• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1
  • Tagged with
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The preparation of polynuclear compounds containing the thiophene ring system

Quo, Sih-gwan January 1959 (has links)
The process of C. K. Bradsher for preparing mesosubstituted anthracene and 1,2-benzanthracene derivatives has been widely extended. The purpose of this research was to extend this process to the thiophene series, in addition to continuing some work on the 9-(dimethyl)- phenylanthracene series and some newly developed l,2-dimethyl-10-phenyl)-anthracene series. 2'-Thienyl-2-benzylbenzophenone was prepared and cyclized to 9-(2-thienyl)-anthracene by the conventional methods in good yields. 3'-Thienyl-2-benzylbenzophenone was prepared in a different way, indirect and tedious. Thiophene was iodinated to tetraiodothiophene and tetraiodothiophene was reduced with aluminum-amalgam to 3-iodothiophene. 3-Thienylmagnesiumiodide was prepared by the entrainment technique and condensed with 2-cyanodiphenylmethane to 3'-thienyl-2-benzylbenzophenone. This ketone was cyclized to 9-(3'-thienyl)-anthracene by the standard acid mixture. 2-(1-Naphthylmethyl)-phenyl-2-thienylketimine formed from the condensation between 2-(1'-naphthylmethyl)- benzonitrile and 2-thienylmagnesiumbromide resisted hydrolysis to the corresponding ketone but cyclized quantitatively to 10-(2-thienyl)-l,2-benzanthracene. Following the classical Bradsher process, the reaction between 2-thienylmagnesiumbromide and o-chlorobenzaldehyde was unsuccessful because the hydrol formed was so reactive that it polymerized rapidly and ended up with tars. A cross-condensation reaction between 2-ethynylmagnesium bromide and o-chlorobenzylchloride was utilized to give the expected 2-(2'-chlorobenzyl)- thiophene in one step. This new procedure has been widely extended to the other series. It is preferred to. the conventional Bradsher process and the Friedel-Crafts method in terms of time, chemicals, and unequivocal products formed. 2-(2'-Chlorobenzyl)-thiophene so formed by the new procedure was converted by von Braun reaction to the corresponding nitrile and the nitrile was allowed to react with phenylmagnesiumbromide to give 2-(2-thienylmethyl)-benzophenone. The above ketone was cyclized almost quantitatively to 4-phenyl-thiophanthrene. The thiophene-containing ketones prepared in this research are very viscous oils. In order to have crystalline derivatives for identification purposes these ketones were oxidized to the corresponding diketones. 2-Thienyl-2-benzylbenzophenone and 2-(2'-thienylmethyl)- benzophenone gave the identical diketone, 2-benzoyl-2'- thienyl-benzophenone. 3 1 -Thienyl-2-benzylbenzophenone was oxidized to anthraquinone by using 25% sulfuric .acid, acetic acid and sodium dichromate. The formation of anthraquinone indicates that the monoketone cyclized first and then split off the thiophene ring. Apparently, the 3-thienyl group is more susceptible to oxidation than the 2’-thienyl group. A study of the oxidation of anthracene derivatives for structure proof was made using 9-phenylanthracene as a model compound. It was oxidized to 10-phenyl-10-hydroxyanthrone which resisted further oxidation to anthraquinone. It is obvious that the tertiary alcohol system stabilized the phenyl ring. In continuing the work on the 9-(dimethyl)-phenylanthracene series, the yields of three ketimine salts and one ketone were improved. Satisfactory analytical data was obtained for 2’,6’-dimethyl-2-benzylbenzophenone. In an attempt to overcome the steric effects offered by 2,6-ortho groups, 2-(2',3'-dimethylbenzyl)-benzonitrile was prepared. The starting material for this series, l-bromo-2,3-dimethylbenzene has been prepared in 47% yield by diazotization in comparison with the previous yield of 30%. / Doctor of Philosophy

Page generated in 0.0313 seconds