Studies of Reactions of Amines with Sulfur Trioxide. V. Transsulfonation of Amine Salts of Some N-Substituted Amidosulfuric Acids

Abstract

4-Methylanilinium butylamidosulfate, butylammonium (4-methylphenyl)amidosulfate, and 4-methylanilinium (4-methylphenyl)amidosulfate were heated separately under reduced pressure at different temperatures ranging from 80 to 180 °C. Butylammonium butylamidosulfate was heated with 4-methylaniline under atmospheric and reduced pressure. The product compositions were determined as functions of reaction time and temperature, and the components were separated and identified. At lower temperatures (4-methylphenyl)amidosulfate and 4-methylaniline-N,2-disulfonate were the major products, while at higher temperatures 4-methylaniine-2-sulfonate and 2,6-disulfonate were the major products. The ease of N–S bond cleavage of the amidosulfate salts (RNHSO3–R′NH3+) (1) depends largely on the basicity of both the parent amine (R′NH2) (2) and the salt-forming base (R′NH2) (3). The results suggest that the initial step of the transsulfonation involves the dissociation of 1 into 3 and the free acid followed by an equilibration between RNHSO3H and RNH2+SO3− (4). It is considered that 4 may be the sulfonating species and the free amines, 2 and 3, should be the receptors of a sulfonate group. In contrast to the widely accepted scheme (transsulfonation and subsequent intramolecular rearrangement), our results show that both the transsulfonation and the rearrangement process occur concurrently and the same type of mechanism (a bimolecular displacement, viz., B+ : SO3−+B′: \ightleftarrowsB+: +B+: SO3−) may be operative.

Sulfamic acid and its N-substituted derivatives

“…Lwowski and Scheiffele414 consider the reaction to proceed via a Curtius-type rearrangement of benzenesulfonyl azide (107) followed by addition of methanol to an intermediate IV-phenylsulfonylamine (108). When the potassium salt of A/-(p-nitrobenzenesulfon- oxy)benzenesulfonamide (109) was added to methanol and stirred for 2 days, methyl phenylsulfamate (110) was obtained in 67% yield. Other preparations of esters of arylsulfamic acids include the preparation of ethyl-A/-phenylsulfamic acid415 by treating iminosulfuroxydifluoride with sodium ethoxide; Griffiths399 has prepared similar esters by refluxing arylsulfamyl azides in benzene and methanol.…”

Rearrangement of Arylsulfamates and Sulfates to Para-Sulfonyl Anilines and Phenols

“…Furthermore, the mechanism by which sulfur trioxide (SO3) is transferred in a SEAr reaction from a sulfamate to afford this type of aryl C(sp 2 )-sulfonate has been of perennial interest and reinvestigated by several groups and is accepted as an intermolecular rearrangement [21][22][23][24][25][26][27][28][29][30][31][32][33]. In turn, methods to prepare these N(sp 2 )-aryl sulfamate precursors under mild, noncorrosive conditions are limited [9][10][11][12][13][14][15], and C(sp 2 )-sulfonated compounds are only achievable under more forcing conditions (Scheme 1) [16][17][18][19][20].…”

“…Furthermore, the mechanism by which sulfur trioxide (SO 3 ) is transferred in a S E Ar reaction from a sulfamate to afford this type of aryl C(sp 2 )-sulfonate has been of perennial interest and reinvestigated by several groups and is accepted as an intermolecular rearrangement [21][22][23][24][25][26][27][28][29][30][31][32][33].…”

A Sulfonative rearrangement of N-Aryl Sulfamates to para-Sulfonyl Anilines

“…[6] Furthermore, the mechanism by which sulfur trioxide (SO3) is transferred in a SEAr reaction to afford these type of aryl C(sp 2 )-sulfonate has been of perennial interest and reinvestigated by several groups. [7][8][9][10][11][12][13][14][15][16][17][18][19] In turn, methods to prepare these N(sp 2 )-sulfamated precursors are limited [20][21][22][23][24] and C(sp 2 )-sulfonated compounds are often only achievable under more forcing conditions (Chart 1). [25][26][27][28][29] An ortho-selective aminative rearrangement of (arenesulfonyl)hydroxylamines has recently been revealed.…”