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Thermolysis of (−)-(S)-1-diphenylmethyl-2-(2-butyl)diazene (−)-(S)-1 at 100 °C in benzene and in benzene containing 1 M butanethiol produces (−)-(R)-1,1-diphenyl-2-methylbutane (−)-(R)-6 with 2 and 6% net inversion of configuration, respectively. These results indicate that the rate determining step is a one-bond cleavage to give diphenylmethyl and 2-butyldiazenyl radicals because a two-bond cleavage process cannot produce a coupling product with net inversion of configuration. The cage effect is at least 13% on thermolysis of (±)-1 at 100 °C in benzene containing 1 M butanethiol. (−)-(R)-6 is not thought to be formed by a displacement reaction of the diphenylmethyl radical on the (S)-2-butyldiazenyl radical. An estimate for the lifetime of the latter radical is ∼10−10 s or less. There is a small viscosity effect on the rate of thermolysis, k, of (±)-1. At 77.6 °C in cumene, octane, and hexadecane k = 4.48, 4.28, and 3.95 × 10−5 s−1, respectively. At 77.6 °C in cumene ΔH≠ = 30.5 ± 1.3 kcal/mol and ΔS≠ = 8.1 ± 4.0 eu for thermolysis of (±)-1.No emission or enhanced absorption due to the methine proton of the diphenylmethyl group of (±)-1 was detected in the nmr spectrum of the thermolysis at 120 °C in hexadecane.Enhanced absorption of the corresponding proton was observed in the nmr spectrum of thermolysis in hexadecane of 1-diphenylmethyl-2-phenyldiazene 7 at 180 °C which indicates one-bond cleavage occurs in this system. No evidence for the formation of crossed azo products was obtained when concentrated solutions of 7 and its tri-p-tert-butyl derivative were thermolized for one half-life (25 s) at 190 °C. This indicates that the phenyldiazenyl radical does not survive long enough to encounter a diphenylmethyl radical produced from another molecule of azo compound.

Die Thermolyse des (‐)‐(S)‐Diazens (IV), erhältlich ausgehend vom (+)‐(S)‐Amin (I) (89% optische Reinheit) über die Stufen (II) und (III), bei 100°C a) in Benzol b) in Benzol unter Zusatz von 1 Mol Butanthiol liefert das (‐)‐(R)‐Butan (V) [unabhängig dargestellt aus der Säure (VI)] mit 2 bzw. 6% Konfigurationsinversion.

Das Phosphoran (I) reagiert mit cis‐ und trans‐Butenoxid (IIa) zu meso‐ und dl‐(IIIa) (62‐74% Ausbeute).

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