bluuebunny/crossref_metadata_2025 huggingface dataset:
The chemistry of small ring compounds. Part XI Oxidation of 1‐methoxycyclopropanol and 1‐methoxy‐2,2‐dimethylcyclopropanol by metal ions
Authors: Schaafsma S. E. , Molenaar E. J. F. , Steinberg H. , de Boer Th. J.
Published: September 2010

On oxidation of 1‐methoxycyclopropanol 1 by ammoniacal cupric sulfate, methyl acrylate 4a and dimethyl adipate 3a are formed exclusively in high yield. It is shown that the latter compound is formed from the intermediate radical 2 by dimerisation and predominantly by addition to methyl acrylate. The same products and a tricarboxylic ester 8 are formed using ferric nitrate as the oxidant.

1‐Methoxy‐2,2‐dimethylcyclopropanol 10 reacts with ammoniacal cupric sulfate to form the tetramethyladipic esters 13 and 14 as the main products and the α,β‐ and β,γ‐unsaturated esters 16 and 17 in smaller quantities. These compounds originate from the radicals 11 and 12.

If the oxidation is carried out with ferric nitrate only radical 12 is produced, which is oxidised further yielding the unsaturated esters 16 and 17 and the β‐hydroxy‐ester 18. The diversity of products obtained from the hemiacetal 10 and ammoniacal cupric sulfate, as compared with the ferric nitrate system, is ascribed to transient copper complexes which affect the transition state of the oxidation.

With ferric chloride the hemiacetals 1 and 10 give the β‐chloro compounds 9 and 19 through an efficient ligand transfer oxidation of the intermediate radicals 2 and 12.
The Reaction of 4,4‐dimethyl‐1‐phenylisochroman with hydriodic acid and phosphorus
Authors: van der Stelt C. , Hofman P. S. , van der Vlies C. , Bickelhaupt F.
Published: September 2010

In continuation of earlier work, the reaction of 4,4‐dimethyl‐1‐phenylisochroman (1) with hydriodic acid and phosphorus was subjected to a closer investigation. 10, 11‐Dihydro‐10, 10‐dimethyl‐5H‐dibenzo[a,d]cycloheptene (2) and 9, 10‐dihydro‐9‐isopropylanthracene (4) were identified as the reaction products in a ratio 2:1. Fractionation of the reaction mixture afforded, among other products, anthracene as a pyrolysis product of compound 4. A plausible reaction mechanism for the formation of 2 and 4 is proposed.
A study of the effect of labelling on the solubility of thallous bromide in water: On the feasibility of the radiometric determination of solubility
Authors: Gelsema W. J. , de Ligny C. L. , Blijleven S. H. A.
Published: September 2010

The solubilities of thallous bromide, both inactive and labelled with 204T1, in water at 25°, have been determined titrimetrically and proved to be identical within experimental error.

The specific count rates of labelled thallous bromide, both in saturated and unsaturated solution, have been determined and proved to be identical within experimental error.

These results lend strong support to the validity of the radiometric method for the determination of solubility, which was challenged recently by Spitsyn et al.

The solubility of thallous bromide in water at 25.0° is 576.7 ± 0.3 mg/l.
Basicity of alkynylphosphines
Authors: Drenth W. , Hogervorst A.
Published: September 2010

The basicity of alkynylphosphines has been measured and correlated with polar substituent constants. The basicity is not affected by mesomeric interaction between phosphorus and triple bond.
Synthesis of 2,3,5‐trimethylterephthalic acid
Authors: Wals L. , Nauta W. Th.
Published: September 2010

Two routes for the synthesis of 2,3,5‐trimethylterephthalic acid are described, starting from 1,2,4‐trimehylbenzene and p‐xylene, respectively.
Inorganic complexes with acetic acid as the ligand
Authors: van Leeuwen P. W. N. M. , Groeneveld W. L.
Published: September 2010

Coordination complexes containing hexa‐acetic acid metal groups are reported with the divalent cations Mg, Mn, Co, Ni, Cu and Zn and with the tetrafluoroborate, perchlorate and nitrate anions. Visible spectra, some infrared data and isomorphism according to X‐ray powder diagrams are recorded. The compounds are prepared from the hydrated salts and acetic anhydride. The spectrochemical position of acetic acid is given and compared with related molecules such as acetamide and urea. The preparation of complexes of the last two ligands is briefly reported.
PMR spectroscopic investigation of structures, stabilities, and rearrangement reactions of C4‐C7tertiary carbonium ions in HF‐SbF5
Authors: Brouwer D. M.
Published: September 2010

Solutions in HF‐SbF5 of the tertiary butyl, pentyl, hexyl, methylcyclopentyl and heptyl cations have been investigated by PMR spectroscopy. A variety of procedures, conventional as well as novel ones, for preparing stable solutions of these cations are briefly described.

Tertiary hexyl and heptyl cations rearrange rapidly to equilibrium mixtures of the isomeric tertiary hexyl and heptyl cations, respectively. The equilibrium compositions show the differences in thermodynamic stability of isomeric tertiary carbonium ions to be small. Equilibrations effected by a single 1,2‐hydride or methyl shift between equivalent positions have half‐lives of less than 10−3 s at ‐ 60 °C. Rearrangements of the type tert‐2‐methylpentyl to tert‐3‐methylpentyl cation have a half‐life of about 0.1 s at 0° (Eact = ∼ 14 kcal/mole, and Sact = ∼ 0). For these rearrangements a stepwise mechanism by successive hydride, methyl and hydride shifts via secondary carbonium ions is in agreement with the experimental data. Rearrangements of tertiary carbonium ions involving a change in the degree of chain branching (monobranched to linear or to dibranched cations) have half‐lives of the order of 10 s at 0°.
Protonation of halogen‐containing benzenes in HF‐SbF5. Part I.: PMR spectra of fluoro‐, chloro‐ and bromomesitylenium and xylenium ions
Authors: Brouwer D. M.
Published: September 2010

2‐Fluoro‐, chloro‐ and bromomesitylenes, and 5‐fluoro‐, chloro‐ and bromo‐m‐xylenes have been found to form stable benzenium ions in HF‐SbF5. The cations give well‐resolved PMR spectra, from which their structures have been derived. The 2‐halomesitylenes are “exclusively” protonated in the unsubstituted ring positions. The 5‐halo‐m‐xylenes give mixtures of two cations, with the captured proton ortho and para to the halogen, respectively, the preference for the para position increasing from Br to Cl to F.

