bluuebunny/crossref_metadata_2025 huggingface dataset:
The potential dependence of the fractional surface coverage at a hanging mercury drop electrode
Authors: Rek J. H. M. , Wijnen M. D. , Sluyters J. H.
Published: September 2010

From double layer capacity measurements the fractional surface coverage of 1‐hexanol, thymol, polyoxethylene lauryl ether and sodium dodecyl sulfate is determined at different potentials. It appears that the fractional surface coverage, defined in terms of the integral capacity, does not change with potential within the range ‐0.20 to ‐1.00 V against the S.C.E.
The addition of bromine to phenanthrene in methanol as a solvent
Authors: van der Linde J. , Havinga E.
Published: September 2010

The reaction of phenanthrene with bromine in methanol as a solvent has been studied. The composition of the rather complex reaction mixture as a function of reaction time has been determined by infrared spectrophotometry. The main reaction products appeared to be trans‐9,10‐dibromo‐9,10‐dihydrophenanthrene, 9‐bromo‐10‐methoxy‐9,10‐dihydrophenanthrene, 9‐methoxyphenanthrene, 10‐bromo‐9‐phenanthrone dimethyl acetal and 10,10‐dibromo‐9‐phenanthrone. The results of this investigation indicate that the bromide ion completing the addition of bromine to the 9,10‐double bond of phenanthrene, is taken up from the solution at random.
On the ratio of successive stepwise complex formation constants: Zinc and cadmium complexes of pyridine and substituted pyridines
Authors: Desai A. G. , Kabadi M. B.
Published: September 2010

Successive formation constants of Zn (II) and Cd (II) complexes of pyridine and substituted pyridines have been tested in the light of van Panthaleon van Eck relationship. The deviations in log K2 values have been correlated with the dipole moments of the ligands.
On the rate of adsorption of some surface‐active substances at a hanging mercury drop electrode
Authors: Rek J. H. M. , Wijnen M. D. , Sluyters J. H.
Published: September 2010

As a more rapid method for the determination of values of the electrode coverage it is proposed to measure the differential capacity as a function of time at an initially clean electrode. This method appears to be applicable if the concentration of the surface‐active substance is lower than a certain value. A theoretical expression for the rate of adsorption on a spherical electrode is derived and good agreement with experiment is obtained for 1‐hexanol. Electrode coverage against √t curves are measured for 1‐hexanol, thymol, sodium dodecyl sulfate and polyoxyethylene lauryl ether.
Equilibration of benzene derivatives: Part II. t‐Butyl‐ and i‐Propyl‐benzenes
Authors: Kooyman E. C. , van der Lans H. N. M.
Published: September 2010

Liquid phase isomer and transalkylation equilibria were determined for some t‐butyl‐ and i‐propyl‐benzenes containing an alkyl or halogen substituent, using aluminium bromide as the catalyst.

Isomer equilibria contained low or zero proportions of ortho‐isomers. Meta‐2 para ratios ranged from 0.6 (di‐t‐butylbenzenes) to 2.0 (t‐butylfluorobenzenes). In all cases, more than 50% of meta isomer was present.

Transalkylation (= disproportionation) equilibrium constants are probably governed mainly by electrostatic substituent interactions, favouring the presence of two groups having opposite polarities within the same molecule. Thus, for processes m‐Z‐C6H4R + C6H5H ⇄ C6H5Z + C6H5R, the extremes are 0.8 (disproportionation of m‐di‐t‐butylbenzene) and 2.4 (for m‐t‐butylchlorobenzene).

The results may be interpreted along the same general lines as those for bromobenzenes reported on earlier1.
Chemistry of acetylenic ethers 79: A new synthesis of Vitamin A aldehyde
Authors: Jacobs H. A. M. , Berg M. H. , Brandsma L. , Arens J. F.
Published: September 2010

Reaction of β‐ionone with the dienynyl ether V under Neff conditions affords the C20 carbinol VI, from which vitamin A aldehyde VIII can be prepared by reduction with lithium aluminium hydride and subsequent hydrolysis of the complex of the reduced C20 carbinol with dilute acids.

The dienynyl ether is synthesized from the acetal CH3COCH2CH(OCH3)2 by addition of propynyl‐lithium, subsequent reaction of the resulting C7 carbinol II with ethyl vinyl ether to yield the C7 diacetal III and treatment of the latter with alkali amide in liquid ammonia. The overall yield of the dienynyl ether V is about 75%, while vitamin A aldehyde is obtained in yields of 55‐60%, calculated on β‐ionone.
The system NbCl5 ‐ Nb2O5: III. The equilibrium constant of the equilibrium 5NbOCl ⇌ 3NbCl + Nb2O
Authors: Hart W.'T , Meyer G.
Published: September 2010

The determination of the partial pressures of NbOCl3 and NbCl5 of the three‐phase equilibrium S ‐ S ‐ G is described. For the partial pressure of NbOCl3 it is found that:

and for the partial pressure of NbCl5:

The equilibrium constant of the equilibrium

is given by the equation:
Derivatives of benzo‐ and indolo‐quinolizines: I Synthesis of 2‐substituted hexahydro‐2H‐benzo[a]quinolizines and octahydroindolo[2,3‐a]quinolizines from substituted glutaric acids
Authors: Gootjes J. , Nauta W. Th.
Published: September 2010

The preparation is described of a number of 2‐substituted 1,3,4,6,7,11b‐hexahydro‐9,10‐dimethoxy‐2H‐benzo[a]quinolizines and 1,2,3,4,6,7,12,12b‐octahydroindolo[2,3‐a]quinolizines, starting from 3‐substituted glutaric acids. The preparation requires seven stages (see Reaction Scheme); the majority of the intermediate products has been isolated and described. The end‐products and some of the intermediate products occur in two diastereoisomeric forms, which were separated by crystallisation.
The copper‐catalysed oxidation of unsaturated carbonyl compounds: Part IV. Oxidation of β,γ‐unsaturated ketones by cupric‐pyridine complexes in the absence of oxygen
Authors: Volger H. C. , Brackman W.
Published: September 2010

The oxidation of 5‐methyl‐4‐hexen‐2‐one and of isomesityl oxide by an equimolecular amount of cupric‐pyridine complex in alkaline methanol yielded dehydrodimers via dienol radicals as intermediates.

