The synthesis and mass spectral studies of t-butyl(deuterated) thiophenes
| dc.contributor.author | Fowler, Rosemary | |
| dc.contributor.committeeMember | Ludeman, Helen | |
| dc.contributor.committeeMember | Foster, Norman | |
| dc.contributor.committeeMember | Mecay, William | |
| dc.date.accessioned | 2023-04-04T13:39:17Z | |
| dc.date.available | 2023-04-04T13:39:17Z | |
| dc.date.issued | 1968-06 | |
| dc.description.abstract | The synthesis and mass spectral studies of t-butyl (deuterated) thiophenes were undertaken to aid in elucidation of the mass spectral fragmentation routes of the unlabeled t-butylthiophenes. The desired 2-(t-butyl chloride-2H9) thiophene and 3-(t-butyl-2H9 thiophene were synthesized by the interaction of 2-theinylmagnesium bromide and the t-butyl chloride-2H9 forming both the 2- and 3-isomers. The isomers were separated by preparative gas chromatography/ The isotopic purity of the 2-(t-butyl-2H9) thiophene was 96.3% and for the 3-(t-butyl-2H9) thiophene was 96.7%. The 2, 5-di(t-butyl-5-2H9) thiophene and the 2, 4-di(t-butyl-4-2H9) thiophene were synthesized by the interaction of 5-t-butyl-2-thienyl magnesium bromide and the t-butyl chloride-2H9 forming both the 2, 4-isomer and the 2, 5-isomer. The isomers were separated by the preparative gas gas chromatography. The isotopic purity of the 2, 5-di(t-butyl-5-2H9) was 98.7% and the 2, 4-di(t-butyl-4-2H9) thiophene was 95.22% Mass Spectral studies of the 2-(t-butyl-2H9) thiophene and the 3-(t-butyl-2H9) thiophene confirmed the direct losses of methyl-2H9 groups from the t-butyl group. Preferred successive losses of methyl-2H3 groups occurred in the fragmentation of the 2-isomer, whereas loss of the t-butyl group is the preferred fragmentation route in the 3-isomer. Positional substitution is an important influence on the mode of fragmentation of the various isomers. The steric relationships of the t-butyl group to the rest of the molecule differs depending upon the location (2 or 3) of the t-butyl group. The favored interaction between the deuterium of the t-butyl group and the sulfur atom are related to the location of the t-butyl group. Mass spectral studies of the 2, 5-di(t-butyl-5-2H9) thiophene and the 2, 4-di(t-butyl-4-2H9) thiophene confirmed that two successive losses, one of methyl and one of methyl-2H3 occurred. Preferential losses of methyl and methyl-2H3 are favored in the 2, 5-isomer, whereas the loss of a t-butyl group is favored by the 2, 4-isomer to a considerable extent and apparently occurs with almost equal probability from either position. The fragmentation of the 2, 5-isomer differs from the 2, 4-isomer in ion production and in the intensity of the ions formed at high voltage. These differences may be related to the steric effects and the interaction of the deuterium of the t-butyl group with the sulfur atom. Additional study of the existing mass spectral data presented is expected to yield considerable information on the fragmentation pathways. The Friedel-Crafts alkylation of the 2-t-butylthiophene with t-butyl chloride-2H9 yielded 2, 5-di-t-butylthiophene, 2, 5-di(t-butyl-5-2H9) thiophene, 2, 5-di(t-butyl-2, 5-2H18) thiophene, 2, 4-di(t-butyl-2, 4-2H18) thiophene. The Friedal-Crafts alkylation of the 3-t-butylthiophene with t-butyl chlodide2H9 yielded a product containing equal amounts of 2, 4-di(t-butyl-2-2H9)thiophene and 2, 4-di(t-butyl-2-2H9)-thiophene 5-2H1. Studies to elucidate the mechanism of these reactions are in progress. | |
| dc.identifier.uri | https://hdl.handle.net/11274/14791 | |
| dc.language.iso | en_US | en_US |
| dc.subject | t-Butyl(deuterated) thiophenes | |
| dc.title | The synthesis and mass spectral studies of t-butyl(deuterated) thiophenes | en_US |
| dc.type | Doctorate | en_US |
| thesis.degree.college | College of Arts and Sciences | en_US |
| thesis.degree.discipline | Radiation Chemistry | en_US |
| thesis.degree.grantor | Texas Woman's University | en_US |
| thesis.degree.level | Doctoral | en_US |
| thesis.degree.name | Doctor of Philosophy in Radiation Chemistry | en_US |