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Reaction of tetramethyl‐1,2‐dioxetane with triphenylphosphine: Activation parameters for the formation of 2,2‐dihydro‐4,4,5,5‐tetramethyl‐2,2,2‐triphenyl‐1,3,2‐dioxaphospholane
Author(s) -
Baumstark Alfons L.,
Barrett Morgan,
Kral Kathleen M.
Publication year - 1982
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570190138
Subject(s) - chemistry , triphenylphosphine , phosphorane , thermal decomposition , triphenylphosphine oxide , medicinal chemistry , phosphine , reagent , phosphine oxide , acetophenone , yield (engineering) , phenylphosphine , acetone , organic chemistry , catalysis , materials science , metallurgy
The reaction of tetramethyl‐1,2‐dioxetane ( 1 ) and triphenylphosphine ( 2 ) in benzene‐d 6 produced 2,2‐dihydro‐4,4,5,5‐tetramethyl‐2,2,2‐triphenyl‐1,3,2‐dioxaphospholane ( 3 ) in ˜90% yield over the temperature range of 6–60°. Pinacolone and triphenylphosphine oxide ( 4 ) were the major side products [additionally acetone (from thermolysis of 1 ) and tetramethyloxirane ( 5 ) were noted at the higher temperatures]. Thermal decomposition of 3 produced only 4 and 5 . Kinetic studies were carried out by the chemiluminescence method. The rate of phosphorane was found to be first order with respect to each reagent. The activation parameters for the reaction of 1 and 2 were: Ea ≅ 9.8 ± 0.6 kcal/mole; ΔS ≠ = −28 eu; k 30° = 1.8 m −1 sec −1 (range = 10–60°). Preliminary results for the reaction of 1 and tris ( p ‐chlorophenyl)phosphine were: Ea ˜ 11 kcal/mole, ΔS ≠ = −24 eu, k 30° = 1.3 M −1 sec −1 while those for the reaction of 1 and tris( p ‐anisyl)phosphine were: Ea ˜ 8.6 kcal/mole, ΔS ≠ = −29 eu, k 30° = 4.9 M −1 sec −1 .