19654-61-6Relevant articles and documents
Competition between SN2 and (general acid-catalysed) E1cB reactions in the aqueous decomposition of methyl N-(substituted phenoxycarbonyl)sulfamate esters
Blans, Patrick,Bergon, Michel,Vigroux, Alain
, p. 963 - 968 (2007/10/03)
The aqueous reaction mechanisms of methyl N-(substituted phenoxycarbonyl)sulfamates 4a-d were examined in the entire pH range 0-14 at 50 °C. The pH-rate profiles indicate a rate law that includes two pH-independent terms. ka (s-1) in acid and kp (s-1) around neutral pH, with ka > kp, and a hydroxide-ion dependent term, kOH (dm3 mol-1 s-1), at high pH. In acid, product analysis reveals that two competitive reactions are involved for hydrolysis with ka = kCO + kMe: a general acid-catalysed acyl-oxygen bond cleavage reaction of anions 4- (kCO) and a methyl-oxygen bond cleavage reaction resulting from water attack at the methyl carbon of neutral compounds 4 (kMe). For all compounds 4 investigated the kMe reaction is the dominant pathway (i.e., > 79%) in 1.0 mol dm-3 HCl solution. In contrast to ka, the spontaneous hydrolysis reaction of 4-, kp, takes place exclusively by acyl-oxygen bond cleavage and leads to the formation of methoxysulfonyl isocyanate as free intermediate. As observed in acid for the kMe reaction, the kOH reaction of 4- is best rationalized by a SN2Al mechanism in which hydroxide ion attacks anions 4- at the saturated methyl carbon leading to methyl-oxygen bond cleavage.