Oxidation of the radicals to carbonium ions does not occur.
Mixed carboxylic acid anhydrides VI. Synthesis of aryl formates
Authors: van Es A. , Stevens W.
Published: September 2010

Effects of various molar intake ratios of reactants, of temperature and of catalysts on the esterification of phenols with formic acid/acetic anhydride reaction mixtures have been studied. Attractive methods of synthesis of pure aryl formates have been found.
Raman spectra of trimethyl phosphinesulfide and bis‐(dialkylphosphinothioyl) compounds
Authors: Gerding H. , Zijp D. H. , Hooge F. N. , Blasse G. , Christen P. J.
Published: September 2010

Raman spectra of (CH3)3PS and of (R2PS)2 where R is CH3, C2H5, n‐C3H7 and n‐C4H9 were measured. From these spectra it may be concluded that the P‐P stretching frequency is near 510 cm−1.
Organophosphorus compounds I: The preparation of some aryl phosph(orothiol)ates and aryl phosphon(othiol)ates
Authors: Boter H. L. , Toet H. J.
Published: September 2010

In this paper is described the preparation of some o‐ and m‐nitrophenyl phosphates and phosphonates, m‐dimethylaminophenyl phosphates and phosphonates, a S‐p‐nitrophenyl phosphorothiolate and a S‐p‐nitrophenyl phosphonothiolate. All the compounds except one were synthesized by the reaction of dialkyl phosphorochloridates or alkyl alkylphosphonochloridates with a substituted (thio)phenol in ether solution in the presence of an organic base as the hydrogen chloride binding agent.

Physical constants and elementary analyses of the isolated compounds were recorded.
Synthesis and conformation of 2‐alkyl‐1‐(ORTHO‐alkyl)phenylcyclohexanols
Authors: Timmerman H. , Rekker R. F. , Nauta W. Th.
Published: September 2010

Several 2‐alkyl‐1‐(ortho‐alkyl)phenylcyclohexanols have been synthesized from lithium compounds (obtained from alkylbromobenzenes) and 2‐alkyl‐cyclohexanones. G.L.C. analysis has shown that only one isomer is formed. The conformation was elucidated with the aid of N.M.R. spectra, which showed that a tert‐alkyl group in the ortho position of the aromate gave rise to an axial position of this aromatic group at the cyclohexane ring.

In all other cases the phenyl group is equatorial.
Microwave absorption spectrum of methoxyethyne
Authors: den Engelsen D. , Dijkerman H. A. , Kerssen J.
Published: September 2010

The microwave absorption spectra, the rotational constants, structure data and the dipole moment of the molecules methoxyethyne (HC≡COCH3) and 2‐deutero‐1‐methoxyethyne (DC≡COCH3) are reported. The potential barrier of the torsional vibration of the methyl group is derived from observed doublet‐splittings.
3,4‐Benzoxanthene cyclic ethers
Authors: Mustafa A. , Latif N. , El‐Namaky H.
Published: September 2010

Treatment of 3,4‐benzoxanthone hydrazone with tetrahalogeno‐α‐benzoquinones gave the corresponding cyclic ethers (IIIa‐b). Reductive cleavage of the latter with lithium aluminium hydride yielded 3,4‐benzoxanthene together with the tetrahalogenocatechol. Whereas active hydrogen compounds effect cleavage of the dioxole ring in IIIa‐b with the formation of the corresponding benzo‐xanthylene, they react with 9‐hydroxy‐3,4‐benzoxanthene yielding the benzoxanthyl derivatives (VIII).

Diazoalkanes on 3,4‐benzoxanthione afford the corresponding ethylene sulfides. The thermochromic properties of the ethylenes, obtained by the action of copper on the ethylene sulfides, are stressed.

Reaction mechanisms are discussed.
Analysis of n‐alkyltrimethylammonium halides by gas chromatography and infrared spectroscopy with isotope substitution of the nitrogen atom
Authors: van Senden K. G.
Published: September 2010

The preparation of some n‐alkyltrimethylammonium halides is described. Their purity is established by surface‐tension measurements, gas chromatography of the alkyl parts, and infrared spectra of the complete molecules.

The assignment of C‐N vibrations to some bands in the spectra has been confirmed by substitution with nitrogen of atomic mass 15 instead of the naturally occurring N14.
Thermolytic reactions of esters part I: Allyl acetate
Authors: Louw R. , Kooyman E. C.
Published: September 2010

Within the scope of a general study on the gas phase chemistry of esters, the thermolysis of allyl acetate was investigated, using a stirred‐flow type (“tank‐flow”‐) reactor operating at atmospheric pressure in the presence of nitrogen as the carrier gas.

Rate and product studies, including the use of toluene or cyclohexene as scavengers and the application of selectively deuterated compounds, demonstrated that under our conditions (400‐500°C) the reaction mainly proceeds via. free radicals, allyl‐oxygen homolysis probably being the intial step. The main decomposition products formed are carbon dioxide, 1‐butene, carbon monoxide and methane; formation of these and other (minor) products may be accounted for in terms of an induced decomposition mainly effected by methyl radicals.
Investigations on organogermanium compounds. IIIN‐Tributylgermyl‐substituted aliphatic and heterocyclic amines
Authors: Rijkens F. , Janssen M. J. , van der Kerk G. J. M.
Published: September 2010

A series of new organogermanium compounds containing a germanium‐nitrogen bond, in many of which the nitrogen atom forms part of an heterocyclic ring, are prepared, in some cases by new methods: transamination reactions and reactions of germoxanes with heterocyclic amines. Striking differences in reactivity towards solvolyzing agents are observed. These are explained by postulating reaction mechanisms in which an important role is assigned to the availability of the electron pair at the nitrogen atom of the germanium‐nitrogen bond.
Aromatic sulfonation XIII determination of the kinetic isotope effect of hydrogen in the sulfonation and sulfonylation of benzene
Authors: Cerfontain H. , Telder A.
Published: September 2010

The kinetic isotope effect of hydrogen in the sulfonation of benzene with sulfur trioxide in nitrobenzene as solvent has been determined at 25° in a competitive study as kH/kD = 1.35 ± 0.16; for nitromethane as solvent kH/kD = 1.25 ± 0.01. Small amounts of diphenylsulfone were obtained as by‐product in the sulfonation reactions. For the sulfonylation reaction in the two solvents the kinetic isotope effect was determined at 25° as kH/kD = 0.96 ± 0.04 and 0.94 ± 0.07 respectively.
The possibilities of dowex A‐1 chelating resin for the separation of metals
Authors: van Willigen J. H. H. G. , Schonebaum R. C.
Published: September 2010

