bluuebunny/crossref_metadata_2025 huggingface dataset:
Microbiological transformation of 9β,10α‐steroids: I. Side chain degradation and 15‐hydroxylation of 9β,10α‐steroids
Authors: de Flines J. , van der Sijde D. , van der Waard W. F.
Published: September 2010

Fermentation of 9β,10α‐progesterone with Sporormia pollaccii yielded mainly 9β,10α‐testosterone.

Fermentation with Helicosporium lumbricopsis afforded 9β,10α‐androst‐4‐ene‐3,17‐dione.

Fermentation with Colletotrichum gloeosporioides afforded 15α‐hydroxy‐9β,10α‐progesterone. This product was converted with Helicosporium lumbricopsis to 15α‐hydroxy‐9β,10α‐androst‐4‐ene‐3,17‐dione. Fermentation of 6‐dehydro‐9β,10α‐progesterone with Mastigosporium heterosporum afforded 9β,10α‐androsta‐4,6‐diene‐3,17‐dione.
Microbiological transformation of 9β,10α‐steroids: II. 16‐Hydroxylation of 9β,10α‐steroids and of progesterone
Authors: van der Waard W. F. , van der Sijde D. , de Flines J.
Published: September 2010

Fermentation of progesterone, 9β,10α‐progesterone, 6‐dehydro‐9β,10α‐progesterone and 9β,10α‐testosterone with Sepedonium ampullosporum afforded the respective 16α‐hydroxy derivatives.
Enamine chemistry VIII. The syntheses of dienamines
Authors: Madsen Peter , Lawesson Sven‐Olov
Published: September 2010

Dienamines have been prepared by reacting n‐alkyl methyl ketones with morpholine. It is suggested that the initial step in the reaction is a condensation of two ketone molecules to an α,β‐unsaturated ketone followed by the reaction with morpholine.
Adducts of thiophosphoryl compounds with metal halides. I.: Addition compounds of triphenylphosphine sulfide
Authors: van der Veer W. , Jellinek F.
Published: September 2010

Addition compounds have been prepared of triphenylphosphine sulfide with HgCl2, AlCl3, AlBr3, SnCl4, TiCl4, TiBr4, SbCl5, NbCl5, TaCl5, FeCl3 and FeCl2, and of triphenylphosphine oxide with AlCl3, AlBr3, TiBr4, SbCl5 and TaCl5. Reaction of NbCl5 with triphenylphosphine oxide yields the addition compound (Ph3PO)2NbOCl3. The syntheses, infrared spectra and some properties of the adducts are described and discussed.
The system titanium‐sulfur. I: The structure of Ti5S8 and the unit cells of Ti3S4 and Ti4S5
Authors: Flink E. , Wiegers G. A. , Jellinek F.
Published: September 2010

The structure of the phase Ti5S8 (rhombohedral) has been determined. It is based on a close packing of sulfur of the type cchh; the octahedral holes between adjacent cc sulfur layers and between adjacent hh layers are fully occupied by Ti, while the octahedral holes between adjacent ch layers are partly (1/5) occupied by metal atoms. The unit‐cell dimensions of Ti3S4 (rhombohedral) and Ti4S5 (hexagonal or trigonal) are given.
Investigations on organotin compounds. XXII: Hydrolysis products of alkyltin trichlorides
Authors: Luijten J. G. A.
Published: September 2010

When ethyl‐, butyl‐ and octyl‐tin trichlorides are subjected to increasingly severe hydrolysis conditions a number of hitherto unknown compounds are formed which are intermediates between alkyltin trichlorides and alkanestannonic acids. The preparation and properties of these compounds and of the corresponding stannonic acids are described.
Structure determination of unknown peptides isolated from pig neurohypophysis, by mass spectrometrical analysis: (Of their 2,4‐dinitrophenyl peptide methyl esters)
Authors: Penders Th. J. , Heerma W. , Copier H. , Dijkstra G. , Arens J. F.
Published: September 2010

The amino‐acid sequence of 2,4‐dinitrophenyl‐peptide methyl esters has been determined by mass spectral analysis. Using this technique, the structure of a number of simple peptides isolated from pig neurohypophysis, could be elucidated. The structure of valyl‐leucine, alanyl‐valyl‐leucine, tyrosyl‐glycine and O‐Acetyl‐tyrosyl‐valine was established.
Conformation of non‐aromatic ring compounds XXX: Dipole moments, NMR spectra and conformations of some trans‐1,2‐dihalogenocyclopentanes
Authors: Altona C. , Buys H. R. , Havinga E.
Published: September 2010

The dipole moments and NMR spectra of trans‐1,2‐dichloro‐ (I), trans‐1,2‐bromochloro‐ (II), trans‐1,2‐dibromo‐ (III) and trans‐1,2‐dibromo‐1‐methylcyclopentane (IV) in several solvents are reported. Special attention is given to the separation of the outer peaks in the low‐field part of the NMR spectra, due to the protons in the CHX‐moiety. This separation is equal to JAX + JBX and is shown to be correlated linearly with the square of the electric moment.

It is proposed that the conformational properties of these molecules be described in terms of a solvent‐dependent dynamic equilibrium aa ⇌ ee, with the diaxial conformation predominating even in a highly polar solvent. Each of the two conformers may correspond to the half‐chair or the envelope model with the halogen atoms in the most puckered part of the ring. A limited pseudolibration about these forms is possible.
Conformation of non‐aromatic ring compounds XXXI: Infrared and Raman Spectra of some trans‐1,2‐dihalogenocyclopentanes
Authors: Buys H. R. , Altona C. , Havinga E.
Published: September 2010

The infrared and Raman spectra of trans‐1,2‐dichloro‐(I), trans‐1‐bromo‐2‐chloro(II), trans‐1,2‐dibromo‐(III) and trans‐1,2‐dibromo‐1‐methylcyclo‐pentane(IV) were measured in carbon disulfide and in the neat liquid. From the properties of the bands assigned to the carbon‐halogen stretching frequencies it is concluded that the diaxial conformations predominate in solution, the halogen atoms occupying the most buckled part of the ring. The absorption bands of I are broader than those of III and IV. This seems to indicate that the ring geometry of I is less defined and that in compound I twisting of the ring in a pseudolibration movement occurs to a larger extent. From a comparison with the carbon‐halogen stretching frequencies in the analogous cyclohexanes several common features emerge.
Studies in transition metal chemistry. part V: Soluble Ziegler‐type catalysts based on vanadium. Part I
Authors: de Liefde Meijer H. J. , van den Hurk J. W. G. , van der Kerk G. J. M.
Published: September 2010

