SPIN-ECHO NMR STUDIES OF CHEMICAL EXCHANGE. III. CONFORMATIONAL ISOMERIZATION OF CYCLOHEXANE AND DEUTERATED-CYCLOHEXANE.
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)
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 22, 1964
- Accession Number
- AD0457507
Entities
People
- Adam Allerhand
- Fu-ming Chen
Organizations
- University of Illinois Urbana–Champaign