of bromobenzenes (PhZBr) in competition runs: (Z = H unity), p‐Cl 0.6, p‐Br 0.4 (x2), m‐Br 0.03 (x2), 3,5‐diBr<0.01. Equilibrium constants are presented for several processes of the type ArBrZ + ArY ⇌ ArZ + ArYBr.

Results are discussed in terms of an intermediate š‐complex ArBrH+, which may lose either a proton or a bromine cation. Equilibria may be correlated with data on bond strengths (Dc‐Br) in substituted bromobenzenes.
On the enthalpy change on formation of a solid compound from a gaseous and a liquid component
Authors: Korvezee A. E. , Pieroen A. P.
Published: September 2010

For the formation of a solid compound from a gaseous substance and a liquid at not too high pressures the relationship between the standard heat of formation of the compound, its actual heat of formation under equilibrium conditions and the heat quantity calculated from the slope of the three‐phase line gas‐liquid‐solid is discussed (equations XIV and XV). In sections 4 and 5 reference is made to the case of a solid compound formed from two partially miscible liquid substances as well as to the case of high pressure equilibria.
Studies in organosilicon chemistry: XLV. The addition of certain organosilicon compounds to ketene
Authors: Limburg William W. , Post Howard W.
Published: September 2010

Nine organosilicon compounds containing OH or NH have been found to add to ketene. Three carbon functional primary alcohols add to give acetates. Four primary amines and one secondary amine form N‐substituted acetamides while butyl‐trimethylsilyalmine yields N‐butyltrimethylsilylacetamide.
Electrochemical properties of a new glass‐electrode containing beryllium oxide
Authors: Tendeloo H. J. C. , Mans A. E. , Kateman I. , Voort F. H. V. D.
Published: September 2010

A glass containing 73 mol % SiO2, 6 mol % BeO and 21 mol % K2O has been made and used as a glass‐electrode. This electrode responds rather well to potassium‐ and sodium‐ions, but not to calcium‐ions, and has a rather poor response to hydrogen‐ions.
Studies in IVth group organometallic chemistry. IX: Synthesis of organosilicon compounds and polymers containing the p‐Phenylene Group
Authors: Noltes J. G. , van der Kerk G. J. M.
Published: September 2010

A number of oligomeric p‐phenylenesilanes containing 2‐6 silicon atoms per molecule and a series of low molecular weight poly‐p‐phenylenesilanes (n = 10‐30) have been prepared by Wurtz‐type condensation reactions involving appropriate combinations of p‐chlorophenyl‐ and chloro‐silanes. The polymeric products have been characterized by infrared spectroscopy, analytical and thermogravimetric data, and number‐average molecular weights, the low value of which is presumably caused by participation of the solvent (toluene) in the reaction. The polymers started to lose weight at temperatures varying from 310 to 485°.
Synthesis and physiological properties of some heterocyclic‐aromatic sulphides and sulphones: III Synthesis of some heterocyclic‐aromatic sulphones
Authors: van Zwieten P. A. , Gerstenfeld M. , Huisman H. O.
Published: September 2010

The synthesis of some heterocyclic‐aromatic sulphones with potential acaricidal properties is described. The benzene nucleus in these sulphones is substituted either with a para‐chlorine atom or with three chlorine atoms in positions 2, 4 and 5. The heterocyclic nuclei used are pyridine, pyrimidine, thiazole or thiophen. Apart from the sulphonyl substituent, these nuclei are unsubstituted or carry a halogen substituent; only in the thiophen series a nitro group is substituted in the heterocyclic nucleus. From the aryl‐pyridyl sulphones the corresponding N‐oxydes have been prepared.
Synthesis and reactions of esters of N‐hydroxyphthalimide and N‐protected amino acids
Authors: Nefkens G. H. L. , Tesser G. I. , Nivard R. J. F.
Published: September 2010

Esters can be prepared from N‐hydroxyphthalimide and N‐carbobenzoxy‐ or N‐phthaloyl‐amino acids using dicyclohexylcarbodi‐imide as condensing agent. The compounds are suitable for the stepwise synthesis of peptides without racemization. With methanol the N‐hydroxyphthalimide ester of N‐phthaloylglycine can be converted into the methyl ester of N‐phthaloylglycine.
Synthesis of the C‐terminal tetrapeptide sequence derived from glucagon
Authors: Beyerman H. C. , Bontekoe J. S.
Published: September 2010

A synthesis is described of the partially protected carboxyl‐terminal tetrapeptide sequence, L‐leucyl‐L‐methionyl‐L‐asparaginyl‐O‐t‐butyl‐L‐threonine t‐butyl ester, which is derived from the pancreatic hormone glucagon.

