2026-09-20T05:10:07Zhttps://dspace.mit.edu/server/oai/request

oai:dspace.mit.edu:1721.1/607412022-01-13T07:54:20Zcom_1721.1_7582com_1721.1_7581col_1721.1_131024

George Büchi. Nelson, David A. (David Alan), 1931- Massachusetts Institute of Technology. Department of Chemistry 2011-01-26T14:17:20Z 2011-01-26T14:17:20Z 1953 http://hdl.handle.net/1721.1/60741 30946880 Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1953. MIT copy bound with: Solution and emulsion copolymerization of alkenyl siloxanes with vinyl type monomers / by Earl W. Mitchell. Includes bibliographical references (leaf 18). Introduction: Safranal is a cyclic monoterpene which occurs naturally in the saffron plant as a glucoside, picrocrocin. In 1922 Winterstein and TeleCzky obtained safranal by hydrolysis of picrocrocin, but its structure was not determined. Kuhn and Winterstein hydrolyzed picrocrocin in 1933 and obtained safranal and glucose in a one to one ratio. The structures for safranal and picrocrocin were determined. [illustration] Since this time there have been many attempts to devise a practical synthesis of safranal. Among these has been the work of Kuhn and Wendt, who obtained safranal in 1-3% yield by dehydrogenation of [beta]-cyclocitral. Karrer and Ochsner attempted its synthesis by bromination of [alpha]-cyclocitral with N-bromosuccinimide followed by dehydrobromination, but a rearrangement took place. Lunt and Sondheimer obtained a homolog of safranal, 4-methyl safranal, by a Diels-Alder type condensation. Other attempted syntheses have proven unsuccessful. This paper presents the results of attempts to synthesize safranal from the enol acetate of cyclocitral. It is a continuation of the work begun by Vittimberg in 1951. He succeeded in obtaining the enol acetate of cn good yield and determined its structure. Cyclocitral was prepared by first forming a Schiff base from citral (I) and aniline. This was cyclized with concentrated sulfuric acid and steam-distilled to give a mixture of [alpha]- and [beta]-cyclocitral (II and III) in a ratio of 2/3 to 1/3. This mixture was treated with a large excess of isopropenyl acetate to form the enol acetate of cyclocitral. Both [alpha]- and [beta]-cyclocitral give the same enol acetate (IV). by David A. Nelson. B.S. ii, 18 leaves eng Massachusetts Institute of Technology M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. http://dspace.mit.edu/handle/1721.1/7582 Chemistry The synthesis of safranal Thesis application/pdf false Publication unknown unknown <Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="8c01c693-f44a-4331-b542-23e50d8a0d48"> <Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type> <Language>eng</Language> <Title>The synthesis of safranal</Title> <PublishedIn> <Publication> </Publication> </PublishedIn> <PublicationDate>1953</PublicationDate> <Authors> <Author> <DisplayName>Nelson, David A. (David Alan), 1931-</DisplayName> <Affiliation> <OrgUnit> </OrgUnit> </Affiliation> </Author> </Authors> <Editors> </Editors> <Publishers> <Publisher> <DisplayName>Massachusetts Institute of Technology</DisplayName> <OrgUnit /> </Publisher> </Publishers> <License>http://dspace.mit.edu/handle/1721.1/7582</License> <Keyword>Chemistry</Keyword> <Abstract>Introduction: Safranal is a cyclic monoterpene which occurs naturally in the saffron plant as a glucoside, picrocrocin. In 1922 Winterstein and TeleCzky obtained safranal by hydrolysis of picrocrocin, but its structure was not determined. Kuhn and Winterstein hydrolyzed picrocrocin in 1933 and obtained safranal and glucose in a one to one ratio. The structures for safranal and picrocrocin were determined. [illustration] Since this time there have been many attempts to devise a practical synthesis of safranal. Among these has been the work of Kuhn and Wendt, who obtained safranal in 1-3% yield by dehydrogenation of [beta]-cyclocitral. Karrer and Ochsner attempted its synthesis by bromination of [alpha]-cyclocitral with N-bromosuccinimide followed by dehydrobromination, but a rearrangement took place. Lunt and Sondheimer obtained a homolog of safranal, 4-methyl safranal, by a Diels-Alder type condensation. Other attempted syntheses have proven unsuccessful. This paper presents the results of attempts to synthesize safranal from the enol acetate of cyclocitral. It is a continuation of the work begun by Vittimberg in 1951. He succeeded in obtaining the enol acetate of cn good yield and determined its structure. Cyclocitral was prepared by first forming a Schiff base from citral (I) and aniline. This was cyclized with concentrated sulfuric acid and steam-distilled to give a mixture of [alpha]- and [beta]-cyclocitral (II and III) in a ratio of 2/3 to 1/3. This mixture was treated with a large excess of isopropenyl acetate to form the enol acetate of cyclocitral. Both [alpha]- and [beta]-cyclocitral give the same enol acetate (IV).</Abstract> <Access xmlns="http://purl.org/coar/access_right" > </Access> </Publication>