bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chemistry of α‐diazosulfones: Part IV. The preparation of N‐(arylsulfonylmethyl)urethanes and N‐(alkylsulfonylmethyl)urethanes
Authors: van Leusen A. M. , Strating J. 
Published: September 2010

AbstractIn the synthesis of α‐diazosulfones (subsequent paper2) the N‐(sulfonylmethyl)urethanes, RSO2CH2NHCO2C2H5, are important intermediates. They have been prepared by means of a Curtius rearrangement of sulfonylacetazides, RSO2CH2CON3, which in turn have been obtained from the corresponding esters via the hydrazides.
Mechanism of reactions of α‐diazosulfones. II: The acid‐catalysed hydrolysis in water and in dioxan‐water mixtures
Authors: Zwanenburg B. , Engberts J. B. F. N. 
Published: September 2010

AbstractThe acid‐catalysed hydrolysis of α‐diazosulfones has been studied in water and in dioxan‐water solutions. From the magnitude of the solvent deuterium isotope effect a fast reversible protonation of the substrate is proposed. This result is supported by H‐D exchange experiments. The reaction rates have been measured in moderately concentrated perchloric acid and hydrochloric acid solutions. The logarithm of the pseudo first order rate constant is linear in Hammett's acidity function, H0. The slopes of these linear plots are appreciably larger for hydrochloric acid than for perchloric acid as catalyst. Bunnett's theory has been used to interpret the rate data in water. The influence of added sodium perchlorate and sodium chloride on the reaction rate is compared. A bimolecular rate‐determining step is proposed with a weak participation of the nucleophile in the transition state. The entropies of activation are consistent with this conclusion. The failure of the Zucker‐Hammett hypothesis is discussed.The influence of para substituents in five aryl α‐diazosulfones is correlated with Hammett's σp and Tsuno's σ+ constants. A weak transition state resonance has been proposed for p‐methoxyphenylsulfonyldiazomethane.Preliminary measurements on the hydrolysis of alkyl α‐diazosulfones are pointing to a similar mechanism to that proposed for the aryl α‐diazosulfones.
Electron diffraction by gases the molecular structure of monochlorodimethyl ether
Authors: Planje M. C. , Toneman L. H. , Dallinga G. 
Published: September 2010

AbstractThe structure of monochlorodimethyl ether has been reinvestigated by means of electron diffraction of the vapour. The rotation of both the chloromethyl group and the methyl group is restricted; the chlorine atom is approximately in the gauche position with respect to the O‐C bond. The carbon‐chlorine bond length is 1.813 Å, significantly larger than in chloroalkanes. The bond between the chloromethyl carbon atom and the oxygen atom is shorter than the carbonoxygen bond in aliphatic ethers.
The isocoumarin analogue of dicoumarol
Authors: Buu‐Hoi N. P. , Jacquignon P. , Mangane M. 
Published: September 2010

AbstractIsochroman‐1,4‐dione reacted with formaldehyde to give a methylenebis compound which is the exact analogue of dicoumarol, although it lacks the latter's potent anticoagulant properties. A similar reaction was observed with pyridine‐2‐aldehyde, but with benzaldehyde, 3‐benzylideneisochroman‐1,4‐dione was obtained.
The structure of the tetrachlorobisdimethylamino‐and trichlorotrisdimethylamino‐1,3,5,2,4,6‐triazatriphosphorine
Authors: Koopman H. , Spruit F. I. , van Deursen F. , Bakker J. 
Published: September 2010

AbstractThe purpose of the investigation was to gather data on the course of the substitution of chlorine by dimethylamine in hexachloro‐1,3,5,2,4,6‐triazatriphosphorine. In the course of this reaction a geminal substitution occurs besides the consecutive substitution in the 2,4 and 6 positions. The structure of the three tetrachlorobisdimethylamino and the three trichlorotrisdimethylamino‐1,3,5,2,4,6‐triazatriphosphorine was determined. Contrary to previously published results1, the 2,4‐bisdimethylamino derivative already described by Becke Goehring2 has the trans configuration.
Heats of combustion of normal saturated fatty acids and their methyl esters
Authors: Adriaanse N. , Dekker H. , Coops J. 
Published: September 2010