Experiments are described aiming at a simplification of the catalyst system originally consisting of a mixture of tetraphenyltin, aluminium bromide and vanadium tetrachloride (or vanadium oxytrichloride). It is shown that tetraphenyltin merely acts as a phenylating agent for the aluminium bromide and that only two of the four phenyl groups are available for this purpose. With regard to catalytic activity the original mixture is equivalent to mixtures of vanadium tetrachloride and excess of monoalkyl‐ or monoaryl‐aluminium halides. Some evidence has been obtained that organic groups are part of the vanadium/aluminium complex occurring in the reaction mixtures.
Fluorescent intermediates in the Maillard reaction
Authors: Berrens L.
Published: September 2010

The development of fluorescent compounds has been studied in mixtures of amines and aldoses undergoing Maillard reaction at moderate temperatures, and the fluorescence emission spectra of some N‐substituted 1‐amino‐1‐deoxy‐2‐ketoses are given. A study of pH‐dependency suggests fluorescence to be mainly due to the 1,2‐enol and 2,3‐enediol tautomers of the Amadori product formed, the latter enol contributing in the form of a cyclic configuration.

Some results are presented illustrating the formation of highly resistant nitrogen‐containing ring systems during Kjeldahl‐digestion of N‐substituted 1‐amino‐1‐deoxy‐2‐ketoses.
Extended Hückel calculations on some conformational problems
Authors: van Eijck B. P.
Published: September 2010

The extended Hückel theory applied to single molecules of simple carboxylic acids is able to provide an explanation for the coplanarity of many carboxyl groups with an α‐substituent, which is observed in the crystalline state. Quantitative agreement with experimental rotation barriers is poor, but the shape of the calculated barriers largely agrees with experimental data.
Transannular course in the addition of halogen to cis‐cyclo‐octene and in some related reactions
Authors: Henniger P. W. , Dukker L. J. , Havinga E.
Published: September 2010

In reactions of (cis)cyclo‐octene with lead tetrachloride and hydrogen chloride/methylene chloride as well as with N‐chlorourea and acetic acid/water, transannular reactions were found to prevail. The dichlorocyclo‐octane fractions isolated from the products of the two reactions, both consisted of a mixture of cis‐ and trans‐1,4‐dichlorocyclo‐octanes, trans‐1,2‐dichlorocyclo‐octane and possibly very small amounts of other compounds. The main product of the reaction with N‐chlorourea in an acetic acid/water medium under standard conditions (vide infra) is 4‐chlorocyclo‐octanol (one isomer), which on treatment with phosphorus pentachloride yields a mixture of the 1,4‐dichlorocyclo‐octanes and some trans‐1,2‐dichlorocyclo‐octane. 4‐Chlorocyclo‐octene on addition of hydrogen chloride yields a mixture of cis‐ and trans‐1,4‐dichlorocyclo‐octanes.

The reactions leading to the corresponding bromo compounds proceed in a similar way; it proved difficult to perform a controlled reaction with lead tetrabromide, however. With the reaction of bromine and cyclo‐octene “transannular addition” is observed at low temperatures (∼ −100°).
Pyrazoles I.: Ionisation constants and UV spectra of 4‐nitropyrazoles
Authors: Habraken Clarisse L. , van Woerkom P. C. M. , De Wind H. W. , Kallenberg C. G. M.
Published: September 2010

The differences in UV spectra and acidity between 4‐nitropyrazole and 3(5)‐methyl‐4‐nitropyrazole and 3,5‐dimethyl‐4‐nitropyrazole indicate the absence of steric influence of ortho‐methyl groups.
The conformation of non‐aromatic ring compounds, part XXXII. The crystal structure of trimethylene sulfite at −100°C
Authors: Altona C. , Geise H. J. , Romers C.
Published: September 2010

Trimethylene sulfite, m.p. − 14°, crystallizes in the orthorhombic system, space group P212121, Z = 4. The unit cell dimensions at − 100° are a = 7.451, b = 7.703 and c = 8.98 Å. The structure was solved by means of a Patterson synthesis and refined by the least squares method, using three‐dimensional reflexion data (MoKa radiation, collected at − 100°). The six‐membered ring has the chair conformation and the SO bond points toward the axial direction. The geometry of the ring is described in terms of torsional angles.
Electrophilic chlorination by sulfuryl chloride
Authors: Bolton R. , De la Mare P. B. D. , Suzuki H.
Published: September 2010

The reaction of sulfuryl chloride with naphthalene and with some aromatic ethers has been shown to involve electrophilic attack by the reagent, probably through the incipient heterolysis magnified image.
Preparation of primary alcohols related to prostaglandins
Authors: Pabon H. J. J. , van der Wolf L. , van Dorp D. A.
Published: September 2010

Primary alcohols related to prostaglandins were prepared by reduction of the methyl ester of prostaglandin E1 with lithium tetrahydridoaluminate. The structures of the reaction products were established by mass spectrometry.
Studies on imidazoles. Part III The Synthesis of Some 7,8‐Dialkylpurines
Authors: Trout G. E. , Levy P. R.
Published: September 2010

The synthesis ‐ using preformed 1,2‐dialkylimidazoles as starting materials ‐ of a number of 7,8‐dialkylpurines is described.
Heats of formation of Ag3PO4 and Ag3AsO4
Authors: Cordfunke E. H. P. , Ouweltjes W.
Published: September 2010

The heats of formation of Ag3PO4 and Ag3AsO4 have been determined by measuring their heats of solution in nitric acid. The results obtained are:magnified image
Equilibration of benzene derivatives. Part III: Mono‐ and poly‐substituted iodo‐ and bromo‐benzenes
Authors: Augustijn G. J. P. , Kooyman E. C.
Published: September 2010

Transiodination occurs when reacting iodobenzenes with other halogeno‐or with alkylbenzene derivatives in the presence of aluminium bromide at room temperature.