Acid constants of Dowex A‐1 chelating resin and stability constants of metalresin complexes have been determined, using a special theoretical approach. The differences found between the stability constants do not encourage the use of this resin for the separation of heavy metals.
Diperoxycarboxylic anhydrides and their urea adducts as peroxy acid precursors
Authors: Heslinga L. , Schwaiger W.
Published: September 2010

Unbranched aliphatic diperoxycarboxylic acids of short chain length can be included in urea by acetylation in the presence of the latter compound. The reactions carried out with diperoxysuccinic, diperoxyadipic and diperoxyazelaic acid proceed almost quantitatively at room temperature. The diacetic diperoxycarboxylic anhydrides thus stabilized readily react with hydrogen peroxide in aqueous solution at room temperature, yielding mixtures of peroxyacetic and diperoxycarboxylic acid in high yield.

Non‐included 3,3′‐dicarboxypropionyl and acetyl 3‐carboxypropionyl peroxide also form peroxy acids under these conditions. However, perhydrolysis of non‐included n‐acyl peroxides R‐C∥‐O‐O‐C‐R∥ is negligible.
The nature of the chemiluminescence of dicumyl peroxide decomposition
Authors: de Kock R. J. , Hol P. A. H. M.
Published: September 2010

The nature of the chemiluminescence phenomenon generally observed during oxidation of organic substances at elevated temperatures, was studied on the system dicumyl peroxide‐polypropylene. Arguments are put forward in favour of the assumption that the luminescence observed during decomposition of dicumyl peroxide, should be interpreted as phosphorescence of the reaction product acetophenone.
Synthesis of some poly‐unsaturated aldehydes
Authors: Ward J. P. , van Dorp D. A.
Published: September 2010

Propargyl aldehyde diethyl acetal (1,1‐diethoxy‐2‐propyne) and 2,5‐hexadiynal diethyl acetal (1,1‐diethoxy‐2,5‐hexadiyne) have been successfully employed in the synthesis of the unsaturated aldehydes 2trans,5cis‐undecadienal, 2trans,5cis,8cis‐tetradecatrienal and 2trans,5cis,8cis, 11cis‐heptadecatetraenal, which were characterized as their 2,4‐dinitrophenylhydrazones.

7‐Chloro‐1,1‐diethoxy‐2,5‐heptadiyne has been prepared and used in the synthesis of 2trans5cis,8cis‐tetradecatrienal.

In addition, the syntheses of the 2,4‐dinitrophenylhydrazones of 2trans,6cis‐dodecadienal, 2trans,6cis,9cis‐pentadecatrienal and 2trans,6trans‐dodecadienal are described.
Determination of the absolute configuration of 3‐bromocamphor
Authors: Northolt M. G. , Palm J. H.
Published: September 2010

The absolute configuration of (+)‐3‐bromocamphor has been determined by X‐ray single crystal diffraction, Br acting as anomalous scatterer for MoKa radiation. The absolute configuration thus determined is in agreement with that proposed by Fredga and Miettinen4 on the basis of chemical evidence: in (+)‐camphor the “bridge” atom C(7) (connecting C(1) and C(4)) is behind the mean plane of the cyclohexane ring atoms, if the latter are numbered clockwise, and the oxo‐oxygen atom is situated at C(2).
Enthalpies of solution of some alkali halides in N‐methylformamide at 25°
Authors: Weeda L. , Somsen G.
Published: September 2010

The enthalpies of solution of LiI, NaI, KF, KCl, KBr, KI, RbI and CsI in anhydrous N‐methylformamide (NMF) at concentrations of about 5 × 10−3 molal have been measured with an adiabatic calorimeter. The enthalpies of dilution in NMF were calculated with the aid of the extended Debye‐Hückel theory. The differences in enthalpy of solution of the alkali iodides between (1) water and formamide and (2) water and NMF are compared with the results of van Eck's theory of ionic solvation.
The conformation of non‐aromatic ring compounds. XXII: The crystal structure of trans‐2,5‐dibromo‐1,4‐dithiane
Authors: Kalff H. T. , Romers C.
Published: September 2010

trans‐2,5‐Dibromo‐1,4‐dithiane crystallizes in the monoclinic system; the space group is P21/c with a = 6.42, b = 7.12, c = 9.01 Å, β = 111.6°, and Z = 2. The structure was solved from a three‐dimensional Patterson function and refined by the least‐squares method using room temperature reflexion data. The dithiane ring has the chair conformation with the bromine atoms in axial positions. Large values (115°) are observed for the valency angles CCS, all other bond angles and bond distances being normal.
Mass spectral identification of the methyl esters of 2,4‐dinitrophenylamino‐acids
Authors: Penders Th. J. , Copier H. , Heerma W. , Dijkstra G. , Arens J. F.
Published: September 2010

The methyl esters of 2,4‐dinitrophenylamino‐acids are suitable for mass spectral analysis of amino‐acids in peptide hydrolysates.
Studies in homogeneous catalysis: Di‐tert‐butyl nitroxide as promoter of the copper‐catalysed oxidation of methanol by oxygen
Authors: Brackman W. , Gaasbeek C. J.
Published: September 2010

The oxidation of methanol by oxygen, catalysed by copper‐phenanthroline complexes and promoted by the stable radical di‐tert‐butyl nitroxide, has been studied. The results are discussed in connection with the previously studied oxidation of methanol by copper‐phenanthroline complexes, catalysed by di‐tert‐butyl nitroxide, in the absence of oxygen.

Similar systems in which ammonia was used instead of phenanthroline were also investigated, both under aerobic and anaerobic conditions. The results indicate that the promoter, di‐tert‐butyl nitroxide, is not involved in any reactions in which oxygen or radicals derived from oxygen participate, but that its sole function is to catalyse the reduction by methanol of cupric complex to the cuprous state. If oxygen is present, the cuprous ion then reacts with one mole of oxygen, yielding cupric complex and \documentclass{article}\pagestyle{empty}\begin{document}\[{\rm O}_{\rm 2}^{-\bullet}\]\end{document}, whereupon the \documentclass{article}\pagestyle{empty}\begin{document}\[{\rm O}_{\rm 2}^{-\bullet}\]\end{document} reacts with methanol coordinated to cupric ion, as in the aerobic oxidation of methanol catalysed by unpromoted copper‐phenanthroline complexes, described in the previous paper.

