Amino acid surfactants
The present disclosure provides derivatives of amino acids that have surface-active properties. The amino acid can be naturally-occurring or synthetic, or they may be obtained via a ring-opening reaction of a lactam, such as caprolactam. The amino acid may be functionalized to form a compound that is surface-active and have advantageous surfactant characteristics. The compounds of the present disclosure have low critical micelle concentrations (CMC) as well as superior ability to lower the surface tension of a liquid.
1. A method of synthesizing an amino acid surfactant, comprising the steps of:
(1) opening a lactam to yield an amino acid having an N-terminus;
(2) reacting the N-terminus of the amino acid with an alkylating agent to yield a tertiary amine;
(3) reacting the tertiary amine with an alcohol under acidic conditions to yield an amino acid ester having an N-terminus; and
(4) reacting the N-terminus of the amino acid ester with an oxidizing agent to yield an amino acid surfactant of the following formula:
wherein R 1 and R 2 may be the same or different, and comprise at least one group selected from the group consisting of C 1 -C 6 alkyl.
2. The method of claim 1 , wherein in step 1, the lactam is caprolactam.
3. The method of claim 1 , wherein in step 2, the alkylating agent is formaldehyde or paraformaldehyde.
4. The method of claim 1 , wherein in step 3, the alcohol is dodecanol.
5. The method of claim 1 , wherein in step 3, the acid is p-toluene sulfonic acid.
6. The method of claim 1 , wherein in step 4, the oxidizing agent is hydrogen peroxide.