摘要:

Results are reported for the photolysis of small, fixed amounts of diazomethane andcis-butene-2 in the presence of increasing pressures of the inert gases He, Ar, Xe, N2, and CF4. The variation in the percentage yield of thetrans-dimethylcyclopropane as a function of the inert gas pressure indicates that two basic mechanisms, with opposite dependencies on the inert gas pressure, are responsible for its formation. An initial decrease in the percentage yield of thistransisomer with increasing pressure indicates that a source is an isomerization of energized molecules. These excited molecules result from the addition of methylene in a singlet state tocis-butene-2. A subsequent rise in the yield of thetransisomer with further increases in the pressure indicates that another mechanism, one whose rate isincreasedby an increase in pressure, must be present. This is attributed to a mechanism involving triplet methylene. The pressure regions for the observation of the singlet or triplet behavior of methylene are thus known and the modes of formation of the other C5products may be determined.

ISSN:0008-4042    

DOI:10.1139/v65-215

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

The occurrence of complexes of boron trifluoride with some fluoborates has been established. Enthalpies of formation were determined for some of these complexes. Infrared and fluorine resonance spectra were obtained in an attempt to elucidate the structures of the complexes.

ISSN:0008-4042    

DOI:10.1139/v65-216

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

Few organic compounds of selenium are known and, consequently, very little published data are available concerning the various vibrations around the selenium atom. The present paper discusses the C=Se vibration in selenosemicarbazones by comparing their infrared spectra with those of corresponding Se-benzyl derivatives in which the C=Se group has been replaced by a C—Se—Bz. On this basis, it can be seen that a band at 800–780 cm−1in the spectra of selenosemicarbazones is absent in the spectra of the benzyl derivatives. This band is assigned to the C=Se vibration.

ISSN:0008-4042    

DOI:10.1139/v65-217

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

The reaction of silver nitrate in dry acetonitrile with 2,5-dideoxy-2,5-diiodo-1,4;3,6-dianhydro-L-iditol resulted in formation of the dinitrate esters of the 1,4;3,6-dianhydrides ofD-mannitol,D-glucitol, andL-iditol. Similarly bothendo- andexo-nitrato groups were introduced in displacement of theendo-halogen in the 2-deoxy-2-iodo-5-O-acetyl and 2-deoxy-2-iodo-5-O-p-toluenesulfonyl derivatives of 1,4;3,6-dianhydro-L-iditol. Since both types of nitrato groups were stable to silver nitrate, the racemization occurred during the displacement and was attributed to formation of cyclic carbonium ion intermediates. The steric effect of the adjacent ring in the carbonium ions apparently suppressed the termolecular, ion-pair mechanism previously established for the metathesis of acyclic alkyl halides and caused preferential formation of theexo-nitrato derivatives.The heterogeneous reaction ofmeso-dibromostilbene with silver nitrate in acetic acid or acetonitrile gavemeso-dihydrobenzoin dinitrate with overall retention of configuration. This result could be most readily reconciled with the contrasting sequence of retention and inversion previously reported formeso- anddl-2,3-dibromobutane if participation of neighboring phenyl groups occurred in the second displacement step.

ISSN:0008-4042    

DOI:10.1139/v65-218

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

The interplanar spacings obtained from the X-ray powder patterns of a series of structurally related semicarbazones were used to unequivocally identify the ketones from which the derivatives were prepared. The advantages of the proposed over the currently used melting points to identify the compounds were cited. The method was found to be applicable to slightly contaminated mixtures of semicarbazones.

ISSN:0008-4042    

DOI:10.1139/v65-219

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

The statistical treatment of the proton model for hydrogen absorption by palladium is extended to include a variation of the electron donation energy with hydrogen content, as determined by a density of states function for the combined 4d- and 5s-bands for palladium. This improved model gives better agreement with the high pressure limiting solubility data and the observed critical composition than the original model, when both are fitted to the critical isotherm by the same method. An apparent anomaly in the variation of the isosteric enthalpy of absorption with content is explained by the improved model.

ISSN:0008-4042    

DOI:10.1139/v65-220

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

Selenium nuclear magnetic resonance spectra have been observed for a number of selenium compounds. Chemical shifts and coupling constants with hydrogen and fluorine have been obtained. Various systems involving selenium compounds have been studied. It was found that a mixture of SeOF2and SeOCl2contains SeOClF and that rapid selenium exchange occurs between SeOCl2and SeOBr2presumably via the intermediate SeOClBr. The reactions of selenium tetrahalides with sulfur and selenium trioxides and with boron trifluoride were studied. It was observed that antimony pentachloride, tin tetrachloride, arsenic trichloride, quinoline, and potassium chloride produce considerable shifts in the resonance of selenium oxychloride. These shifts can be interpreted in terms of the acid–base behavior of the solutes.

ISSN:0008-4042    

DOI:10.1139/v65-221

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

Surface properties of the dehydration catalyst, boron phosphate (BP), prepared by the reaction of triethyl borate and phosphoric acid, were investigated by the use of a microbalance system. During evacuation at elevated temperatures, weight changes of the BP were obtained. Nitrogen adsorption isotherms were measured after each treatment. Surface areas appear to increase, and reach a maximum in the range 200–300 °C. Weight changes are initially large but begin to level off as the temperature is increased. Ammonia isotherms were obtained at 25.00 °C on aliquots of the same BP sample after various pretreatments. Amounts of ammonia remaining adsorbed after evacuation overnight were taken as the quantity chemisorbed. An approximate value of 8.9 kcal/mole of ammonia was obtained for the heat of chemisorption of ammonia by measuring the pressure and weight change as the amount of chemisorbed ammonia is decreased on heating the BP to various temperatures in a closed system. Results are interpreted in terms of change of number of active sites with surface area and the deactivation of sites on loss of water.

ISSN:0008-4042    

DOI:10.1139/v65-222

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

The addition of "BrF", usingN-bromoamides in anhydrous hydrogen fluoride, to a number of aliphatic alkenes has been studied. As expected, the bromine atom in the resultant vicinal fluorobromides exhibited relatively low reactivity in nucleophilic and hydrogenolytic reactions.

ISSN:0008-4042    

DOI:10.1139/v65-223

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

α-Monofluoroalkanoic acids are important intermediates in the synthesis of biologically active fluorine compounds. General methods of preparation have been examined, based on the three following reagents: (a) hydrogen fluoride +N-bromoacetamide; (b) diethyl monofluoromalonate; and (c) perchloryl fluoride. The first of these is the recommended procedure for simple unsubstituted α-fluoro acids; however, the fluoromalonate route is less vigorous, and is therefore the method of choice for those α-fluoro acids that contain labile functional groups.

ISSN:0008-4042    

DOI:10.1139/v65-224

出版商:NRC Research Press    

年代:1965

数据来源: NRC