Undecanoic acid, 11-bromo

The addition of hydrogen bromide (but not the iodide or chloride) in the presence of an added peroxide catalyst proceeds by a radical mechanism, giving rise to a regioselectivity which is opposite to that of the ionic mechanism (anti-Markownikoff). An example is provided in the preparation of 11-bromo-undecanoic acid (Expt 5.65). 

Bromine appears at the 10-position on addition of HBr to 10-undecanoic acid or its ethyl ester in benzene if the HBr is introduced under H2, diphenylamine is added as antioxidant, or impurities (aldehydes) that form peroxides in air are previously removed.200,213 However, in presence of peroxides (which may be specifically added or formed from adventitious aldehyde and atmospheric oxygen), radical addition of HBr occurs, leading to 11-bromo-undecanoic acid or its ethyl ester 200 213... 

Alternatively, the TTF or the dithiapyrene was lithiated, treated with elemental sulfur, and allowed to react with the potassium salts of co-bromo- or 0)-iodo-undecanoic acid or -hexadecanoic acid (Fig. 3, compounds 4, 5,6, 7, and 8). 

PHAs Brominated units Nonanionic and octanionic acids H-6-bromohexanoic, 8-bromo-octanoic acid or 11-bromo-undecanoic acid [59]... 

L-a Glycerophosphorylcholine cadmium chloride complex was prepared by hydrolyzing egg lecithin which was isolated from egg yolk. 1-Dodecyne, undecylenic acid, 11-bromo undecanoic acid, nonanoic acid, lithium acety-lide ethylenediamine complex, dimethylaminopyridine (DMAP), and dicyclo-hexylcarbodiimide (DCC) were purchased from Aldrich Chemical Co. Milwaukee, WI. Tridecyne was obtained from Farchan Laboratories, Gainesville, FL, and 1,2-dihexanoyl and 1,2-dipalmitoyl PC were purchased from Avanti Polar Lipids, Birmingham, AL. Mixed bed resin AG 501-X8(D) was procured from Bio-Rad Laboratories, Richmond, CA. Chloroform was distilled freshly over phosphorus pentoxide just before the use. Other solvents were used as received. The water was triply distilled and deionized. 

This p. is based on - undecylenic acid, which derives from - castor oil and represents a p. of type II. Undecylenic acid is reacted with HBr in the presence of peroxides or air in, e.g., toluene at 30°C. 11-Bromo-undecanoic acid is formed in over 95% yield. Further reaction with 25% aqueous ammonia gives the desired 11-amino-undecanoic acid. Repeated crystallization enhances the pinity of the monomer. The polycondensation is carried out in a column with three zones melting, main reaction and equilibration of m.w. Phosphorous and phosphoric acids and their salts act as catalysts. The resulting p. (m.p. 190 °C) is very hydrophobic, has a low moisture content and is therefore used in electrical insulation. Other applications are as filament, powder - coatings and - molded goods. Castor oil consumption for this area was 35000 mt (1988). 

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