Unsaturated hydrobromination

The starting amino acid for nylon-11 is produced from methyl ricinoleate [141 -24-2] which is obtained from castor oil (qv). The methyl ricinoleate is pyrolized to methyl 10-undecylenate [25339-67-7] and heptanal [111-71-7]. The unsaturated ester is hydroly2ed and then converted to the amino acid by hydrobromination, followed by ammoniation and acidification. The CO-amino acid product is a soft paste containing water, which is dried in the first step of the polymeri2ation process. 

Like alkenes, the double bonds of ,/3-unsaturated acids can be brominated, hydroxylated, hydrated, and hydrobrominated, although the reactions often are relatively slow. In the addition of unsymmetrical reagents the direction of addition is opposite to that observed for alkenes (anti-Markownikoff). Thus propenoic (acrylic) acid adds hydrogen bromide and water to form 3-bromo-and 3-hydroxypropanoic acids ... 

Xfi-Dienes. The reagent undergoes a light-catalyzed regioselective addition to al-kenes, particularly mono-, 1,1-di-, and trisubstituted alkenes. The adducts undergo de-hydrobromination to a,p-unsaturated bromomethyl sulfones. On treatment with potassium... 

Electroreduction of pyridazines in the presence of acetic anhydride gives the acylated open-chain diamines (cf. 117 -> 222). In aqueous solution a 1,2-dihydropyridazine is formed, which decomposes to nitrogen and an unsaturated hydrazino-aldehyde that polymerizes. Allylic bromi-nation of l,2-dicarbomethoxy-l,2,3,6-tetrahydropyridazine followed by de-hydrobromination gives l,2-dicarbomethoxy-l,2-dihydropyridazine. Catalytic hydrogenation gives the hexahydro compound." ... 

PREPARATIVE TECHNIQUES Nylon 11 is prepctred by a condensation polymerization reaction. The commercial monomer is 11, aminoundecanoicacid. This aminoacid is unique among the nylon monomers because it is made from Ccistor oil, a renewable, agricultural raw material. The 18-carbon ricinoleicacid is thermally cracked to 7-carbon and 11-carbon fractions. The 11-carbon portion has an omega unsaturation, which is hydrobrominated then aminated to the aminoacid monomer. ... 

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