bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and physiological properties of some heterocyclic‐aromatic sulphides and sulphones: II. Synthesis of some aryl‐pyrimidyl, aryl‐thiazolyl and aryl‐thienyl sulphides
Authors: van Zwieten P. A. , Huisman H. O. 
Published: September 2010

AbstractThe synthesis of some heterocyclic‐aromatic sulphides with potential acaricidal properties is described. The benzene nucleus in these sulphides is substituted either with a para‐chlorine atom or with three chlorine atoms in positions 2,4 and 5. The heterocyclic nuclei are pyrimidine, thiazole and thiophen. These nuclei are either unsubstituted or carry a halogen substituent; only in the thiophen series a nitro group is substituted.
The chemistry of cycloheptatriene: Part V: Reactions of tropone and 2‐chlorotropone with Grignard reagents
Authors: ter Borg A. P. , van Helden R. , Bickel A. F. 
Published: September 2010

AbstractInteraction of tropone and phenylmagnesium bromide yields 2‐phenyl‐2,7‐dihydrotropone (II). This compound is in thermal equilibrium with 2‐phenyl‐6,7‐dihydrotropone (III) in a 1: 4 ratio.The reaction of 2‐chlorotropone with isopropylmagnesium bromide yields a mixture of chloroisopropyldihydrotropones, which upon dehydrochlorination gives rise to 2‐isopropyltropone. This compound may be converted into 3‐isopropyltropolone (α‐thujaplicine).
The photooxidation of nylon 6 and 66
Authors: Boasson E. H. , Kamerbeek B. , Algera A. , Kroes G. H. 
Published: September 2010

AbstractThe chemical changes occurring in nylon (6 and 66) on irradiation have been studied.The results confirm earlier work on model systems which showed the main attack to be between the‐NH‐group of the amide bond and the adjacent‐CH2‐group. However, a number of products were found that indicate a more complicated course of the reaction.The similarily of photooxidation and thermal degradation8 is pointed out.
The t‐butoxy group, a novel hydroxyl‐protecting group for use in peptide synthesis with hydroxy‐amino acids
Authors: Beyerman H. C. , Bontekoe J. S. 
Published: September 2010

AbstractWe have found a novel way of protecting the hydroxyl function in hydroxy‐L‐amino acids, making use of the t‐butoxy group, which is readily split by acids, but not by bases.This group is introduced by acid‐catalysed addition of isobutene to N‐acylated hydroxy‐L‐amino acids. The blocking group is easily removed at or below room temperature with trifluoroacetic acid without racemization and without breaking peptide bonds 1,2
Exchange of alkylgroups in triethyl aluminium, diethyl aluminium chloride and a mixture of these substances, and in a mixture of methyl aluminium dichloride and dimethyl aluminium chloride
Authors: Smidt J. , Groenewege M. P. , de Vries H. 
Published: September 2010

AbstractProton magnetic resonance has shown that there is exchange between the outer‐ and the bridge‐alkylgroups in dimeric triethyl aluminium at room temperature. At lower temperatures the rate of exchange diminishes, and at −60° exchange is hardly noticeable.In diethyl aluminium chloride no exchange of alkylgroups was found between room temperature and −60°. The observation fits in well with the concept of chlorine bridges in the dimer.In a 1:1 mixture of both compounds exchange of alkylgroups was observed at room temperature. Lowering of the temperature first stops the exchange between the alkylgroups of the two different compounds and then also stops the exchange between the alkylgroups in the triethyl aluminium.In a 1:1 mixture of methyl aluminium dichloride and dimethyl aluminium chloride it was also found that upon a lowering of the temperature the exchange between alkylgroups stops.
Note on the reactivity of some o‐(hydroxybenzoyl) benzoic acids towards diazomethane
Authors: Bellaart A. C. , Kooistra C. , Koningsberger C. 
Published: September 2010

