High-concentration aqueous solutions of betaines or amine oxides
View Patent ↗The present invention relates to a composition and a method for preparing high-concentration aqueous solutions of betaines or amine oxides which comprise a water-soluble carbohydrate. The high-concentration aqueous solutions of the present invention are pumpable, viscous liquids which are self preserving and remain storage stable for long periods without any bacterial decomposition. The high-concentration aqueous solutions of the present invention are prepared by adding a water-soluble carbohydrate such as cyclodextrins or dextrans to an aqueous solution of the betaine or amine oxide and concentrating the aqueous solution to provide the high-concentration aqueous solution.
1. A method for preparing a pumpable, high-concentration aqueous liquid solution of betaines or amine oxides, said method consisting of admixing 32 to 38 percent by weight of said betaines or amine oxides during or after synthesis of said betaines or amine oxides in water and from 0.05 to 2 percent by weight of a cyclodextrin selected from the group consisting of β-cyclodextrin, γ-cyclodextrin, and mixtures thereof and optionally removing a portion of the water to provide said pumpable, high-concentration aqueous liquid solution.
2. The method of claim 1 , wherein the betaines or amine oxides are compounds of the following formulae
where R is an alkyl, hydroxyalkyl or alkylphenyl group having 8 to 22 carbon atoms, each radical R 1 , independently of the others, is an alkyl or hydroxyalkyl group having 1 to 3 carbon atoms or a polyethylene oxide group having 1 to 3 ethylene oxide units, or two R 1 groups are joined together via an —O or —NH group to form a ring, R 2 is an alkylene group having 2 to 3 carbon atoms or mixtures thereof and x is an number from 0 to 10.
3. The method of claim 1 , wherein the amine oxide or betaines is cocoamidopropylbetaine and the cyclodextrin is β-cyclodextrin.
4. The method of claim 1 , wherein the betaines is a synthesis product of cocoamidopropylamine and monochloroacetic acid in the presence of sodium hydroxide and the cyclodextrin is γ-cyclodextrin.
5. A pumpable, viscous liquid prepared according to the method of claim 1 .