Chain reactions propagated by hydroxymethyl radicals do not occur in the present reaction.
Purification des substances organiques par fusion de zone: Un appareil permettant de traiter un kilogramme de produit
Authors: Maire Jean Claude , Delmas Marc Arthur
Published: September 2010

L'appareil décrit permet l'extension de l'application de la méthode de fusion de zone, au traitement d'une quantité de produit organique voisine du kilogramme. Il appartient à la série des appareils dont le tube est vertical et les zones chauffantes fixes. La vitesse du tube, entraîné par un système hydraulique, est comprise entre 10 et 40 mm par heure. La chauffage est assuré par six résistances et régulé par un pyrectron. Deux essais sur des mélanges synthétiques confirment l'efficacité de la méthode ainsi adaptée à cette échelle, et surtout le grand progrès apporté par l'introduction d'un tuyau flexible de téflon destiné à absorber les variations de volume du produit.
On the oscilloscopic determination of rate constants of electrode reactions by means of square wave and sine wave current: I. The moment of zero diffusion polarization in the square wave case
Authors: Teppema P. , Sluyters‐Rehbach M. , Sluyters J. H.
Published: September 2010

A new and simple derivation of the diffusion polarization as a function of time is presented for the case wherein a square wave current passes an electrode‐solution interface. The moment of zero diffusion polarization, which was already known to be 0.09, is calculated more precisely to be 0.094 of the whole period of the square wave signal. The consequences as regards the cyclic current step method for the determination of rate constants of electrode reactions, are discussed.
Polynuclear heterocyclic systems. III: Reaction of 2‐aminocyclanones with dimethyl acetylenedicarboxylate
Authors: Pandit U. K. , Huisman H. O.
Published: September 2010

The condensation of cyclic α‐aminoketones II, III and IV with dimethyl acetylenedicarboxylate has been studied. The reaction of II provides a convenient new route to 4,5‐dihydro‐3H‐benz(e)indolecarboxylic acids and esters. NMR spectra of the latter compounds afford a method for recognizing the position of the ester function in certain isomeric esters.
Syntheses of carotenoidal compounds. I. Preparation of some substituted polyenes with a cross‐conjugation
Authors: Haeck H. H. , Kralt T. , van Leeuwen P. H.
Published: September 2010

The syntheses and absorption spectra in visible light of condensation products of retinal and retinylideneacetone with several cyanoacetic esters and related compounds are reported.
1,1,2‐Triphenylethylenes with trifluoromethyl substituents
Authors: Buu‐Hoï N. P. , Nam N. H. , Xuong N. D.
Published: September 2010

A number of 1,1,2‐triphenylethylenes bearing trifluoromethyl substituents in various positions have been synthesized and their oestrogenic activity investigated. It is shown that the introduction of trifluoromethyl groups decreases the oestrogenicity, this effect being more pronounced in the para derivatives than in the ortho and meta isomers. Possible explanations for this effect are discussed.
Chemistry of acetylenic ethers 81: synthesis of β‐alkoxy‐β‐chloroacrylic chlorides by addition of phosgene to 1‐alkynyl ethers
Authors: van den Bosch G. , Bos H. J. T. , Arens J. F.
Published: September 2010

1‐Alkynyl ethers of the type R‐C≡C‐OR′ (R = H or alkyl and R′ = alkyl) were converted by addition of phosgene into β‐alkoxy‐β‐chloroethene carbonic chlorides RO‐CCl = CR‐CO‐Cl (II). From the adducts some amides were prepared.

Hexachloroacetone and chloral reacted with ethoxyethyne without a catalyst to (CCl3)2CCH‐COOC2H5 (I) and CCl3CHCHCOOC2H5 respectively.

Sulfur dichloride already adds on to ethoxyethyne at a low temperature, forming bis(2‐ethoxy‐2‐chlorovinyl) sulfide (VIII), which upon alcoholysis yields bis(ethoxycarbonylmethyl) sulfide (IX).
Chemistry of acetylenic ethers 82: On the different influence of alkylthio and alkoxy groups on the course of 1,4‐Eliminations
Authors: van Boom J. H. , Brandsma L. , Arens J. F.
Published: September 2010

1,4‐Elimination of alkanethiols RSH from the bis‐thioethers RSCH2CCC;H2SR with sodium ethoxide in liquid ammonia at −33°, affords two products viz. enynyl thioethers CH2CHC≡CSR and dienyl‐bis‐thioethers CH2CH‐C(SR)CHSR resulting from readdition of thiolate. Experimental evidence for the occurrence of cumulenyl thioethers CH2CCCHSR as intermediates in these elimination reactions is described.

Reaction of the “mixed” compounds RSCH2C≡CCH2OR′, RSCH2C≡CCH(CH3)OR′ and RSCH2C≡C‐C(CH3)2OR′ with sodium ethoxide at −33° in liquid ammonia results in an elimination of the OR′ [R′ = alkyl or ‐CH(CH3)OC2H5] group and formation respectively of the enynyl thioethers RSC≡CCHCH2, RSC≡CCHCHCH3 and a mixture of RSC≡CCHC(CH3)2 and the carbinol

RSCH≡C(OH)(CH3)] = CCH–C

The carbinol can also be obtained by reaction of RSCHCCHC(CH3) = CH2 with lithium amide and acetaldehyde.
Reserpine analogues V: Optical antipodes of two methoxy‐β‐phenylethylaminoalkyl methoxybenzoates
Authors: Kralt T. , Haeck H. H. , Peperkamp H. A.
Published: September 2010

Preparation of the optical antipodes of I and of II is described. The absolute configuration of the antipodes is determined, correlating the structures with that ofD(+)paredrine. The musculotropic as well as the neurotropic activities of the antipodes are given.
Chemistry of 1,2‐di‐tert.Butylbenzene and derivatives i. nitration of 1,2‐di‐tert.butylbenzene
Authors: van de Graaf B. , Wepster B. M.
Published: September 2010

