摘要:

Thirty-five milliliters of an aqueous solution containing 5 to 70 micromoles of volatile C2to C8acids was distilled to constant volume without refluxing. The distillate was titrated, made alkaline, and evaporated to dryness at 110°C. The free acids were regenerated by the addition of 0.03 ml. of 10 Nsulphuric acid, absorbed on filter paper, and extracted quantitatively with 3 ml. of chloroform–butanol (99: 1). Acids present in the extract were separated by chromatography on a composite silica-gel column employing two internal indicators, and after elution were determined by titration, the details for which are given. The preparation of a reproducible silica is described.

ISSN:0008-4042    

DOI:10.1139/v51-071

出版商:NRC Research Press    

年代:1951

数据来源: NRC

摘要:

The effect of varying the concentrations of nitric acid and ammonium nitrate on the yield of RDX has been determined at 35°C., using hexamine, hexamine mononitrate, and hexamine dinitrate. The activation energies for the formation of RDX from hexamine, hexamine mononitrate, and hexamine dinitrate were found to be approximately 11 kcal., 12.5 kcal., and 16.5 kcal., respectively.

ISSN:0008-4042    

DOI:10.1139/v51-072

出版商:NRC Research Press    

年代:1951

数据来源: NRC

摘要:

A study has been made of the variation of the reaction rate constant with increasing dilution in the case of three reactions between pairs of dipolar substances in ethanol solution. The reactions examined were those between aniline and 2,4-dinitrochlorobenzene,p-toluidine and 2,4-dinitrochlorobenzene, andp-toluidine and 2,4-dinitrobromobenzene. As the concentrations of the reactants in the first two cases are increased 50-fold, the bimolecular velocity coefficient decreases by approximately 12% in the case of the first reaction, and by 7% in the case of the second one. The rates decrease sharply as the solubility limits of the products in ethanol are approached, while they become relatively constant as high dilutions are attained.

ISSN:0008-4042    

DOI:10.1139/v51-073

出版商:NRC Research Press    

年代:1951

数据来源: NRC

摘要:

Radiotracer studies with Br82show that bromine and bromate ion in perchloric acid solution undergo isotopic exchange at a measurable rate. The kinetics of the process suggest that secondary chemical reactions occur, leading to the formation of significant concentrations of hypobromous acid in the system. The isotopic exchange between hypobromous acid and bromine is complete within the time required to separate these species.

ISSN:0008-4042    

DOI:10.1139/v51-074

出版商:NRC Research Press    

年代:1951

数据来源: NRC

摘要:

Spectral and chemical data are presented which show that bromine and bromate ion in acid solution are unstable with respect to, formation of hypobromous acid. At higher concentrations of hypobromous acid, the reaction is reversed, and this species decomposes relatively rapidly to bromine and bromate. Some aspects of the kinetics of these reactions are described, from which deductions are made regarding possible mechanisms of the two processes.

ISSN:0008-4042    

DOI:10.1139/v51-075

出版商:NRC Research Press    

年代:1951

数据来源: NRC

摘要:

The phytochemical reduction of the β-keto-n-caproic and β-keto-n-caprylic acids yielded the correspondingD-β-hydroxyacids. This observation is contrasted to bioreduction of β-ketobutyric acid toL-β-hydroxybutyric acid. The basis for the assignment of the above configurations is discussed.L-α-Hydroxy-n-valeramide was reduced with lithium aluminium hydride and the product was acetylated to yieldL-1-acetamido-2-acetoxypentane. The enantiomorphic form of the latter compound was obtained through the Curtius degradation ofD-β-hydroxy -n-caprohydrazide. The configurations assigned to the β-hydroxy-n-caprylic acids are based on the Levene–Marker Rule for the optical rotations of homologous compounds. The β-hydroxy-n-caproic and β-hydroxy-n-caprylic acids derived from ustilagic acid were thus shown to belong to theL-series. The use of infrared spectroscopy in configurational correlations is discussed and the infrared spectra ofL-β-hydroxybutyrhydrazide,L-β-hydroxy-n-caprohydrazide,L- andDL-β-hydroxy-n-caprylhydrazides andD-,L-, andDL-1-acetamido-2-acetoxypentane are given.

ISSN:0008-4042    

DOI:10.1139/v51-076

出版商:NRC Research Press    

年代:1951

数据来源: NRC

摘要:

The distribution of Cl34among different valence states following the Cl35 (γ,n) Cl34reaction in solid sodium chlorate has been investigated, using a betatron as the source of gamma rays. The percentage of the activity in the hypochlorite and perchlorate fractions differed from zero by less than the experimental error; the small activity separated with the chlorite fraction could be accounted for by an exchange reaction between chloride and chlorite ions. The major part of the activity, 91 ± 2%, was present in the chloride fraction, the remainder of the activity being present as chlorate ion. One-quarter of the activity in the chlorate fraction could be accounted for by an exchange reaction between chloride and chlorate ions. The results were not affected by an alteration in the peak energy of the gamma rays or by a change in the amount of radiation. The results are compared with those following the Cl37 (n, γ) Cl38reaction in the same compound.

ISSN:0008-4042    

DOI:10.1139/v51-077

出版商:NRC Research Press    

年代:1951

数据来源: NRC

摘要:

Measurements of the P-V isotherms for sulphur hexafluoride in a small temperature range of approximately 1.5°C. in the critical region have been made to determine the validity of some theoretical considerations recently proposed. No evidence has been found to support the postulates of Mayer with respect to anomalous second order transitions over a finite temperature range above the temperature of disappearance of a liquid meniscus designatedTm. All isotherms above the latter are found to have a finite slope and it is not possible to conclude that theTmisotherm has a finite horizontal portion or "flat top". These conclusions are borne out by the nature of the isometrics which have been plotted and discussed qualitatively in relation to the existing theories.The temperature of meniscus disappearanceTmis estimated to be 45.547 ± 0.003°C. and at the previously determined critical density (1) of 0.7517 gm./cm.3the corresponding pressure is found to be 37.113 ± 0.003 atm. The critical density was found to be approximately 0.73 gm./cm.3

ISSN:0008-4042    

DOI:10.1139/v51-078

出版商:NRC Research Press    

年代:1951

数据来源: NRC

摘要:

not available

ISSN:0008-4042    

DOI:10.1139/v51-079

出版商:NRC Research Press    

年代:1951

数据来源: NRC

摘要:

not available

ISSN:0008-4042    

DOI:10.1139/v51-080

出版商:NRC Research Press    

年代:1951

数据来源: NRC