Methyl 10-undecenoate (2b) has been oxidized with tert-butyl hydroperoxide/selenium dioxide and potassium dichromate to 53% of methyl 9-oxo-10-undecenoate (4). Based on the conversion of 2b, the yield of 4 is 81%. Residual selenium in ester 5 was determined to be less than 1 ppm. The electrophilic double bond in enone 4 reacts in good to excellent yield with a variety of nucleophiles. With dimethyl malonate, acetylacetone, and methyl acetoacetate Michael-adducts at C-11 of enone 4 were obtained in 88-99% yield. Corresponding additions were achieved with nitroethane, 1-and 2-nitropropane in 78-89% yield. In a Nef-reaction some nitroalkyl adducts were converted to methyl esters of 9,12-dioxofatty acids in 99% yield. In methanol/sodium methoxide the ester methyl 11-methoxy-9-oxoundecanoate was obtained in 86% yield from enone 4. In a three step reaction with ammonium chloride/sodium cyanide, hydrochloric acid/acetic acid, and methanol/2,2-dimethoxypropane the ester 4 yielded 63% of dimethyl 4-oxo-dodecanedioate. With the cyanide ion the electrophilic carbon atom in aldehydes can be converted into a nucleophile (Stetter-reaction). Catalysed by sodium cyanide in DMF aromatic and heteroaromatic aldehydes RCHO with R ¼ phenyl, 2-thienyl, 2-furyl and 3-pyridyl were added to enone 4 to afford methyl 12-aryl-and methyl 12-heteroaryl-9,12-dioxododecanoates in 54-73% yield.Practical applications: The prepared oleochemicals are useful as precursors for pharmaceuticals and as monomers for polyesters and polyamides. They also may be applied to synthesize fatty acid conjugates by providing suitable connectors for biological active compounds and to attach groups with suitable physical properties for materials.

Amount of adsorbedacid inMethods for the conversion of renewable raw materials into synthetic intermediates have received increasing interest [21. In this field belongs the halogenation, hydroxylation or dehydrogenation of the alkyl chain in fatty acids. One of the challenging problems there is the selective chlorination of the terminal CH bonds in fatty acids. With N-chlorodialkylamines as reagents protonated fatty acids are chlorinated fairly selectively in the (This selectivity can be further improved, when additional steric and electronic factors are utilizedl41. The chloroalkanoic acids, which are obtained in these chlorinations, can be converted in good yields into the corresponding formyloxy-, azido-, amino-, oxoalkanoic acids, and unsaturated fatty acidsc5].An alternative to the electrostatic deactivation of CH bonds, used above, offers partial shielding of the alkyl chain. This seems to be possible by adsorption of the fatty acid in a monolayer on an inert support. Thereby the nonterminal methylene groups should screen each other and the chlorination of the terminal ones should be favored. When carboxylic acids with six to eight carbon atoms are adsorbed on alumina and chlorinated as a suspension in carbon tetrachloride the selectivity for the (w -1)-position is low[61. However, for the chlorination of stearic acid, that is adsorbed on alumina, with gaseous chlorine a high selectivity has been reportedC7]. This remarkable observation has caused us to investigate the selectivity of this reaction with regard to the chlorinating agent, the temperature and the chain length of the fatty acid. ResultsAmong the examined adsorbents, namely silica gel (grain sizes: 0.04 -0.063 mm and 0.063 -0.2 mm), acidic, neutral and basic alumina, neutral alumina has proved to be most favorable with regard to the amount of adsorbed fatty acid. The quantity of fatty acid, that can be adsorbed on neutral alumina (specific surface: 155 m'/g) depends on the chain length of the acid. It decreases from 61.5 mmo1/100 g A1203 for hexanoic acid (1) to 50.7 mmo1/100 g for stearic acid (7) and 44.8 mmo1/100 g for docosanoic acid (9), when the quantity is calculated on the amount of adsorbed moles of fatty acid; however, the quantity rises with increasing chain length, when this amount is calculated on percentage by weight of the adsorbed acid. The amount of adsorbed acid (see Table 1) is constant within the same batch of alumina but varies in different batches to an extent of +14%. The fatty acids must be mainly adsorbed perpendicular to the alumina surface and cover it with a monolayer to about 49% in the case of hexanoic acid and to 40% in the case of stearic acid. This follows from the required area for a fatty acid molecule, which is 20.5 A2 perpendicular to the surface[81 and 114 A* parallel to it in the case of stearic acid.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.