摘要:

Starch pastes are classified according to the "length" of the flow or texture, and the practical importance of this characteristic in commercial applications for starch pastes is noted,e.g. for culinary uses. The differences in flow and texture may be attributed to the differences in phase-volume relations and the deformability of the swollen granules in the paste. It is shown that heating in water below the gelatinization point reduces both the volume occupied per unit concentration by the dispersed phase, and also increases the rigidity of the swollen granules. The viscosity of the paste is greatly reduced and the critical concentration of the starches is correspondingly increased by this treatment. The effect is particularly large in the case of potato starch, but is appreciable also with corn and wheat starches. Suspension of starches in dilute sulphurous acid (0.25% SO2) effects a similar change in somewhat greater degree, hence it is probable that the flow characteristics of corn starch are altered during the process of extraction. The practical application of these modifications is briefly discussed.

ISSN:1923-4287    

DOI:10.1139/cjr36b-047

出版商:NRC Research Press    

年代:1936

数据来源: NRC

摘要:

The condensation of propionaldehyde, isobutyraldehyde, trimethylacetaldehyde and dibromoacetaldehyde with glycerol has been carried out in the presence of a catalyst (40% sulphuric acid) at 90 °C., and the resulting products have been shown to consist in each case of a mixture of the five- and six-membered cyclic acetals. The separation of these isomers from the acetal mixture was rendered possible by the difference in the physical properties of their benzoates. The structure of the latter was proved by saponification, methylation, hydrolysis and isolation of the resulting glycerol α- and glycerol β-methyl ethers respectively.With the isomers from dibromoacetaldehyde this method could not be used, owing to the labile character of the bromine atoms in presence of alkali. Their structures were proved by direct synthesis of the five-membered acetal benzoate from glycerol α-benzoate and dibromoacetaldehyde.The data obtained provide additional evidence of the marked influence exerted by the polar character of the aldehyde on the extent and character of acetal condensation. Increase in the electronegative character increases the amount formed of the five-membered acetal and decreases that of the six-membered. Trimethylacetaldehyde condensed readily with glycerol in absence of a catalyst. Lowering of temperature, in presence of the catalyst, favored the formation of the six-membered acetals, in agreement with the earlier work of van Roon. The results further confirm the Hibbert-Michael Ring Partition Principle.A general comparison is made of the physical properties of the ethylidene–, propylidene–, isobutylidene–,t–amylidene–, bromoethylidene–, and dibromoethylidene glycerol acetals.By substituting diphenylamine for aniline in the synthesis of trimethylacetaldehyde from trimethylpyruvic acid the yield is increased from 25 to 40%.

ISSN:1923-4287    

DOI:10.1139/cjr36b-048

出版商:NRC Research Press    

年代:1936

数据来源: NRC

摘要:

A new flowmeter and preheater for the Friedrich carbon-hydrogen determination are described. The micromethoxyl apparatus as described by Pregl has been simplified, only one absorption tube being necessary.

ISSN:1923-4287    

DOI:10.1139/cjr36b-049

出版商:NRC Research Press    

年代:1936

数据来源: NRC

摘要:

The kinetics of countercurrent towers absorbing a gas which obeys Henry's law have been worked out by a more rigid method than that used by Donnan and Masson (2). An equation is obtained which, unlike the Donnan and Masson formula, is the expression of a process which is thermodynamically irreversible. This is in accordance with the requirements of thermodynamics. The theoretical variation of the concentration of the soluble gas in the two phases throughout the tower is examined by means of the new equation.

ISSN:1923-4287    

DOI:10.1139/cjr36b-050

出版商:NRC Research Press    

年代:1936

数据来源: NRC

摘要:

The sorption of deuterium oxide by cellulose at 23.4 °C. was investigated over the whole range of vapor pressures and found to show the same characteristics as that of water. The molar quantities sorbed at a given pressure are equal, and the kinetic curves exhibit the same features. After desorption of deuterium oxide, a small but permanent increase in the weight of the cellulose was observed. This suggested an exchange reaction between deuterium and hydrogen atoms.

ISSN:1923-4287    

DOI:10.1139/cjr36b-051

出版商:NRC Research Press    

年代:1936

数据来源: NRC