Isomer equilibria among iodobenzenes resemble those for the corresponding bromides1. Di‐ and tri‐substituted bromo‐ and iodo‐benzenes show equilibrium patterns agreeing with those computed on the basis of addivitity, using patterns for monosubstituted halogenobenzenes. Results are discussed in terms of partial equilibrium factors1, believed to be mainly governed by electrostatic and steric interactions.

Results of direct brominations (AlBr3 catalyst, no solvent) indicate that for halogeno‐ and alkylbenzenes the main difference between the isomer ratios observed and those at equilibrium consists in the large proportions of meta (or 1, 3, 5) isomer found in the latter case.
Investigations on sterols XXXI: Synthesis and conformation of ring B of 6,6‐dihalo‐9β,10α‐testosterones
Authors: Westerhof P. , Hartog J.
Published: September 2010

Halogenation of 3‐ethoxy‐6‐halo‐9β,10α‐androsta‐3,5‐dien‐17β‐ol 17‐acetates with perchloryl fluoride, N‐chlorosuccinimide or N‐bromosuccinimide gives rise to the formation of 6,6‐difluoro‐, 6α‐ and 6β‐chloro‐6‐fluoro‐ and 6α‐ and 6β‐bromo‐6‐fluoro‐9β, 10α‐testosterone 17‐acetates. With perchloryl fluoride, besides fluorination at position 6, introduction of fluorine at position 4 takes place. The dehydrohalogenation of the 6,6‐dihalo compounds is investigated. NMR data indicate that ring B of 6β‐bromo‐6‐fluoro‐9β,10α‐testosterone 17‐acetate has a boat‐conformation.
Alcohols as ligands. I. Crystalline hexa‐ethanol metal salts
Authors: van Leeuwen P. W. N. M.
Published: September 2010

The syntheses of approximately twenty coordination complexes with the ligand ethanol are reported. A new synthetical method is used to obtain these crystalline hexa‐alcohol solvates. About ten perchlorates and fluoroborates of divalent metal ions are easily prepared by dissolving the corresponding hydrates in ethyl orthoformate. In the solid state, even the nitrates contain hexa‐ethanol coordinated metal ions. The electronic and vibrational spectra, a summary of the proton magnetic resonance spectra and some X‐ray powder patterns are given. The complexes of this very weak ligand are now easily obtainable and will be of great importance because ethanol may be replaced simply by many ligands.
Chemistry of acetylenic ethers. Part 88: Synthesis of β‐hydroxy‐alkynes, substituted at the α‐carbon atom
Authors: Schaap A. , Brandsma L. , Arens J. F.
Published: September 2010

Metallation of allenyl thioethers, R1CHCCHSC2H5 (I) (R1 = alkyl), by means of methyl‐ or butyl‐lithium in ether, followed by addition of aldehydes or ketones, R2R3C  O (R2 and R3 are H or alkyl), affords a mixture of the two carbinols R1CHCC[CR2R3C(OH)](SC2H5) (III) and R1CH[CR2R3(OH)] CCSC2H5 (IV). By treatment of the mixture with an excess of potassium amide in liquid ammonia IV is converted into the metallated β‐hydroxy‐alkyne R1CH[CR2R3(OH)]CCH (VI), probably via a nucleophilic substitution at sulfur. In the cases where R1  CH3, ethanethiol is eliminated from III with formation of the metallated enynyl alcohol HCCCHCH[CR2R3(OH)], (V). A number of alkylated derivatives RCCCHR1CH2OH have been prepared from VI (with R2 and R3 = H).
Reactions of γ‐thiopyran‐1,1‐dioxide
Authors: Molenaar E. , Strating J.
Published: September 2010

Addition reactions of γ‐thiopyran‐1,1‐dioxide (I), are compared with those of divinyl sulfone (II). In contrast with II no Diels‐Alder reactions could be realized with I. Fairly strong nucleophiles, however, give addition products with I; usually only one mole is added and the remaining double bond is shifted from the α‐ to the β‐position with respect to the sulfonyl group.
Aromatic Sulfonation. Part XVI: Sulfonation of naphthalene and its monosulfonic acids in concentrated aqueous sulfuric acid
Authors: Cerfontain H. , Telder A.
Published: September 2010

The sulfonation of naphthalene in concentrated aqueous sulfuric acid has been reinvestigated. Rate measurements have been made in the region of 79.0‐83.4 wt‐% H2SO4 at 25°. The kinetically determined isomer distribution has been determined in the acid range of 75.5‐95.2 wt‐% H2SO4. At 25°, the ratio of 1‐ to 2‐naphthalenesulfonic acid decreases from 5.9 to 4.1 on varying the acid concentration from 75 to 95 wt‐% H2SO4. The higher reactivity of the 1‐ as compared with the 2‐position of naphthalene is largely due to the difference in enthalpy of activation, for the difference in entropy of activation is very small. The partial rate factors for sulfonation at the 1‐ and 2‐ positions decrease with increasing acid concentration. The ratio of the logarithms of these partial rate factors is 1.60 ± 0.03.

The ratio of the rate constants of sulfonation of 1‐ and 2‐naphthalenesulfonic acid at 25° is ∼ 0.08. The partial rate factors for the most reactive positions of these acids have been compared with those for meta‐substitution of benzenesulfonic acid.
The structure of α‐parabutylchloral
Authors: Barón Máximo
Published: September 2010

The structure of α‐parabutylchloral was reexamined on the basis of the NMR spectra at room and high temperature of two model compounds.
Chemistry of propadiene. Part IV: The addition of formaldehyde to propadiene in aqueous sulfuric acid solution
Authors: Peer H. G. , Schors A.
Published: September 2010

The reaction between propadiene and formaldehyde in aqueous sulfuric acid solution was investigated. When an excess of formaldehyde is present, it reacts with propadiene in a molecular ratio of 8: 1, yielding the 2,4,10,12,15‐pentaoxadispiro[5.1.5.3]hexadecan‐7‐one.
Chemistry of the silylamines. Part VI: Condensation of N,N‐diethylaminotrimethylsilane with alcohols
Authors: Pike R. M. , Weaver S. J.
Published: September 2010

The rate of condensation of a series of alcohols with N,N‐diethylaminotrimethylsilane have been measured. It was observed that the relative rate varied inversely with the chain length of the straight chain primary alcohols investigated. Branched alcohols reacted at slower rates than the straight chain alcohols through n‐octyl alcohol.
Structure determination of the allergenic agent, isolated from tulip bulbs
Authors: Brongersma‐Oosterhoff Ulrika W.
Published: September 2010

Handling of tulip bulbs taking place in bulb nurseries often causes a typical allergic reaction of the skin (“tulip fingers”). It is the purpose of this paper to report the results of an investigation into the structure of the chemical compound, possessing the allergic properties.

