Electronic and Steric Effects of Alkyl Group on Denitrosation of 3-Alkyl-1-methyl-1-nitrosothioureas

Article abstract of DOI:10.1246/bcsj.58.2844

A series of 3-alkyl-1-methyl-1-nitrosothioureas with R=CH3, C2H5, cyclo-C6H11 (3), (CH3)2CH (4), C2H5(CH3)CH, and (CH3)3C were synthesized and their rates of acid catalyzes (pH<6.5) denitrosation measured.According to rate measurements in CH3COOD-D2O, the kinetic isotope effect k_H:k_D is 1.25 for 4.Except 3, a linear plot of log k_R/k_Me for the denitrosation of RNHCSN(NO)CH3 vs. ?^* provides ρ^*=-0.98(r=-0.997).The significant factor affecting the rate determining step of the denitrosation of these N-nitrosothioureas at pH 4.6 is the electronic effect of the substituent at the N₃ position.