摘要:

Sixty sulphides and disulphides have been prepared from mercaptans and alkyl and alkylene halides for testing as insecticides.

ISSN:0008-4042    

DOI:10.1139/v57-073

出版商:NRC Research Press    

年代:1957

数据来源: NRC

摘要:

The preparation ofsym-tetraethylnitroguanidine now shows that a ketimino group can be nitrated directly. The mode of nitration has been evaluated first by determination of the ionization of guanidine bisulphate (prepared anew) and tetraethylguanidine in nearly-anhydrous sulphuric acid by means of an improved cryoscope, and by comparison of these ionizations with those of substances the ionizing behavior of which may be reliably predicted. Subsequent studies show that the stronger base,sym-tetraethylguanidine, is nitrated more slowly than guanidine, both reactions being reversible. Detailed kinetic studies were not made because of the irreversible side-reaction yielding tetraethylurea. This irreversible reaction, which is suppressed by sodium bisulphate but not by nitric acid, is presumptive for the existence of an intermediate nitrotetraethylguanidinium salt out of which the tetraethylnitroguanidine or tetraethylurea may arise.

ISSN:0008-4042    

DOI:10.1139/v57-074

出版商:NRC Research Press    

年代:1957

数据来源: NRC

摘要:

A study has been made of the effects of column loading and eluting agent on the cation-exchange separation of the alkaline earths—beryllium, magnesium, calcium, strontium, barium, and radium. The principal eluting agents tested were ammonium lactate, ammonium citrate, and hydrochloric acid. Dowex-50 resin (Ion X, 300–400 mesh) was used throughout the investigation, and the column temperature was maintained at approximately 80 °C. Under optimum conditions, involving the use of 0.25 g. of resin per milliequivalent of sample and with ammonium lactate eluant (0.55 Mat pH 5 for beryllium, and 1.5 Mat pH 7 for magnesium, calcium, strontium, barium, and radium), a quantitative separation of all six elements in a single sample is possible in 5 hours. This procedure has been applied to the routine analysis of Sr90in bulk milk ash samples, containing 20 mg. of strontium carrier, with yields of 85–95%. By the same method trace amounts of strontium naturally occurring in milk have also been determined.

ISSN:0008-4042    

DOI:10.1139/v57-075

出版商:NRC Research Press    

年代:1957

数据来源: NRC

摘要:

The photosensitized polymerization of methacrylonitrile has been investigated at temperatures above 100 °C. A study of the kinetics suggests that at these temperatures the reverse (depropagation) reaction is important. From the experimental data, the heat and entropy change for the polymerization has been calculated.

ISSN:0008-4042    

DOI:10.1139/v57-076

出版商:NRC Research Press    

年代:1957

数据来源: NRC

摘要:

Extraction of beechwood chlorite holocellulose with hot water yielded a hemicellulose in 13.4% yield (based on original extractive-free wood) containingD-xylose 72%,D-galactose 11.0%, and uronic acid 13.2%. Purification of the crude hemicellulose by complexing with Fehling's solution yielded a chemically homogeneous fraction containingD-xylose 83% and 4-O-methyl-D-glucuronic acid 15.5%. Hydrolysis of the fully methylated hemicellulose yielded 2,3,4-tri-O-methyl-D-xylose, 2,3-di-O-methyl-D-xylose, 3-O-methyl-D-xylose, and 3-O-methyl-2-O-(2,3,4-tri-O-methyl-D-glucopyranosyluronic acid)-D-xylose in a molar ratio of 2:35:3:5. On the basis of the methylation data, periodate oxidation, reducing power determinations, and weight average molecular weight values a possible structure for the hemicellulose is proposed.

ISSN:0008-4042    

DOI:10.1139/v57-077

出版商:NRC Research Press    

年代:1957

数据来源: NRC

摘要:

A detailed mechanism of the molecular split of ethylene into acetylene and hydrogen, which occurs when ethylene is photosensitized by Hg(3P1), is presented. It is suggested that the triplet ethylene molecule which is first formed isomerizes to a molecule of uncertain lifetime in which two hydrogen atoms act as "bridges" between the two carbon atoms. The hydrogen molecule which splits from the ethylene molecule is formed when these two atoms leave simultaneously. The experimental observations on the decomposition of ethylene when photosensitized by Cd(1P1) or Zn(1P1) are consistent with the primary interaction of the excited metal atom with either a C–H group or with the π electrons.

ISSN:0008-4042    

DOI:10.1139/v57-078

出版商:NRC Research Press    

年代:1957

数据来源: NRC

摘要:

not available

ISSN:0008-4042    

DOI:10.1139/v57-079

出版商:NRC Research Press    

年代:1957

数据来源: NRC

摘要:

not available

ISSN:0008-4042    

DOI:10.1139/v57-080

出版商:NRC Research Press    

年代:1957

数据来源: NRC

摘要:

not available

ISSN:0008-4042    

DOI:10.1139/v57-081

出版商:NRC Research Press    

年代:1957

数据来源: NRC

摘要:

not available

ISSN:0008-4042    

DOI:10.1139/v57-082

出版商:NRC Research Press    

年代:1957

数据来源: NRC