摘要:

He(I) photoelectron (pe) spectroscopy is applied to determine the preferred gas phase conformations of a limited number of flexible allylic ethers and alcohols. Based on earlier observations that the π-ionization energy is increased more when the allylic C—O bond is coplanar (with the π-system) than when it is perpendicular, the pe spectrum ofcisandtrans-4-tert-butyl-2-cyclohexanol and their corresponding ethers, and 5α-hydroxy(and methoxy)-10α-Δ3-octalin have been determined. The results indicate that when a coplanar arrangement of the allylic C—O bond can be attained, it is preferred, leading to a favored conformation of the allylic alcohol or ether.

ISSN:0008-4042    

DOI:10.1139/v79-300

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The study of the polymerisation of the 3-halogenomethyl-5-methyl(or 5-phenyl)-3′(5′)-methyl-1,5′(3′)-dipyrazolylmethane allowed the isolation of five new macrocyclic compounds with four or six pyrazole rings. Their structures have been determined by mass spectrometry and proton nmr spectroscopy.A scheme is proposed which takes into account the different possible orientations of this reaction.

ISSN:0008-4042    

DOI:10.1139/v79-301

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The structures 4′,5-dihydroxy-2′,3,7,8-tetramethoxyflavone and 5-hydroxy-2′,3,4′,7,8-penta-methoxyflavone have been attributed to two new compounds isolated from a farinose exudate ofNotholaenaaffinis; this result is derived from uv, ms, and nmr spectra of the natural products and their derivatives.

ISSN:0008-4042    

DOI:10.1139/v79-302

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The preparation of phosphoranes C6H5PF2HOR by the oxidative addition of alcohols to C6H5PF2, followed by elimination of HF to give phosphines C6H5PFOR (R = CH3, CH2CH3, CH2CF3, CH(CF3)2, CH(CF3)C6H5, C(CH3)3), is described. All products were characterized by1H,19F, and31P nmr spectroscopy. The31P nmr spectrum of C6H5PFOCH(CF3)C6H5confirms the presence of diastereomers. Rapid ligand exchange in phosphoranes C6H5PF2HOR occurs upon addition of a base such as pyridine.

ISSN:0008-4042    

DOI:10.1139/v79-303

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

An unexpectedly strong interaction between electrons and closely packed cyclopropane molecules has been discovered through measurement of electron mobilities in the liquid and gas phases. In the low density vapors the mobilities fell in the expected order cyclopropane > propane > propene; at STP they were 9000, 6000, and 2040 cm2/V s, respectively. In the liquids the order was propane > propene > cyclopropane; at 273 K the mobilities were 1.4, 0.12, and 0.017 cm2/V s, respectively. The abnormally low mobility in liquid cyclopropane is attributed to the formation of transient dimeric anions. The reaction is only significant at densities greater than about 0.4 times the critical density.

ISSN:0008-4042    

DOI:10.1139/v79-304

出版商:NRC Research Press    

年代:1979

数据来源: NRC