摘要:

Much higher heats of solution than have previously been observed for hydrates of zinc sulfate have been measured for various new vacuum dehydration products. It is suggested that the maximum heat of transition to normal crystalline form of 82.8 cal/g, 23.8 kcal per mole of heptahydrate, or 8.3 × 103 cm−1is a satisfactory measure of the ligand field splitting energy for the hexaaquozinc(II) ion.

ISSN:0008-4042    

DOI:10.1139/v65-437

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

Ultraviolet absorption spectra have been recorded, at low temperatures, for pure crystals of the following compounds: hexachlorobenzene,o,m, andp-dichlorobenzenes,o,m, andp-dibromobenzenes, 1,2,3-trichlorobenzene, and 1,2,4,5-tetrachlorobenzene. In all cases, the first electronic transition corresponding to the1B2u−1A1gtransition of benzene has been studied. For six of these compounds the spectra were sufficiently well resolved to permit complete analyses of the vibrational fine structure of the electronic bands. The results indicate that only totally symmetrical vibrations appear in conjunction with the observed electronic transitions. Several changes in published vibrational assignments are proposed, in the light of present results.

ISSN:0008-4042    

DOI:10.1139/v65-438

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

The ultraviolet absorption spectra of nine samples of soluble, ribosomal, and viral ribonucleic acid (RNA) were studied over the range 3 500 to 1 830 Å. The spectra and the spectral changes which occur upon denaturation were the same for all types of RNA examined, which suggests that their secondary structure is comparable. Dehydration of solid films of RNA at room temperature caused spectral changes resembling those which occur when RNA is heated in aqueous solution. This indicates that the dehydration of RNA, like the dehydration of deoxyribonucleic acid (DNA), causes some loss of the regular stacking and pairing of the nucleotide bases in the helical regions. In contrast to DNA, the rehydration of RNA was not always complete at 98% relative humidity. The decrease of absorbance in the 2 900 Å region upon denaturation, previously reported by Rich and Kasha, was not confirmed with any of the RNA samples studied.

ISSN:0008-4042    

DOI:10.1139/v65-439

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

The following fatty acids were identified in the respective seed oils; α-eleostearic inKentranthusmacrosiphon;trans-8,trans-10,cis-12-octadecatrienoic inOsteospermumhyoseroides; 9-hydroxy-10,12- and 13-hydroxy-9,11-octadecadienoic inTageteserecta. Dimorphecolic acid was obtained fromOsteospermumecklonisin pure crystalline form. It gave 9-D-hydroxystearic acid on hydrogenation, thus establishing theD-configuration of the parent acid. Dehydration of dimorphecolic acid gave a mixture of all-trans-8,10,12- and all-trans-9,11,13-octadecatrienoic acids.

ISSN:0008-4042    

DOI:10.1139/v65-440

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

The photolysis of tetramethylcyclobutan-1,3-dione was investigated in a nitrogen matrix at 4°K and in solution in cyclohexane at room temperature. Infrared spectra of the reactant after irradiation showed the formation of carbon monoxide, dimethylketene, tetramethylethylene, and a compound with an intense absorption at 1 840 cm−1which has been identified as tetramethylcyclopropanone. Since the dimethylketene that was formed was also capable of undergoing secondary photolysis, the effect of light (mainly 2 537 Å) on dimethylketene in solution or in a nitrogen matrix, was also studied. It has been found that in solution 0.2 of the molecules of tetramethylcyclobutandione which decompose, do so to give two molecules of dimethylketene, while approximately the same number of molecules decompose to tetramethylcyclopropanone and carbon monoxide. The remainder of the molecules seem to give tetramethylethylene and carbon monoxide in a concerted process.

ISSN:0008-4042    

DOI:10.1139/v65-441

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

The pyrolysis of 2-alkylpseudouronium fluorides and fluoroborates at approximately 185° gave alkyl fluorides in yields of up to 77%. The method is most useful for the preparation of primary alkyl fluorides; attempts to prepare secondary fluorides, such as cyclohexyl fluoride, gave the corresponding alkenes.

ISSN:0008-4042    

DOI:10.1139/v65-442

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

Substitutedsyn-benzaldoxime esters are transformed, in an alcoholic solution, to the corresponding nitriles according to first-order kinetics. All ortho substituents were observed to accelerate the rate of nitrile formation relative to the corresponding para derivative. While theko/kpratios for the bromo, chloro, fluoro, methoxy, and methyl substituents fall within the range of 2 to 9, the iodo and methylthio substituents are 119 and 11 000 respectively. Isotopic replacement of the aldoximino hydrogen by deuterium gives rise to a kinetic isotope effect,kH/kDbeing 5.21 forsyn-o-chlorobenzaldoximep-toluenesulfonate, 1.22 forsyn-o-iodobenzaldoximep-toluenesulfonate, and 1.23 forsyn-o-methylthiobenzaldoximeo-iodobenzoate. The marked enhancement of rate and the absence of an appreciable isotope effect are considered to be associated with sulfur and iodine participation in the rate-determining step. A mechanism which is capable of explaining the results observed is suggested.

ISSN:0008-4042    

DOI:10.1139/v65-443

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

A linear correlation exists between the proton shifts of some alkyl chlorides and some hydrocarbons and the occupation numbers of the hydrogen 1s orbitals in the C—H bonds. The occupation numbers are those given by the self-consistent group orbital and bond electronegativity method. The application of this correlation to the prediction of starting values for occupation numbers, to the derivation of bond anisotropies in ethylene and acetylene, and to the prediction of hydrogen-bonded shifts of C—H protons is discussed.

ISSN:0008-4042    

DOI:10.1139/v65-444

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

The infrared spectra of some tetramethyl-, tetraethyl-, and triethylmethyl-arsonium salts, and that of tetramethylstibonium triiodomercurate(II) have been recorded in the region 4 000 to 200 cm−1. Vibrational assignments are given for the quarternary 'onium cations, and comparisons are made with the spectra of alkylorganometallic compounds of germanium and tin.

ISSN:0008-4042    

DOI:10.1139/v65-445

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

A series of titanium(IV) halide – diamine complexes have been prepared and their infrared spectra measured in the solid state between 4 000 and 300 cm−1. The configuration of the ligand and extent of aminolysis of the titanium–halide bond are discussed in relation to the spectra. Some assignments are proposed in the 600–300 cm−1region for the ethylenediamine complexes.

ISSN:0008-4042    

DOI:10.1139/v65-446

出版商:NRC Research Press    

年代:1965

数据来源: NRC