摘要:

The determination of hydrogen peroxide at concentrations higher than those normally covered in polarography was studied with various electrodes. The diffusion current was found to increase linearly with the peroxide concentration up to 0.15% with the dropping mercury electrode and up to nearly 1% with a fixed platinum microelectrode. Under these conditions the limiting current was about 10 times greater than that usually observed. Although the solutions were supersaturated with oxygen, traces of strychnine sulphate were sufficient to suppress all maxima.

ISSN:1923-4287    

DOI:10.1139/cjr48b-081

出版商:NRC Research Press    

年代:1948

数据来源: NRC

摘要:

D,L-Alanine was prepared in an 80% over-all yield by heating lactonitrile with ammonium carbonate to give 5-methylhydantoin, and hydrolyzing the latter with barium hydroxide into the free amino acid. D,L-Phenylalanine was likewise prepared from phenylacetaldehyde, by way of the bisulphite addition compound and 5-benzylhydantoin, followed by hydrolysis. A 40% over-all yield of the amino acid was obtained.

ISSN:1923-4287    

DOI:10.1139/cjr48b-082

出版商:NRC Research Press    

年代:1948

数据来源: NRC

摘要:

Lecithin completely free of amino nitrogen and having N/P ratios of 1.00 to 1.01 has been obtained by cooling 10% solutions of mixed egg phospholipides in absolute ethanol to −35 °C. and eliminating the insoluble portions by filtration. These samples of lecithin have been considerably more unsaturated (I.N. 70 to 80) than those prepared by the cadmium chloride method of Pangborn (I.N. 55).

ISSN:1923-4287    

DOI:10.1139/cjr48b-083

出版商:NRC Research Press    

年代:1948

数据来源: NRC

摘要:

The inherent viscosities of dilute solutions of acidic polyesters of high purity have been compared with number average molecular weights accurately determined by end-group titration. For unfractionated resins with a degree of polymerization from 2 to 11the viscosity – molecular weight relation is linear in chloroform at 25 °C. Where,K = 1.923 × 10−5and β = 0.0176. For fractionated polyesters fromDP5 to 8,K = 1.959 × 10−6and β = 0.0161. For unfractionated resins with aDP > 11, molecular weights increase more rapidly than inherent viscosities. Abovefor fractionated resins linearity is resumed, and the slope increases. Several attempts have been made to explain this complex relation. Apparently the short chains remain linear, and the formation of anisotropic fibers at aDPclose to 100 establishes a degree of molecular orientation in the long-chain superpolyesters. Isomerization oflevo-diol to the diastereoisomer during polycondensation is without effect on the dilute solution viscosity of the resulting resin. Preferential degradation of the longer chains is assumed to be partially responsible for the decreasing slope fromDP11 to 65. As yet it has not been possible to assess the roles played by changes in size distribution, and variation in solvation with increasing chain length, but the data point to a curved viscosity – molecular weight relation in chloroform at 25 °C.

ISSN:1923-4287    

DOI:10.1139/cjr48b-084

出版商:NRC Research Press    

年代:1948

数据来源: NRC