In this synthesis we used successfully a novel combination of blocking groups, the t‐butoxy group and t‐butyl ester, together with N‐phthaloyl protection.
A novel synthesis of the diastereomeric 5‐phenylprolines
Authors: de Graaff G. B. R. , Melger W. Ch. , van de Kolk G.
Published: September 2010

As a preliminary to a synthesis of the diastereomeric 5‐(3′‐pyridyl)‐prolines, which will be reported in a subsequent paper, a preparation of the analogous 5‐phenyl‐prolines is described. As a result of the reaction sequence, a mixture of the two dl‐diastereomers was obtained, which were isolated and characterised.
The interaction of free radicals and aromatics: III The kinetics of the addition of cyanoisopropyl and trichloromethyl radicals on to anthracene derivatives
Authors: Farenhorst E. , Kooyman E. C.
Published: September 2010

The addition of cyanoisopropyl radicals to anthracenes obeys simple kinetics at high dilution and in the presence of a large excess of azoisobutyronitrile.

The actual mechanism is shown to be rather complex, owing to transient formation of compounds containing the thermally unstable ketenimine structure. The simple kinetics observed apparently result from mutual compensation of anthracene‐consuming and ‐producing reactions.

This would make the significance of relative cyanoisopropyl reactivities of different anthracenes rather doubtful. Nevertheless, these reactivities agree with those of trichloromethyl radicals towards anthracenes, found from the retardation by these anthracenes of the benzoyl‐peroxide‐initiated addition of bromo‐trichloromethane to styrene.
Aminations of bromo‐derivatives of 4‐ethoxy‐ and 2,4‐diethoxy‐pyridine, probably involving a 2,3‐pyridyne as intermediate
Authors: Pieterse M. J. , den Hertog H. J.
Published: September 2010

The amination of 3‐bromo‐4‐ethoxypyridine with potassium amide in liquid ammonia yielding 2‐amino‐4‐ethoxypyridine as chief product has been reinvestigated. It is shown that 2‐amino‐5‐bromo‐4‐ethoxypyridine is formed as a byproduct, probably via 3,5‐dibromo‐4‐ethoxypyridine and 5‐bromo‐4‐ethoxy‐2,3‐pyridyne as intermediates.

In order to check the mechanism proposed for the process described above, aminations of 3‐ and 5‐bromo‐2,4‐diethoxypyridine were studied. Both reactions yield 6‐amino‐2,4‐diethoxypyridine as chief product. It was found that 3‐bromo‐2,4‐diethoxypyridine was converted first into the 5‐bromo‐isomer. It seems likely that in both aminations 2,4‐diethoxy‐5,6‐pyridyne is an intermediate.
Microbiological conversion of 19‐nortestosterone: (I) 16‐hydroxylation
Authors: de Flines J. , van der Waard W. F. , Mijs W. J. , Szpilfogel S. A.
Published: September 2010

The microbiological transformation of 19‐nortestosterone with Mycosphaerella latebrosa and with Hypomyces aurantius, leading to the 16β‐ and 16α‐hydroxy‐derivatives, respectively, is described.
Microbiological conversion of 19‐nortestosterone: (III) 12‐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 reaction of 19‐nortestosterone with Colletotrichum derridis yielding mainly 12β‐hydroxy‐19‐nortestosterone, is described.
Chemistry of acetylenic ethers 63: The synthesis of α,β‐unsaturated thiolesters from carbonyl compounds, acetylenic thioethers, and boron trifluoride
Authors: Bos L. B. , Arens J. F.
Published: September 2010

The α,β‐unsaturated thiolesters listed in Table I have been prepared by treating a mixture of a carbonyl compound and boron trifluoride with an acetylenic thioether (see reaction scheme 2). Good yields are obtained when ethers are used as solvents. The configuration of the esters prepared from aldehydes is trans. From unsymmetrical ketones mixtures of cis and trans isomers are formed.
Thermal substitution reactions of cupric benzoate II
Authors: Schoo W. , Veenland J. U. , de Boer Boer Th. J. , Sixma F. L. J.
Published: September 2010