4‐Chloro‐m‐xylene and 2‐chloro‐p‐xylene give “stable” cations, which slowly rearrange to the 5‐chloro‐m‐xylenium ion. Protonation of 2‐ and 4‐bromo‐m‐xylenes at 0° yields instantaneously the 5‐bromo‐m‐xylenium ion, probably as the result of intermolecular reactions.

A novel and facile synthetic route to 5‐bromo‐m‐xylene is described.
Ligand field interpretation of the visible spectrum of the tetrabromoferrate(III) anion : Short communication
Authors: Breman Ina W. , Balt S.
Published: September 2010

The visible spectrum of FeBr4− in solution and in the solid state at low temperature (20° K) has been compared with energy and intensity calculations on this ion.
Adducts of thiophosphoryl compounds with metal halides. Part II: Addition compounds of thiophosphoryl chloride
Authors: van der Veer W. , Jellinek F.
Published: September 2010

Thiophosphoryl chloride is a much weaker donor towards metal chlorides than phosphoryl chloride. The only addition compounds of thiophosphoryl chloride that could be isolated in a pure state are Cl3PS · SbCl5 and Cl3PS · SO3; moreover, two adducts of PSCl3 with AlCl3 were obtained. AlBr3 reacts with PSCl3 with irreversible exchange of the halogen atoms; adducts are found as intermediates in this reaction. Infrared spectroscopy of the solid addition compounds of PSCl3 shows sulfur to be coordinated at the metal atoms. The adducts Cl3PS · SbCl5 and Cl3PS · SO3 decompose at about 120° and−10°, respectively, with formation of elemental sulfur. For comparison, adducts of phosphoryl chloride with SbCl5, AlCl3 and AlBr3 were also studied.
The nuclear magnetic resonance spectra of some substituted benzenes with D2h‐symmetry, in a nematic solvent
Authors: Bulthuis J. , Gerritsen J. , Hilbers C. W. , Maclean C.
Published: September 2010

Nuclear magnetic resonance spectra have been measured and interpreted of a number of substituted benzenes with D2h‐symmetry in the nematic phase of 4,4′‐di‐n‐hexyloxyazoxybenzene (1 p‐dichloro‐, 2 p‐dibromo‐, 3 p‐di‐iodo and 4 p‐difluoro‐benzene and 5 symm‐tetrafluorobenzene). The fine structure is caused by the average direct dipolar interaction between the spins and by the indirect couplings1‐3. The direct interactions are distance‐dependent meaning that the spectra are related to the molecular geometry. Thus ratios of proton‐proton distances have been calculated for molecules 1‐4 and molecular models have been designed with which the NMR spectra are in agreement.

The liquid crystal NMR spectra allow of comparison of the direct interactions with the indirect interactions. If the sign of the former is known the sign of the latter can be inferred. Thus for symm‐tetrafluorobenzene J = ‐ 17.8 Hz, JFFp = + 11.1 Hz. For p‐difluorobenzene only the sign of the sum (J + JHFm) can be determined. Subject to the restriction that anisotropic contributions to the indirect couplings can be neglected its value is + 12.2 Hz. In symm‐tetrafluorobenzene the indirect coupling between fluorine spins in ortho position contain such anisotropic contributions; the anisotropy of the indirect coupling has, in part, been inferred from the experimental data.
Complexes with ligands containing nitrile groups: Part V: Metal(I) and metal(II) methyl cyanide complexes with tetrachlorometallate(III) anions
Authors: Reedijk J. , Groeneveld W. L.
Published: September 2010

A number of complexes of the general formula M(CH3CN)+pn(M′Cl4)−p is reported. The anions are the tetrachlorometallates: BCl−4, AlCl−4, GaCl−4, InCl−4, TICI−4, and FeCl−4. The cations M are the monovalent cations: Li, Na, Cu, Ag, (C2H5)4N, and the divalent cations: Be, Mg, Ca, Sr, Ba, Mn, Fe, Co, Ni, Cu, Zn, Cd, Hg, and Pd. The cations are completely solvated by methyl cyanide in these complexes, except the tetraethylammonium salts and most of the sodium complexes.

The compounds were synthesized in methyl cyanide by reaction of the metal chlorides with BCl3, AlCl3, GaCl3, InCl3, TlCl3 and FeCl3, respectively.

A large number of complexes proved to be isomorphous from their X‐ray powder‐patterns. Information about the structure of the complexes was obtained from ligand‐field spectra, infrared spectra, and Mössbauer spectra. Structural information concerning the anions was obtained from far‐infrared spectra.
Studies on polypeptides VI: Synthesis of protected hexa‐ and octa‐peptide hydrazides related to the N‐terminal part of bovine pancreatic ribonuclease a using the solid‐phase method
Authors: Visser S. , Roeloffs J. , Kerling K. E. T. , Havinga E.
Published: September 2010

Merrifield's solid‐phase method was applied to the synthesis of all‐L‐t‐butoxycarbonylthreonylalanylalanylalanyl‐Nϵ‐benzyloxycarbonyllysylphenylalanine hydrazide and all‐L‐Nα, Nϵ‐di‐t‐butoxycarbonyllysyl‐γ‐t‐butylglutamylthreonylalanylalanylalanyl‐Nϵ‐benzyloxycarbonyllysylphenylalanine hydrazide. Cleavage from the solid support with a solution of hydrazine hydrate in dimethylformamide and additional purification gave homogeneous products in high overall yields. Conventional syntheses of these compounds led to identical products.
The condensation of resorcinol with benzil
Authors: Bunn A. , Cudby M. E. A. , McGowan J. C.
Published: September 2010

The condensation of benzil and resorcinol is shown to give 3,8‐dihydroxy‐5a, 10b‐diphenylcoumarano‐2′, 3′, 2, 3‐coumaran.
Kinetics of rearrangements of methylbenzenium ions in HF
Authors: Brouwer D. M.
Published: September 2010

