摘要:

The infrared spectra of undeuterated and partially deuterated LiI.3H2O were recorded between 4000 and 1000 cm−1. The splitting of the fundamentals of isotopically dilute HDO indicates that the water molecules are distorted and form one strong, linear OH … I−hydrogen bond and one weak, non-linear hydrogen bond. The non-equivalence of the two hydrogens of the water molecule disagrees with the space groupP63mc − C6υ4for this hydrate, proposed on the basis of X-ray diffraction studies. It is concluded that the space group, including hydrogens, is one of lower symmetry,P63 − C66. The gradual broadening and convergence of the HDO fundamentals at increasing temperature is explained by increasing librational motion of the water molecules

ISSN:0008-4042    

DOI:10.1139/v71-058

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Surface defects of silica gel formed by a microwave electric discharge in a stream of oxygen and of nitrogen have been studied by means of electron spin resonance (e.s.r.) spectroscopy. The magnetic center is identified as a hole trapped by a surface oxygen atom which is formed by the removal of a hydrogen atom from a hydroxyl group. The principal values of theg-tensor were found to begxx = 2.037,gyy = 2.008, andgzz = 2.002, respectively, where the direction ofx-axis was taken along the O—Si bond. The center has a weak hyperfine interaction with a hydrogen nucleus of an adjacent hydroxyl group. The hyperfine splitting is 15 Oe.

ISSN:0008-4042    

DOI:10.1139/v71-059

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Using an energy-resolved electron beam, ionization potentials for the following free radicals have been measured: vinyl 8.95 V, allyl 8.07 V, benzyl 7.27 V. For vinyl and allyl ions new measurements of thresholds for dissociative ionization give ΔHf(C2H3+) = 266 kcal/mol and ΔHf(C3H5+) = 226 kcal/mol, leading to neutral radical heats of formation ΔHf(C2H3) = 59.6 kcal/mol and ΔHf(C3H5) = 40 kcal/mol. The data for benzyl radical and ion give ΔHf(benzyl cation) = 213 kcal/mol.

ISSN:0008-4042    

DOI:10.1139/v71-060

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The X-ray induced polymerization in the gas phase of pure vinyl chloride and of its mixtures with O2, NO, SF6, NH3, CH3NH2, H2O, HCl, and C2H2were examined. About 75% of the polymerization proceeds via a radical mechanism. The experiments indicate that most of the additives are deactivating chain transfer agents. Gel permeation chromatography showed that the polymer is activated by X-ray absorption during the time it takes to fall to the bottom of the irradiation cell, and forms a branched polymer.

ISSN:0008-4042    

DOI:10.1139/v71-061

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The competitive ortho directing (c.o.d.) influence of a 1-methoxy group and a 4-methyl group and a 4-methyl was studied in the Diels–Alder addition of 1-methoxy-1,3-pentadiene (1) to 2,6-dimethylbenzoquinone (2). It was found that the c.o.d. influence of a terminally located methoxy is stronger than the effect of a terminal methyl group in the diene since only adduct3could be isolated. The influence of non-terminal substituents compared to terminal substituents in diene appears to be insignificant. This was demonstrated by obtaining only adduct5form the addition of 3-ethoxy-1,3-pentadiene (4) with 2,6-dimethylbenzoquinone (2). The following order of c.o.d. influence was suggested in the diene relative to a methyl group in the dienophile OCH3 > CH3 > H.

ISSN:0008-4042    

DOI:10.1139/v71-062

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The photolysis reactions of the complex ions [Cr(en)2ox]+and [Cren(ox)2]−have been studied in the pHrange 1 → 3 and at temperatures from 0 to 25 °C. It has been found that both ions photoaquate to a monodentate protonated ethylenediamine complex which then undergoes further aquation thermally with loss of the ethylenediamine ligand. Quantum yields for these aquations were measured for irradiation into the ligand field bands, the values obtained being 0.18 and 0.02, respectively. The results are discussed in terms of known empirical correlations for Cr(III) complexes. Assuming these reactions may occur from the4T2gstate as precursor, arguments are presented that the correlation between quantum yield and ΔEmay depend on mixing of the4T2gand2Egstates, and its effect on the intersystem crossing rate constant.

ISSN:0008-4042    

DOI:10.1139/v71-063

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The biosynthesis of lobinaline (1) in intact plants ofLobelia cardinalisL. was studied by tracer methods. The incorporation data are consistent with the view that the alkaloid is formed by dimerization of α-phenacylpiperidine (3), whose piperidine nucleus is derived from lysine via a nonsymmetrical intermediate, and whose sidechain originates, as an intact C6–C2unit, from phenylalanine via cinnamic acid.

ISSN:0008-4042    

DOI:10.1139/v71-064

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Polarography in acetonitrile is useful for the study of the electrochemical behavior of organometallic compounds because acetonitrile is a suitable solvent for this class of compounds and provides a wide potential range over which their electrochemical behavior can be investigated. This inquiry was undertaken to enhance the understanding of the chemistry of these compounds. The polarographic behavior of three related iron compounds was studied and attempts were made to identify the products of the electrochemical reactions.

ISSN:0008-4042    

DOI:10.1139/v71-065

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Iodonium nitrate in chloroform-pyridine at room temperature undergoes atransstereospecific electrophilic addition to alkenes to form (i) iodoaliphatic nitrate esters, (ii) iodoalkane pyridinium nitrates, or (iii) alkene pyridinium iodides depending on the substrate. The addition is sensitive to steric hindrance effects and anti-Markovnikov addition is commonly encountered. In similar additions to conjugated dienes 1,2-additions in a Markovnikov fashion to form 1:1 adducts of type (ii) are the rule. Terminal acetylenes give alkynyl iodides in fair yield.

ISSN:0008-4042    

DOI:10.1139/v71-066

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The theory for ionic conduction in solids based upon the homogeneous, field-assisted generation of defect pairs is developed in a general, three dimensional form, and its range of applicability is examined. At high field strengths the equations reduce to those of the so-called high field Frenkel defect theory, proposed originally by Bean, Fisher, and Vermilyea. At low field strengths, the steady-state expression reduces to the well-known conduction equation derived originally by Mott for ionic conduction in the alkali halides. At intermediate field strengths, more complicated relationships obtain. The homogeneous generation of defect pairs, whether field or current assisted, is shown to be inapplicable as a mechanism for the high field anodic oxidation of the valve metals, since either type of theory predicts unacceptable behavior for the mean free path of the mobile defects. Any such conduction mechanism can be acceptable only for the case of thick films (» 104 Å).

ISSN:0008-4042    

DOI:10.1139/v71-067

出版商:NRC Research Press    

年代:1971

数据来源: NRC