After thermal decomposition of cupric benzoate in the presence of deuterium oxide 43% of ortho‐deutero‐benzoic acid can be obtained beside phenol. A radical mechanism for the air oxidation of benzoic acid to phenol under the catalytic influence of copper oxide should therefore be reasonable.
Chemistry of acetylenic ethers, 64: Some remarks concerning the “nucleophilic substitution at an acetylenic carbon”
Authors: Arens J. F.
Published: September 2010

The suggestion is put forward that nucleophilic displacements of a group X in compounds RC  CX may occur through substitution at X rather than at the acetylenic carbon atom bearing X.
Synthesis of β‐Phenylethylamine derivatives VIII: Four diastereoisomers of 1‐(4′‐hydroxyphenyl)‐2‐(1″‐methyl‐3″‐phenylpropylamino)propanol
Authors: van Dijk J. , Keizer V. G. , Moed H. D.
Published: September 2010

The two racemic‐ and the four diastereoisomeric erythro forms of the aminoalcohol II were prepared and characterized

magnified image

The relative configurations were established by synthesizing the diastereoisomers of II from the enantiomers oferythro‐p‐hydroxynorephedrine and from those of 1 ‐methyl‐3‐phenylpropylamine.

The absolute configurations of the enantiomers of 1 ‐methyl‐3‐phenylpropylamine were determined by correlation with those of 2‐amino‐4‐phenylbutyric acid, of which the confuguration was known.

On the basis of these experiments the configurations of the four erythro forms can be given as follows:

(+)‐erythro‐II = αS : βR : γR

(−)‐erythro‐II = αR : βS : γS

(+)‐alloerythro‐II = αS : βR:γS

(−)‐alloerythro‐II = αR : βS : γR

Biological experiments confirmed these configurations.
Separation of amino acids on ion exchange paper
Authors: Hartel J. , Copper J. A. , van Bochove C.
Published: September 2010

It is very useful to employ ion‐exchanging chromatography papers for a rapid separation of a mixture of amino acids. Various separations are described, in some cases taking only one hour. Special papers were developed for this purpose based on chemical modification of cellulose and containing basic or acid groups. The possibilities for using these papers in a quantitative determination are discussed.
Chemistry of acetylenic ethers 65: 4‐Hydroxyalkynyl ethers, their synthesis and conversion into γ‐lactones
Authors: Vollema G. , Arens J. F.
Published: September 2010

4‐Hydroxyalkynyl ethers can be prepared from epoxides and ethoxyethynyllithium in liquid ammonia or bis‐ethoxyethynylmagnesium in ether‐tetrahydrofuran.

Under other conditions, notably in the presence of metal halides other products are obtained, including halohydrins and 3‐hydroxyalkynyl ethers, the latter arising from carbonyl compounds formed by isomerisation of the epoxides. For propylene oxide two types of isomerisation into carbonyl compounds have been described in the literature. Lewis acids like magnesium bromide convert the substance into propionaldehyde or into acetone. We found that the same change can also be caused by lithium iodide. For the preparation of pure 4‐hydroxyalkynyl ethers from epoxides it is therefore desirable to employ solutions of metallated acetylenic ethers devoid of salts.

The reaction of epichlorohydrin with metallated ethoxyethyne or metallated ethylthioethyne leads to three and four successive products, respectively, depending on the reaction conditions and the solvent. The primary product is a 5‐chloro‐4‐hydroxyalkynyl (thio)ether which under alkaline conditions is converted into a 4,5‐epoxyalkynyl (thio)ether and, when sodamide is present, into a 5‐hydroxy‐Δ3,4 alkynyl (thio)ether. The thio compound (but not the oxygen analogue) finally undergoes ring closure to 2‐(alkylthiomethyl)furan.

Hydrolysis and also pyrolysis of 4‐hydroxyalkynyl ethers gives γ‐lactones in good yields.
On the impedance of galvanic cells: VII. Alternating current polarography in the complex impedance plane, experimental verification
Authors: Sluyters‐Rehbach M. , Sluyters J. H.
Published: September 2010

The theory developed in part IV1 and part VI2 of this series has been verified by experiments.

