Proton spin-lattice relaxation in MBDBP

Abstract

We have measured the proton spin-lattice relaxation rate R in 4,4′-methylenebis(2,6-di-t-butylphenol) (MBDBP) and MBDBP-OD (deuteriated hydroxyl proton) between 88 K and 380 K. The experimental results are compared with those from a previous study in the closely related but simpler molecule 4-methyl-2,6-di-t-butylphenol (MDBP). The present experiment is analysed in terms of relaxation resulting from intramolecular reorientation modulation of the proton spin-spin interaction. This intramolecular reorientation involves different combinations of superpositions of methyl, t-butyl, aromatic ring and hydroxyl group reorientation and a discussion is presented concerning the effects on the relaxation of superimposing these motions. The MBDBP-OD data is best fitted with the assumption that only methyl and aromatic ring reorientations occur. In MBDBP it is found that, in addition, an OH flip-flop motion is superimposed on the aromatic ring reorientation.

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Notes on contributors

Meigan Aronson

Undergraduate student on the Helena Rubinstein Scholarship (summer, 1979).

Victoria Guerra

Part of this paper forms part of the requirements for the A.B. degree with Honours (Bryn Mawr College, 1979).

Cheryl Schwamb

Part of this paper forms part of the requirements for the M.A. degree (Bryn Mawr College, 1979).

Swee Lian Tan

Undergraduate student on the Helena Rubinstein Scholarship (summer, 1979).