Nitration of 1,2‐di‐tert.butylbenzene gives, in addition to 4‐nitro‐1,2‐di‐tert.‐butylbenzene, a remarkably high percentage of 3‐nitro‐1,2‐di‐tert.butylbenzene. Upon further nitration of these compounds, 3,5‐dinitro‐1,2‐di‐tert.butylbenzene and 4,5‐dinitro‐1,2‐ditert.butylbenzene are formed from the 4‐nitro derivative, and 3,4‐dinitro‐1,2‐di‐tert.butylbenzene and 3,5‐dinitro‐1,2‐di‐tert.butylbenzene from the 3‐nitro derivative.
Sulfonylmethyl isocyanates, a new class of isocyanates
Authors: Strating J. , van Oven H. O. , van Leusen A. M.
Published: September 2010

Five alkyl‐ and aryl‐sulfonylmethyl isocyanates have been isolated
Tetracyclic γ‐carboline derivatives: Synthesis of 2,8‐substituted octahydroindolo[3,2‐α]quinolizines
Authors: Corts G. J. B. , Nauta W. Th.
Published: September 2010

The preparation of a number of 2,8‐substituted 1,2,3,4,6,7,8,12c‐octahydroindolo[3,2‐α]quinolizines, using a 2‐(2‐aminoethyl)indole derivative and 3‐substituted glutaric anhydrides, or 3‐substituted 5‐bromovalerates, as starting materials, is described.
Studies on imidazoles, part II: The action of phosphorus pentachloride on some symmetrical N,N′‐dialkyloxamides
Authors: Trout G. E. , Levy P. R.
Published: September 2010

A series of 5‐chloro‐1,2‐dialkylimidazoles have been prepared in good yield by the action of phosphorus pentachloride on a series of symmetrical N,N′‐dialkyloxamides and their infra‐red spectra recorded.
1,1‐Dialkoxyalkyl alkane‐ and arene‐carboxylates. I.: Synthesis of dialkoxymethyl esters
Authors: Scheeren J. W. , Stevens W.
Published: September 2010

Dialkoxymethyl esters of carboxylic acids have been prepared.
Catalyst specificity in the benzoin type condensation of picolinaldehyde. A direct test for cyanide ion
Authors: Poziomek E. J. , Kronenberg M. E. , Havinga E.
Published: September 2010

Of thirty‐five reagents tested only cyanide rapidly catalyzes the formation of α‐pyridoin from picolinaldehyde in water. Visual observation of product precipitating offers a rapid and specific method of detecting cyanide at concentrations of 5 μg per ml or higher.
Preparation of dithioesters from alkynethiolates and thiols: Evidence for the intermediate occurrence of thioketenes
Authors: Schuijl P. J. W. , Brandsma L. , Arens J. F.
Published: September 2010

Dithioesters magnified image have been obtained in satisfactory yields by adding ethereal solutions of lithium alkynethiolates, RCCSLi, to an excess of a thiol. Thioketenes RCHCS are supposed to be intermediate species.
The synthesis of 1‐ and 2‐alkyladamantanes
Authors: Hoek W. , Strating J. , Wynberg Hans
Published: September 2010

When thiophene is alkylated with 1‐bromoadamantane a separable mixture of 2‐(1‐adamantyl)thiophene and 3‐(1‐adamantyl)thiophene is formed. Using 2‐bromoadamantane a similar mixture of 2‐(2‐adamantyl)thiophene and 3‐(2‐adamantyl)thiophene is formed. Desulfurization furnished the corresponding alkyl adamantanes.
Synthesis of β‐diazosulfones
Authors: Strating J. , Heeres J. , van Leusen A. M.
Published: September 2010

Three β‐diazosulfones are obtained by alkaline fission of N‐(2‐arylsulfonylethyl)‐N‐nitrosourethanes. Alternative approaches, i.e. oxidation of phenylsulfonylacetone hydrazone and alkaline decomposition of the corresponding tosylhydrazone, did not succeed.
The addition of bromine chloride to some cyclohexene derivatives
Authors: Hageman H. J. , Havinga E.
Published: September 2010

The addition of bromine chloride, prepared in situ from N‐bromosuccinimide and hydrogen chloride, to a number of alkyl cyclohexenes has been studied. The addition leads to mixtures of isomeric trans‐bromochloroalkylcyclohexanes. A two‐stage mechanism, involving the formation of a cyclic bromonium‐ion intermediate, followed by a trans‐diaxial opening of the cyclic intermediate is proposed to account for the experimental results.
Analysis of the NMR spectra of 1,2,4‐trichlorobenzene and methyl vinyl ketone
Authors: van Meurs N.
Published: September 2010

The ABC‐type NMR spectra of 1,2,4‐trichlorobenzene and methyl vinyl ketone were re‐examined. Improved sets of coupling constants have been obtained for these compounds.
Specificity in the enzymic conversion of polyunsaturated fatty acids into prostaglandins
Authors: Struijk C. B. , Beerthuis R. K. , Pabon H. J. J. , van Dorp D. A.
Published: September 2010

The enzyme specificity in the biosynthesis of prostaglandins has been investigated by incubation of a particulate fraction of sheep vesicular glands with ω6 tri‐ and tetraenoic C18 ‐ C22 fatty acids and isomers of ω6 eicosatrienoic acid (20: 3 ω6). The chemical synthesis of the various substrate fatty acids is described. The tetraenoic fatty acids were converted into a series of prostaglandin E2 homologues and the trienoic fatty acids into a series of prostaglandin E1 homologues. The only isomer of 20: 3 ω6 which showed a fairly high conversion into an isoprostaglandin E1 was the ω7 compound. Maximum conversions were obtained from ω6 C20 acids.

The smooth muscle stimulating activity of prostaglandin E1 and E2 appears to be very specific. All other prostaglandins had much lower activities.
Ketene thioacetals from dithioesters
Authors: Schuijl P. J. W. , Brandsma L. , Arens J. F.
Published: September 2010

Ketene thioacetals R′CH=C(SR″) (SR′″) (with R′=H or alkyl and R″, R′″=alkyl) have been obtained in very good yields by treatment of dithioesters R′CH2C=S(SR″) with one equivalent of potassium amide in liquid ammonia and subsequent alkylation with alkyl halide R′″Br or R′″I.
Reinvestigation of authentic samples of auxins a and b, and related products by mass spectrometry
Authors: Vliegenthart J. A. , Vliegenthart J. F. G.
Published: September 2010

Authentic samples of auxin‐a, auxin‐b and auxin‐a lactone ‐ discussed in papers from this laboratory in the period 1931‐1944 ‐ are found to be identical with cholic acid, thiosemicarbazide and hydroquinone, respectively. Auxin glutaric acid turns out to be phthalic acid, and the 3,5‐dinitrobenzoyl ester of auxin‐b is ethyl α‐cyanophenylpyruvate.

