Method for producing aqueous ortho-phthalaldehyde solutions
View Patent ↗A method for producing aqueous ortho-phthalaldehyde solutions which comprises introducing an acetal of the o-phthalaldehyde into water and subsequently setting a pH <7 by adding an acid, whereupon, then at a temperature between 10° C. and 90° C., the acetal is converted into the o-phthalaldehyde by eliminating the corresponding alcohol, and also use of OPA acetals for producing these solutions.
1. A method for producing an aqueous ortho-phthalaldehyde solution which comprises the steps of:
(a) forming a precursor solution by introducing an acetal of the o-phthalaldehyde into water,
(b) acidifying the precursor solution to a pH <7 by adding an acid to the precursor solution,
(c) forming an aqueous ortho-phthalaldehyde solution consisting of ortho-phthalaldehyde, water and the eliminated corresponding alcohol by bringing the acidified precursor solution obtained according to step (b) to a temperature between 10° C. and 90° C. to thereby convert the acetal into o-phthalaldehyde by eliminating the corresponding alcohol, and
(d) retaining the corresponding alcohol eliminated according to step (c) in the aqueous ortho-phthalaldehyde solution so as to aid in the dissolution of the converted o-phthalaldehyde therein.
2. The method as claimed in claim 1 , wherein the acetal of the o-phthalaldehyde is a dialkylacetal or a dialkoxyphthalane having 1 to 6 carbon atoms in the alkyl moiety.
3. The method as claimed in claim 1 , wherein step (b) is practiced by adding to the precursor solution a mineral acid or an organic acid.
4. The method as claimed in claim 1 , wherein the precursor solution is acidified to a pH up to 3.
5. The method as claimed in claim 1 , wherein the aqueous o-phthalaldehyde solution obtained by steps (a) through (d) contains between 0.025 to 9% by weight o-phthalaldehyde.
6. The method as claimed in claim 1 , further comprising adding to the precursor solution a solubilizer which is at least one selected from the group consisting of polyethylene glycol, N-methylpyrrolidone, acetone and glutaraldehyde.
7. The method as claimed in claim 1 , further comprising adding to the precursor solution at least one aid selected from the group consisting of stabilizers, antioxidants, fragrances and dyes.
8. The method as claimed in claim 1 , further comprising after step (c) the step of neutralizing the aqueous o-phthalaldehyde solution to a pH of 4 to 10 by adding a base thereto.
9. The method as claimed in claim 1 , wherein the aqueous ortho-phthalaldehyde solution is produced in an automated disinfection apparatus.
10. The method as claimed in claim 3 , wherein the mineral acid is at least one selected from the group consisting of sulfuric acid and hydrochloric acid.
11. The method as claimed in claim 3 , wherein the organic acid is at least one selected from the group consisting of formic acid, acetic acid and glyoxylic acid.
12. An aqueous ortho-phthalaldehyde solution which consists of o-phthalaldehyde, water and a corresponding alcohol eliminated by an acidified reaction of an acetal of the o-phthalaldehyde.