AbstractAccurate heats of combustion of the title compounds were measured in an electrically calibrated calorimeter; the liquid samples were burned in Pyrex ampoules; the water content in the samples was titrated by the Karl Fischer method.The increment of the standard enthalpy of combustion, ‐ΔHR25liq. (=‐ΔHC0liq.) for one CH2 group in the chain proved to be 653.8 kj/mole for both the acids and the methyl esters studied, which is the same value as determined for the liquid paraffins. The following formulae, in which c = the number of carbon chain atoms (c > 5) can be used to calculate the standard enthalpies of combustion (based on the 1951 atomic weights):
‐ΔHliq. = 653.8 c − 430.2 kj/mole for the acids, accurate to 0.03 − 0.04%,
‐ΔHliq. = 653.8 c + 292.6 kj/mole for the methyl esters, accurate to 0.02%.
The theoretical heat of esterification of a fatty acid with methanol at 25 °C, disregarding heats of solution and dilution, was calculated to be 3.8 ° 0.6 kj/mole, which can be compared with the value of 4.2 ° 0.3 kj/mole for the theoretical heat of esterification of acetic acid with ethanol at about 20 °C, determined directly by Mme Bérenger‐Calvet.
Correlations between molecular structure and mass spectra I.: An anomalous type of rearrangement ions found in the mass spectra of carboxylic acids and nitriles
Authors: Rol N. C. 
Published: September 2010

AbstractAn important type of rearrangement ions is common to the mass spectra of several classes of organic compounds, e.g. ketones, aldehydes, acids, nitriles, etc. For its explanation McLafferty proposed a six‐membered ring transition state through which a hydrogen atom was thought to be transferred.In the spectra of certain branched acids and nitriles we have observed an additional type of rearrangement ions. In the case of the nitriles one must discriminate between the actual rearrangement ions CnH2n‐1N+ and the ions Cn+1H2n+1+, of nearly the same mass. With a mass spectrometer of high resolving power (A.E.I., MS 9) the presence of both types of ions was established; their relative abundances vary widely for different substances.Although at first sight related to the McLafferty‐rearrangements, the newly found rearrangements are not readily explained in exactly the same way. They can be accounted for by a simple modification of McLafferty's scheme, involving a seven‐ or even eight‐membered ring transition state instead of the usual six‐membered one.
Solubility of aromatic hydrocarbons in aqueous sulfuric acid
Authors: Cerfontain H. 
Published: September 2010

AbstractThe solubilities of various aromatic hydrocarbons in aqueous sulfuric acid were determined at 25°. All hydrocarbons studied exhibit a minimum solubility in the 40‐70 wt‐% H2SO4 region.UV and NMR studies indicate that with benzene the variation in solute‐solvent interaction with variation in sulfuric acid concentration is small. The variation of the benzene solubility is therefore rationalized in terms of variations in internal pressure of the sulfuric acid solvent. With dipolar hydrocarbons in aqueous sulfuric acid, solute‐solvent interaction is observed. Solute‐solvent interaction energies of some monoalkylbenzenes relative to benzene have been estimated.
The solubility of toluene and benzene in concentrated aqueous sulfuric acid; implications to the kinetics of aromatic sulfonation
Authors: Cerfontain H. , Telder A. 
Published: September 2010

AbstractThe solubility of benzene and toluene in aqueous sulfuric acid > 75 wt‐% has been determined at 5, 25 and 45°.Molar heats of solution have been calculated. The benzene to toluene activity coefficient ratio is slightly greater than unity. The relatively large difference in activation entropy for sulfonation of the para‐position in toluene and a single position in benzene1 is therefore attributed mainly to differences in solvation of the transition states.
Mixed carboxylic acid anhydrides: IV. formic anhydride
Authors: Schijf R. , Scheeren J. W. , van Es A. , Stevens W. 
Published: September 2010

AbstractCompound X2 found in formic acetic anhydride after disproportionation and in formic acid/carboxylic acid anhydride reaction mixtures was proved to be formic anhydride. This anhydride could be synthesized in 90% molar purity.
Studies on polypeptides IV: Syntheses and activities of some angiotensin‐like peptides
Authors: Schattenkerk Cecile , Havinga E. 
Published: September 2010