Auxins a and b, as unique individuals, are therefore to be considered as non‐existent.
Proton magnetic resonance spectra of some acetylenic phosphorus compounds
Authors: Drenth W. , Rosenberg D.
Published: September 2010

Proton magnetic resonance spectra of ethynylphosphines, ethynylphosphine oxides and their saturated analogues have been measured. An analysis of the data indicates the presence of 3d‐orbital participation in the PC bond. This participation seems to be equal in the phosphines and the phosphine oxides.
Evidence for “through‐space” long‐range proton‐proton coupling in acetone
Authors: de Jeu W. H. , Deen R. , Smidt J.
Published: September 2010

According to the theory of long‐range proton spin coupling by pi electrons, |JHH| in acetone should decrease with increasing polarity of the carbonyl group. Experimentally the opposite has been found. To explain the observed trend a “through‐space” mechanism is proposed. JHH is now interpreted as the result of a negative coupling by the pi electrons and a positive “through‐space” contribution. On this hypothesis a better fit numerically can also be obtained.
The chemistry of polythienyls. Part III: The synthesis of terthienyls
Authors: Kooreman H. J. , Wynberg Hans
Published: September 2010

The synthesis of some terthienyls using 1,2‐ and 1,4‐ diketones as precursors, is described. Most of the 1,4‐diketones are prepared by the Stevens rearrangement of N,N‐di(2‐thenoylmethyl)‐N,N‐dimethylammonium salts followed by elimination of dimethylamine and reduction of the resulting 2‐butene‐1,4‐diones.

Of the fourteen possible isomeric terthienyls only four were known prior to this work. Using the methods described two new isomeric systems have been prepared.
Pyrazoles. III. PMR studies of pyrazoles
Authors: Habraken Clarisse L. , Munter H. J. , Westgeest J. C. P.
Published: September 2010

Substituents with electron withdrawing capacities are found to induce a paramagnetic displacement of the chemical shifts of protons and methyl groups in the remaining positions of the pyrazole ring. For the 4‐position this effect is considered to be due primarily to resonance interaction of substituent and pyrazole ring.
A solid‐phase Edman sequence determination
Authors: Dijkstra A. , Billiet H. A. , van Doninck A. H. , van Velthuyzen H. , Maat L. , Beyerman H. C.
Published: September 2010

The sequence of the amino acids in a peptide covalently bound to a polymer could be determined by reaction with methyl isothiocyanate. This extension of the Edman degradation is likely to facilitate the automation of the sequence determination of peptides and proteins.
Optical rotatory dispersion of pelletierine, confirmation of the absolute configuration
Authors: Beyerman H. C. , Maat L. , Visser J. P.
Published: September 2010

From the difference between the optical rotatory dispersion of pelletierine in acid and in alkaline aqueous solution the absolute configuration was deduced by comparison with 2‐methylpiperidine. It confirms our absolute‐configuration determination by another method. The conclusion contradicts that of a recent publication.
NMR Substituent constants in alkylbenzenes
Authors: van Meurs N.
Published: September 2010

The substituent constants of alkyl groups in alkylbenzenes have been determined for dilute solutions in carbon tetrachloride. Especially for compounds with isolated substituents the constants derived satisfactorily correlate the chemical shifts of the ring protons with the substitution type.
Chemistry of acetylenic ethers 87: Preparation of cumulenyl ethers by 1,4‐elimination
Authors: Montijn P. P. , van Boom J. H. , Brandsma L. , Arens J. F.
Published: September 2010

Cumulenyl ethers of the type R′R″C  C  C  CHOCH3 (with R′ and R″ alkyl) have been prepared in good yields by treatment of bis‐ethers of the type (C2H5O)CH(CH3)OC(R′)(R″)CCCH2OCH3 with two equivalents of sodamide in liquid ammonia.

From the bis‐ether (C2H5O)CH(CH3)OCH(CH3)CCCH2OCH3 a mixture of cis and trans CH3CCCH  CHOCH3 was obtained in good yield by the same procedure.
Thermolytic reactions of esters. Part II. Structural effects in the radical decomposition of simple allyl esters
Authors: Louw R. , Kooyman E. C.
Published: September 2010

Vapour phase thermolysis at 485°C of methallyl acetate and the allyl esters of benzoic, phenylacetic and trifluoroacetic acid proceeds by radical mechanisms analogous to that proposed for allyl acetate1. Rates of primary allyl‐oxygen homolysis appear to depend only slightly on the nature of the acyl moiety.

The induced radical decomposition proceeds mainly by addition to ester, followed by β‐elimination, polymerization being unimportant under the present experimental conditions.

An explanation is offered for the fact that allyl(ic) esters of aromatic acids ‐ in contrast to those of aliphatic acids ‐ produce a substantial amount of carboxylic acid in addition to the main oxygen‐containing product, carbon dioxide.
Structure of disulfide dioxides (thiolsulfonates) (short communication)
Authors: Noordik J. H. , Vos Aafje
Published: September 2010

An X‐ray diffraction study of a disulfide dioxide has shown the compound to be a thiolsulfonate rather than a disulfoxide.
Complexes of ligands containing SO: II. Infrared spectra of diphenylsulfoxide compounds
Authors: van Leeuwen P. W. N. M.
Published: September 2010

The infrared spectra of several complexes of diphenylsulfoxide (DPSO) are reported. Only one SO stretching frequency has been found, at lower wavenumbers than in DPSO itself, indicating that all DPSO's are coordinated to the metal ion. The asymmetric stretching frequencies of CIO⊖ and BF4⊖ have been observed as unusually sharp absorptions.
An attempt at the interpretation of the ligand hyperfine structure in the epr‐spectra of mox ‐ions
Authors: Verbeek J. L. , Cornaz P. F.
Published: September 2010

In this contribution we propose a simple model for the observed ligand hyperfine structure in complexes of the type MOX (where M = Cr, Mo, W and X = F, Br), in the limits of the less complicated case I = ½ as is realised with F as the ligand.