The results are:
1‐(2‐Dialkylaminoethyl)‐methoxybenzimidazoles
Authors: Foster R. , Hanson P.
Published: September 2010

A series of l‐(2‐dialkylaminoethyl)‐x‐methoxy‐benzimidazoles has been synthesised. Two of these compounds are the O‐methylated benzimidazole analogues of psilocine and of bufotenine.
Chemistry of acetylenic ethers 66: Thermal decomposition of l‐ethoxyvinyl esters
Authors: Zwanenburg B.
Published: September 2010

The thermal decomposition of some 1‐ethoxyvinyl esters is described. The first step of the decomposition is rearrangement to a β‐keto ester, the enolic form of which is subsequently acylated by the 1‐ethoxyvinyl ester.
Über das Elektrische Potential von Oxidelektroden: I. Manganoxidelektroden
Authors: Drotschmann C.
Published: September 2010

Bei chemischem Abbau von rhombischem γ‐MnO2 ‐ besser η‐MnO2** ‐ ebenso wie von tetragonalem β‐MnO2 entsteht monokilines γ‐MnOOH. Das Ruhepotenital beider‐teilweise‐reduzierter Oxide sinkt mit sinkendem Sauerstoffgehalt. Der Potentialabfall ist nicht in rechnerischer Übereinstimmung mit dem Konzentrationsverhältnis [Mn4+]:[Mn3+] Vielmehr wird das Potential beeinflusst durch die Konzentration von Mn2+.

Die aus I Gramm‐Mol Braunstein maximal erhältliche Kapazität in Amperstunden ist abhängig von sekundären, nicht elektrochemisch wirksamen Reaktionen des primär gebildeten Mn2+ (Abdiffusion, chemisorptive oder chemische Bindung von Mn2+).

Das Braunsteinpotenital sowohl im Ruhezustand der Elektrode wie auch während elektrischer Entladungen gehorcht den Forderungen der Gleichung: e = e0 + RT/2F in (H+)4 ‐ RT/2F in (Mn2+)

Die Ansicht, dass konstante Ruhe‐Potentiale gemessen werden, wenn ein Oxid durch chemischen Abbau in eine niedrigere Oxidationsstufe in heterogener Phase umgewandelt wird, und dass mit sinkendem Oxidationsgrad sinkende Potentiale gemessen werden, wenn der Abbau in homogener Phase erfolgt, ist im Falle der Manganoxide, nicht bestätigt.
The chemistry of 3‐ketotetrahydrofurans I: Syntheses of 3‐ketotetrahydrofuran by oxidation
Authors: Weiland J. H. Sperna , Dijkstra H. , Pik A. B.
Published: September 2010

3‐Ketotetrahydrofuran (II) has been obtained spectroscopically as well as gas‐chromatographically pure. A major modification in the dichromate‐sulphuric acid oxidation of the starting alcohol (I) has almost doubled the yield to 60%.

The chromium trioxide‐pyridine oxidation of (I) is described for the first time and yields as high as 70% are obtained. The NMR spectrum of (II) is reported.
Stoichiometric considerations on the reaction between titanium trichloride and aluminum trimethyl
Authors: Miotto Mirella
Published: September 2010

The dependence of uptake of Al(CH3)3 by solid TiCl3 on the surface area of the latter has been studied. A “step reaction” technique permits the investigation of the stoichiometry of the reaction at different degrees of advancement, the amount of chlorine abstracted from the TiCl3 being taken as the advancement parameter.

Methane evolution and aluminum and carbon fixation on the solid phase appear to be linearly related to this parameter and the slopes of the respective lines are taken as significant parameters from which the stoichiometry of the reaction is deduced.
The chemistry of cycloheptatriene: Part VIII: Transannular 1‐5 shifts of hydrogen in phenylcycloheptatriene
Authors: ter Borg A. P. , Kloosterziel H.
Published: September 2010

7‐Phenylcycloheptatriene‐1,3,5 rearranges on heating to a mixture of the 3‐, 1‐ and 2‐isomers. These are formed in the order indicated by successive trans‐annular 1‐5 shifts of hydrogen. The isomerization of the 7‐ to the 3‐isomer, by which the trienic and aromatic systems enter into conjugation, is appreciably faster than the 1‐5 shift in cycloheptatriene itself. The interconversion of the 3‐ and 1‐isomers, however, proceeds at a rate comparable with that of the unsubstituted compound.