Rate constants and activation parameters of the following methylbenzenium ion rearrangements have been determined by direct measurement in HF containing SbF5: o‐xylenium and p‐xylenium to m‐xylenium, 1,2,3,4‐ to 1,2,3,5‐tetramethylbenzenium, 1,2,3‐ to 1,2,4‐ and 1,2,4‐ to 1,3,5‐trimethylbenzenium ions. The rate constants at 25° are 80, 335, 155, 8.9 and 1.4 × 10−5 s−1, respectively. The differences in rate of these rearrangements, which take place by successive 1,2‐hydrogen and methyl shifts with the latter as rate‐determining steps, are entirely due to differences in heat of activation, which varies from 19.8 to 23.3 kcal · mole−1, the activation entropy being about −3 cal · mole−1 · deg−1. These differences can be fully rationalized by considering the stabilities of the intermediate cations. Data on the relative stabilities of isomeric methylbenzenium ions are presented. In methylbenzenium ions the 1,2‐methyl shifts proper, the free energies of reaction of which vary from −6.5 to +6.5 kcal · mole−1, have free energies of activation of 15 to 22 kcal · mole−1, corresponding to rate constants of 35.5 to 0.00065 s−1 at 25°.
Syntheses of carotenoidal compounds IV carotene‐α, β‐dicarboxylic acids
Authors: Haeck H. H. , Kralt T.
Published: September 2010

The syntheses of some carotene‐α,β‐dicarboxylic acids by means of Stobbe condensations is described.

According to the wavelengths of their absorption maxima in UV and visible light these compounds exhibit a high degree of steric hindrance.
Chemistry of 1,2‐di‐tert. Butylbenzene and derivatives: Part II. Hydrogenation of 1,2‐di‐tert.butylbenzene on platinum and rhodium catalysts. Synthesis of cis‐ and trans‐1,2‐di‐tert.butylcyclohexane
Authors: van de Graaf B. , van Bekkum H. , Wepster B. M.
Published: September 2010

The course of the hydrogenation of 1,2‐di‐tert.butylbenzene under the influence of rhodium and platinum catalysts has been investigated. Cis‐ and trans‐1,2‐di‐tert.butylcyclohexane and the intermediate product 2,3‐di‐tert.‐butylcyclohexene always appearing in the hydrogenations have been isolated and characterized. The rate of hydrogenation of 1,2‐di‐tert.butylbenzene has been compared with that of benzene and that of some 1,2‐dialkylbenzenes.
Complexes of some divalent metals with phosphorus oxychloride
Authors: Driessen W. L. , Groeneveld W. L.
Published: September 2010

A series of new complexes is reported with phosphorus oxychloride as a ligand: viz., complexes of Mg(II), Ca(II), Sr(II), Mn(II), Co(II), Ni(II), Cu(II) and Zn(II). Reflection spectra in the visible and near infrared region indicate an octahedral configuration of the metal ion and the POCl3 molecules.
A rapid procedure for the preparation of [5‐3H]cytidine
Authors: Vaalburg W. , van Zanten B. , Buijze C.
Published: September 2010

[5‐3H]Cytidine was obtained in a yield of 50‐60% by catalytic dehalogenation of 5‐iodocytidine with tritium gas. The isolation and purification of the [5‐3H]‐cytidine was accomplished in a single column chromatographic separation. The radiochemical purity of the final product was > 99%.
Oxidation products of 1‐phenylthiosemicarbazides and their antifungal activity
Authors: Pluijgers C. W. , Berg J. , Sijpesteijn A. Kaars , Tempel A. , Verloop A.
Published: September 2010

The appearance of an orange‐red colour in aged aqueous solutions of 1‐phenylthiosemicarbazide is ascribed to the formation of a red oxidation product, phenylazothioformamide.

Another oxidation product, phenylazothioformamide‐S‐oxide, is obtained upon oxidation of 1‐phenylthiosemicarbazide with hydrogen peroxide in aqueous solution.

Phenylazothioformamide, its S‐oxide, and certain of their substitution products are potent antifungal agents.

They afford protection against certain plant diseases. In some cases phyto toxicity was observed.
Preparation, metallation and alkylation of allenyl ethers
Authors: Hoff S. , Brandsma L. , Arens J. F.
Published: September 2010

Propargyl ethers HCCCH2OR [R = alkyl or‐CH(CH8)(OC2H5)] have been isomerized with good yields into the corresponding allenyl ethers CH2CCHOR by warming with potassium tert.‐butoxide at 70°.

These allenyl ethers can be metallated with butyllithium in ether or alkali amides in liquid ammonia. In ether, subsequent alkylation with alkyl halides R′Hal affords α‐substituted allenyl ethers CH2CC(R′)OR. Alkylation in liquid ammonia produces a mixture of this same compound and the γ‐substituted product R′CHCCHOR. In both cases reasonable yields are obtained. Sodamide and potassium amide quickly convert allenyl ethers CH2CCHOR into metallated propargyl ethers MCC‐CH2OR (M = Na or K). If alkylation is not performed almost simultaneously with the metallation with sodamide or potassium amide, the only alkylation product obtained is R′CCCH2OR.
The stabilizing effect of an electron‐withdrawing substituent in aromatic isoanellated systems
Authors: Wynberg Hans , Feijen J. , Zwanenburg D. J.
Published: September 2010

The synthesis of a reasonably stable 5‐substituted benzo[e]thiophene is described. The use of this substituent in the 5‐position is briefly discussed.
Complexes with ligands containing nitrile groups: Part VII. Metal‐ligand vibrations in methyl cyanide solvates
Authors: Reedijk J. , Groeneveld W. L.
Published: September 2010

Far‐infrared spectra in the region 450‐150 cm−1 for a number of compounds of the type M(CH3CN)m (anion), have been investigated. Band assignments have been made with regard to the octahedral group M(NCC)6n+.

Metal‐nitrogen stretching vibrations are shown to occur in the 200‐350 cm−1 region for most bivalent metal ions. The frequency order found for the transition‐metal ions is Mn < Fe < Co < Ni < Cu > Zn, in agreement with the general Irving‐Williams stability order. A comparison with metal‐ligand vibrations in solvates containing other ligands has also been made.
The metabolism of hydroxyanthranilic acids. Part III: The synthesis of some aminocresotic acids
Authors: Cox M. C. L. , Diamond E. M. , Levy P. R.
Published: September 2010

The synthesis is described of 2‐amino‐3,4‐, ‐3,5‐, and ‐3,6‐cresotic acids.
Quenching of triplets by iodo compounds: The photosensitized decomposition of iodoacetic acid
Authors: van Zwet H.
Published: September 2010

Benzophenone triplets are rapidly quenched by HI and ICH2COOH. This effect is discussed in terms of external heavy‐atom spin‐orbital coupling.