It is assumed that contact interaction and dipole‐dipole interaction between the unpaired electron and the ligands are the origin of this ligand hyperfine structure.

An estimate is made for the energies associated with certain orientations of an external magnetic field with respect to the axes of symmetry of the complex molecule.

It is shown that a remarkable resemblance exists between a spectrum based on these assumptions and the spectrum measured at X‐band of a frozen solution of CrOF in 38% hydrofluoric acid.
Photoreactions of aromatic compounds XIII: Photosubstitution of 4‐nitroveratrole with methylamine; a convenient synthesis of N‐methyl‐4‐nitro‐o‐anisidine
Authors: Kronenberg M. E. , van der Heyden A. , Havinga E.
Published: September 2010

4‐Nitroveratrole reacts with methylamine in water on illumination with ultraviolet light (mainly 313 mμ) to yield N‐methyl‐4‐nitro‐o‐anisidine as the major product. The reaction is zero order; the quantum yield is 0.19. With dimethyl‐amine as a partner analogous photosubstitution occurs but the reaction is complicated inter alia by the photosensitivity of the products. A short discussion of some practical and theoretical aspects is given.
Triphenylphosphonium and triethylphosphonium halides
Authors: van den Akker M. , Jellinek F.
Published: September 2010

Reaction of triethylphosphine with HI, HBr or HCl in ethereal solution yields the solid triethylphosphonium salts Et3PHI, Et3PHBr and Et3PHCl, respectively. Infrared spectroscopy indicates the presence of hydrogen bonds Et3PHX, the strengths of these bonds increasing in the sequence X = I < Br < Cl. By reaction of triethylphosphine with HF liquid products are obtained, consisting of (mainly) Et3PHF or Et3P · 2 HF (depending on the ratio of the reactants). While Et3PHF shows very strong PHF bonding and thus resembles a (polar) molecular compound, Et3P · 2 HF is salt‐like, consisting of the ions [Et3PH]⊕ and [HF2]⊖. Solutions of water in triethylphosphine contain a considerable proportion of Et3PHOH, which has a PHOH bond of moderate strength.

Triphenylphosphine in ether reacts with HI or HBr to form the solid triphenylphosphonium salts Ph3PHI and Ph3PHBr; with HCl the solid salt Ph3P · 2 HCl is formed. This salt consists of the ions [Ph3PH]⊕ and [HCl2]⊖; it is the first reported [HCl2]⊖ salt of a phosphonium base. Ph3P · 2 HCl slowly decomposes into triphenylphosphine and hydrogen chloride; Ph3PHCl may be an unstable intermediate in this reaction, but no evidence was found for the existence of Ph3PHCl as a stable compound. The alleged compound Ph3P · 1.33 HCl1 is a mixture of Ph3P · 2 HCl and Ph3P. Triphenylphosphine reacts with HF to form liquid products consisting of Ph3PHF and Ph3P · 2 HF, the latter compound consisting of [Ph3PH]⊕ and [HF2]⊖ ions. Very strong PHX bonds are found in Ph3PHF; in Ph3PHBr and Ph3PHI the PHX bonds are considerably less strong, while such bonds are absent in Ph3P · 2 HCl and Ph3P · 2HF. The differences between triphenylphosphine and triethylphosphine in their reactions with hydrogen halides (and water) can be explained by their difference in basicity.
The conformation of non‐aromatic ring compounds. Part 37: The Crystal Structure of 2‐Oxo‐2‐phenoxy‐1,3,2‐dioxaphosphorinane
Authors: Geise H. J.
Published: September 2010

2‐Oxo‐2‐phenoxy‐1, 3, 2‐dioxaphosphorinane (propane‐1, 3‐phenylphosphate) crystallizes in the orthorhombic system, space group Pna21, Z = 4. The unit cell dimensions are a = 15.55, b = 11.06, c = 5.97 Å. The structure was solved by the heavy atom technique and refined by the method of least squares using eye‐estimated three‐dimensional data obtained with copper radiation at room temperature. The dioxaphosphorinane ring has the chair conformation with the double‐bonded oxygen in equatorial and the phenoxy group in axial position.
The degradation reaction of histidine with iodine
Authors: Schutte L. , Havinga E.
Published: September 2010

The reaction of histidine and some other imidazole derivatives with iodine at pH8 and 50° has been followed to completion (uptake 8 moles I2 per mole histidine). Products of the I2‐degradation of histidine are: carbonate, iodoform, oxalic acid, ammonia and iodide. The origin of the reaction products has been traced by using radioactively labelled compounds. An overall equation for the reaction is deduced and a tentative scheme for a reaction path is presented.
Properties of diazosulfonates. Part I: The dissociation of methoxybenzenediazosulfonates
Authors: van Beek L. K. H. , Helfferich J. , Jonker H. , Thijssens Th. P. G. W.
Published: September 2010

The sulfite concentrations in aqueous solutions of methoxybenzenediazosulfonates of pH = 7.8 were determined by dead‐stop end‐point titrations at 25°. ortho‐Methoxybenzenediazosulfonate dissociates slowly after being dissolved in water.

Dissociation and rate constants derived are K = 2.4 × 10−10 mole l−1 = ka/kb, with ka = 9.0 × 10−8 s−1 and kb = 375 1 mole−1 s−1. para‐Methoxybenzenediazosulfonate is immediately at its equilibrium dissociation in solution with K = 6.6 × 10−10 mole l−1, ka = 1.5 × 10−8 s−1 and kb = 23 1 mole−1 s−1.
Peak broadening in paper chromatography as a function of the flow‐rate of the eluent
Authors: de Ligny C. L. , Remijnse A. G.
Published: September 2010

Peak broadening in paper chromatography has been investigated as a function of the flow‐rate of the eluent.

The contribution of longitudinal diffusion and the combined contributions of resistance to mass‐transfer and eddy diffusion to peak broadening have been calculated separately.

The last‐mentioned effects are responsible for more than 50% of the peak broadening at the flow‐rate which is obtained in practice, and for medium Rf values.