AbstractThe following heptapeptides and octapeptides have been synthesized: (des‐Asp1)‐L‐Arg2(NO2)‐Ile5‐angiotensin II, (des‐Asp1)‐D‐Arg2(NO2)‐Ile5‐angiotensin II, D‐Asp(NH2)1‐Ile5‐angiotensin II, D‐Asp(NH2)5‐D‐Arg2‐Ile5‐angiotensin II, Gly1‐D‐Arg2‐Ile5‐angiotensin II, Asp1(NH2)‐Cit2‐Ile 5−‐angiotensin II*. Possible structure‐activity relationships are discussed.
Conversion of δ‐lactones into γ‐lactones: Extension of the scope of the fittig reaction
Authors: de Jonge A. P. 
Published: September 2010

AbstractThe observations described in the literature that alkenoic acids by heating with 80% sulfuric acid (Fittig reaction) yield γ‐lactones have been confirmed. In addition it has appeared that besides the γ‐lactone a small percentage of δ‐lactone is formed.Further it has been found that on heating δ‐lactones under the conditions of the Fittig reaction also γ‐lactones are obtained. By variation of the reaction conditions, γ‐ and δ‐lactones can be obtained in varying ratios.For the quantitative analysis of a mixture of isomeric γ‐ and δ‐lactones, paper chromatography of the corresponding hydroxy‐acid anilides is perfectly practicable.
Studies in group iv organometallic chemistry. XX: Addition of Trialkyltin Hydrides to Substituted Acetylenes: The Structure of the Addition Products
Authors: Leusink A. J. , Marsman J. W. , Budding H. A. 
Published: September 2010

AbstractThe addition of trialkyltin hydrides to mono‐ and di‐substituted acetylenes has been studied more closely. The identity and geometry of the resulting 1:1 adducts have been established by means of GLC, IR and NMR spectroscopy, elementary analysis and degradation reactions.Both terminal and non‐terminal addition of the trialkylstannyl group has been observed. Trans‐addition of the Sn‐H bond across the triple bond seems to occur mainly.
Mixed carboxylic acid anhydrides: V. Synthesis of alkyl formates
Authors: van Es A. , Stevens W. 
Published: September 2010

AbstractThe investigations into the esterification of primary, secondary and tertiary alcohols with formic acid/acetic anhydride reaction mixtures have been extended. The effect of various molar intake ratios of formic acid and acetic anhydride as well as the influence of temperature, solvents, and catalysts have been examined. The results obtained led to simple methods of synthesis of pure alkyl formates in high yields.
Investigations on sterols XXV: Synthesis and configuration at C‐20 of epimeric 20‐hydroxy‐9β,10α‐pregnane derivatives
Authors: van Kamp H. 
Published: September 2010

AbstractThe synthesis is reported of 20α‐hydroxy and 20β‐hydroxy‐9β,10α‐pregna‐4,6‐dien‐3‐one and their corresponding 6,7‐dihydro derivatives. The assignment of the configuration at C‐20 is based on alternative synthesis by Baeyer‐Villiger oxidation of the corresponding 20‐formyl compounds. Molecular rotation relationships and N.M.R. spectra are discussed.
The mannich condensation of sulfinic acids, aldehyde, and ethyl carbamate II.: The use of higher aldehydes
Authors: Engberts J. B. F. N. , Strating J. 
Published: September 2010

Abstractα‐Aryl‐ and α‐alkyl‐N‐(sulfonylmethyl)urethanes have been prepared by a Mannich condensation of a sulfinic acid, an aldehyde, and ethyl carbamate. Three procedures for this reaction are discussed.
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

AbstractFrom 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

AbstractThe 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

AbstractSuccessive 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

AbstractAs 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

AbstractLiquid 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

AbstractReaction 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

AbstractThe 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

AbstractThe 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

AbstractThe 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.
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

AbstractRaman 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

AbstractIn 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

AbstractSeveral 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

AbstractThe 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

AbstractTreatment 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

AbstractThe 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

AbstractWithin 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

AbstractA 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

AbstractThe 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

AbstractAcid 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.