Benzophenone sensitizes the decomposition of ICH2COOH; the quantum yield of iodine release very much depends on the solvent, and benzophenone/2‐ propanol appears to be a favourable combination for high iodine yields. The heavy‐atom effect on the triplet state of benzophenone is ascribed to some π‐π* character of the n‐π* type excited state of the aromatic ketone. Phenanthrene and anthracene also sensitize the photodecomposition of iodoacetic acid, although the triplet state of anthracene is not high enough to supply all the energy required to break the C‐I bond; a concerted bond‐breaking bond‐forming process is therefore proposed.
1,1‐Dihydroperoxycyclohexane isolation and evidence of structure
Authors: Cosijn A. H. M. , Ossewold M. G. J.
Published: September 2010

Two different ways of preparing and isolating the hitherto unknown, crystalline 1,1‐dihydroperoxycyclohexane are described.

In one route the gem‐dihydroperoxide is prepared by peroxidation of cyclohexanone with an excess of concentrated hydrogen peroxide in triethyl phosphate and subsequently isolated from the reaction mixture by column chromatography.

In the second route the gem‐dihydroperoxide is formed by disproportionation of 1‐hydroperoxy‐1′‐hydroxydicyclohexyl peroxide and isolated by preparative thin‐layer chromatography.

The peroxide has a melting point of approx. 47° ‐ 50°. It is sensitive to impact and friction and extremely hygroscopic. It tends to decompose during drying procedures.
Chemistry and spectroscopy in strongly acidic solutions. Part XVIII: Novel ring contraction of cyclohexenones via dicarbonium ions
Authors: Hogeveen H.
Published: September 2010

A novel quantitative conversion of cyclohex‐2‐enone into 3‐methylcyclopent‐2‐enone in HF‐SbF5 solution is reported. The acidity dependence of the rate constant shows that the mechanism involves a protonated keto‐carbonium ion (dicarbonium ion) as an intermediate. Rate constants and activation parameters have been determined. The rate in FSO3H‐SbF5 is much lower than that in HF‐SbF5, which is compatible with the lower acidity of the former solvent system.

Cyclohex‐3‐enone is also converted into 3‐methylcyclopent‐2‐enone, after initial isomerization to cyclohex‐2‐enone. This constitutes proof of a rapid equilibration between the cyclohexenones prior to the rate‐determining formation of 3‐methylcyclopent‐2‐enone.

5‐Methylcyclohex‐2‐enone is converted into 3‐methylcyclohex‐2‐enone, which shows that hydride shifts in the intermediate dication are more rapid than the ring‐contraction steps.
Chemistry and spectroscopy in strongly acidic solutions. Part XX: Configurational equilibration in protonated formic acid and protonated acetic acid (dihydroxycarbonium ions): (Short communication)
Authors: Hogeveen H.
Published: September 2010

In a number of protonated organic molecules configurational isomerism around a partly double CO bond has recently been established2. We thought it of interest to determine the energy barriers of configurational equilibration around this bond (and similar partly double bonds), and to compare these experimentally determined activation energies with those calculated quantum‐mechanically3. For dimethoxymethylcarbonium ion this barrier was recently determined to be 11 ± 4 kcal · mole−1.
The use of the equal‐G curve in the interpretation of isobaric binary phase‐equilibrium diagrams
Authors: Oonk H. A. J.
Published: September 2010

It is shown that for the thermodynamic description of isobaric binary phase equilibria a convenient use can be made of the curve in the T,X‐plane representing the set of points of intersection of the curves for the Gibbs energy functions of the two phases. The relation of this curve, for which the name equal‐G curve is proposed, with the phase diagram is illustrated with the help of hypothetical systems. The applicability to practical cases is demonstrated on the basis of some experimental solid‐liquid equilibrium diagrams.
Some aspects of the solvolysis of 1‐phenylethyl chloride
Authors: de La Mare P. B. D. , Hall D. Muriel , Mauger Elizabeth
Published: September 2010

The rate of solvolysis of 1‐phenylethyl chloride has been followed both polarimetrically and titrimetrically in 60% and in 70% dioxan. The polarimetric rate exceeds the titrimetric rate, and the extent of racemisation decreases slightly with increasing water‐content of the medium. The effects of added salts (LiCIO4, NEt4CIO4, LiCl, and in less detail NaOH, and LiBr) have been examined; these results confirm the conclusion to be drawn from the discrepancy between the polarimetric and titrimetric rate coefficients, namely that ion‐pair intermediates are involved in this reaction. They suggest also that the first stage of solvolysis is slightly reversed by added chloride ions. The exchange of radiochloride into the organic chloride has also been examined, and is consistent with the above conclusion. The possibility that styrene is an intermediate significant in these solvolyses has been excluded.
Preparation and diastereoisomerism of four substituted epoxycyclopentanones
Authors: Heslinga L. , van Gorkom M. , van Dorp D. A.
Published: September 2010

Epoxidation of 4‐acetoxy‐2‐(6′‐methoxycarbonylhexyl)‐2‐cyclopenten‐1‐one in alkaline medium yielded the two possible diastereoisomers of 2,3‐epoxy‐4‐hydroxy‐2‐(6′‐methoxycarbonylhexyl)‐1‐cyclopentanone. The structure and configuration of these compounds have been elucidated by first order analysis of the normal and spindecoupled proton magnetic resonance spectra. Both stereoisomeric epoxides can also be obtained via an alternative synthetic route by epoxidation of 2‐(6′‐carboxyhexyl)‐4‐hydroxy‐2‐cyclopenten‐1‐one. The separate cis and trans isomers of 2‐(6′‐carboxyhexyl)‐2,3‐epoxy‐4‐hydroxy‐1‐cyclopentanone are correlated with the stereoisomers of 2,3‐epoxy‐4‐hydroxy‐2‐(6′‐methoxycarbonylbexyl)‐1‐cyclopentanone by interconversion with diazomethane as well as by comparison of the proton spectra.
Isomerisation, alkylation and hydroxyalkylation of cumulenyl ethers
Authors: Selling H.A. , Rompes J.A. , Montijn P.P. , Hoff S. , van Boom J.H. , Brandsma L. , Arens J.F.
Published: September 2010

In dimethyl sulfoxide 1,2,3‐trienyl ethers RR′CCCCHOCH3 (with R and R′ = alkyl or RR′C = cyclohexyl) are isomerised by potassium tert‐butoxide, first to 1,2,4‐ and then to 1,3,5‐trienyl ethers. In the case of RR′C = cyclohexyl, thus with magnified image elimination of methanol takes place and further isomerisation finally leads to aromatisation to 1‐propenylbenzene. Acid hydrolysis of CH2 = C(CH3)CHC = CHOCH3 in dimethyl sulfoxide affords the aldehyde CH2C(CH3)CHCHCHO.