It appeared, once more, that longitudinal diffusion occurs both in the mobile and in the stationary phase.
The synthesis of lactones. Part II: Some 2‐alken‐5‐olides and 2,4‐dodecadien‐5‐olide
Authors: Lamberti V. , Weller W. T. , Schogt J. C. M.
Published: September 2010

A series of 2‐alken‐5‐olides has been prepared from 1‐alkyn‐4‐ols by carbonation of their Grignard reagents and selective hydrogenation of the triple bond of the obtained 5‐hydroxy‐2‐alkynoic acids. The lactones were prepared by dehydration of the 5‐hydroxy‐2‐alkenoic acids.

The reaction between 2‐alkenals and malonic acid to give 2,4‐dienoic acids also results in the formation of 2‐alken‐5‐olides as by‐products.

2,4‐Dodecadien‐5‐olide was prepared by bromination of 2‐dodecen‐5‐olide with N‐bromosuccinimide followed by dehydrobromination.
Synthesis of acetals by alkylation of 1,1‐diethoxy‐2‐propyne
Authors: Ward J. P. , van Dorp D. A.
Published: September 2010

Acetals were synthesized by alkylation of 1,1‐diethoxy‐2‐propyne with pentyl bromide, isopentyl bromide, phenyl‐2‐propynyl bromide, trans‐cinnamyl bromide, or with 1‐bromo‐2‐phenylacetylene or 1‐bromo‐1‐heptyne (Cadiot‐Chod‐kiewicz coupling). The results of partial hydrogenation with Lindlar's catalyst and of reduction with sodium in liquid ammonia of some of the products are described.
Ring transformations in reactions of heterocyclic halogeno compounds with nucleophiles. Part X: A tracer study of the conversion of 4‐chloro‐2‐phenylpyrimidine into 4‐amino‐2‐phenylpyrimidine
Authors: van Meeteren H. W. , van der Plas H. C.
Published: September 2010

It is shown that in radioactive 4‐amino‐2‐phenylpyrimidine, obtained as a minor product in the reaction of 4‐chloro‐2‐phenylpyrimidine‐4‐14C with potassium amide in liquid ammonia, the 14C label is present in position 4 of the ring. This result proves that the formation of the 4‐amino compound cannot be accomodated with a mechanism initiated by the attack of an amide ion on the 6 position, but probably occurs by an addition‐elimination mechanism on the C(4) carbon atom.
The chemistry of cyclopropanones. Part VI: Addition of 1,1‐dihydroxycyclopropane
Authors: Schaafsma S. E. , Steinberg H. , de Boer Th. J.
Published: September 2010

On adding a slight excess of water to cyclopropanone, 1,1‐dihydroxycyclopropane (cyclopropanone hydrate) can be isolated in a high yield.

The hydrate adds to cyclopropanone giving a mixture of α,ω‐dihydroxypoly‐(oxycyclopropylidenes), which are isolated as the acetates.
Preparation and thermal decomposition of 5‐pentyl‐1,2,3,4‐thiatriazole
Authors: Wijers H. E. , Brandsma L. , Arens J. F.
Published: September 2010

The unstable 5‐pentyl‐1,2,3,4‐thiatriazole (IV) has been prepared from acetylthiohexyne (I) and ammonium azide in dimethyl sulfoxide. Thermal decomposition of IV in polar solvents gives pentyl cyanide, sulfur and nitrogen, whereas in non‐polar solvents in addition to these products pentyl isothiocyanate also is formed during thermolysis.
Electron diffraction by gases: The length of the peri‐bonds in perylene
Authors: Dallinga G. , Toneman L. H. , Traetteberg M.
Published: September 2010

The authors have reconsidered what is known about the structure of perylene and carried out some additional calculations concerning earlier gas diffraction work. They conclude that the length of the peri‐bonds is now well established at 1.473 ± 0.005 Å, which is the average of the gas‐diffraction value (1.474 ± 0.014 Å) and two X‐ray results. This value does not differ significantly from theoretical values based on bond order‐bond length relations.
Natural coumarins. Part IX: Mass spectrometric evidence for the structure of psoralidin
Authors: Abdel‐Hay F. M. , Abu‐Mustafa E. A. , Fayez M. B. E.
Published: September 2010

Psoralidin (C20H16O5, m.p. 290‐292°) is another coumarin constituent of the seeds of Psoralea corylifolia L. Its constitution has recently been disputed and it has been shown by spectral and degradative evidence to be represented by I which was later supported by synthesis. The skeleton of psoralidin (I) is also present in wedelolactone, coumestrol and erosnin which constitute a rare type of natural 3,4‐benzofuranocoumarins.
Properties of diazosulfonates. Part IV: The absorption spectra of o‐ and m‐ substituted benzenediazosulfonates
Authors: van Beek L. K. H. , Helfferich J. , Houtman H. J. , Jonker H.
Published: September 2010

The electronic absorption spectra of o‐ and m‐substituted benzene‐trans‐diazosulfonates in aqueous solution support the assignments given in Part III to the transitions in p‐substituted trans‐BDS. The intensity of the π→π* absorption decreases on OCH3‐trans‐BDS in the sequence para > ortho > meta. The Φ→Φ*, π→Φ*, and Φ→π* absorptions are most intense in 3‐OCH3‐trans‐BDS. In 2‐Cl‐cis‐BDS the π→π* intensity is greatly reduced, whereas the Φ→Φ* intensity is unaffected by trans‐cis isomerization. Electron‐with‐drawing substituents (‐NO2, ‐CO2H, halogen) do not have much influence on the locations of the absorption bands, but electron‐donating groups (‐CH3, ‐OCH3, ‐OH) produce bathochromic shifts of the same order in the ortho, meta, and para positions, whereas an intermediate place is taken by ‐SCH3 and ‐SO3NA. The locations of the Φ→Φ* band (at 210 nm) and the n – π* band (at 420 nm) are not affected by changes in substituents.
Sulfur compounds in free radical reactions. Part I: Cis‐trans isomerism and ultraviolet spectra of arenediazothiolates
Authors: van Zwet H. , Kooyman E. C.
Published: September 2010

Alkyl or aryl arenediazothiolates (Ar ‐N = N ‐SR; R = alkyl or aryl), are readily synthesized by reaction of diazonium ions with mercaptides. The former products are generally obtained in the form of cis‐isomers which rearrange thermally to the trans‐derivatives; these may be reconverted to cis‐compounds by exposure to diffuse daylight. Aryl arenediazothiolates were isolated only as trans‐compounds. Cis‐trans isomerism and UV spectra are discussed on the basis of substituent effects both in the aryl and in the alkylthio (or arylthio) moiety.