摘要:

The molecular complexes of urea and even-numberedn-paraffins up to C28undergo thermal decomposition below the melting point of urea at temperatures which increase with then-paraffin chain length. The decomposition is endothermal and is accompanied by changes in crystal structure, appearance, and by loss of then-paraffin. Based on the enthalpy change a mechanism for the decomposition process is proposed.

ISSN:0008-4042    

DOI:10.1139/v62-341

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

The extracellular polysaccharide isolated from cultures ofXanthomonasoryzaeis composed ofD-glucose (5 molecular proportions),D-glucuronic acid (2 molecular proportions), andD-mannose (5 molecular proportions). Acid hydrolysis of this polysaccharide, which contains 0.3% combined pyruvic acid, yields 2-O-β-D-glucopyranosyluronic acidD-mannose, which has been characterized as its crystalline fully methylated β-glycoside. Hydrolysis of the methylated polysaccharide gives 2,3,4,6-tetra-O-methyl-D-mannose (3 molecular proportions), 2,3,4-tri-O-methyl-D-glucuronic acid (1 molecular proportion), 2,3,6-tri-O-methyl-D-glucose (4 molecular proportions), 3,4,6-tri-O-methyl-D-mannose (2 molecular proportions), 2,6-di-O-methyl-D-glucose (3 molecular proportions), 2,3-di-O-methyl-D-glucose (1 molecular proportion). The polyalcohol derived from the polysaccharide by periodate oxidation followed by sodium borohydride reduction gives upon acid hydrolysis glycerol (2 molecular proportions), erythritol (1 molecular proportion), andD-glucose (1 molecular proportion). The general structural significance of these findings is discussed.

ISSN:0008-4042    

DOI:10.1139/v62-342

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

Six new dipeptides containing either 1-aminocyclopentanecarboxylic acid or 1-aminocyclohexanecarboxylic acid placed at either the N-or the C-terminal ofL-phenylalanine orL-leucine have been synthesized. Two molecules of 1-aminocyclopentanecarboxylic acid were also linked with a peptide bond. These seven dipeptides were cyclized into the corresponding substituted 2,5-piperazinediones.

ISSN:0008-4042    

DOI:10.1139/v62-343

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

Some complexes of titanium isopropoxide, titanium ethoxide, aluminum isopropoxide, tantalum isopropoxide, and zirconium isopropoxide with ethylenediamine (en) are described. Two complexes of titanium isopropoxide with ethylenediamine, i.e. Ti(OPri)4,en and Ti2(OPri)8,en, were established by cryoscopic, X-ray powder photograph, and phase rule studies. The structure and stability of these complexes is discussed. Also isolated were Ti2(OEt)8,en; Zr2(OPri)8,en; Ta2(OPri)10,en, and Al2(OPri)6,en. Cryoscopic studies on the aluminum complex suggested that an octameric complex, Al8(OPri)24, (en)4, is present in equilibrium with the dimer. The structural implications of the existence of these complexes are discussed.Phase studies on the binary systems containing titanium tetraisopropoxide and pyridine, diethylamine, ortert-butyl acetate gave no clear indication of complex formation.

ISSN:0008-4042    

DOI:10.1139/v62-344

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

N-L-Seryl-D-glucosamine has been prepared by the condensation ofN-carbobenzoxy-L-serine withD-glucosamine in the presence of dicyclohexyl carbodiimide followed by hydrogenolysis of the resultingN-(N-carbobenzoxy-L-seryl)-D-glucosamine to remove theN-carbobenzoxy protecting group.N-L-Threonyl-D-glucosamine has been prepared by (a) the condensation of 1,3,4,6-tetra-O-acetyl-α- (and β-)D-glucosamine andN-carbobenzoxy-O-tetrahydropyranyl-L-threonine in the presence of diisopropyl carbodiimide followed by the removal of the protecting groups from the resultingN-(N-carbobenzoxy-O-tetrahydropyranyl-L-threonyl)-1,3,4,6-tetra-O-acetyl-α- (and β-)D-glucosamine, and (b) by the condensation ofN-carbobenzoxy-L-threonine withD-glucosamine in the presence of dicyclohexyl carbodiimide followed by removal of theN-carbobenzoxy group from the resultingN-(N-carbobenzoxy-L-threonyl-D-glucosamine by hydrogenolysis.