The 1,2,3‐ and 1,2,4‐trienyl ethers have been metallated in the 1‐position by lithium amide and butyllithium, and subsequently alkylated or hydroxy‐alkylated.

Recently 1,2,3‐trienyl ethers RR′CCCCHOCH3 have become available 1.

The present paper describes some reactions with these compounds.
Etude de l'effet isotopique secondaire du deuterium dans la décomposition de la combinaison bisulfitique de la tertiobutyl‐4 cyclohexanone. Énergie conformationnelle du groupe SO3−
Authors: Lamaty G. , Roque J. P.
Published: September 2010

The rate constants for the hydrolysis of the bisulfite addition compounds of cyclohexanone, 4‐tert‐butylcyclohexanone and their α‐deuterated homologues have been measured.

There is a large difference between the isotope effects observed for the cyclohexanone (kH/kD = 1.10) and the “slow” isomer from the 4‐tert‐butylcyclohexanone (‐ SO3− equatorial; kH/kD = 1.05). This result is discussed in terms of the existing difference between the geometries of the transition states.

The conformational energy of the ‐ SO3− group has been determined and found to be equal to 2.25 kcal/mole.
Heterocyclic steroids XV. Synthesis of 13,14‐diazasteroidal systems
Authors: Pandit U. K. , de Jonge K. , Huisman H. O.
Published: September 2010

β‐Tetralone (Ia) and 6‐methoxy‐β‐tetralone (Ib) have been alkylatedviathe corresponding pyrrolidine enamines to their 1‐alkoxycarbonylmethyl derivatives IIIa and IIIb. Reaction of IIIa and IIIb with hydrazine hydrate gave benzo[f]cinnolones IVa and IVb, which were reduced with lithium aluminium hydride to tricyclic hydrazines VIa and VIc, respectively. Treatment of the latter with malonyl dichloride and triethylamine led to the formation of 13,14‐diazasteroids IXa and IXb. Condensation of IIIb with hexahydropyridazine (XIII) gave the D‐homo‐diazasteroidal system XIV in one step.
1,1‐dialkoxyalkyl alkane‐ and arene‐carboxylates. Part II. Synthesis of dialkoxymethyl esters and of 2‐acetoxy‐1,3‐dioxolanes
Authors: Scheeren J. W. , van Der Veek A. P. M. , Stevens W.
Published: September 2010

Dialkoxymethyl acetates and 2‐acetoxy‐1,3‐dioxolanes have been prepared from orthoformates and a “formic acid/acetic anhydride reaction system”. The rǒle of the “reaction system” is discussed. Other methods of synthesis of these acetates and other carboxylates are also described.
The formation of 1,2,4‐oxadiazoles from imidazoles by the action of hydrogen peroxide in alkaline solution
Authors: van Meeteren H. W. , van der Plas H. C.
Published: September 2010

A hitherto unknown transformation of alkyl‐(aryl)‐imidazoles into alkyl‐(aryl)‐1,2,4‐oxadiazoles is described.
Synthesis of β‐alkyl and β‐aryl π‐allylic palladium halide complexes and its mechanistic aspects
Authors: Volger H. C.
Published: September 2010

π‐Allylic palladium halide complexes, substituted by an alkyl or aryl group at the central carbon atom, can be obtained in high yields in a one‐step synthesis by introducing the appropriate olefin into a sodium chloropalladite solution in glacial acetic acid in the presence of sodium acetate at 85°C.

The reaction has been found to proceed via the π‐olefinic palladium complex, which is in equilibrium with small amounts of the π‐allylic complex according to:

magnified image

An equivalent amount of sodium acetate shifts the equilibrium completely to the right‐hand side.

Specifically deuterated olefins can be obtained by dissolving the olefins in a solution of sodium chloropalladite in CH3COOD. Addition of sodium acetate after completion of the exchange affords the deuterated π‐allyl complexes.

The scope of the reaction and the mechanism are discussed.
Synthesis and stability of tri‐sec‐aminomethanes
Authors: Scheeren J. W. , Nivard R. J. F.
Published: September 2010

Tri‐sec‐aminomethanes and dialkoxy‐sec‐aminomethanes can be obtained from chloroform sodium alkoxide and sec‐amines. The tri‐sec‐aminomethanes can be converted into tetra‐sec‐aminoethylenes by thermolysis. It appears that tri‐sec‐aminomethanes and tetra‐sec‐aminoethylenes have been mistaken one for the other more than once in the literature.

Some interesting properties of the compounds synthesized are discussed.
Chemistry and spectroscopy in strongly acidic solutions. Part XXIV: Electrophilic substitution at alkanes
Authors: Hogeveen H. , Bickel A. F.
Published: September 2010

A survey is given of the possible reactions between alkanes and protons or carbonium ions and in addition new kinetic data for some of these electrophilic aliphatic substitutions, including the hydrogen‐deuterium exchange in mono‐deuteroethane, and the cleavage of 2,2,3,3‐tetramethylbutane into isobutane and tert‐butyl cation. Comparison of present and former results shows that, when the proton is the electrophilic agent, electronic substituent effects predominate over steric effects. Electrophilic substitution at alkane‐carbon is likely to involve a retention of configuration, which implies a C8‐type geometry for the transition state.

That the proton reactivity is lower in FHSO3‐SbF5 than in HF‐SbF5 is probably due to the lower acidity of the former solvent system.
Ring transformations in reactions of heterocyclic halogeno compounds with nucleophiles (XIV): Conversion of 2‐substituted 4‐chloropyrimidines by potassium amide in liquid ammonia into 2‐substituted‐4‐methyl‐s‐triazines
Authors: van der Plas H. C. , Zuurdeeg B.
Published: September 2010

Upon reaction with potassium amide in liquid ammonia 4‐chloro‐2‐(β‐naphthyl)‐, 4‐chloro‐2‐(N‐methylanilino)‐ and 4‐chloro‐2‐(N,N‐dimethyl‐amino)‐pyrimidines were converted into s‐triazine derivatives, while from 2‐anilino‐4‐chloro‐, 2‐benzyl‐4‐chloro‐ and 4‐chloro‐2‐(N‐methylamino)‐pyrimidines the corresponding 4‐amino compounds and no s‐triazines were obtained.

