Accession Number : AD0457507

Title :   SPIN-ECHO NMR STUDIES OF CHEMICAL EXCHANGE. III. CONFORMATIONAL ISOMERIZATION OF CYCLOHEXANE AND DEUTERATED-CYCLOHEXANE.

Descriptive Note : Technical rept.,

Corporate Author : ILLINOIS UNIV AT URBANA WILLIAM A NOYES LAB

Personal Author(s) : Allerhand, Adam ; Chen, Fu-ming

Report Date : 22 DEC 1964

Pagination or Media Count : 24

Abstract : Equations derived previously for nmr chemical exchange effects were used in proton spin-echo studies at 26.85 Mc/sec of the chair-chair isomerization of cyclohexane and d(11)-cyclohexane in 1:1 v/v solutions in CS2. The d11-cyclohexane is particularly suited for such studies because of its very long natural relaxation time, and exchange rates of 5,300 to 38,000/sec were determined for it in the temperature range between -98 and +25 C. The heteronuclear coupling in d11-cyclohexane does not affect the spin-echo results. However, in cyclohexane the homonuclear coupling and the shorter relaxation time restricted the temperature range of accurate rate determinations to -60 and 25 C, respectively. The exchange rates are the same within experimental error for both compounds. Several factors governing the use of spin-echoes to study chemical exchange are discussed. (Author)

Descriptors :   (*CYCLOHEXANES, MOLECULAR ISOMERISM), (*DEUTERIUM COMPOUNDS, CYCLOHEXANES), RELAXATION TIME, NUCLEAR MAGNETIC RESONANCE, MOLECULAR STRUCTURE, REACTION KINETICS, THERMODYNAMICS, HEAT OF ACTIVATION, EXCHANGE REACTIONS, CARBON COMPOUNDS, SULFIDES.

Distribution Statement : APPROVED FOR PUBLIC RELEASE