摘要:

The reaction of acetylene with silicon difluoride at low temperatures has been studied. Three products have been identified as volatile species after the reaction: tetrafluorodisilacyclobutene, 3,4-tetrafluorodisilahex-1-yne-5-ene, and 5,6,7-hexafluorotrisilanorborn-2-ene. Spectroscopic data for the compounds are presented, together with a possible mechanism to account for the formation of the observed products.

ISSN:0008-4042    

DOI:10.1139/v72-071

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The reactions between silicon difluoride and propyne, propyne-d1, 1-butyne, 2-butyne, and 3,3-dimethyl-1-butyne were studied. In each case products resulting from combining ratios (SiF2:alkyne) of 2:1 and 2:2 were isolated and identified. The 2:1 compounds were shown to be derivatives of disilacyclobutene, while three types of 2:2 compounds were identified. These either had an open chain structure, resulting from migration of either α (to C≡C)—CH or acetylenic H, or were derivatives of disilacyclohexadiene. Rationalizations of the types of products found and of the conditions which affect the reaction mechanism are discussed.

ISSN:0008-4042    

DOI:10.1139/v72-072

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The pKavalues often substituted primary anilines and six substituted tertiary anilines have been determined in 70% DMSO–water. The ΔpKavalues relative to those in aqueous solution indicate that DMSO is about 2 log units stronger as a base than H2O. The normal order of basicity (tertiary > primary) is inverted in this solvent system and the Hammett ρ values for the two series provide evidence for a different ionization mechanism than that in water.

ISSN:0008-4042    

DOI:10.1139/v72-073

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The vapor pressure and vapor composition of the methanol–cyclohexane system were investigated at temperatures ranging from 25 to 50°. The same properties of the binary systems: acetone–methanol and acetone–cyclohexane, as well as those of the ternary system: methanol–cyclohexane–acetone, were determined experimentally at 25°. The total pressures and compositions of the vapor for solutions lying close to the critical solution temperature of the binary system or close to the plait point of the ternary system are constant within the range of experimental accuracy. All these systems show azeotropic behavior. The methanol–cyclohexane system has an equimolar excess Gibbs free energy,GE, at 25° of 384.7 cal/mol, while the corresponding equimolar value ofGEfor the acetone–methanol system at 25° is 102.6 and for the acetone–cyclohexane system, at 25°, it is 274.5 cal/mol.

ISSN:0008-4042    

DOI:10.1139/v72-074

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Hydrogen and oxygen adsorption have been measured on neodymium oxide and dysprosium oxide from 77 to 771 °K up to equilibrium pressures of approximately 6 Torr. In addition, hydrogen adsorption measurements have been made on samarium oxide and gadolinium oxide from 77 °K to approximately 100 °K. The adsorption is effectively instantaneous in all cases except for oxygen adsorption on neodymium oxide at 491 and 541 °K. Adsorption appears to be dissociative for all cases studied except for hydrogen adsorption on neodymium oxide at all temperatures and for hydrogen adsorption on dysprosium oxide at high temperatures. For neodymium oxide and dysprosium oxide three types of adsorption are observed in different temperature ranges. At low temperatures, the adsorption is probably physical; at intermediate temperatures, it is either physical, or chemical on isolated double sites; and at high temperatures it is chemical. In general, the Freundlich isotherm gives the highest correlation between calculated and experimental data. The isosteric heat of adsorption and the equilibrium uptake of hydrogen increase as the ionic radius of the metal ion decreases.

ISSN:0008-4042    

DOI:10.1139/v72-075

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

An audiofrequency-pulse n.m.r. spectrometer has been used to measure the nuclear relaxation times of individual protons of the alkaloid, vindoline. For this substance in deuterochloroform solution the spin–lattice relaxation times (T1) vary between 1.15 and 1.50 s and the spin–spin relaxation times(T2)are between 0.90 and 1.40 s. TheN-methyl group has the shortest relaxation time of those resonances which were measured. A discussion of the apparatus and methodology is given.

ISSN:0008-4042    

DOI:10.1139/v72-076

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Heteronuclear1H–{2H} INDOR spectroscopy has been used to measure the deuterium chemical shifts of acetone-d5dimethylsulfoxide-d5, and of 1,2:5,6-di-O-isopropylidene-α-D-allofuranose-3-d.

ISSN:0008-4042    

DOI:10.1139/v72-077

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Treatment of 5,6-dideoxy-1,2-O-isopropylidene-α-D-xylo-hex-5-enofuranose (1) with silver trifluoroacetate and iodine in acetonitrile gave 3,6-anhydro-5-deoxy-5-iodo-1,2-O-isopropylidene-α-D-gluco(and β-L-ido)furanose (2) and 5-deoxy-5-iodo-1,2-O-isopropylidene-6-O-trifluoroacetyl-α-D-gluco(and/or β-L-ido)furanose (3). Component2was converted into 3,6-anhydro-5-deoxy-1,2-O-isopropylidene-α-D-xylo-hexofuranose (5) by hydrogenation over Raney nickel, and component3was converted into 5-deoxy-1,2-O-isopropylidene-α-D-xylo-hexofuranose (6) by treatment with methanol, followed by hydrogenation. Treatment of 5,6-dideoxy-1,2-O-isopropylidene-3-O-trifluoroacetyl-α-D-xylo-hex-5-enofuranose (7) with silver trifluoroacétate and iodine in acetonitrile gave the addition product8, but no 3,6-anhydro derivative;8was converted into the iodohydrin4by treatment with methanol. The preparation of the 5-deoxy derivative6by way of the iodohydrin4represents an overall anti-Markovnikov hydration of the olefin1; the reactions described are a convenient alternative to the hydroboration–oxidation procedure for the preparation of6.

ISSN:0008-4042    

DOI:10.1139/v72-078

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Synthetic studies and pKameasurements are reported on a number of highly fluorinated tertiary alcohols and diols, namely (CF2CF)C(CF3)2OH, (CF2CF)2C(CF3)OH, (C6F5)C(CF3)2OH, (C6F5)2C(CF3)OH, (C6F5)3COH, (C6H5)C(CF3)2OH, [(CF3)2COH]2, and [(C6F5)C(CF3)OH]2. General agreement is found with earlier work reporting a correlation between pKavalues and differences between free and H-bonded O—H stretching frequencies.The reaction of C6F5Li with the acyl halides CF3COCl and C6F5COCl in appropriate molar ratio gives the esters (C6F5)2C(CF3)OCOC6F5and (C6F5)3COCOC6F5, respectively; this constitutes a useful preparative route to fully fluorinated esters.

ISSN:0008-4042    

DOI:10.1139/v72-079

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Proton n.m.r. chemical shifts and coupling constants are reported for trimethylene sulfite and 10 alkyl derivatives in CCl4. Data are discussed in terms of possible chair and non-chair conformations and results are compared with those from dipole moment studies. The shift reagent Eu(dpm)3is used to aid configurational assignments. Conclusions from n.m.r. and dipole moments are consistent and indicate that several of the sulfites exist to a considerable degree in non-chair conformations.

ISSN:0008-4042    

DOI:10.1139/v72-080

出版商:NRC Research Press    

年代:1972

数据来源: NRC