The principle is a yellow, hygroscopic, non‐crystalline substance, which can be obtained by extraction of the tulip bulb (tulipa gesneriana) with 70% ethanol or 70% acetone and resolving the crude extract by paper chromatography. Paper chromatography (paper Whatman no. 1) gives a Rf‐value of 0.63 in ethyl acetate: pyridine: water = 2: 1: 2. The allergenic principle is soluble in ethanol and water, but not in cyclohexane, carbon tetrachloride, chloroform, diethyl ether and ethyl acetate. Since it could not be obtained in crystalline form, X‐ray analysis could not be used and for this reason other chemical and physical methods had to be used.
Properties of diazosulfonates. Part II: The rate of the reaction between 2‐methoxybenzenediazonium and sulfite ions
Authors: van Beek L. K. H. , Helfferich J. , Jonker H. , Thijssens Th. P. G. W.
Published: September 2010

The reaction between 2‐methoxybenzenediazonium and sulfite ions in aqueous solution was followed by polarography. The polarographic waves of sulfite, diazonium, and diazosulfonate were studied in the pH range of 1‐7. The second order rate constants found at 11° and 20° and the rate constant at 25°C reported in part I were corrected to zero ionic strength yielding values of 400, 700, and 2000 1 mole−1 s−1, respectively.
Optical activity of symmetrically substituted acetic acids. Part I: The stability against racemization of some ortho‐alkyl‐substituted diphenylacetic acids
Authors: Akkerman O. S. , Coops J.
Published: September 2010

The theoretically possible conformations of a substituted diphenylacetic acid and their interconversions are discussed. The activation parameters for the racemization of a series of ortho‐alkyl‐substituted diphenylacetic acids are determined.
Nuclear magnetic resonance studies in coordination chemistry. Part II: Kinetic studies of reactions occurring in the system [(π‐C4H7)PdCl]2‐triphenylarsine
Authors: Vrieze K. , Cossee P. , Hilbers C. W. , Praat A. P.
Published: September 2010

An NMR study has been made of the reactions occurring in systems which contain either the monomeric complex (π‐C4H7)PdCl(Ph3As) and the dimer [(π‐C4H7)PdCl]2, or only monomer and free triphenylarsine (in CDCl3). In the former case reactions were observed of Ph3As ‐ formed by the dissociation of the monomer (reaction (a)) ‐ with the dimer (b) and the monomer (c), respectively:

In the latter case, where only monomer and Ph3As are present, two reactions were studied. The first, which was observed between ‐70° and ‐40° with a very small excess of Ph3As, and which involves the exchange of Ph3As (reaction (c)), is first‐order in the arsine ligand. This reaction and the reactions in the presence of dimer were studied by measuring the rates at which the syn‐protons (or the anti‐protons) of the allyl group become magnetically equivalent. The second reaction, in which also exchange of Ph3As takes place, was measured between +10° and +80° with a higher excess of free Ph3As. This reaction is also first‐order in Ph3As, but involves the formation of either a s̀‐allyl intermediate or an activated state resembling the s̀‐allyl form. The activation energies and frequency factors of the above reactions are reported.

At still higher excess of Ph3As (Ph3As/Pd ∼ 2‐3) an equilibrium (π‐C4H7)PdCl(Ph3As) + Ph3As ⇆ [(π‐C4H7)Pd(Ph3As)2]+Cl− becomes notticeable. This equilibrium moves to the right with increasing Ph3As/Pd ratio and decreasing temperature. The amount of ionic species, however, is so small that the kinetics of the above reactions are but little influenced by it.
The crystal structure of trispyridinecupriacetate
Authors: Anzenhofer K. , ten Rouwelaar L. N. A.
Published: September 2010

The crystal and molecular structure of the complex Cu(C5H5N)3(CH3COO)2 has been determined with three‐dimensional Patterson and Fourier methods. The copper is surrounded by two acetate and two pyridine groups, while the third pyridine molecule is not bonded to Cu at all. The arrangement of the nitrogen and the oxygen atoms around Cu is slightly but definitely non‐planar and tetrahedrally distorted.
Photolysis of dibenzyl sulfide
Authors: Laarhoven W. H. , Cuppen Th. J. H. M. , Nivard R. J. F.
Published: September 2010

The mixture of products formed by irradiation of dibenzyl sulfide has been analyzed by G.L.C. Dibenzyl and phenanthrene appeared to be the major products. In addition, several other products were characterized.

Benzyl 1,2‐diphenylethyl sulfide was found to be a precursor in the formation of phenanthrene. The suggestion has been made that thermolysis of dibenzyl sulfide follows the same free radical mechanism as the photolysis.
Coupled and decoupled processes in the autoxidation of partially reduced pteridines and flavins
Authors: Mager H. I. X. , Addink R. , Berends W.
Published: September 2010

Organic hydroperoxide formation has to be regarded as the primary process in the autoxidation of partially reduced pteridines and flavins, to be distinguished from secondary oxidations and H2O2‐production. Material balances between oxidized products, O2‐uptake and H2O2‐formation have been determined under varying experimental conditions and found to be in agreement with a general formula based on the new theory. Spontaneous oxidation of a blocked dihydroalloxazine afforded a tetrahydroquinoxaline‐2‐spiro‐5′‐hydantoin as the ring‐contraction product of the transient hydroperoxide, confirming the structure previously proposed by us.
Comparison of X‐ and Q‐band ESR spectra of the ions CrOF52− and MoOF52−
Authors: Verbeek J. L. , Vink A. T.
Published: September 2010

The previously proposed model of Verbeek and Cornaz to account for the ESR‐spectra of the ions CrOF52− and MoOF52− was checked by measurements at two frequencies (X‐ and Q‐band) and by using central ion isotopes with different nuclear spins.

