Teruel Mariano, de Moraes Patricia R P, Xavier Luciano A, Riveros José M
Universidad Nacional de Córdoba, Facultad de Ciencias Químicas, INFIQC, RA-5000 Córdoba, Argentina.
Eur J Mass Spectrom (Chichester). 2003;9(4):279-85. doi: 10.1255/ejms.553.
Gas-phase C, H(3), S ions obtained by electron impact from (CH(3))(2)S at 14 eV undergo two distinct low-pressure ion-molecule reactions with the parent neutral: proton transfer and charge exchange. The kinetics of these reactions studied by Fourier transform ion cyclotron resonance (FT-ICR) techniques clearly suggests the C, H(3), S species to be a mixture of isomeric ions. While proton transfer is consistent with reagent ions displaying the CH(2)SH(+) connectivity, the observed charge exchange strongly argues for the presence of thiomethoxy cations, CH(3)S(+), predicted to be stable only in the triplet state. Charge exchange reactions are also observed in the reaction of these same C, H(3), S ions with benzene, toluene and phenetole. For these substrates, the CH(2)SH(+) ions can promote proton transfer and electrophilic methylene insertion in the aromatic ring with elimination of H(2)S. The results obtained for the different substrates suggest that the fraction of long-lived fraction of thiomethoxy cations obtained at 14 eV by electron ionization of dimethyl sulfide amounts to ~(22 -/+ 4)% of the C, H(3), S fragments.
通过在14电子伏特下对二甲硫醚进行电子轰击获得的气相C, H(3), S离子，与母体中性分子发生两种不同的低压离子-分子反应：质子转移和电荷交换。利用傅里叶变换离子回旋共振（FT-ICR）技术研究这些反应的动力学，清楚地表明C, H(3), S物种是异构离子的混合物。虽然质子转移与显示CH(2)SH(+)连接性的试剂离子一致，但观察到的电荷交换有力地证明了硫甲氧基阳离子CH(3)S(+)的存在，预计其仅在三重态下稳定。在这些相同的C, H(3), S离子与苯、甲苯和苯乙醚的反应中也观察到了电荷交换反应。对于这些底物，CH(2)SH(+)离子可促进质子转移和亲电亚甲基插入芳环并消除H(2)S。针对不同底物获得的结果表明，通过二甲硫醚的电子电离在14电子伏特下获得的硫甲氧基阳离子的长寿命部分占C, H(3), S碎片的~(22 -/+ 4)%。
