Rearrangement of epoxy fatty esters to keto fatty esters

Series of octadecenoic (cis and trans), octadecynoic, octadecadienoic (cis, cis and trans, trans), and octadecadiynoic acids have been synthesized and employed in a comparative study of some physical (melting point, Raman spectra, NMR spectra, Ag + thin layer chromatography, and gas liquid chromatography) and biological properties. The results show that the position of unsaturation has a considerable influence on the physical and biological properties of isomeric unsaturated acids. Several chemical reactions of linoleic acid and of the related oxygenated acids ricinoleic or vernolic (12,13-epoxyoleic) furnish cyclopropane compounds and 1,4-(or 1,5-)epoxides. The formation of these is rationalized in terms of neighboring group participation. The oxymercuration-demercuration reaction is the basis of a new method of examining acids with A3, A4, or A5 unsaturation.

Section: Cyclopropane Esters From/3-hydroxyalkenes And/3~(-epoxyalkensupporting

confidence: 73%

Some physical, chemical, and biological properties of natural and synthetic unsaturated C₁₈ acids

Gunstone

1973

“…The experimentally determined ratios of C, H, and O were 80.82, 12.80, and 6.38%, respectively. (21) also found that the rearrangement of the epoxy group in the middle of the chain of FA esters catalyzed by BF 3 produced ketones. The catalysts produced a ketone according to the reaction in Scheme 2 (18).…”

Section: Resultsmentioning

confidence: 93%

The study of oxazolidone formation from 9,10‐epoxyoctadecane and phenylisocyanate

Javni

Guo

Petrovìć

2003

The formation of oxazolidone from 9,10-epoxyoctadecane and phenylisocyanate was studied. One branch of epoxidized vegetable oil with one epoxy group per chain corresponds to 9,10-epoxyoctadecane. This model could explain the probability of oxazolidone formation from natural oil-derived epoxides. Epoxidized natural oils are TG consisting of glycerin and three FA with or without one to three epoxy groups in the middle of the chain. To study oxazolidone formation from an internal epoxy group without possible interference from the side reactions on the ester group, 9,10-epoxyoctadecane was selected as the most appropriate model compound. Epoxy groups in the middle of a long aliphatic chain are of low reactivity toward isocyanates, and preparation of oxazolidones requires fairly harsh conditions such as high temperatures and catalysts, which also promote side reactions. The dominant side reaction is rearrangement of the epoxy groups. We found that the direction and magnitude of the rearrangement and the yield of any particular product depended on the catalyst used. Lithium chloride, aluminum trichloride, and zinc iodide catalyzed oxazolidone formation, along with the catalysis of side reactions such as ketone and carbonate formation. Aluminum trichloride showed the highest conversion of 9,10-epoxyoctadecane to oxazolidone. Aluminum triisopropoxide, triphenylantimony iodide, and imidazole did not catalyze the formation of oxazolidone. They were effective as catalysts of epoxy group rearrangement and promoted the formation of hydroxyl, ketone, and carbonate compounds. Hydroxyl groups reacted with isocyanate to produce urethane.Paper no. J10256 in JAOCS 80, 595-600 (June 2003).FIG. 1. FTIR spectra of the liquid product synthesized with zinc iodide, lithium chloride, and aluminum trichloride as catalysts.

“…The reaction involves a pinacol rearrangement in the long-chain wax, even though it is much slower than that in short chains (Zeltser, I., and A. Shani, unpublished results). Its advantage is that no hydroxy derivatives are formed, in contrast to the classical pinacol rearrangement of long-chain epoxyacids and esters (8).…”

Section: Resultsmentioning

confidence: 99%

Pinacol rearrangement of jojoba bis‐epoxide

Zeltser

Shani

2002

Jojoba bis-epoxide (1.6 mmol) undergoes pinacol rearrangement upon reaction with the iodide ion (60 mmol) under slightly acidic conditions, via an iodohydrin as an intermediate, to yield bis-ketojojoba in high yield (92%) after 25 h reflux in THF; no hydroxy derivatives were detected. Since the nucleophilic opening of the epoxide ring is statistically equal on both sides, the rearranged product may have the two carbonyl groups on either side of the original carbon atoms of the two epoxide rings, both completely opened. MS of the rearranged products reveals that the ring opening is approximately equal on both sides of the epoxide ring. Other nucleophiles, such as acetate and amine, open the ring sluggishly without rearrangement. SCHEME 1 CH 3 (CH 2 ) 7 CH=CH(CH 2 ) m COO(CH 2 ) n CH=CH(CH 2 ) 7 CH 3 I m = 7, 9, 11, 13 n = 8, 10, 12, 14 Average composition (%) 11, 71, 14, 1 1, 45, 44, 9 CH 3 (CH 2 ) 7 CH-CH(CH 2 ) m COO(CH 2 ) n CH-CH(CH 2 ) 7 CH 3 O O