The agreement with the theoretical expectations is satisfactory.
Hydrogen atom transfer from alkanes and aromatic proton complexes to aromatic cations and quinones
Authors: Buck H. M. , Oosterhoff L. J. , Sluys‐v. d. Vlugt M. J. v. d. , Verhoeven K. G.
Published: September 2010

In strongly acidic media alkanes react as hydrogen donating agents towards the positive radical ions of anthracene, perylene and tetracene. The aromatic radical ions appear to be converted into their related proton complexes. These proton complexes reduce quinones to hydroquinones. Qualitative data on the latter reaction are discussed in relation to its mechanism. A direct reduction of quinones by alkanes has not been observed.
Physical significance of activity coefficients of individual ions: The interaction of ions of organic acids and bases with the solvent and the influence of substitution by alkyl and phenyl groups
Authors: Alfenaar M. , de Ligny C. L.
Published: September 2010

A study has been made of the influence of substitution by alkyl and phenyl groups in organic acids and bases on the interaction of the ions of these substances with the solvent.

Knowledge of single ion activity coefficients is essential for the interpretation of the different effects.
Anticoagulants. Part II: Heterocyclic analogues of 4‐hydroxycoumarins
Authors: Kralt T.
Published: September 2010

In a search for compounds with anticoagulant activity analogues of 4‐hydroxy‐coumarin have been made in which the benzene nucleus has been replaced by thiophene. The compound 7‐hydroxy‐5‐thieno[3,2‐b]pyran‐5‐one (Ia) was obtained. From Ia two derivatives were prepared with substituents from known anticoagulants of the 4‐hydroxycoumarin group.
Cleavage of the carbon‐silicon bond in 1‐alkynylsilanes by silver nitrate: Protection of a terminal triple bond in hydrogenation reactions with the trimethylsilyl group
Authors: Schmidt H. M. , Arens J. F.
Published: September 2010

It is possible to reduce non‐terminal triple bonds in poly‐ynes selectively when the terminal triple bonds are previously protected silylation. Desilylation after the reduction can be easily effected with aqueous alcoholic silver nitrate.
The conformation of non‐aromatic ring compounds. Part 38 The chlorination of 1,4‐thioxane in carbon tetrachloride and the NMR analysis of 1,4‐thioxane, 1,4‐thioxene and some chloro‐substituted thioxanes
Authors: de Wolf N. , Henniger P. W. , Havinga E.
Published: September 2010

A study has been made of the chlorination of 1,4‐thioxane under varying conditions, yielding mono‐, di‐, tri‐ and tetra‐chloro derivatives (cf. Fig. 1). Inspection of the NMR spectra of the compounds and fractions isolated leads to the following generalisations:

Substitution of chlorine takes place preferentially at a carbon atom adjacent to the sulfur atom and, up to three chlorine atoms, in one half of the ring. The use of peroxide catalysts favours substitution adjacent to the oxygen atom.

Of the compounds studied the following were found to occur as a conformational equilibrium, the two (half) chair conformations both being present to a substantial percentage: thioxane, 3,3‐dichlorothioxane (IIb), 2,2,3,3‐tetrachlorothioxane (IVc), thioxene, 3‐chlorothioxene (Ib), 3,5‐dichlorothioxene (IId). Except for the last one these compounds show a similar A2B2‐system due to the four protons at the unsubstituted side of the molecule. Conformationally fixed compounds such as 3‐chlorothioxane (Ia), trans‐2,3‐dichlorothioxane (IIc) and 2,3,3‐trichlorothioxane (IIIb) show an ABCD pattern due to the four protons in the unsubstituted half. Dipole moments have been determined and have been used in the conformational analysis of a few compounds.
Non‐enzymic conversion of all‐cis 8,11,14‐eicosatrienoic acid into prostaglandin E1
Authors: Nugteren D. H. , Vonkeman H. , van Dorp D. A.
Published: September 2010

It is shown that prostaglandin E1 is formed during autoxidation of all‐cis 8,11,14‐eicosatrienoic acid. However, the yield is low, which is due to the occurrence of many side reactions and the complex stereochemistry of the products. This non‐enzymic prostaglandin formation may give rise to artifacts in biological studies.
Heterocyclic Steroids. Part XI 1‐Hydroxy‐1‐vinylquinolizidine ‐ its synthesis, stereochemistry and attempted conversion to 5‐azasteroids
Authors: van Hes R. , Pandit U. K. , Huisman H. O.
Published: September 2010

Reaction of vinylmagnesium bromide with quinolizidine‐1‐one yielded a mixture of two stereoisomeric 1‐hydroxy‐1‐vinylquinolizidine systems (III and IV). Structural assignments of the latter are based upon infrared, nuclear magnetic resonance and mass spectral data. Attempts to transform the vinyl alcohols into 5‐azasteroids were unsuccessful.
Base‐catalysed elimination‐addition reactions of ethyl N‐(tosylmethyl)‐ or ethyl N‐(α‐tosylbenzyl)‐carbamates and ‐thiocarbamates
Authors: Olijnsma T. , Engberts J. B. F. N. , Strating J.
Published: September 2010

Base‐catalysed elimination‐addition reactions of ethyl N‐(tosylmethyl)‐ or ethyl N‐(α‐tosylbenzyl)‐carbamates and ‐thiocarbamates were carried out with secondary aliphatic amines, thiophenol, methanol or the carbamate itself as nucleophilic reagents. The reaction with sodium borohydride has been investigated in two cases.
Bond lengths in diphenyloctatetraene
Authors: Olthof Roeli , Vos Aafje , Kracht D.
Published: September 2010

The crystal structure of all trans‐diphenyloctatetraene has been refined. The C‐C bond lenghts from previous work were confirmed. The experimental bond lenghts are compared with the values calculated by the Hückel method both with constant and variable β, and with those calculated by the approximate SCMO method for three sets of parameters. The discrepancies between the best theoretical bond lengths and the experimental values need not be significant.
The synthesis of lactones. Part III: δ‐Enollactones and lactones with exocyclic double bonds
Authors: Begemann P. Haverkamp , Lamberti V. , Weller W. T.
Published: September 2010

A series of 4‐alken‐5‐olides has been prepared by dehydration of the corresponding 5‐oxoalkanoic acids. These enollactones are sensitive to both oxygen and moisture.