ISSN:0008-4042    

DOI:10.1139/v62-345

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

The following coordination complexes of titanium (IV) have been prepared: TiCl4•2CO(NH2)2, TiCl4•CO(NHCH3)2, TiCl4•2CO(NHCH3)2, 2TiCl4•2NH2CON(C6H5)2, 2TiCl4•2CO(NHC6H5)2TiCl4•2CS(NH2)2, 2TiCl4•CS(NHC2H5)2, 2TiCl4•NH2CSN(C6H5)2, and 2TiCl4•CS(NHC6H5)2; their infrared spectra have been measured and their molecular weight determined. For urea and its derivatives the coordination to titanium (IV) is always through the oxygen atom. The phenyl derivatives of urea led to dinuclear complexes which were best explained by assuming halogen bridging between the titanium atoms. Thiourea and its derivatives gave complexes in which coordination occurred through one of the nitrogens in the case of thiourea and through both nitrogens in the case of the derivatives. Halogen bridging was again assumed to explain the formation of the dinuclear complexes.

ISSN:0008-4042    

DOI:10.1139/v62-346

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

Coordination complexes between titanium tetrachloride and some chlorine-substituted monoesters have been prepared.Infrared spectra of these complexes and their melting points indicate that the strength of the coordination bonds decreases as the number of chlorines increases in the acid radical. When the substitution is in the alkyl radical, it is possible to prepare complexes of the formula TiCl4•2 ester, since the chlorine substitution decreases the basic properties of the oxygen of the ether group in the ligand.

ISSN:0008-4042    

DOI:10.1139/v62-347

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

When the polymerization of vinyl acetate or acrylonitrile is initiated by persulphate in the presence of cellophane, grafting onto the cellulosic backbone occurs. This is proved by comparing the graft with a physical mixture of cellulose and homopolymer.Some aspects of the mechanism of this grafting are studied by means of model compounds, in particular pinacol. It is found that the rate of polymerization of acrylonitrile initiated by persulphate is increased by the addition of pinacol, but decreases on addition of more pinacol. This may be explained by assuming that the radicals formed from the pinacol can terminate each other and that this reaction competes with the reaction between these radicals and the monomer. The amount of acetone formed by the persulphate oxidation of pinacol at low pinacol concentrations is about 0.5 mole per mole persulphate and decreases with increasing pinacol concentration. This indicates complexities that do not exist in the ceric ion oxidation of pinacol.

ISSN:0008-4042    

DOI:10.1139/v62-348

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

Sequences of at least three α-1,3-linked mannose units have been shown to occur in phosphomannan Y-2448 through isolation of 3-O-[3-O-(α-D-mannopyranosyl)-α-D-mannopyranosyl]-D-mannose from partial acid hydrolyzates of both the native and the periodateoxidized phosphomannan. 3-O-(α-D-Mannopyranosyl)-D-mannose has been obtained also. The mannosidic bond in these oligosaccharides appears to be more stable to acid hydrolysis than that by which the mannose 6-phosphate unit is held in this macromolecular polysaccharide derivative. It has been established that theD-mannose 6-phosphate unit is oxidized by periodate and that orthophosphate is the form which occurs in this phosphomannan.

ISSN:0008-4042    

DOI:10.1139/v62-349

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

The starch present in the kernel of water chestnut (TrapabispinosaRoxb) has been isolated and obtained free from protein. Potentiometric titration showed that the starch contained 15% amylose. The starch was resolved into amylose and amylopectin through complex formation. The components were characterized by chemical and enzymic techniques. The average length of unit chain has been shown to be 22 in the amylopectin and 360 in amylose by both methylation and periodate oxidation studies. Molecular weights of the two components by viscosity and light scattering are also described.

ISSN:0008-4042    

DOI:10.1139/v62-350

出版商:NRC Research Press    

年代:1962

数据来源: NRC