Thesis--University of Adelaide, Dept. of Organic Chemistry, 1968.

Thesis (Ph. D.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains xvi, 200 p. : ill. Includes abstract. Includes bibliographical references (p. 95-97).

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Orientador: Sebastião Ferreira Fonseca / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-12T12:48:57Z (GMT). No. of bitstreams: 1 Gomes_AlexLinardi_M.pdf: 2844676 bytes, checksum: bebeabd6bc573155e21e9f681146ff57 (MD5) Previous issue date: 2008 / Resumo: A fotodimerização de compostos orgânicos no estado sólido vem sendo utilizada como um método de síntese promissor na obtenção de substâncias ciclobutânicas. Pesquisas recentes relataram as atividades analgésicas e anticancerígenas dessas substâncias. Este trabalho teve como objetivo a obtenção de substâncias ciclobutânicas pelas fotodimerizações de ácidos trans-cinâmicos e cumarinas, no estado sólido, usando lâmpadas de vapor de mercúrio de 125W e 400W e um controle sistemático do tempo de exposição, com posteriores reações de transformações de grupos funcionais. Essas transformações forneceram substâncias com estruturas análogas às de lignanas ciclobutânicas naturais. A seqüência sintética envolveu a síntese dos ácidos trans-cinâmicos, fotodimerização no estado sólido, esterificação dos diácidos e posterior redução dos ésteres metílicos. Os resultados mais promissores foram obtidos com os ácidos 4-hidroxi-trans-cinâmico e trans-2-furilacrílico, que forneceram os dímeros a-truxílico e b-truxínico, respectivamente. Das três cumarinas irradiadas, 3-ácido carboxílico-cumarina, 7-metoxicumarina e 7-metilcumarina, apenas a última não mostrou evidências claras de dimerização. Os resultados obtidos foram correlacionados com o empacotamento cristalino favorável ou não das substâncias recristalizadas e submetidas a irradiação. As dimerizações foram confirmadas, inicalmente, pelo desaparecimento gradual da banda olefínica nos espectros de infravermelho e, depois, pelos sinais dos hidrogênios e dos carbonos do anel ciclobutânico, nos espectros de RMN H e RMN C, respectivamente. / Abstract: Photodimerization of organic compounds in the solid state has been used as promising synthetic method in the obtention of cyclobutanic substances. Accounts of recent research have mentioned the analgesic and anticarcinogenic activities of those substances. This work had as objective the obtention of cyclobutanic substances by the photodimerization of trans-cinnamic acids and coumarins, in the solid state, using mercury steam lamps of 125W and 400W and systematic control of the exposition time, with subsequent reactions of functional groups transformation. The synthetic sequence was developed by the syntheses of the trans-cinnamic acids, photodimerization in the solid state, esterification of the diacids and subsequent reduction of the methyl esters. The most promising results were obtained for 4-hydroxy-trans-cinnamic and trans 2-furylacrylic acids, which afforded a-truxillic and b-truxinic dimers, respectively. From the three coumarins irradiated, 3-carboxylic acid-coumarin, 7-methoxycoumarin and 7-methylcoumarin, only the last one do not showed clear evidence of dimerization. Those results were correlated with the favorable or unfavorable crystalline package of the substances recrystallized and submitted to the irradiation. The dimerizations were confirmed, initially, by the gradual disappearance of the olefinic band in the infrared spectra and, later, by the signals of the hydrogens and carbons of the cyclobutanic rings in the spectra of RMN H and RMN C spectra, respectively. / Mestrado / Quimica Organica / Mestre em Química

The thermal decomposition of cyclobutane is a homogeneous,unimolecular reaction;ethylene being the only product.The rate law :- K = 10¹⁵•³ e⁻⁶¹’⁰⁰⁰[symbol omitted] sec.⁻¹ was found to be obeyed in the pressure region 10 to 40 mm. and temperature range 398° to 450°C. Cyclobutane undergoes a wall reaction to form propylene and 1-butene. The high pressure rate constant falls off at low pressures and reaches a limiting low pressure rate when activation is maintained by collision with the walls of the reactor. The low pressure limiting rate decreases as the size of the reactor increases. The fall off curves gave best agreement with values of the Slater parameter, n, between 5 and 8, and values of the Kassel parameter, s, between 3 and 7. It was concluded that the ring vibrations are of major importance in the dissociation, and that the C—H bond vibrations are relatively unimportant. No evidence for a tetramethylene biradical intermediate was found. The reaction mechanism probably involves the simultaneous splitting of two opposite C—C bonds. / Science, Faculty of / Chemistry, Department of / Graduate