Regiospecificity for water elimination. A mass spectral study of 1‐tetralol and 2‐tetralol

Abstract

In order to provide a comparison with the extensive research on the mechanism for elimination of water from various cydohexanols, the mass spectra of 1-tetralo1(1,2,3,4-tetrahydro-l-naphthalenol) and 2-tetralol(l,2,3,4-tetrahydro-2-naphthalenol) have been investigated. Deuterium labeling experiments show that the 1-tetralol molecular ion expels water by a highly specific 1,4 elimination, whereas 2-tetra101 undergoes a 1,3 elimination. Both of these processes are competitive with cydoreversion reactions. The ionization potentials and appearance potentials for the major fragments [M-H,O]? and the cycloreversion products have been measured using the Electron Distribution Difference method. In addition, the kinetic energy release in the metastable decompositions to lose water have been measured. It has been found that the 1,4 elimination for 1-tetrdol releases over 50% of the available energy in the transition state, which is unexpected in view of the 6-membering. ring transition state involved. This research also indudes 811 investigation of the nature of the various [CloHlo]* ions formed in the rearrangement reaction to lose water.

Application of the principle of least motion to organic reactions. 4. More complex molecular rearrangements

“…Phys., 54, 2276 (1971). (8) In view of more recent studies9,10 our earlier choice of C-C distances for singlet and triplet ethylenes2a seem too long. The use of shorter bond lengths would certainly result in smaller values of Emin, but it is doubtful that this would substantially alter the stereochemistry of the least motion pathways for the processes considered.…”