摘要:

In the pyrolysis of pure acetaldehyde at 450–525 °C it was found that ketene, although stable under these conditions, is not formed as a final reaction product. This result requires a modification of the mechanism of Liu and Laidler, according to whom the ethenoxy radical CH2CHO splits into CH2CO and H. It is concluded that instead of splitting unimolecularly, CH2CHO disappears mainly through the reactionand that it also undergoes the process

ISSN:0008-4042    

DOI:10.1139/v70-386

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

The method of preparation and analysis of liquid mixtures of chlorine dioxide and chlorine is described. The mixtures of chlorine dioxide and chlorine were found to be completely miscible. The freezing points were determined by using the dynamic method of measurement and the extrapolation procedure. An eutectic point was found to exist at −101.6 ± 0.1 °C. The eutectic solution contains 1.6 mole % of chlorine dioxide.

ISSN:0008-4042    

DOI:10.1139/v70-387

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

The gas phase fluorescent and triplet yields of 1,2,4,5-, 1,2,3,4-, and 1,2,3,5-tetrafluorobenzene (TFB) excited in the 2600 Å region have been determined. For 1,2,4,5-TFB, the maximum fluorescent yield (Φf = 0.338) occurs at λex = 2670 Å and the triplet yield at this wavelength = 0.515. For 1,2,3,4-TFB, the maximum fluorescent yield is 0.186 and is obtained at λex = 2645 Å; the triplet yield at this wavelength = 0.220. For 1,2,3,5-TFB the maximum fluorescent yield = 0.029 and the maximum triplet yield is 0.141, at an exciting wavelength of 2680 Å. The fluorescent and triplet yields of the three molecules, at any exciting wavelength studied, are not quenched by the addition ofcis-butene-2 (c-B-2).

ISSN:0008-4042    

DOI:10.1139/v70-388

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

cisandtransgeometric isomers of low spin octahedral cobalt(III) complexes containing either thiosemicarbazide (Htsc) or its anion (tsc) have been prepared and electronic spectra are presented and discussed. For the ionic form [Co(Htsc)3]3+both isomers were resolved and absolute configurations were assigned on the basis of optical rotatory dispersion and circular dichroism measurements. The interconversion of these optically active complex ions in aqueous solution was studied and a bond rupture mechanism is proposed to account for the observed inversion and isomerization.

ISSN:0008-4042    

DOI:10.1139/v70-389

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

Hydroboration and subsequent oxidation of 2-methoxy-3,4-dihydro-2H-pyran gave a 1:2 mixture ofcis- andtrans-5-hydroxy-2-methoxytetrahydropyran (2). From the methylated product4,trans-2,5-dimethoxytetrahydropyran could be obtained by gas–liquid chromatography. Thecis-2,5-dimethoxy-tetrahydropyran (8) was obtained by conversion of4to 3-methoxy-3,4-dihydro-2H-pyran (6) which upon bromomethoxylation and subsequent reduction with palladium catalyst gave8.Bothcis- and trans-2,5-dimethoxy-6-methyltetrahydropyran (11) were obtained by hydroboration and oxidation of 2-methoxy-6-methyl-3,4-dihydro-2H-pyran (9) followed by methylation of the resulting product.

ISSN:0008-4042    

DOI:10.1139/v70-390

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

3-Bromo-2,5-dimethoxytetrahydropyran (2), obtained by bromomethoxylation of 3-methoxy-3,4-dihydro-2H-pyran (1), was dehydrohalogenated tocis-2,5-dimethoxy-5,6-dihydro-2H-pyran (3). The epoxide5, derived from3, was converted to methyl 4-O-methyl-α-DL-arabinopyranoside (7) by treatment with aqueous potassium hydroxide. The structure and conformation of7and of its diacetate8were proven by analysis of their 100 MHz proton magnetic resonance spectra. Subsequent comparison with an authentic sample of methyl 4-O-methyl-α-L-arabinopyranoside corroborated the structural assignment.

ISSN:0008-4042    

DOI:10.1139/v70-391

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

The mass spectrometry of the ozonides of ring substituted styrenes has been studied, with R = p-CH3O,p-CH3, H,p-Cl,m-Cl, andp-NO2. Electron withdrawing substituents favor, in general, the appearance of molecular ions. The intensities of the carbonyl fragmentsfrom the fragmentation of the molecular ions follow the Hammett relationship (ρ = −0.44), as does the formation of [RC6H4CH2]+from [M-32]+(ρ = −1.36) The relative abundance of [M-32]+to that of the molecular ion is independent of R (ρ ≈ 0). The possible participation of electronically excited states in the primary fragmentation process of them-chlorostyrene ozonide has been invoked to explain its particular behaviou

ISSN:0008-4042    

DOI:10.1139/v70-392

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

Nuclear magnetic resonance and certain conductivity data are reported for solutions of perchloric and fluorosulfuric acids in sulfolane. Additional measurements were made on solutions of disulfuric and hexachloroantimony (V) acids. HSbCl6is a strong acid in this weakly basic dipolar aprotic solvent. HClO4, HSO3F, and H2S2O7are incompletely dissociated withK = 10−2.7, 10−3.3, and ~ 10−5, respectively. The acid strength in dilute solution in sulfolane follows the order HClO4 > HSO3F > H2S2O7, which differs from that known in H2SO4which is a strongly associated polar protic solvent.

ISSN:0008-4042    

DOI:10.1139/v70-393

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

The interaction of the oxine adduct, UO2(C9H6NO)2•C9H6NOH, and of the bis compound, UO2(C6H6NO)2, with several solvents has been studied. The oxine ligand in the adduct is displaced by DMSO but the adduct is stable in solvents of relatively low polarity. The bis compound is unstable and reacts to form both the adduct and solvates. Under appropriate conditions, the addition reaction between the bis compound and a solution of oxine is quantitative. Studies with [14C]-oxine revealed that the addition is accompanied by two exchange reactions.

ISSN:0008-4042    

DOI:10.1139/v70-394

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

Ketones can be reduced with sulfurated sodium borohydride. Very high yield (≈90%) of the corresponding alcohol is obtained with the appropriate ratio of ketone and hydride at room temperature. The reaction is much influenced by the steric environment around the carbonyl group. At high temperature (65°) disulfides and tetrasulfides are produced. In some cases the structure of those sulfides have been established. Conjugated ketones can be reduced to the corresponding alcohols with very high yield

ISSN:0008-4042    

DOI:10.1139/v70-395

出版商:NRC Research Press    

年代:1970

数据来源: NRC