For the synthesis of 9cis‐dodecen‐5‐olide, 4‐heptynylmagnesium bromide was coupled with cyclopentanone to form 1‐(4‐heptynyl)cyclopentanol, which was oxidized to 5‐oxo‐9‐dodecynoic acid. Two‐step reduction and dehydration yielded the lactone. Similarly, 5‐oxo‐6‐dodecynoic acid, prepared from 1‐heptynylmagnesium chloride and glutaric anhydride, was converted into 6cis‐dodecen‐5‐olide.

6cis‐Dodecen‐4‐olide was synthesized by coupling 2‐octynylmagnesium bromide with methyl 4‐oxobutanoate to give methyl 4‐hydroxy‐6‐dodecynoate; this was converted into 6‐dodecyn‐4‐olide, which was partially hydrogenated. The product was separated gas‐chromatographically from the accompanying 5‐vinyl‐4‐decanolide.
Hydrogenation of hexamethylbicyclo[2.2.0]hexa‐2,5‐diene (hexamethyldewarbenzene)
Authors: Volger H. C. , Hogeveen H.
Published: September 2010

Hexamethylbicyclo[2.2.0]hexa‐2,5‐diene can be hydrogenated nearly quantitatively, with preservation of the bicyclic structure, to either the dihydro or the tetrahydro compound, depending on the reaction conditions. In both hydrogenation products the hydrogens are located in the exo position, as revealed by NMR spectroscopy. The corresponding dideutero compound was also prepared.

Thermal isomerization of the dihydro product yields cis‐1,2,3,4,5,6‐hexamethylcyclohexa‐1,3‐diene quantitatively.
Aromatic sulfonation. Part XIX: Two mechanisms of sulfonation in aqueous sulfuric acid
Authors: Kort C. W. F. , Cerfontain H.
Published: September 2010

The dependence of the sulfonation rates and isomer distributions of several aromatic compounds on the sulfuric acid concentration is explained in terms of two reaction mechanisms. One involves H2S2O7 as the sulfonating entity and predominates at high sulfuric acid concentrations; the other, with H3SO4+ as the sulfonating entity, predominates at lower acid concentrations. The latter mechanism is more selective than the former.
Chemistry of acetylenic ethers. Part 89: The reaction of organolithium compounds with 1‐alkynyl ethers
Authors: Kooyman J. G. A. , Hendriks H. P. G. , Montijn P. P. , Brandsma L. , Arens J. F.
Published: September 2010

Disubstituted acetylenes C4H9C≡CR are produced in the reaction of 1‐ethoxy‐1‐hexyne C4H9C≡COC2H5 with organolithium or Grignard compounds RLi or RMgBr. The yields are moderate to satisfactory. Ethoxyethyne HC≡COC2H5 and phenyllithium C6H5Li afford phenylacetylene HC≡CC6H5 (after hydrolysis) in moderate yield.

The formation of acetylenes probably proceeds by an addition‐elimination mechanism.
Interrelation of thioethers containing conjugated systems with 6π‐electrons: (Base‐catalysed isomerisations in liquid ammonia)
Authors: van Boom J. H. , Brandsma L. , Arens J. F.
Published: September 2010

The present investigation deals with interrelations between thioethers of the types R1CH2CR2 = CH ‐C≡CSCH3 (3‐en‐1‐yne thioethers)

R1CH = C(R2)CHC = CHSCH3 (1,2,4‐trienyl thioethers)

R1CHC(R2)C≡CCH2SCH3 (4‐en‐2‐yne thioethers) and

R1CH2CR2 = C = C=CHSCH3 (1,2,3‐trienyl thioethers). Under the influence of sodium ethoxide in liquid ammonia all compounds with R1=H are isomerised quantitatively into 3‐en‐1‐yne thioethers CH3 − C(R2)=CH‐C ≡ CSCH3, whereas the homologues with R1 = CH3 are quantitatively converted into a mixture of 1,2,4‐trienyl thioether and 4‐en‐2‐yne thioether. For further details see Table I.

Treatment of our substrates with an excess of sodamide in liquid ammonia and subsequent hydrolysis always produces 1,2,4‐trienyl thioethers; 1,2,3‐trienyl thioethers are the presumed intermediates (Tables II‐V).

The yields of the sodamide reactions are often rather low because of side‐reactions, among which polymerisation is included. Certain substrates suffer extensive loss of the thioether group by nucleophilic attack at sulfur (see Table II).

In Appendix III a simple method for expressing the notation of unsaturated systems is developed; it is useful in drawing conveniently arranged diagrams depicting interrelations.
The crystal structure of glycerol and its conformation
Authors: van Koningsveld H.
Published: September 2010

The crystal structure of glycerol was determined by X‐ray analysis, with the aid of a direct method. Out of six possible staggered conformations of glycerol the structural investigation leads to the symmetrical aa‐conformation. This result is compared with the results of extended Hückel calculations supplemented by other considerations.
Conformation of open chain compounds. Part II: Dipole moments and conformational equilibrium of some vicinal dibromides, the “benzene effect”
Authors: Altona C. , Hageman H. J.
Published: September 2010

The dipole moments of some acyclic vicinal dibromides have been measured in carbon tetrachloride and in benzene. The gauche Br…. Br interaction energy is solvent dependent; its value in benzene is consistently 380 ± 30 cal/mole lower than in carbon tetrachloride.
Formation and structural assignments of four trimethylcyclopentadienes
Authors: de Haan J. W. , Kloosterziel H.
Published: September 2010

Thermolysis of isobornyl acetate in an inert gas atmosphere in a tube reactor, at temperatures between 420° and 480°C yields four trimethylcyclopentadienes as well as other compounds. Their isolation is described. Their structures were established by hydrogenation and by spectroscopic methods.

A number of vicinal, allylic, homoallylic and long‐range coupling constants were obtained from the NMR spectra. The formation of 2,5,5‐trimethylcyclopentadiene from bornene is discussed.
Synthesis of N‐acetyl‐N‐(3‐amino‐2,4,6‐triiodophenyl)‐ β‐aminoalkanoic acids suited for use as oral cholecystographic agents
Authors: Korver J. A.
Published: September 2010

The reaction of m‐nitroaniline with α,β unsaturated acids like acrylic acid, methacrylic acid and crotonic acid gives N‐(m‐nitrophenyl)‐β‐aminoalkanoic acids which are converted to N‐acetyl‐N‐(3‐amino‐2,4,6‐triiodophenyl)‐β‐aminoalkanoic acids by successive acetylation, reduction and iodination.

