EFFECT OF CHAIN-LENGTH ON AGGREGATION OF N-ALKANES IN CCL3F MATRICES AT 77-K - FURTHER ESR EVIDENCE FOR THE OCCURRENCE OF HYDROGEN AND OR PROTON-TRANSFER BETWEEN HIGHER ALKANES AND THEIR CATIONS

被引:10
作者
LUYCKX, G
CEULEMANS, J
机构
[1] Department of Chemistry, K.U. Leuven, B-3001 Leuven
来源
RADIATION PHYSICS AND CHEMISTRY | 1993年 / 41卷 / 03期
关键词
D O I
10.1016/0969-806X(93)90021-L
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
After gamma-irradiation of hexane and decane at low concentration in CCl3F at 77 K only the ESR spectrum of the corresponding radical cations is observed. At higher concentrations (from about 3 mol% hexane and 0.5 mol% decane), the spectra of alkyl radicals also appear. The signal intensity and relative contribution of these alkyl radicals to the observed ESR spectra increases with increasing alkane solute concentration. In contrast, alkane radical cations but no alkyl radicals are observed after irradiation of hexane and decane in CCl3CF3 and other matrices at concentrations where alkyl radicals are already quite prominent in CCl3F. This contrast is especially pronounced in the case of decane, the signal intensity and relative contribution of alkyl radicals in the ESR spectrum of irradiated CCl3F-decane systems being much higher than in irradiated CCl3F-hexane systems. Most of the alkane radical cations observed possess the extended structure, resulting in a triplet with substructure for hexane and a broad singlet for decane, but different conformers are also observed, viz. for hexane in CCl3CF3 and for decane in CCl3F. The results provide conclusive evidence for the occurrence of hydrogen and/or proton transfer between C6 (only weakly) and C-10 (very pronounced) n-alkanes and their cations. They show further that in CCl3F at 77 K alkanes are present as small aggregates to which hole transfer still occurs efficiently and, in conjunction with other data, indicate that the extent of such aggregation increases with increasing chain length of the alkane solute.
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页码:567 / 573
页数:7
相关论文
共 20 条
[1]   SPECTRA, YIELDS, AND PHOTOLABILITY OF CATIONS, CARBANIONS, RADICALS, AND SCAVENGER ANIONS IN GAMMA-IRRADIATED ALKANE GLASSES [J].
BHATTACHARYA, D ;
WILLARD, JE .
JOURNAL OF PHYSICAL CHEMISTRY, 1980, 84 (02) :146-155
[2]   THE RADIATION-CHEMISTRY OF CRYSTALLINE ALKANES [J].
CHAPPAS, WJ ;
SILVERMAN, J .
RADIATION PHYSICS AND CHEMISTRY, 1980, 16 (06) :437-443
[3]  
DOLIVO G, 1985, Z NATURFORSCH A, V40, P52
[4]   ELECTRON-SPIN-RESONANCE, STRUCTURE, AND REACTIONS OF SPECIFICALLY DEUTERIUM-LABELED PENTANE CATIONS IN X-IRRADIATED FREON MATRICES [J].
DOLIVO, G ;
LUND, A .
JOURNAL OF PHYSICAL CHEMISTRY, 1985, 89 (19) :3977-3984
[5]   COMPARISON OF RADICAL AND NONRADICAL PROCESSES IN CONDENSED-PHASE RADIOLYSIS OF N-HEXADECANE [J].
FALCONER, WE ;
SALOVEY, R .
JOURNAL OF CHEMICAL PHYSICS, 1966, 44 (09) :3151-&
[6]   CHEMISTRY OF POSITIVE IONS .3. RADIATION CHEMISTRY OF SOLID N-HEXANE AT 77DEGREESK [J].
KEVAN, L ;
LIBBY, WF .
JOURNAL OF CHEMICAL PHYSICS, 1963, 39 (05) :1288-&
[7]   CATIONS AND ELECTRONS IN HYDROCARBON GLASSES AND LIQUIDS STUDIED BY PULSE-RADIOLYSIS [J].
KLASSEN, NV ;
TEATHER, GG .
JOURNAL OF PHYSICAL CHEMISTRY, 1985, 89 (10) :2048-2053
[8]  
LIAS SG, 1975, ION MOL REACTIONS TH, P109
[9]   ELECTRON-SPIN-RESONANCE AND STRUCTURE OF SPECIFICALLY DEUTERATED N-ALKANE CATIONS IN HALOGENATED MATRICES [J].
LUND, A ;
LINDGREN, M ;
DOLIVO, G ;
TABATA, M .
RADIATION PHYSICS AND CHEMISTRY, 1985, 26 (05) :491-498
[10]   ESR SPECTROSCOPIC OBSERVATION OF ALKANE AGGREGATION AND OF HYDROGEN PROTON-TRANSFER BETWEEN ALKANE RADICAL CATIONS AND ALKANE MOLECULES IN CCL3F MATRICES AT CRYOGENIC TEMPERATURES [J].
LUYCKX, G ;
CEULEMANS, J .
JOURNAL OF THE CHEMICAL SOCIETY-CHEMICAL COMMUNICATIONS, 1991, (15) :988-989