AbstractReactions between diazomethane and several o‐(hydroxybenzoyl)benzoic acids were studied both in purely ethereal solutions as well as in presence of methanol. In all cases the phenolic groups involved appear to be more or less sluggish in their response. On the other hand, it is also noted that nitro groups can exercise an activating influence.
The synthesis of the optical isomers of 3,5,5‐trimethylcyclohexyl mandelate (cyclandelate)
Authors: Ernsting M. J. E. , Nauta W. Th. 
Published: September 2010

AbstractTo investigate possible differences in spasmolytic activity the four isomers of cyclandelate (the DL‐mandelate of low melting 3,5,5‐trimethylcyclohexanol) as well as the corresponding isomeric esters from high melting 3,5,5‐trimethylcyclohexanol were prepared.
Investigations on organogermanium compounds I: On the redistribution reaction between tetra‐n‐butylgermanium and germanium tetrachloride
Authors: van der Kerk G. J. M. , Rijkens F. , Janssen M. J. 
Published: September 2010

AbstractThe redistribution reaction between tetra‐n‐butylgermanium and germanium tetrachloride has been investigated. Under suitable conditions it is possible to prepare tributylgermanium chloride and dibutylgermanium dichloride by this reaction in yields of over 80%. The presence of anhydrous aluminium chloride is required. The analogous preparation of butylgermanium trichloride in good yield has not been realized.The relative reactivity of the compounds BunGeCl4‐n (n = 0, 1 or 2) with respect to alkylation by tetrabutylgermanium in the precence of aluminium trichloride was found to be Bu2GeCl2> BuGeCl3>> GeCl4.The new compound butylgermanium trichloride is characterized.
Free‐radical reactions of allene the interaction of allene and thiyl radicals
Authors: van der Ploeg H. J. , Knotnerus J. , Bickel A. F. 
Published: September 2010

AbstractThe free‐radical addition of 1‐propanethiol, benzenethiol (thiophenol) and α‐toluenethiol (benzyl mercaptan) to allene in benzene solution has been investigated.At high allene/thiol ratios the two sulfides resulting from the addition of one mole of RSH to allene (isopropenyl‐SR and allyl‐SR) are formed in yields of the same order of magnitude.At low allene/thiol ratios the more reactive isopropenyl sulfide is not present among the products, since it is quantitatively converted into 1,2‐di‐SR‐propane. Thiol addition to the allyl sulfide to yield 1,3‐di‐SR‐propane is a much slower process.
A simple synthesis of some hydroxypyridine carboxylic acids
Authors: Broekman F. W. , van Veldhuizen A. , Janssen H. 
Published: September 2010

AbstractA simple method for the synthesis of 3‐hydroxypicolinic acid and 4‐hydroxynicotinic acid via the cyano compounds starting from 3‐hydroxy‐2‐iodo‐ or 4‐hydroxy‐3‐iodopyridine, is described.
Studies on cyclohexane derivatives: IV Preparation and chemical proof of the configurations of the two 4‐isopropylcyclohexanecarboxylic acids
Authors: van Bekkum H. , Kleis A. A. B. , Medema D. , Verkade P. E. , Wepster B. M. 
Published: September 2010

AbstractThe preparation of pure low‐melting 4‐isopropylcyclohexanecarboxylic acid (m.p. 40–41°) is described for the first time. It was isolated from mixtures of the low‐melting and the high‐melting isomer, making use of the fact that only the latter gives an inclusion compound with thiourea.By chemical means it is proved that low‐melting 4‐isopropylcyclohexanecarboxylic acid has the cis‐configuration and the high‐melting isomer the trans‐configuration. For this purpose these acids were converted into cis‐ and trans‐1‐methyl‐4‐isopropylcyclohexane (cis‐ and trans‐para‐menthane) respectively, using reactions which take place without any change of configuration at the cyclohexane nucleus. The configuration of these two hydrocarbons has been proved in paper III of this series.
Bromination of pyridine in fuming sulphuric acid
Authors: den hertog H. J. , van der Does L. , Landheer C. A. 
Published: September 2010

