摘要:

The wavenumbers of the fundamental, first and second overtones have been measured for HI in liquid CCl4. The solvent shifts calculated, assuming a Lennard–Jones–Devonshire cell model of the solution, are in good agreement with the experimental data.

ISSN:0008-4042    

DOI:10.1139/v72-551

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Adsorption and subsequent reaction of H2S on alumina gave major i.r. bands at 1341, 1568, 1625, and 3400 cm−1. Relative band intensities were used to follow the first order decomposition of adsorbed H2S and formation of H2O. Rate constants of the surface reaction at 23, 55, and 80 °C were 0.70, 1.48, and 3.42 × 10−3 s−1, respectively. A mechanism consistent with the observed spectral and kinetic data involved adsorption to an exposed Al ion forming an Al—S surface bond, and hydrogen bonding to neighboring O and OH species. It was assumed that the sulfur remained on the surface as a sulfide. The 1568 cm−1band was discussed in terms of an Al—O species.With adsorption on MoS2–Al2O3, bands appeared at 1330 and 1575 cm−1. Behavior in all respects was similar to that observed on the alumina support alone.

ISSN:0008-4042    

DOI:10.1139/v72-552

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Anodic methoxylation at a platinum electrode of α,α′-dimethoxystilbene yielded benzil tetramethylketal (2) which upon further electrolysis in methanol gave a 62% yield of trimethyl orthobenzoate. The mechanism of this new anodic fission reaction is briefly discussed.

ISSN:0008-4042    

DOI:10.1139/v72-553

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Rate constants for quenching of triplet excited acetone by primary and tertiary amines in solution have been measured directly by flash and pulsed laser techniques. The rate constants were found to be independent of solvent dielectric constant over the range ϵ 1.9 to ϵ 80, but were influenced by amine ionization potential. The results are interpreted as supporting a charge-transfer model for the quenching of triplet ketones by tertiary amines. The intervention of free ions in the quenching process is discussed. Free energy calculations indicate that electron transfer fromN,N-dimethylaniline to triplet ketones is exothermic but is slightly more favorable for triplet aromatic ketones than for triplet acetone. Evidence for direct hydrogen atom transfer was obtained for quenching of triplet acetone byn-hexylamine.

ISSN:0008-4042    

DOI:10.1139/v72-554

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The complex of manganese(III) withtrans-1,2-diaminocyclohexanetetraacetic acid has been shown to exist as the crystalline monohydrate, KMnIIICyDTA(H2O), where CyDTA represents the ligandtrans-1,2-diaminocyclohexanetetraacetate.In aqueous methanol (2.5% water v/v) three forms of the complex exist: MnIIICyDTA(H2O)−in neutral solution, MnIIICyDTA(OH)2−in base, and HMnCyDTA(H2O) in acid. In basic methanol the complex decomposes by disproportionation following first-order kinetics. When the same solvent system contains acid the disappearance of MnIIIis first-order in complex and first-order in acid but in this case methanol is oxidized to formaldehyde.The isotope effects observed in the oxidation of CH3OD, CD3OH, and CD3OD are all small (1.25 or less). This together with the acid dependence indicates that the oxidation proceeds by rate-controlling electron abstraction from methanol by the protonated form of the complex, possibly via an intermediate in which one of the coordinating ligands is replaced by methanol.

ISSN:0008-4042    

DOI:10.1139/v72-555

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

A series of 4-substituted-2,6-di-t-butylphenols has been oxidized with potassiumtrans-1,2-diaminocyclohexanetetraacetatomanganate(III) KMnIIICyDTA(H2O), in methanol containing 2.5% water by volume. Addition of either acid or base greatly accelerates the reaction, acid because it produces HMnIIICyDTA(H2O), and base because it produces both MnIIICyDTA(OH)2−and the phenolate ion.In acidic methanol HMnIIICyDTA(H2O) reacts with both methanol and the phenol leading to formation of both methoxy and aryloxy radicals. The latter are stable in some instances and in others undergo further reaction. The methoxy radicals produced by the concomitant oxidation of methanol are competed for by MnIIIand by phenol; formaldehyde and MnIIbeing the products in the former case and methanol and aryloxy radicals in the latter case.In basic methanol MnIIICyDTA(OH)2−converts the hindered phenols to aryloxy radicals, some of which are stable and others of which undergo further reaction.Isotope effects,kH/kD, between 5 and 6 are observed for the oxidation of the phenols in acidic or neutral CH3OD. Smaller effects (less than 2) are observed in basic solution. Substituents have a large effect on the reaction only in basic solution. The ρ of 2.69 in base probably reflects the effect of substituents on the ionization of the phenol.

ISSN:0008-4042    

DOI:10.1139/v72-556

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The infrared spectra of authenticated samples of ethylene oxide hydrate and deuterate at 100 °K have been measured between 360 and 20 cm−1. The spectra confirm that the water molecules are orientationally-disordered and reorient slowly compared to far-infrared frequencies. An empirical correlation is suggested between the frequencies of strong absorption and the number of non-equivalent hydrogen bonds, their length and distribution. The contribution to the spectrum by the ethylene oxide intermolecular vibrations is discussed.

ISSN:0008-4042    

DOI:10.1139/v72-557

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Condensed phase enthalpies of dissociation of [R4N][SiF5(NH3)], in which R = C2H5, C3H7, and C5H11, are in the order: C2H5— < C3H7— < C4H9— > C5H11—, and a lower limit of 16.8 ± 0.6 kcal mol−1is suggested for the gas phase interaction of NH3with. Enthalpies of dissociation of the amine adducts, [(C5H11)4N][SiF5L], in which L = CH3NH2, (CH3)2NH, and (CH3)3N are in the order:.

ISSN:0008-4042    

DOI:10.1139/v72-558

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

A total synthesis of (±)-ishwarane, a novel tetracyclic sesquiterpenoid possessing a tricyclo[3.2.1.02,7]octane system, is described. Completion of the synthesis of ishwarane firmly establishes the structure assigned to this sesquiterpenoid and provides corroboration of the structure assigned to the related sesquiterpenoid ishwarone. A total synthesis of (±)-isoishwarane, a transformation product of ishwarone, is also described.

ISSN:0008-4042    

DOI:10.1139/v72-559

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The cycloaddition of cyclopentenone to all the halogenated ethylenes has been studied. There is no evidence, as has been previously suggested, that specific β addition takes place as the first step. The details of the two-step closure are discussed and it is concluded that spin relaxation is probably of no relevance for the stereochemical outcome.

ISSN:0008-4042    

DOI:10.1139/v72-560

出版商:NRC Research Press    

年代:1972

数据来源: NRC