Gas phase ion–molecule reactions of dimethylsulphoxide

Abstract

MARCH. Can. J. Chem. 56, 2324 (1978).The gas phase ion-chemistry of dimethylsulphoxide (DMSO) and deuterated dimethylsulphoxide (DMSO-d6) has been examined using a quadrupole ion store (QUISTOR) a s an ion-molecule reaction chamber. The QUISTOR results are compared with those obtained by ion trapping and high pressure mass spectrometry as reported by other workers. The performance of the QUISTOR demonstrates the versatility of the technique for ion-molecule reaction studies with variation of ambient pressure and duration of ion storage.JOHN EDWARD FULFORD, JOSEPH WAYNE DUPUIS et RAYMOND EVANS MARCH. Can. J. Chem. 56, 2324 (1978).On a Ctudie, faisant appel a un rkservoire d'ions quadrupolaires (QUISTOR) sous forme de chambre de reaction ion-molecule, la chimie ionique en phase gazeuse du dimCthylsulphoxyde (DMSO) et du dimCthylsulphoxyde deutere (DMSO-cf). O n compare les resultats QUISTOR avec ceux obtenus par spectrometrie de masse avec piegeage ionique et haute pression tels que rapportes par d'autres auteurs. Le bon succes de QUISTOR dkmontre la versatilite de la technique pour des etudes de reactions ion-molCcule avec variation d e la pression ambiante et de la duree de l'entreposage des ions.[Traduit par le journal] Introduction mass s~ectrometrv which were carried out in order

Structure and mechanism of an inverting alkylsulfatase from Pseudomonas sp. DSM6611 specific for secondary alkyl sulfates

“…In order to facilitate the departure of the sulfate moiety, it has to be converted into a good leaving group. Catalytic sulfate ester hydrolysis can be achieved by protonation of the sulfate ester (the p K a values of monomethylsulfate were calculated and estimated to be −8.4 and −3.4, respectively ) by a strong acid of p K a < 2 to yield HSO 4 − as a good leaving group (the p K a of H 2 SO 4 is −9 to −3 and the p K a of HSO 4 − is 1.9–2.7). On the other hand, basic conditions generate SO 4 2− , which, being the anion of a weak acid, is a poorer leaving group.…”

Quadrupole ion traps

“…An alternative explanation (Todd et al, 1978) was based on the premise that space-charge-induced shifts in the b z ¼ 0 boundary of the stability diagram would affect the stability of the two ionic species differently. However, in a subsequent experimental and theoretical study of mixtures of neon and carbon dioxide, the March group demonstrated unequivocally the importance of ion migration (Doran et al, 1980), both for ions formed from these species and from the compound d 6 -dimethyl sulfoxide (Fulford, Dupuis, & March, 1978).…”

“…This focusing effect on trapped ions in collision with a light buffer gas was pursued also in great detail by André and co-workers (André, 1976;André, Vedel, & Vedel, 1979) and was vital to the subsequent commercial development of the ion trap (Kelley, Stafford, & Stephens, 1985). In addition to inelastic collisions, reactive ion/molecule collisions were studied with particular emphasis on ion/molecule equilibria for the determination of proton affinities (Kamar, Young, & March, 1986a) and the chemistry of gaseous ions (Fulford, Dupuis, & March, 1978).…”

A Stereoselective Inverting sec-Alkylsulfatase for the Deracemization of sec-Alcohols

“…HSO 4 – rather than SO 4 2– . ( 20 ) Consequently, acid-catalyzed sec -sulfate ester hydrolysis is a fast process, which proceeds through retention at C. 21 , 18 Based on the crystal structure of Pisa1,( 16 ) an acid–base-type mechanism for the inverting enzymatic alkyl sulfate hydrolysis can be proposed (Figure 1 ).…”