AbstractWhen pyridine (4 moles) is heated at 130° in fuming sulphuric acid with bromine (1 mole), 1.6‐1.8 moles of pure 3‐bromopyridine are formed according to the equation 2 C5H5N + 2 SO3 + Br2 → 2 C5H4BrN + SO2 + H2SO4. The reaction product contains but a small amount of dibromopyridines (less than 0.1 mole), 2,5‐dibromopyridine being the chief component in the mixture.The reaction products were analysed semiquantitatively by gas chromatography.
The thermal decarboxylation of alkali trichloroacetates in aprotic solvents IV decarboxylation in the presence of hexa‐ and pentachloroacetone
Authors: Wagner W. M. , Kloosterziel H. , Bickel A. F. 
Published: September 2010

AbstractThermal decarboxylation of sodium trichloroacetate in the presence of hexachloroacetone yields CO2, CO, CCl4, perchloroisopropenyl acetate and perchloroisopropenyl acrylate. A mechanism is suggested involving Cl+‐abstraction by a CCl3− ion from the ketone as the primary step, followed by Favorskii rearrangement of the resulting anion CCl3COCCl2.−In the corresponding reaction of sodium trichloroacetate with pentachloroacetone both H+‐abstraction from the ‐CHCl2 group and Cl+ ‐abstraction from the ‐CCl3 group occur.
Some 1,2‐dihalogeno derivatives of cycloheptane and cyclo‐octane
Authors: Henniger P. W. , Wapenaar E. , Havinga E. 
Published: September 2010

AbstractCis‐1,2‐dibromocycloheptane and cis‐1,2‐dibromocyclo‐octane and the corresponding trans dibromo‐ and ‐dichloro compounds have been prepared. Dipole moments have been calculated from data on solutions of the compounds in benzene and in carbon tetrachloride. Infrared absorption spectra were taken from solutions in carbon disulphide. A short discussion is given comparing the results with those formerly obtained for the cyclohexane derivatives.
Investigations into the hydrogen bonding between n‐butanol and some ketones by infra‐red spectroscopy
Authors: Hoeke Miss M. , Koevoet A. L. 
Published: September 2010

AbstractOn considering the hydrogen bonding of n‐butanol with several ketones it appears that there is a regular increase in the value of the association constant on the introduction of methyl groups. Introduction of a phenyl group into a ketone brings about a decrease in hydrogen bonding. The cyclic ketones have high association constants, presumably due to their convenient structure for hydrogen bonding. An exception is formed by cyclopentanone, in which the sterical effect is counteracted by the larger double bond order of the >CO‐group. With sterically hindered molecules, such as di‐isopropyl ketone and di‐tert.‐butyl ketone there is less hydrogen bonding.From the results of the experiments no conclusions, as to the existence of a simple relation between K on the one side and the half width v½ and the frequency‐shift Δv on the other, could be drawn.
Investigations on organotin compounds XVII: The structure of trialkyltin acylates
Authors: Janssen M. J. , Luijten J. G. A. , van der Kerk G. J. M. 
Published: September 2010

AbstractBy infrared spectroscopy it is shown that trialkyltin acylates in the solid state occur as coordination polymers in which each tin atom is penta‐coordinated,viz. by three alkyl groups and two oxygen atoms belonging to different acylate groups. In apolar solvents or in the liquid state, however, the compounds are monomolecular and show resemblance to organic esters. Only in very concentrated solution or just above the melting point is association detected. In a search for the generality of the concept it was found that the occurrence of the polymeric crystal structure is counteracted by steric hindrance, that it does not occur with thio‐ or dithio‐acetates and, finally, that lead behaves like tin but germanium and silicon compounds are monomolecular throughout.
Aromatic sulphonation V: A kinetic study on the sulphonation of toluene, ethylbenzene and isopropylbenzene in aqueous sulphuric acid
Authors: Kaandorp A. W. , Cerfontain H. , Sixma F. L. J. 
Published: September 2010