N‐Acetyl‐N‐(3‐amino‐2,4,6‐triiodophenyl)‐β‐aminoisobutyric acid* was found to be an excellent oral cholecystographic agent of low toxicity.
Conformation of non‐aromatic ring compounds.: Part 45. Carbon‐halogen stretching frequencies and conformation of 1‐alkyl‐1‐halogenocyclohexanes
Authors: Altona C. , Hageman H. J. , Havinga E.
Published: September 2010

The conformational properties of some 1‐alkyl‐1‐halogenocyclohexanes have been studied by infrared and Raman spectroscopy. Carbon‐halogen stretching frequencies were assigned to the possible conformations by comparing the observed values with those predicted by using the previously determined THHH, TCHH and TCCH frequencies.

In solution, as well as in the neat liquid, the most stable conformation has the halogen atom in axial position. The side chain methyl group in 1‐ethyl‐1‐halogenocyclohexanes prefers to assume the gauche conformation with respect to the halogen atom.

The dipole moments were measured in carbon tetrachloride and in benzene; no information about the equilibrium composition could be obtained by this method.
Acetylacetone as a ligand in nickel(II) perchlorate
Authors: van Leeuwen P. W. N. M.
Published: September 2010

A new type of complex is described containing acetylacetone (acaH) as neutral ligand. Three compounds are described in detail [Ni(acaH)3](ClO4)2, [Ni)acaH)2(AcOH)2](ClO4)2 and [Ni(acaH)2(H2O)2](ClO4)2. AcaH is shown to be a fairly strong ligand also without the loss of its 3‐proton from the spectrochemical parameters Dq being 976 cm‐1 and B being 933 cm‐1. The infrared spectra and some near‐infrared absorptions are reported. It is tentatively proposed that the keto‐tautomer is present in the complexes.
Diffusion‐controlled stress relaxation in cross‐link density determinations, applied to ethylene‐propylene rubber
Authors: Knibbe D. E.
Published: September 2010

On stretching a rubber vulcanizate in an excess of solvent the degree of swelling will increase. It has been found possible to calculate the rate and extent of the increase in swelling from stress relaxation data. This method yields more accurate cross‐link density data than when the additional swelling is neglected, as is usually done.

For ethylene‐propylene‐diene rubber in n‐heptane at 20°C a polymer/solvent interaction parameter of 0.42 ± 0.01 was found, irrespective of the degree of extension or amount of solvent present during the vulcanization within the ranges studied. Diffusion coefficients derived in this report are in accordance with literature data.
The standard chemical free enthalpy, enthalpy, entropy and heat capacity of hydration of the hydrogen ion, and the surface potential of water at 25°C
Authors: de Ligny C. L. , Alfenaar M. , van der Veen N. G.
Published: September 2010

The standard chemical free enthalpy, enthalpy, entropy and heat capacity of hydration of the H+ ion have been determined. The determination is based on a cyclic process in which the ferricinium ion and the ferrocene molecule are involved.

No rather arbitrary divisions or long‐range extrapolations of thermodynamic data for electroneutral combinations of ions have to be made in this method. The accuracy of the values obtained, especially of the entropy, is high, and is determined mainly by the accuracy of the experimental data. For the first time an estimate of the heat capacity of a single ion is given.

From the value of the chemical free enthalpy of hydration obtained and literature data on the real free enthalpy of hydration, the surface potential of water can be calculated.

If 1 atm fugacity and 1 molal concentration are used as standard states in the gas‐phase and the aqueous solution, respectively, the following values are obtained (at 25 °C):
Interpretation of solubility data on the n‐alkanes and some other substances in the solvent water
Authors: Nelson H. D. , de Ligny C. L.
Published: September 2010

Data on the free enthalpy, enthalpy and entropy of solution in water for the n‐alkanes are interpreted, following the lines of the work of Némethy and Scheraga and of Pierotti.

Solubility data for polar compounds are discussed on the basis of Butler's principle of additive contributions of the various constituent groups.
Electrochemical reduction of aza aromatics. Part I. Polarographic reduction of aromatic di‐aza compounds and correlation of results with H.M.O. calculations
Authors: van der Meer D. , Feil D.
Published: September 2010

The polarographic reduction of di‐aza compounds has been investigated in N,N‐dimethylformamide (d.m.f.) by two‐ and three‐electrode polarography with an Hg‐pool and Ag/AgCl in d.m.f. as reference electrodes, respectively. The i vs. V curves of the di‐aza compounds show that the reduction products are more sensitive to water than the negative ions of the comparable hydrocarbon aromatics. From the results obtained, we can conclude that, even with a water content less than 0.05%, protonated products are formed. This can also be concluded for the mono‐aza compounds from a critical examination of literature data. The E1 values obtained for the first wave have been found to fit the correlation with the energy of the lowest vacant π‐molecular orbital in the H.M.O. approximation.
Synthesis of DL‐Prostaglandin B1 and its reduction product DL‐prostaglandin E1‐237
Authors: Klok R. , Pabon H. J. J. , van Dorp D. A.
Published: September 2010

Coupling of 3‐(2′‐tetrahydropyranyloxy)‐1‐octynylmagnesium bromide with 2‐(6′‐carboxyhexyl)‐2‐cyclopenten‐1‐one followed by Oppenauer oxidation and removal of the protecting group yielded crystalline DL‐2‐(6′‐carboxyhexyl)‐3‐(3′‐hydroxy‐1′‐octynyl)‐2‐cyclopenten‐1‐one. Hydrogenation of the latter substance in the presence of Lindlar's catalyst and subsequent elaidination gave DL‐2‐(6′‐carboxyhexyl)‐3‐(3′‐hydroxy‐1′‐trans‐octenyl)‐2‐cyclopenten‐1‐one ‐ shown to be identical with authentic PGB1 ‐ whereas hydrogenation in the presence of Pd on BaSO4 afforded DL‐2‐(6′‐carboxyhexyl)‐3‐(3′‐hydroxyoctyl)‐2‐cyclopenten‐1‐one known as PGE1‐237.
Intramolecular charge transfer in some donor‐acceptor molecules as N‐picrylauramine
Authors: Knoop F. W. E. , Buck H. M. , Oosterhoff L. J.
Published: September 2010