The influence of the character of the substituent in position 2 of the pyrimidine ring on the reaction pathway chosen i.e. transformation into s‐triazines or conversion into 4‐aminopyrimidines is discussed.
Kinetics of the oxidation of phenylhydrazine and phenylhydrazinesulfonic acids. Part. I: Hexacyanoferrate(III) oxidations
Authors: Verwey A. M. A. , Jonker J. A. , Balt S.
Published: September 2010

The kinetics of the oxidation of phenylhydrazine and its sulfonic acids by the hexacyanoferrate(III) ion has been studied at constant temperature and ionic strength in 0.1 to 1 M aqueous perchloric acid. The reactions were first order in the ferrate and, apart from a small ion pairing contribution, also first order in the hydrazines. The dependence of the reaction rates on the hydrogen ion concentration could be explained by assuming a competition between the oxidation of the protonated and the unprotonated form of the phenylhydrazines. Due to the complicated nature of the interactions involved no clear picture of the ion pairing and the effects thereof on the reaction rates could be obtained.
Alkyltetrahydrofuryl and ‐pyryl cations: Formation by cyclization of protonated alkenones and transformations in different acids
Authors: Brouwer D. M.
Published: September 2010

A PMR spectroscopic study has been made of the protonation of 1‐hexen‐5‐one (I), 2‐methyl‐l‐hexen‐5‐one (II), 2‐hepten‐6‐one (III) and 2‐methyl‐2‐hepten‐6‐one (IV) in different acids (HF, HF‐SbF5, H2SO4, FSO3H, FSO3H‐SbF5). With two exceptions, the first observable cations were alkyltetrahydrofuryl and/or alkyltetrahydropyryl cations. The cyclizations are very fast. Only in the case of I could the primary “stable” protonation product, the O‐protonated ketone, be observed below ‐ 40° in HF. Ketone IV gives a stable dication, C,O‐diprotonated IV, in the very strong acid HF‐SbF5.

The heterocyclic cations derived from I and II are very stable. Those derived from III and IV give subsequent reactions, namely simple interconversion of five and six‐membered heterocyclic rings, skeleton isomerizations proceeding via acyclic dications, and in the case of the ions derived from IV the eventual formation of 1,3‐dimethylcyclohexenyl ion.

The rates of all transformation reactions and the ratios of the products formed were found to depend strongly on the acid used. In the case of the skeleton isomerizations the rates depend on the acidity of the solvent (HF‐SbF5〉〉FSO3‐SbF5〉〉〉HF, H2SO4, FSO3H). For the other types of reactions the rates strongly vary with the type of solvent (HF versus H2SO4 or FSO3H).
Synthese und Biologische Eigenschaften der 8‐Mono‐ und 8,17,18‐Tri‐Ornithin‐β‐Corticotropin‐(l‐24)‐Tetracosapeptiden
Authors: Tesser G. I. , Rittel W.
Published: September 2010

This article describes the synthesis of two analogues of β‐corticotropin‐(l‐24)‐tetracosapeptide, in which the amidine function in one or in all three arginyl residues has been replaced by hydrogen.

In connection with previous work, the weak biological) activity of both analogues proves the essentiality of a guanidine function in position 8 for hormonal activity.
The crystal structure of monochloroacetic anhydride
Authors: de Kok A. J. , Romers C.
Published: September 2010

Crystals of monochloroacetic anhydride are monoclinic. The space group is P21/c and Z = 4. The unit‐cell dimensions are a = 5.20, b = 7.95, c = 16.88 Å and β = 100.4°.

The structure was solved by application of a Buerger minimum function and refined by the method of least squares. The two C‐CO‐O fragments are planar and the angle between these moieties is 43°. The valency angle of the ether oxygen is unusually large with a value of 121°. The geometry of the molecule is given in terms of dihedral angles, the symmetry being approximately C2.
Isomerization of cyclic olefins in basic media. Part 4: The double bond migration of [14C]‐cyclopentene and [l‐14C]‐cycloheptene
Authors: Tjan S.B. , Steinberg H. , de Boer Th. J.
Published: September 2010

The base‐catalyzed double bond migration of [14C]‐cyclopentene and [1‐14C]‐cycloheptene has been studied in a solution of potassium tert‐butoxide in dimethyl sulfoxide at three temperatures. The activation parameters for cyclopentene are ΔH‡ = 22.1 ± 1.6 kcal/mole and ΔS‡ = ‐23.3 ± 2.6 e.u. and for cycloheptene ΔH‡ = 18.3 ± 0.5 kcal/mole and ΔS‡ = −24.5 ±0.8 e.u. It has been found that the isomerization rate increases with increasing ring size. This result is discussed in terms of angles between the planes formed by the bonds H‐C(allyl)‐C(olef.) and the nodal plane of the double bond.
Chemistry and spectroscopy in strongly acidic solutions. Part XXVI: Reduction of the norbornyl cation with molecular hydrogen. Ring opening of norbornane with protons
Authors: Hogeveen H. , Gaasbeek C.J.
Published: September 2010

The norbornyl cation is smoothly reduced to norbornane with molecular hydrogen; the rate of this reaction is about the same as that of the reactions of the tertiary butyl and adamantyl ions to the corresponding hydrocarbons. Reduction of the norbornyl cation with D2 affords undeuterated, mono‐, di‐, tri‐, tetra‐ and pentadeuterated norbornane.

