摘要:

A method for quantitative determination of glucose, maltose, and reducing dextrins in starch hydrolyzates is described. The components are separated by paper chromatography and determined colorimetrically by measurement of their reducing power with alkaline copper and arseno-molybdate reagents. The probable error of the determinations with the use of this method is about 2%. A compact apparatus was designed, suitable for handling a large number of samples in the chromatographic separation. It is particularly useful for compounds with lowRfvalues.

ISSN:1923-4287    

DOI:10.1139/cjr50b-063

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

A modified technique is described for applying partition chromatography, using a silica column, to the separation of simple organic compounds which are difficult to extract from water. An aqueous solution is pipetted directly on a Celite–water column the upper 15% of which has been left dry to receive it. Acetoin, 2, 3-butanediol, 1, 2-propanediol, ethanediol, glycerol, and erythritol can be separated from each other and from sugars and sugar alcohols containing five or more carbon atoms if the column is properly developed by ethyl acetate and benzene–butanol mixtures. After separation the compounds can be estimated by a rapid colorimetric determination of the acetaldehyde or formaldehyde formed by periodate oxidation. The recoveries are quantitative, thus making it possible to determine 1 to 2 mgm. of glycerol or 2, 3-butanediol within an error of ± 3% even when they are mixed with larger amounts of closely related compounds which cause interference in the usual methods.

ISSN:1923-4287    

DOI:10.1139/cjr50b-064

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

Porous aluminum oxide layers may be obtained by anodic oxidation in sulphuric acid. The base of the pores is separated from the metal by a thin insulating barrier layer. The experiments show that the ultimate thickness of the barrier layer remains constant after a critical value has been reached. The dependence of the final thickness on current density, concentration, and temperature has been investigated. It is suggested that an electronic current is involved in the mechanism which limits the growth of the barrier layer.

ISSN:1923-4287    

DOI:10.1139/cjr50b-065

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

The rate of decomposition of cumene hydroperoxide in styrene at 30 °C. is increased considerably by the presence of various metal salts and complexes. The rate increases in the presence of certain metal salts and complexes whether the metal is oxidizable, reducible, or incapable of undergoing a valence change. Both the metal and the nonmetal portion appear to influence the rate. The molar ratio of cumene hydroperoxide decomposed to metal complex added may be well over 1000. Most of the decomposition of cumene hydroperoxide in the presence of ferric phthalocyanine does not produce free radicals capable of initiating the polymerization of styrene and may proceed by an ionic chain mechanism.

ISSN:1923-4287    

DOI:10.1139/cjr50b-066

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

The Arndt–Eistert reaction offers a convenient method for the synthesis of the higher members of the aliphatic carboxylic acid series. Nonadecanoic acid, eicosanoic acid, and heneicosanoic acid have been prepared successively from stearic acid in good yields. An efficient method of purification of the synthetic products is described. The ultraviolet absorption maxima for some diazoketones derived from the higher members of the aliphatic carboxylic acid series are recorded.

ISSN:1923-4287    

DOI:10.1139/cjr50b-067

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

2-5 Tetradecamethylene and 2-5 decamethylene phthalic anhydride have been obtained by dehydrogenation of the corresponding tetrahydro compounds. A 10-membered para-bridged acyloin, VI, has also been obtained in 70% yield by ring closure. From these results it is concluded that it should be possible to synthesize compounds with para-bridges containing less than 10 carbons.

ISSN:1923-4287    

DOI:10.1139/cjr50b-068

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

Using the well known methods of statistical mechanics, partition function ratios for many isotopic sulphur compounds have been calculated. These partition function ratios are used to determine equilibrium constants for many possible exchange reactions involving the isotopes of sulphur. The results indicate that considerable fractionation of the sulphur isotopes can be expected in laboratory and natural occurring processes. The predicted exchange constants are discussed in the light of recent results on the distribution of the sulphur isotopes in nature.

ISSN:1923-4287    

DOI:10.1139/cjr50b-069

出版商:NRC Research Press    

年代:1950

数据来源: NRC