Intramolecular charge transfer in picryl derivatives of benzophenonimide has been studied. Dipole moments and NMR spectra reveal that the contribution of charge transfer structures to the ground state is of minor importance in contrast with what could be expected. The discrepancy can be explained if a geometrical structure is assumed which closely resembles that of N,N‐diphenyl‐N′‐picrylhydrazyl.
Botrallin, a novel quinone produced by Botrytis allii
Authors: Overeem J. C. , van Dijkman A.
Published: September 2010

Botrallin, a metabolic product of Botrytis allii, is shown to be a benzoquinone substituted with a methyl, a methoxyl and a 2‐carboxy‐3‐hydroxy‐5‐methoxy‐phenyl group.
The reaction of aldopentoses and secondary amine salts, a convenient method of preparing 4‐hydroxy‐5‐methyl‐2,3‐dihydrofuran‐3‐one
Authors: Peer H. G. , van den Ouweland G. A. M. , de Groot C. N.
Published: September 2010

4‐Hydroxy‐5‐methyl‐2,3‐dihydrofuran‐3‐one was prepared from aldopentoses and secondary amine salts. A proposed mechanism for the reaction could be verified experimentally and led to reaction conditions giving an optimum yield.
Synthesis of 4‐hydroxy‐5‐methyl‐2,3‐dihydrofuran‐3‐one from D‐ribose 5‐phosphate
Authors: Peer H. G. , van den Ouweland G. A. M.
Published: September 2010

4‐Hydroxy‐5‐methyl‐2,3‐dihydrofuran‐3‐one (I) is prepared in reasonable yield by β‐elimination of phosphoric acid from D‐ribose 5‐phosphate. The reaction mechanism is discussed and supported by tracer experiments.
The unit cell dimensions of some alkali lead and alkali strontium halides
Authors: Jansen P. W. J.
Published: September 2010

The unit‐cell dimensions of the compounds AB2X5 with A = K, Rb or NH4; B = Pb or Sr and X = Cl or Br have been determined. The alkali strontium chlorides are isostructural with the alkali lead chlorides and bromides.
Configuration and conformation of all four cocaines from nmr spectra
Authors: Sinnema A. , Maat L. , van der Gugten A. J. , Beyerman H. C.
Published: September 2010

The configurations of (±)‐allococaine and (±)‐allopseudococaine have been determined, for the first time in an unambiguous way, by means of NMR spectroscopy. The known configurations of (±)‐cocaine and (±)‐pseudococaine receive independent confirmation.

The preferential conformation of the piperidine ring of the tropane nucleus is found to be the chair form in all four isomers, and also in the methyl esters of the four corresponding isomers of ecgonine.

The preparation of (±)‐allococaine and (±)‐allopseudococaine has been improved.
Chemistry and spectroscopy in strongly acidic solutions. Part XVI: Evaluation of 13C‐H coupling constants in protonated formic acid
Authors: Hogeveen H. , Mackor E. L. , Ros P. , Schachtschneider J. H.
Published: September 2010

The values of 13C‐ Ha,13C‐ Hβ,13C‐ Hγ coupling constants in the isomeric protonated formic acid species (I) and (II) were measured at low temperatures. Double‐resonance measurements showed the signs of the13C‐Ha and13C‐Hβ coupling constants to be opposite to that of the positive13C ‐Hγ coupling constant.

Quantum‐mechanical calculations of the Iterative Extended Hückel type were performed for several isomers of protonated formic acid in order to obtain expressions for the molecular orbitals and values for the one‐electron energies of these systems. The results of these calculations were used to obtain approximate theoretical values for the spin‐spin coupling constants. Theoretical and experimental values agree only qualitatively.
The UV absorption of substituted benzhydrols and of the corresponding 2‐(dimethylamino)ethyl ethers
Authors: Rekker R. F. , Nauta W. Th.
Published: September 2010

The present paper gives UV measurements on a number of substituted benzhydrols and the corresponding 2‐(dimethylamino)ethyl ethers. As far as investigated, all spectra clearly demonstrate the existence of interaction between the component chromophoric parts, despite the presence of a saturated carbon atom as the connecting link. In its absorption, every asymmetrically substituted compound shows additivity with respect to its symmetrically substituted analogues.
Synthesis of some derivatives of cephalosporamine: On the synthesis of cephalosporin antibiotics II
Authors: Reinhoudt D. N. , Tan H. S. , Beyerman H. C.
Published: September 2010

Erlenmeyer condensations of 1,3‐dihydroxyacetones (9 and 12) with 2‐phenyl‐1,3‐oxazolin‐5‐one gave α‐benzamido‐β‐hydroxymethylbutenolide (15). Starting from the latter, via α‐benzamido‐β‐chloromethylbutenolide (18) α‐benzamido‐β‐acetylthiomethylbutenolide (19, N‐benzoyl‐S‐acetylcephalosporamine) was obtained. Compound 19 could be converted by an acid‐catalysed alcoholysis into α‐benzamido‐β‐mercaptomethylbutenolide (22, N‐benzoyl‐cephalosporamine), which showed unexpected stability.

The structure proof of the α‐benzamidobutenolides obtained (15 to 22) was furnished by correlation of α‐benzamido‐β‐triphenyl‐methylthiomethylbutenolide (20) with the reaction product of the known α‐amino‐β‐triphenyl‐methylthiomethylbutenolide (8) with benzoyl chloride. Spectroscopic evidence agreed with this.

Preparation of butenolides in this way is of potential interest for a synthesis of Cephalosporin C.
Aromatic halogen displacement by cyclohexyl radicals
Authors: Shelton J. Reid , Uzelmeier Christopher W.
Published: September 2010

Cyclohexyl radicals displace either halogen or hydrogen from dihalobenzenes to give mono‐ and di‐halogenated cyclohexylbenzenes. The unusual reactivity of fluorine in the sequence, F > I > Br > Cl, shows that breaking of the carbon‐halogen bond is not involved in the rate‐determining step. Halogens ortho to each other are consistently more reactive toward displacement than hydrogen in the same molecule. This higher reactivity is explained by a combination of electronic and steric effects plus the ability of halogen ortho to the reaction site to stabilize a cyclohexadienyl radical, while the preference for fluorine displacement is attributed to the nucleophilic nature of the cyclohexyl radical which reacts more readily at a position of low electron density.