摘要:

Acid methanolysis ofD-mannose 1,2-(methyl orthoacetate) 3,4,6-triacetate (I) yields mainly 3,4,6-tri-O-acetyl-D-mannose (II).D-glucose 1,2-(ethyl orthoacetate) 3,4,6-triacetate (VIII) yields 3,4,6-tri-O-acetyl-D-glucose and methyl 3,4,6-tri-O-acetyl-β-D-glucopyranoside. The rate of methanolysis of II differs little from that of VIII, in marked contrast to the relative rates of hydrolysis of these compounds in aqueous acid. Several concurrent reactions appear to take place in methanol initiated by protonation at different positions on the orthoester ring.During isolation, II is converted partially to 2,4,6-tri-O-acetyl-D-mannose (VI), a novel instance of acyl migration in the sugar series. Structural assignments for these two triacetates are based on chemical and proton magnetic resonance spectral data. The 2-acetate group of VI migrates during methylation, both II and VI yielding the same 2-O-methyl ether.

ISSN:0008-4042    

DOI:10.1139/v63-082

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

The addition of ethylene and propylene reduces the rate of azomethane decomposition as measured by the rate of nitrogen production, and also reduces the ratio CH4/N2in the products, but the reduction in the value of both quantities is different for each of the two olefins. In 100% decomposition, ethylene and propylene both increase somewhat the ratio (nitrogen recovered)/(azomethane decomposed). These results are interpreted to mean that there is in fact a short chain in the pyrolysis, but that ethylene and propylene are unsuitable inhibitors.The addition of a few millimeters of NO reduces the rate to a minimum which is lower than that with added propylene or ethylene (apparent chain length 2 to 3), but further addition of NO increases the rate again. Identical result is obtained in a packed vessel. The yield of methane, ethane, and ethylene is reduced to almost zero with a sufficient amount of NO. The ratio (NO consumed)/(nitrogen produced) reaches the value of two in the neighborhood of the rate minimum. It is concluded that the net inhibited rate, i.e. rate corrected for the stimulatory effect of NO, refers to the initial unimolecular process CH3N2CH3 → 2CH3 + N2. The rate as well as the activation energy of this process is found to be pressure dependent.It is shown by the use of the isotopic nitric oxide15NO that about one-half of the rate increase at higher NO pressures is due to nitrogen produced from NO. The remainder of the rate increase is accounted for by a NO-induced decomposition of azomethane.

ISSN:0008-4042    

DOI:10.1139/v63-083

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

The electron density distribution for the water molecule in its equilibrium configuration is determined by requiring that the forces exerted on the nuclei by this distribution (as calculated by the Hellmann–Feynman theorem) balance the nuclear forces of repulsion. The density distribution is expressed in terms of equivalent orbitals, and to achieve electrostatic equilibrium it is found necessary to have an angle between the bonding orbitals which is less than the structural bond angle (bent bonds), to delocalize the equivalent orbitals and to place the lone pair electrons insphybrid orbitals. Further, a discussion of the forces operative in XH2and XH3molecules (X = C, N, O) leads to an explanation of the observed bond angles and to general conclusions regarding the hybridization to be expected in such molecules.

ISSN:0008-4042    

DOI:10.1139/v63-084

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

A simple procedure is described whereby the complete stepwise degradation of 2-deoxy-D-ribose was achieved. Yields as high as 90% or better of the available carbon was obtained. The 2-deoxy pentose was reduced (KBH4) to the corresponding polyol and the latter oxidatively cleaved with periodate. Formic acid (C4) was converted to CO2quantitatively by oxidation with HgO. Formaldehyde and β-hydroxypropionaldehyde were oxidized with bromine. Formic acid (C5) thus formed was converted to CO2in quantitative yields and the hydroxy acid decarboxylated with permanganate; thusly C3was obtained. The acetic acid (from C1and C2) was extracted with ether and subsequently degraded by the Schmidt–Phares procedure. The procedure was further used to degrade some 2-deoxy hexoses.

ISSN:0008-4042    

DOI:10.1139/v63-085

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

A synthesis of N-benzyl-6-azacholestane is described and the generality of the approach is exemplified by the successful synthesis of 17β-hydroxy-N-benzyl-6-azaandrostane. This represents the first synthesis of a 6-aza derivative in the androstane series.

ISSN:0008-4042    

DOI:10.1139/v63-086

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

Reaction between 2-p-anisylethanol-1-C14and thionyl chloride was carried out with pyridine,n-hexane, toluene, dioxane, or excess thionyl chloride as solvent. The 2-p-anisylethyl chloride obtained showed rearrangement of the C14label from the C-1 to C-2 positions ranging from about 0.5% for the reaction in pyridine to about 46% for the reaction in excess thionyl chloride. The results can be explained on the basis of varying degrees of involvement of the ethylene-p-methoxyphenonium chlorosulphite ion pair, thus supporting the suggestion that thermal decomposition of alkyl chlorosulphites to give chlorides may be considerably ionic in character.

ISSN:0008-4042    

DOI:10.1139/v63-087

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

Spectroscopic studies by infrared, ultraviolet, and n.m.r. methods have shown that '3-hydroxypyrroles' exist in the 4-oxo-Δ2-pyrroline form and are not tautomeric substances.

ISSN:0008-4042    

DOI:10.1139/v63-088

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

Tetrakis-(trimethylsilyloxy)-titanium Ti(OSiMe3)4has been hydrolyzed under controlled conditions in dioxane. The initial products of hydrolysis undergo facile disproportionation, e.g. 3Ti2O(OSiMe3)6 → 4Ti(OSiMe3)4 + polymeric Ti2O3(OSiMe3)2. Molecular weight determinations were made on the titanium oxide trimethylsilyloxide polymers (polytrimethylsiloxanotitanoxanes) obtained by thermal disproportionation. Structures have been suggested for the polymers on the basis of the variation of number-average degree of polymerization with the degree of hydrolysis.

ISSN:0008-4042    

DOI:10.1139/v63-089

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

l-Acetyl-D-gulo(ido)-2,3,4,5-tetrahydroxypiperidine, a sugar derivative with nitrogen in the ring, has been synthesized fromD-xylose. The synthetic route and proof of structure are described.

ISSN:0008-4042    

DOI:10.1139/v63-090

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

Several minor pigments from cultures ofPenicillium herqueiare described. One of these has been identified as the naphthalic anhydride which is formed when atrovenetin is oxidized with alkaline peroxide. Evidence is presented which suggests that the characteristic green pigment found in this fungus is formed by a reaction analogous to that between ninhydrin and amino derivatives. InP.herqueithe 1,2,3-trione is probably generated by mild oxidation of perinaphthenone pigments known to be produced by this organism.

ISSN:0008-4042    

DOI:10.1139/v63-091

出版商:NRC Research Press    

年代:1963

数据来源: NRC