The thermal decomposition of diazirines: 3-(3-methyldiazirin-3-yl)propan-1-ol and 3-(3-methyldiazirin-3-yl)propanoic acid

Abstract

The thermolyses of 3-(3-methyldiazirin-3-yl)propan-1-ol (1) and 3-(3-methyldiazirin-3-yl)propanoic acid (2) have been studied in solution over the temperature range 96–125 °C. The reactions are unimolecular and fit linear Arrhenius plots with K(1)= 10^{13.85 ± 0.69}exp[–31.80 ± 1.21 kcal mol^–1/RT]s^–1 and K(2)= 10^{12.38 ± 0.43}exp[–29.26 ± 0.75 kcal mol^–1/RT]s^–1

The major products are the alkenes derived from the corresponding carbenes MeCH₂CH₂CH₂OH (3) and MeCH₂CH₂CO₂H (4). The new rate data, taken together with previous work, tend to confirm that diazirine thermolysis involves ring opening to a ‘complex’ followed either by nitrogen loss or by isomerization to a diazo compound. Whereas (1) gives no product of closure onto oxygen, the acid (2) affords about 5%γ-valerolactone.