AbstractRate measurements have been made on the homogeneous sulphonation of toluene in aqueous sulphuric acid varying from 70.0 to 95.9 wt‐% at 5.0°, 25.0° and 45.0°. In addition, rate constants have been determined for the homogeneous sulphonation of ethylbenzene and isopropylbenzene at 25.0° in aqueous sulphuric acid solutions varying from 72.4 to 89.1 wt‐%. All reactions were found to be first order with respect to the aromatic compound. It is suggested that the differences in the overall rate constants for the sulphonation of toluene, ethylbenzene and isopropylbenzene originate predominantly from steric hindrance for ortho‐substitution.
Microbiological conversion of 19‐nortestosterone: (IV) 15α‐hydroxylation
Authors: de Flines J. , van der Waard W. F. , Mijs W. J. , Szpilfogel S. A. 
Published: September 2010

AbstractMicrobiological reaction of 19‐nortestosterone with Penicillium sp.ATCC 11598 leading to about equal amounts of the 15α‐hydroxy‐derivative and 15α‐hydroxy‐19‐nor‐androst‐4‐one‐3,17‐dione is described. Fermentation of 19‐nortestosterone with Fusarium orthoceras afforded mainly 15α‐hydroxy‐19‐norandrost‐4‐ene‐3,17‐dione and only minor amounts of 15α‐hydroxy‐19‐nortestosterone.
Synthesis of spirocyclic compounds by the intramolecular michael reaction
Authors: de Jongh H. A. P. , Wynberg Hans 
Published: September 2010

AbstractThe double Michael reaction between the acyclic cross‐conjugated dienones dibenzalacetone or divinyl ketone and cyclohexane‐1,3‐diones gives new, substituted spiro [5,5] undecane‐l,5,9‐triones. Some of these are reduced to the corresponding spirodiketone or monoketone.
Thermodynamic study of melting equilibria under pressure of a supercritical gas
Authors: de Swaan Arons J. , Diepen G. A. M. 
Published: September 2010

AbstractThe modified course of the melting curve of a single substance is discussed for the case where, at its melting point, it is subjected to pressure of a supercritical gas. Unlike the melting curve of the pure substance, the new melting curve represents a three‐phase equilibrium solid‐liquid‐gas (S‐L‐G).In section I equations are given for the slope of the S‐L‐G‐curve at the triplepoint of the least volatile component in P‐x‐, P‐T‐ and T‐x‐projections respectively. As a test the slope dP/dT is calculated for the system ethylene‐naphthalene. Agreement with the experimental value is found to within 2 %.In section II the derivation is given of an equation for the equilibrium liquid composition as a function of pressure and temperature, provided that the solvent behaves like an ideal solution. A calculation for the system ethylenenaphthalene gives an idea of the departure from ideality at high pressures. Finally, equations are given for calculating the P‐T‐x behaviour of the S‐L‐G‐curve in the vicinity of the triplepoint of the least volatile component.
Thermal decomposition of hydrated uranium peroxides
Authors: Cordfunke E. H. P. , Aling P. 
Published: September 2010

AbstractThe water vapour pressure of the equilibrium between the hydrates UO4.4H2O and UO4. 2H2O has been measured as a function of the temperature. The results can be expressed as: log pH2O(mm) = 11.020 − 3082/TThermal decomposition of these hydrates results in the formation of amorphous (A‐) UO3, α‐UO3 or the UO2.9‐phase. These transformations were studied by thermogravimetric and differential thermal analysis.At 520° recrystallization of these oxides takes place with formation of γ‐UO3.
Charge transfer complexes between iodine and various thioanisoles
Authors: van der Veen J. , Stevens W. 
Published: September 2010

AbstractSpectrophotometric studies of solutions in cyclohexane of iodine with various thioanisoles have given results that are consistent with the formation of 1 : 1 charge transfer complexes.The thermodynamic and spectral characteristics of these complexes have been investigated.The equilibrium constants are in accordance with a Hammett type of relationship suggesting that complex formation depends on the electron availability of the sulphur atom in the compounds studied.
On the structure of phycaron
Authors: Hackeng W. H. L. , Copier H. , Salemink C. A. 
Published: September 2010

AbstractThis communication describes the isolation of new pigments from Phyllosticta caryae Peck. One of these pigments, phycaron, is identified as 1,2‐diaceto‐5,10‐dihydroxy‐3,6,9,12 (or 6,7,8,9)‐tetramethoxy‐1,2‐dihydrobenzperylene‐4,11‐quinone.
Conversion of thiolesters of α,β‐unsaturated acids into the free acids
Authors: Bos L. B. , Arens J. F. 
Published: September 2010