The nature of the solvent has no influence on the rate of the 1‐5 shift.
Thiophen chemistry VIII: Michael Additions to 2(5H)‐thiophenone
Authors: Jakobsen Hans Jørgen , Larsen Ertk Holger , Lawesson Sven‐Olov
Published: September 2010

2‐Hydroxythiophen exists at room temperature mainly in the tautomeric form 2(5H)‐thiophenone13 and is conveniently prepared3 by splitting 2‐thienyl t‐butyl ether by heating it with catalytic amounts of p‐toluenesulphonic acid at about 150°. 2(5H)‐Thiophenone, an α,β‐unsaturated cyclic thioester (thiolactone), has been shown to undergo Michael addition with different types of so‐called active methylene compounds.
Miscellaneous glycerol derivatives III: Some trityl, benzyl, and benzylidene derivatives
Authors: Verkade P. E.
Published: September 2010

Below a brief description is given of a number of hitherto unknown acyl‐trityl, acyl‐benzyl, and acyl‐benzylidene derivatives of glycerol.
An apparatus for the automatic recording of temperature‐time curves of condensed phases
Authors: Block R. , Mijlhoff F. C.
Published: September 2010

In studying transitions in condensed phases temperature‐time diagrams are frequently used. In this paper the principles for the construction of an apparatus for automatic recording of these diagrams using thermocouples are outlined. Temperature intervals and their initial points can be chosen at will; the lower limit of the interval depends only on the recorder‐sensitivity, and is in our case 6°. The diagram obtained is exactly interpretable in terms of thermal emf's. Constant specific heat of the sample is represented in the diagram by a line of constant slope.
Aromatic sulphonation VIII: Partial rate factors in the sulphonation of toluene with aqueous sulphuric acid
Authors: Cerfontain H. , Kaandorp A. W. , Vollbracht L.
Published: September 2010

The ratio of the overall rate constants for the sulphonation of toluene and benzene in aqueous sulphuric acid at 25° decreases from 110 to 25 on varying the acid concentration from 78 to 92 wt‐%. Similar trends are observed at 5° and 45°.

The partial rate factors for ortho‐, meta‐ and para‐substitution in the sulphonation of toluene with aqueous sulphuric acid all decrease strongly with increasing acid concentration. The partial rate factor for para‐substitution is temperature independent, indicating a negligible difference in activation enthalpy between substitution at the para‐position in toluene and at a single position in benzene. The corresponding difference in activation entropies is 7 ± 2 cal · deg−1 · mole−1.

The latter difference is ascribed to differences in solvation of the starting hydrocarbons or/and of the transition states. These differences in solvation may also be responsible for the small but apparent deviations from the Selectivity Relationship observed in the present study. It is suggested that the sulphonation of toluene and benzene in aqueous sulphuric acid proceeds via a Wheland type of intermediate.
Usefulness of the phthalimidomethyl group for the reversible protection of carboxyl functions
Authors: Nefkens G. H. L. , Tesser G. I. , Nivard R. J. F.
Published: September 2010

The stability of the ester bond in phthalimidomethyl benzoate has been tested under a wide variety of circumstances, applied for the removal of protecting groups from amino acids. The chemical properties of the ester (table I) warranted the expectation that the phthalimidomethyl group would be useful for the protection of carboxyl functions in peptide syntheses.

Several amino acid esters of phthalimidomethanol (table III) have been prepared by simple methods. Some of these compounds have been converted into peptides by conventional routes (table IV). No racemization was observed during these reactions.

The usefulness of the phthalimidomethyl esters in peptide syntheses has been investigated further with amino acid and peptide esters containing also amino or other carboxyl protecting groups (benzyloxycarbonyl, benzyl, p‐nitrobenzyl or tert.‐butyl). In all cases the phthalimidomethyl group as well as the other substituents could be removed separately and very specifically, giving pure products in satisfactory or good yields (see e.g. schemes A and B).
Equilibration of benzene derivatives: Part I. Bromobenzenes
Authors: Augustijn G. J. P. , Kooyman E. C. , Louw R.
Published: September 2010

Relative rates of aluminium bromide catalyzed debromination of bromobenzenes have been determined by competition runs at room temperature. Ortho‐halo‐substituents have an accelerating effect; the influence of m‐ and p‐substituents is also different from that observed in electrophilic substitutions.

Isomer equilibria among halo‐bromobenzenes showed low proportions of ortho‐isomers (5‐6%) and meta/para ratios of about 1.7‐2.0; with alkyl‐bromobenzenes, appreciable proportions of ortho‐isomers were found. This difference is attributed to dipole interactions having opposite signs in the two cases. Equilibrium patterns for disubstituted bromobenzenes agreed with isomer distributions computed from mono‐substituted bromobenzenes on the basis of additivity; steric effects may cause deviations, e.g. in the bromo‐ortho‐xylenes.

