Aminoundecanoic acid (BioDeep_00000003960)

描述信息

11-Aminoundecanoic acid is an organic compound with the formula H2N(CH2)10CO2H. This white solid is classified as an amine and a fatty acid. 11-Aminoundecanoic acid is a precursor to Nylon-11.[1]

As practiced by Arkema, 11-aminoundecanoic acid is prepared industrially from undecylenic acid, which is derived from castor oil.[2] The synthesis proceeds in four separate reactions:

1. Transesterification of castor oil to methyl ricinoleate:

Crude castor oil consists of about 80\\% triglycerides, from the ricinoleic acid, itself representing about 90\\% of the oil.[3] It is quantitatively transesterified with methanol to methyl ricinoleate (the methyl ester of ricinoleic acid) in the presence of the basic sodium methoxide at 80 °C within 1 h reaction time in a stirred reactor. At the end of the reaction, the resulting glycerol separates and the liquid methyl ester is washed with water to remove residual glycerol.

2. Pyrolysis of methylricinoleate to heptanal and methyl undecenoate:

Methylricinoleate is evaporated at 250 °C, mixed with hot steam (600 °C) in a 1:1 ratio and decomposed in a cracking furnace at 400 - 575 °C at a retention time of about 10 seconds into its cleavage products heptanal and methyl undecenoate. The cleavage of the aliphatic chain occurs in this variant of the steam cracking selectively between the hydroxymethylene and the allyl-methylene group. Besides heptanal and methyl undecenoate, a mixture of methyl esters of saturated and unsaturated C18-carboxylic acids is obtained. This mixture is known under the trade name Esterol and is used as a lubricant additive.

3. Hydrolysis of methyl undecenoate to 10-undecenoic acid

The hydrolysis of the methyl ester with sodium hydroxide proceeds at 25 °C within 30 min with quantitative yield. After acidification with hydrochloric acid, solid 10-undecenoic acid (undecylenic acid) is obtained.

4. Hydrobromination of 10-undecenoic acid to 11-bromoundecanoic acid

The undecenoic acid is dissolved in toluene and, in the presence of the radical initiator benzoyl peroxide (BPO), gaseous hydrogen bromide is added, in contrary to the Markovnikov rule ("anti-Markovnikov"). When cooled to 0 °C, the fast and highly exothermic reaction produces 11-bromoundecanoic acid in 95\\% yield - the Markovnikov product 10-bromoundecanoic acid is produced in small quantities as a by-product. Toluene and unreacted hydrogen bromide are extracted under reduced pressure and reused.

5. Bromine exchange of 11-bromoundecanoic acid to 11-aminoundecanoic acid

11-Bromodecanoic acid is mixed at 30 °C with a large excess of 40\\% aqueous ammonia solution. When the reaction is complete, water is added and the mixture is heated to 100 °C to remove the excess ammonia.

The acid can be recrystallized from water. For further purification, the hydrochloride of 11-aminoundecanoic acid, which is available by acidification with hydrochloric acid, can be recrystallized from a methanol/ethyl acetate mixture.

Aminoundecanoic acid. CAS Common Chemistry. CAS, a division of the American Chemical Society, n.d. https://commonchemistry.cas.org/detail?cas_rn=2432-99-7 (retrieved 2024-07-01) (CAS RN: 2432-99-7). Licensed under the Attribution-Noncommercial 4.0 International License (CC BY-NC 4.0).

CONFIDENCE Reference Standard (Level 1); INTERNAL_ID 1006

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