AbstractEthanethiolesters can be converted into free acids by:
treatment with a mixture of mercuric chloride and mercuric oxide in aqueous acetone (table I),
treatment with benzaldehyde and boron trifluoride in chloroform (table II). The latter procedure probably involves the reactions (1)‐(4).
π‐Complexes derived from the anhydride, amide, and esters of 3,5‐dinitrobenzoic acid
Authors: Buu‐Hoï N. P. , Jacquignon P. , Roussel Odette 
Published: September 2010

AbstractIt is shown that the anhydride, the amide, and the esters of 3,5‐dinitrobenzoic acid all give highly coloured π‐complexes with a variety of polycyclic aromatic and heterocyclic compounds. The complexes derived from the anhydride contain one molecule of the anhydride to two molecules of the electron‐donor, whilst the others are of the 1 : 1 type.
Mechanism of reactions of unsaturated ethers and thioethers. VIII: Acid‐catalyzed addition of water to 1‐alkynyl ethers
Authors: Stamhuis E. J. , Drenth W. 
Published: September 2010

AbstractAdditional evidence for the occurrence of a rate determining proton transfer in the hydration of 1‐alkynyl ethers is afforded by the value of the solvent deuterium isotope effect, k/k = 1.7.The addition of water to 1‐ethoxy‐1‐propyne was investigated in a series of alcohol‐water mixtures. Application of the criterium of Grunwald indicates that a solvent molecule is not bound covalently in the slow proton transfer step.
Mechanism of reactions of unsaturated ethers and thioethers X: Neighbouring group effect in the acid‐catalyzed rearrangement of ethoxyethynyl carbinols
Authors: Hekkert G. L. , Drenth W. 
Published: September 2010

AbstractThe velocity of the acid‐catalyzed hydration of 1‐alkynyl ethers, RCCOC2H5, has been determined, and the second order rate constants are correlated with Taft's equations. This correlation is used to estimate the rate of rearrangement of ethoxyethynyl carbinols, R2C(OH)CCOC2H5, into α,β‐unsaturated esters. The experimental values are approximately one power of ten larger, suggesting an anchimeric effect of the hydroxyl group.
Mechanism of reactions of unsaturated ethers and thioethers. XI: Acid‐catalyzed addition of water to 1‐alkynyl thioethers
Authors: Hogeveen H. , Drenth W. 
Published: September 2010

AbstractInfrared analysis has shown that acid‐catalyzed hydration of ethylthioethyne in heavy water does not involve the uptake of deuterium in the initial compound. This confirms earlier evidence that protonation of the triple bond is the rate‐determining step.Values for the entropy of activation of five 1‐alkynyl thioethers were determined. They range between −1 and −6 e.u. The rate of hydration of 1‐tert.‐butylthio‐1‐propyne in 0–98.7 weight‐percent ethanol‐water mixtures has been analyzed by a theory of Grunwald. A plot of (log k1−log fH⊕) against Y0 gives a straight line. The triple bond of vinylthioethyne has been hydrated in moderately concentrated perchloric acid solutions. A Zucker‐Hammett plot of these data affords a straight line with a slope of 1.07 and a Bunnett plot a “straight” line with a slope of −0.9. These facts suggest that the addition of the water molecule takes place in a step subsequent to protonation.
The chemistry of sulfenyl halides: Part III: Photochlorination of alkyl chlorides with trichloromethylsulfenyl chloride
Authors: Kloosterziel H. 
Published: September 2010

AbstractThe photochlorination of some alkyl chlorides with trichloromethylsulfenyl chloride has been investigated. Product distributions and reactivities relative to alkanes were determined. The results show the importance of polar effects and can be correlated with the polar substituent constants σ*. A chlorine atom reduces the reactivity of a neighbouring carbon‐hydrogen bond by a factor of 45. The reactivities at other positions correspond to a loss factor of 1.6. A methyl group exerts a slight activating polar effect.A correlation with NMR chemical shifts suggests that the differences in reactivity of methylene groups in hydrocarbons, as reported in Part II 2, are also due to polar effects.
The thermal decarboxylation of sodium trichloroacrylate in an aprotic medium
Authors: Wagner W. M. , Vriesman L. , Kloosterziel H. , Bickel A. F. 
Published: September 2010

