Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Patent
1997-02-12
1999-03-30
Shah, Mukund J.
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
510476, 510490, 510533, 525418, 525419, 525420, 525532, 525539, 528328, 528363, 528392, C08G 6910, C11D 337, C02F 512, G08G 7306
Patent
active
058889590
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a process for preparing polycondensates of aspartic acid by polycondensation of aspartic acid at from 140.degree. to 300.degree. C. in the presence of acidic catalysts and to the use of the reaction mixtures obtainable in the condensation as additive to phosphate-free or reduced phosphate detergents and cleaners.
DISCUSSION OF THE BACKGROUND
J. Med. Chem. 16 (1973) 893 discloses the polycondensation of aspartic acid in the presence of phosphoric acid. The molecular weight of the polycondensates depends on the ratio of aspartic acid to phosphoric acid.
DD-A-262 665 discloses the preparation of polyaspartimide by polycondensation of aspartic acid in the presence of, preferably, polyphosphoric acid and, where appropriate, subsequent further condensation of the polyaspartimide in solid phase at from 160.degree. to 200.degree. C.
In the process disclosed in DE-A-4 023 463, aspartic acid is polycondensed in the presence of phosphoric acid under pressures below 1 bar in at least 2 stages. The condensing agent used is phosphoric acid, phosphorus pentoxide or polyphosphoric acid. In the first stage of the process, mixtures of aspartic acid and condensing agent are polycondensed at from 100.degree. to 250.degree. C. to give polysuccinimides with molecular weights of about 10,000-100,000. The resulting compact, hard reaction mixture is subsequently comminuted mechanically and further condensed in a second polycondensation stage under the same temperature and pressure conditions as in the first stage.
The processes described above have the disadvantage that the phosphoric acid or polyphosphoric acid used as catalyst must be washed out of the polycondensate. A measure of this type is associated with considerable expense in industry. In addition, the phosphoric acid extracted from the polycondensates must be reconcentrated in order to be reusable as catalyst in the polycondensation.
WO-A-93/24661 discloses, inter alia, the preparation of polyaspartic acid and cocondensates of aspartic acid in the presence of inorganic acids. Apart from the acids of phosphorus which have been mentioned above, mention is made of hydrohalic acids, phosphorus acids in which the phosphorus has a lower oxidation state than plus 5, sulfuric acid, disulfuric acid, sulfur trioxide and sodium and potassium bisulfates.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a process for preparing polycondensates of aspartic acid in which polycondensates with a higher molecular weight than in the prior art are obtained.
We have found that this object is achieved by a process for preparing polycondensates of aspartic acid by polycondensation of aspartic acid at from 140.degree. to 300.degree. C. in the presence of acidic catalysts when sulfuric acid which is partially neutralized with ammonia and/or amines is used as catalyst.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The aspartic acid which is polycondensed by the process according to the invention can be in the form of L-, D,L- or D-aspartic acid. Polycondensation can be carried out with aspartic acid of the desired crystal size. The diameter of fine-particle aspartic acid subjected to the polycondensation is, for example, from 0.01 to 5 mm.
The polycondensation of the aspartic acid is carried out at from 140.degree. to 300.degree., preferably 150.degree. to 240.degree. C., in the presence of sulfuric acid which is partially neutralized with ammonia and/or amines. The molar ratio of sulfuric acid to ammonia and/or amines in the acidic ammonium bisulfates is, for example, from 1:0.5 to 1:1.5. The acidic catalyst which is preferably used is a partially neutralized sulfuric acid which is neutralized with from 0.8 to 1.2 mol of ammonia and/or amine per mol of sulfuric acid. Particularly preferred acidic catalysts have a molar ratio of sulfuric acid to ammonia and/or amines of 1:1. Ammonium bisulfate, trimethylammonium bisulfate and triethylammonium bisulfate are among the particularly
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Journal of Medicinal Chemistry, 1973, vol. 16, No. 8, Philip S. Portoghese, Editor.
Kroner Matthias
Schornick Gunnar
BASF - Aktiengesellschaft
Kifle Bruck
Shah Mukund J.
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