When norbornane is dissolved in HF‐SbF5 solution at room temperature an equilibrium mixture of methylcyclohexyl and 1,2‐ and 1,3‐dimethylcyclopentyl ions is formed. Reduction of this mixture with hydrogen, which occurs at the same rate as that of tertiary butyl ion, affords methylcyclohexane as the sole product, in agreement with its thermodynamic stability.
Aromatic sulfonation. Part 23: Sulfonation of p‐xylene in aqueous sulfuric acid
Authors: Kaandorp A.W. , Cerfontain H.
Published: September 2010

The rate of the homogeneous sulfonation of p‐xylene in aqueous sulfuric acid varying in concentration from 72 to 89% H2SO4 has been determined. Pseudo first order rate constants and apparent activation energies are reported as a function of the sulfuric acid concentration. The mechanism of the sulfonation of p‐xylene is briefly discussed.
Thermal rearrangement of 3‐ and 2‐(propargylthio)thiophene: Formation of the thiopyrans 5H‐thieno[3,2‐b]thiin and 6H‐thieno[2,3‐b]thiin
Authors: Brandsma L. , Bos H.J.T.
Published: September 2010

5H‐Thieno[3,2‐b]thiin (III) and 6H‐thieno[2,3‐b]thiin (VI) are formed in excellent yields by heating solutions of 3‐ and 2‐(propargylthio)thiophene (I) and (IV), respectively, in hexamethylphosphoric triamide at 170–180°.
The photochemistry of bifluorenylidene
Authors: de Gunst G. P.
Published: September 2010

Products have been isolated and identified from two photochemical reactions of 9,9′‐bifluorenylidene (I). The photo‐oxidation of I yields 9‐fluorenone, the cyclodehydrogenation fluoreno(1,9a,9‐a,b)fluoranthene together with the reduced form of I, 9,9′‐bifluorene.
Dehydrohetarenes XVIII : Reactions of dibromopyridines with lithium piperidide and piperidine: (Preliminary communication)
Authors: Bos L. B. , den Hertog H. J.
Published: September 2010

Animations of the six dibromopyridines with lithium piperidide and piperidine in ethereal solution have been investigated. In boiling solution 2,6‐dibromo‐pyridine is converted into 2,6‐dipiperidinopyridine and both 3,4‐ and 3,5‐dibromopyridine give a mixture of 2,4‐ and 3,5‐dipiperidinopyridine. The other dibromopyridines yielded chiefly tarry products, 2, 4‐dibromopyridine together with some 2, 4‐dipiperidinopyridine, 2, 5‐dibromopyridine together with a small quantity of a mixture of 2,4‐ and 2,5‐dipiperidinopyridines.

The mechanisms of these reactions are discussed. In this connection it was necessary to study the animations of five bromopiperidinopyridines too. Derivatives of 2,3‐ and 3,4‐dehydropyridine are assumed to be involved as intermediates in several replacement reactions.
The oxidation of methyl cyanide by vanadium(IV) chloride
Authors: van Driel C. A. A. , Groeneveld W. L.
Published: September 2010

The reaction products of VCl4 and excess CH3CN have been characterized by several methods. The main oxidation product is 2‐methyl‐4,6‐bis(trichloromethyl)‐1, 3, 5‐triazine.
Conformation of non‐aromatic ring compounds‐LIV: The calculation of dihedral angles from vicinal proton coupling constants in six‐membered ring compounds
Authors: Buys H. R.
Published: September 2010

For six‐membered ring compounds existing in solution as an equilibrium mixture of two equivalent conformers, and having a ‐ CH2 ‐ CH2‐ or a ‐ CH2 ‐CHR‐ moiety, the ratio of the vicinal coupling constants R = Jtrans/Jcis is expressed as a function of the ring dihedral angle ψ in that fragment. From the experimental coupling constants of a number of compounds the ψ values are calculated and compared with the corresponding dihedral angles obtained from X‐ray or electron diffraction data. In most cases the difference between the two results does not exceed 1‐2°.
Optical rotatory dispersion and absolute configuration XIII sedridine and allosedridine
Authors: Beyerman H. C. , Maat L. , Vlsser J. P. , Craig J. Cymerman , Chan Rosalind P. K. , Roy S. K.
Published: September 2010

A method involving the combined use of ORD and CD is described by which both the relative and absolute configuration of the two asymmetric centres in amino alcohols, containing only the amino and hydroxyl chromophores, may be determined.

Application of the method to both sedridine and allosedridine (resolved for the first time) is discussed.
A semi‐empirical energy‐level diagram for octahedral cobalt(II) complexes
Authors: Reedijk J. , Driessen W. L. , Groeneveld W. L.
Published: September 2010

Methods of calculation for the parameters Dq and B from the ligand‐field spectra of octahedral cobalt(II) compounds are discussed. A method of calculation is introduced, which considers the lowering of the 4T1g (F) state by spin‐orbit splitting. This calculation is applied to the spectra of 43 octahedrally coordinated cobalt(II) compounds.

With the aid of the spectral data an energy‐level diagram is constructed, into which the absorption bands are fitted.

Comparison of calculated Dq and B values with corresponding values for isomorphous nickel(II) compounds shows that ‐ in general ‐ the crystalfield parameter Dq is highest for cobalt, although the differences with nickel are less than 4 % in most cases. The calculated B values corresponds with those of Ni, with differences less than 1 % for many ligands.
Alkylthiolation of ambident anions derived from some unsaturated organic sulfides
Authors: Wildschut G. A. , Brandsma L. , Arens J. F.
Published: September 2010

Reaction of the anions derived from 1,1‐bis(alkylthio)‐2‐alkynes RCCCH(SC2H5)2 (R = alkyl, vinyl or phenyl) with dialkyl disulfides R′SSR′ or alkyl alkanethiosulfonates R′SSO2R′ gives 1,1,3‐tris(alkylthio)‐1,2‐alkadienes RC(SR′) = C = C(SC2H5)2 in good yields. Alkylthiolation of CH3SC ≡ CC(SC2H5)2 with CH3SSCH3 affords (CH3S)2C = C = C(SC2H5)2. The 1‐alkynyl sulfides C2H5C≡CSC2H5 and CH3C≡CSCH3 have been converted into CH3C(SC2H5)=C=C(SC2H5)2 and (CH3S)2C = C=C(SCH3)2, respectively by reaction with alkali metal amide in liquid ammonia and dialkyl disulfide. The latter compound dimerises on heating. Tris(alkylthio)allenes R″CH2C(SR′)=C=C(SC2H5)2 isomerise to the conjugated dienes R″CH=C(SR′)‐CH=C(SC2H5)2 when heated in the presence of acids. Ethylthiolation of the anions of R′CH2C(R″)=C(SC2H5)2 (R″ = H or CH3; R′ = H, CH3 or SC2H5) gives predominantly R′CH=C(R″)‐C(SC2H5)3 as isolable products.
A chronopotentiometric study of the reduction behaviour of some complexes of copper(II), palladium(II) and rhodium(III)
Authors: Woodburn S. I. , Cardwell T. J. , Magee R. J.
Published: September 2010

The chronopotentiometric reduction behaviour of several complexes of copper(II), palladium(II) and rhodium(III) has been investigated at platinum and mercury electrodes. The aquo complexes examined were shown to undergo some dissociation before reduction at the mercury electrode.