AbstractSodium trichloroacrylate decomposes in 1,2‐dimethoxyethane at 90° to give quantitative yields of CO2 and NaCl. Evidence is presented that this decarboxylation involves the trichlorovinyl anion, CCl2CCl−, as an intermediate.
On the impedance of galvanic cells: VIII. The abnormal behaviour of the Tl+/Tl(Hg) electrode
Authors: Sluyters‐Rehbach M. , Timmer B. , Sluyters J. H. 
Published: September 2010

AbstractThe anomalous behaviour of the Tl+/Tl(Hg) electrode in 1 KNO3 + 0.1 M KCl solution has been studied experimentally applying the theory described in parts IV and VI of this series. It is shown that this anomaly can be explained assuming that the double layer capacity increases on adding thallous ions. The increase Δ C appears to be proportional to the TI+ concentration. The phase angle Φ of the faradaic impedance is equal to π/4.
A new synthesis of nitriles
Authors: Brackman W. , Smit P. J. 
Published: September 2010

AbstractNitriles can be obtained in good yields (60‐80%) by treatment with oxygen at 30° of a methanolic solution of the corresponding aldehyde, containing ammonia, a strong base and a catalytically active copper complex. Yields are lower for base‐sensitive aldehydes.In a similar way, but in much poorer yields, cyanide and cyanate are formed from methanol, ammonia and oxygen, and isonitriles from methanol, a primary aliphatic amine and oxygen.
Synthesis and anthelmintic activity of isopelletierine and a series of side‐chain homologues
Authors: van Noordwijk J. , Mellink J. J. , Visser B. J. , Wisse J. H. 
Published: September 2010

AbstractThe preparation and anthelmintic properties of isopelletierine and four side‐chain homologues are described. The compounds were prepared from Δ1‐piperideine and 3‐oxo‐acids at pH 4‐5. pK′a− and Rf‐values were determined. Anthelmintic activity as tested in vitro on the liver fluke, by three methods, was highest for 1‐(2′‐piperidyl)butanone‐2. The differences in anthelmintic properties of the compounds are discussed.
Mechanism of reactions of unsaturated ethers and thioethers XII: Reaction of 1‐ethoxyvinyl esters with carboxylic acids in non‐aqueous solvents
Authors: Zwanenburg B. , Drenth W. 
Published: September 2010

AbstractThe reaction of 1‐ethoxyvinyl esters and carboxylic acids has been investigated in non‐aqueous solvents. The kinetics in benzene follow the rate expressionV = k30 · C1‐ethoxyvinyl ester · C2acidwhile in dioxan and sulpholane the following equation is obeyedV = (k30 · C2acid + k4 · C3acid) · C1‐ethoxyvinyl esterThe rate constants in sulpholane are 20 to 30 times as large as those in dioxan, while the rate of reaction in benzene is approximately equal to that in sulpholane. The kinetic isotope effect, kH/kD, for the reaction of 1‐ethoxyvinyl acetate and either acetic acid or O‐deuteroacetic acid, amounts to 4.0 in benzene and to 3.6 in sulpholane as solvent. During this reaction no deuterium was incorporated into the vinyl ester molecule.Addition of tetrabutylammonium perchlorate to the solvent dioxan increases the rate constant of the reaction between 1‐ethoxyvinyl chloroacetate and chloroacetic acid in accordance with the equationk3 = (k3)conc. salt = O (1 + b · Csalt)The value of the coefficient b amounts to 4 1/mole.From these results it was concluded, that in a number of pre‐equilibria a solvation complex is formed between a molecule of 1‐ethoxyvinyl ester and two, three or four molecules of carboxylic acid. These pre‐equilibria are followed by the rate determining step in which a proton is transferred to the substrate giving an ion pair as intermediate. The products are formed from this ion pair.