Equilibrium constants for exchange reactions PhZ + PhBr⇄BrPhZ + PhH were found to be 1.45, 1, 0.055, 0.10 and 0.075 for Z = CH3, H, Br, Cl and F, respectively. Combination of these constants with the isomer distributions leads to “partial equilibrium factors” for the exchange of a bromine and a hydrogen atom at a given position in a substituted benzene relative to benzene.
The photo‐oxidation of nylon 6 and 66
Authors: Kroes G. H.
Published: September 2010

On the basis of experimental results published earlier1 and data from the literature2, an extension of the complex of reactions taking place in the photooxidation of polyamides is proposed.

It is shown that after the completion of a chain break, at least one of the ends formed is shortened step by step until suitable conditions for termination are present. In this connection the availability of oxygen as well as the relative immobility of the activated ends are of importance.
Syntheses of the isomeric amino‐ and bromo‐1,5‐naphthyridines
Authors: Czuba W.
Published: September 2010

Syntheses of the three isomeric bromo‐1,5‐naphthyridines from 2‐hydroxy‐1,5‐naphthyridine, 3‐amino‐5‐bromopyridine (Skraup‐synthesis) and 4‐hydroxy‐1,5‐naphthyridine are described.

New methods for the preparation of 2‐ and 3‐amino‐1,5‐naphthyridine are given.

Some physical and chemical properties (inter alia the infrared spectra) of the substances investigated have been established.
Rearrangements during aminations of bromo‐1,5‐naphthyridines, probably involving a naphthyridyne as an intermediate
Authors: Czuba W.
Published: September 2010

When reacted with potassium amide in liquid ammonia both 3‐bromo‐and 4‐bromo‐1,5‐naphthyridine are converted into a mixture containing 3‐amino‐ and 4‐amino‐1,5‐naphthyridine. The course of these reactions can be explained by a mechanism involving 1,5‐naphthyridyne‐3,4 as an intermediate.

An abnormal reaction takes place during the aminations of 2‐bromo‐1,5‐naphthyridine, a compound, C8H8N4, together with the chief product 2‐amino‐1,5‐naphthyridine and 1,5‐naphthyridine being formed.

In the case of 3‐bromo‐2‐ethoxy‐1,5‐naphthyridine an amination reaction afforded only 3‐amino‐2‐ethoxy‐1,5‐naphthyridine. Syntheses of 3‐bromo‐2‐ethoxy‐1,5‐naphthyridine and 3‐amino‐2‐ethoxy‐1,5‐naphthyridine are described.
9‐pyridylidenefluorenes, a new class of anti‐inflammatory substances
Authors: Buu‐Hoï N. P. , Delbarre F. , Jacquignon P. , Brouilhet H. , Rose A. , Sabathier J. F. , Sinh M. P.
Published: September 2010

The condensation of fluorene with the three formylpyridines and 2‐formyl‐6‐methylpyridine has been investigated, and the 9‐pyridylidenefluorenes obtained have been tested in rats for anti‐inflammatory activity. 9‐(3‐Pyridylidene)fluorene proved the most potent compound, with an activity half of that of subcutaneously injected prednisone, in an oral dose ten times greater.
Investigations on sterols XXI: An alternative route for the synthesis of some 6‐dehydro‐9β,10α‐steroid hormone analogues
Authors: Smit A. , Westerhof P.
Published: September 2010

Selective ozonisation of isolumisterone produced 9β,10α‐bisnorchola‐4,6‐dien‐3‐on‐22‐al. This compound could be converted into: 6‐dehydro‐9β,10α‐progesterone (9β,10α‐pregna‐4,6‐diene‐3,20‐dione); 6‐dehydro‐17α‐hydroxy‐9β,10α‐progesterone (9β,10α‐pregna‐4,6‐dien‐17α‐ol‐3,20‐dione) and 6‐dehydro‐9β,10α‐testosterone (9β,10α‐androsta‐4,6‐dien‐17β‐ol‐3‐one).
Hetarynes VI: Amination of bromoethoxypyridines
Authors: den Hertog H. J. , Pieterse M. J. , Buurman D. J.
Published: September 2010

Aminations of 2‐bromo‐3‐ethoxy‐, 2‐bromo‐4‐ethoxy‐, 2‐bromo‐5‐ethoxy‐, 3‐bromo‐2‐ethoxy‐ and 4‐bromo‐2‐ethoxy‐pyridine with potassium amide in liquid ammonia are described.

A survey is given of the behaviour of the 10 isomeric bromoethoxypyridines towards this reagent.