With the exception of the ethylenediamine system ligand adsorption was observed on the mercury pool electrode. As a result it was possible to calculate the degree of adsorption of some of the ligands.

The rate constants for the reduction of the copper complexes were measured and found to follow the same order as the polarographic reduction potentials.
Solubilities of some alkali and tetraalkylammonium perchlorates in mixtures of water with methanol, ethanol, dioxane, acetone and acetic acid, and differences between the standard chemical potentials of these salts in their solutions in water and in the mixed or nonaqueous solvents, at 25°C
Authors: de Ligny C. L. , Bax D. , Alfenaar M. , Elferink M. G. L.
Published: September 2010

Solubilities of some alkali and tetraalkylammonium perchlorates in mixtures of water with methanol, ethanol, dioxane, acetone and acetic acid have been determined conductometrically. From these solubilities the standard chemical potential differences for the transfer from water to the mixed or nonaqueous solvents have been calculated. In these calculations deviations from ideal behaviour caused by salt effects and ionic association have been taken into account.
Base‐induced 1,4‐eliminations with 3,4‐dialkoxy‐1, 2‐alkadienes: Formation of 3‐methoxy‐3‐alken‐1‐ynes
Authors: Hoff S. , Steenstra B. H. , Brandsma L. , Arens J. F.
Published: September 2010

Treatment of 4‐ethoxy‐3‐methoxy‐1,2‐alkadienes H2C=C=C(OCH3)CH(R)OC2H5 (R = H or alkyl) with potassium amide in liquid ammonia affords 3‐methoxy‐3‐alken‐l‐ynes HC≡C‐C(OCH3)=CHR in excellent yields. The starting compounds can be obtained in good yields by reaction of α‐lithiated methoxypropadiene H2C=C=C(Li)OCH3 with α‐chloroethers ClCH(R)OC2H5.
Kinetics of the oxidation of phenylhydrazine and phenylhydrazinesulfonic acids. Part II: Oxidation by cationic iron(III) complexes
Authors: Verwey A. M. A. , Balt S.
Published: September 2010

The kinetics of the oxidation of phenylhydrazine and its sulfonic acids by cationic iron(III) complexes has been studied at constant temperature and ionic strenght in 0.1 to 1.0 M aqueous perchloric and hydrochloric acid. After correcting for associations, the reactions are first order in the iron(III) and the phenylhydrazines. Only the unprotonated phenylhydrazines are oxidized. All evidence points to an outer sphere mechanism for the reactions. Complex formation between metal ions (Fe3+, Mn2+, Ni2+) and the sulfonic acids seems to occur via the oxygen donor atoms of the sulfonic acid group.
Aromatic Sulfonation 26: Kinetics and mechanism of the sulfonation of some polyfluorobenzenes in fuming sulfuric acid
Authors: Kort C. W. F. , Cerfontain H.
Published: September 2010

The mechanism of sulfonation in oleum proposed by Brand et al. 3 ‐ stepwise attachment of SO3 and H+ to the substrate, followed by the loss of the proton from the benzene ring ‐ is shown to be inconsistent with the substrate isotope effects reported 3 by these authors. The sulfonation kinetics of p‐di‐, 1,2,3,4‐tetra‐, and penta‐fluorobenzene in 97‐109% sulfuric acid are discussed in terms of an extrapolation of the mechanism proposed recently 7 for aqueous sulfuric acid. In weak oleum — below 104% sulfuric acid — the rate‐limiting step is

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Chemistry and spectroscopy in strongly acidic solutions. Part XXVIII: Degenerate and non‐degenerate rearrangements of monocyclic C7H13⊕ ions
Authors: Hogeveen H. , Gaasbeek C. J.
Published: September 2010

Degenerate isomerizations of methylcyclohexyl, 1,2‐dimethylcyclopentyl and 1,3‐dimethylcyclopentyl cations and reversible interconversions between these ions were studied by NMR line‐broadening. In addition, some classical kinetic measurements were carried out on the latter type of rearrangement. From the results the following conclusions can be drawn:

A course of non‐chain‐branching rearrangements (type‐A) as proposed for acyclic alkylcarbonium ions ‐viz. successive 1,2‐hydrogen and methyl shifts via secondary carbonium ions with the secondary‐secondary methyl shift as rate determining step ‐is consistent with the experimental data.

The impossibility of a parallel orientation of the empty p‐orbital and the CH or CC bond to be broken in type‐A rearrangements decreases the rate of this process compared with acyclic alkylcarbonium ions.

Also discussed is the remarkable stability of the monocyclic C7H13⊕ ions as compared with acyclic tert. heptyl ions.
Types of TX phase‐diagrams derived from Gibbs functions with the help of the equal‐g curve
Authors: Oonk H. A. J. , Sprenkels A.
Published: September 2010

It is shown that the derivation of the possible types of phase‐equilibrium diagrams can be performed in an elegant manner with the help of the equal‐G curve. Such a derivation is worked out, within the model of regular solutions, for the isobaric binary equilibrium between solid and liquid solutions. Attention is paid to the relation to the original derivation of Bakhuis Roozeboom and a remark is made about the obstacles encountered in the thermodynamical interpretation of phase diagrams. The thermodynamic excess functions are presented in the form of a series of sine terms.
The crystal structure of crassin p‐iodobenzoate
Authors: Hossain M. Bilayet , van Der Helm Dick
Published: September 2010

The crystal structure of crassin p‐iodobenzoate has been determined by the heavy‐atom technique and refined by the least‐squares method using three dimensional intensity data. The crystal is monoclinic with cell dimensions: a = 6.492 ± 0.002, b = 18.098 ± 0.006, c = 11.209 ± 0.004 Å, β = 97.1° ± 0.1°, with Z = 2; space group P21. The absolute configuration of the crassin molecule has been determined by using the anomalous dispersion of the iodine atom and the stereochemistry of the molecule has been confirmed. The molecule is found to consist of a 14‐membered cembrane ring fused with a δ‐lactone.