FI57427B - FOERFARANDE FOER FRAMSTAELLNING AV POLY-ALFA-HYDROXIAKRYLSYRA - Google Patents

Description

ESFH M (11) Announcement 5 74 2 7 VÄTTO L J '' UTLÄGGN I NGSSKRIFT ° 1 n e '' ·% ΛΡ C (45); -1 '° ^ v' (51) Kv.ik.3 / im.a.3 0 08 F 20 / 04-, 8/22 ENGLISH - FI N LAN D (21) Ptt * nttlh «lMmu» —pMMtmteknlns 2U6 / 73 (22) Hakemltpllv · »Aiweknlnpdii 29.01.73 (23) AlkupiWi — GlM | h« tsdaf 29.01.73 (41) Interpreters Swept - Bltvlt offmtllg 10.09.7 3 PMHittl · and the National Board of Registers N «ht» vtk.lp « on |. month |

Patent and registration authorities Antöktn utltgd och utl. * Krifwn pubiicurad 30.0U.80 (32) (33) (31) Pyydetty «uolkwi —B« gird prlorltut 09.03.72

Federal Republic of Germany-Förbundsrepubliken lyskland (DE) P 2211256.7 (71) Hoechst Aktiengesellschaft, 6230 Frankfurt (Main) 80, Federal Republic of Germany-Förbundsrepubliken Tyskland (DE) (72) Wilhelm Vogt, Hiirth-Efferen, Maingar - Edgar Fischer, Frankfurt Schwanheim, Eberhard Auer, Erftstadt-Liblar, Federal Republic of Germany Förbundsrepubliken Tyskland (DE) (7U) Oy Kolster Ab (5U) Process for the preparation of poly-α-hydroxyacrylic acid - Förfarande för framställning av poly-oHydydroxyacryl

The invention relates to a process for the preparation of poly-β-hydroxyacrylic acid having a molecular weight of about 800 to 30,000.

A large number of complexing agents have long been known and are used in particular in the manufacture of detergents and in the textile industry. In this case, their function is to complex bind calcium and magnesium ions, which cause the natural hardness of the water, and thus remove the hardness of the water. Sodium tripolyphosphate is most commonly used for this. Other good complexing agents include compounds of the aminoacetic acid type, such as nitrile acetic acid or ethylenediaminetetraacetic acid and the like. The use of these known complexing agents has the disadvantage that, due to their nitrogen and phosphorus content, they can contribute to the eutrophication of natural waters or wastewaters.

Thus, there is a need for substitutes which are equivalent in value to known complexing agents in terms of their complexing ability, but which do not have the above-mentioned disadvantages of known complexing agents.

Such substitutes are described in German Offenlegungsschrift No. 2,572,417,90¼9 ^ 0 as straight-chain or cross-linked polymers containing carboxylic, carboxylate and hydroxyl groups, having carbon-carbon bonds in the main chain and having a degree of polymerization of 3-5,000, preferably 3-600, whereby the polymers may consist of for example, units with general formulas:

R. R

r1 I

- CHp - C - (I) and - CHQ - C - (II) and / or

I I

: C00A CH2OH

~ H

- ch2 - C - (III)

OH

In the general formulas I, II and III A represents hydrogen or one valence of a monovalent or polyvalent metal, R 1 and are alkyl groups or hydrogen atoms and R 1 is an alkyl group or a hydrogen or halogen atom.

The complexing ability of these polymers with respect to calcium ions, expressed as complexing constants, is 1.8 to about 2.3 and is not sufficient for many applications. Moreover, these polymers can only be produced with poor yields, so that their use is uneconomical.

Other oligo- and / or polymers containing carboxyl and hydroxyl groups suitable as complexing agents, as described in German Offenlegungsschrift No. 2,168,888, are products obtained by hydrolysis of halogen-containing copolymers having a halogen content of about 5 to 60% by weight, these the halogen-containing copolymers are composed in the main chain of units of arbitrary order of general formulas (III) and (IV) or (III) and (V).

X Y Z HR

I II II

- CH '- C - (III) - C - C (IV) - C - C - (V)

I II II

R R R H CH0-R. 1-m m lm 2 5 i- - L_ _1 J_ Λ 3 57427

In the general formulas III, IV and V, X, Y and Z denote a hydrogen and / or halogen atom, at least one of the substituents being a halogen atom. R is a carboxyhalogen radical, a carboxylic, ester, nitrile or anhydride group and a molar proportion m of greater than 0 and less than 1. Polymers are obtained by hydrolysis of o (-halogenated copolymers of acrylic acid and maleic acid or their derivative acids and itaconic acids). , and their kcmplex formation constant for calcium is logK ^^ ^ ++ = 5 ~ β.

It has now surprisingly been found that the poly-of-chloroacrylic acid hydrolyzate already known per se has an excellent complexing ability with respect to polyvalent metal ions and thus does not have to be prepared from the complex and expensive copolymers described above.

The process according to the invention is characterized in that polyacrylic acid dissolved in glacial acetic acid or a mixture of glacial acetic acid or trichloroacetic acid and carbon tetrachloride is reacted with a stoichiometric amount of chlorine gas or bromine in the presence of a small amount of phosphorus trichloride and a very small amount of iodine at about 80 ° C. separating the excess chloro or vast, bromine by heating the reaction mixture to reflux, and then evaporating a portion of the solvent, precipitating the poly-of-chloro- or vast-bromoacrylic acid, then separating the precipitated poly-o (-chloro- or vast-bromoacrylic acid) and dissolving it into water, the solution is filtered and the poly-Of-hydroxyacrylic acid is recovered by evaporating the solution to dryness.

The poly-of-hydroxyacrylic acid is preferably prepared via poly-of-bromo-acrylic acid. The hydrogen bromide formed by the bromination of polyacrylic acid can be converted back to bromine by oxidation, so that the bromine is present only as an oxidant in the preparation of poly-hydroxyacrylic acid. No (-hydroksiakryylihappo.

The products according to the invention have an excellent kmplexing capacity, in particular with regard to calcium ions, and their stability constant I ° KKstab Ca ++ ° n The stability constant is thus of the same order of magnitude as with nitrile acetic acid having 6, h. Complexation of calcium ions with poly-o-hydroxyacrylic acid occurs, except for the effect of a small statistical distribution, in a stoichiometric ratio of 1: 3, i.e. three carboxyl groups are required to bind one calcium ion. The calcium chelate complex can be represented by the following formula: * · 57427,. CH / CH \ / CH OH CH.

/ >> x 2'y "

I I

ο xo ο θ (ο, o

The effect of the products according to the invention is not limited to the ability to form complexes with respect to calcium ions or other ions, but they can also keep certain amounts of calcium ions in solution in the presence of carbonate ions. Precipitation of CaCO 2 occurs in the presence of carbonate ions only when the stoichiometric ratio of poly-O 2 -hydroxyacrylic acid to Ca ions is exceeded, i.e. when less than two carboxyl groups are present for each calcium ion.

The complexing agents prepared according to the invention are technically superior to the previous complexing agents because, on the other hand, they are free of types and phosphorus and do not cause eutrophication of water bodies and their complexation constant with respect to calcium is of the technically required order of magnitude 5-8.

Hydrolysis of poly-T5 (haloacrylic acid) gives, as already described by Marvel, J.Am.Chem.Soc. 62, 3 ^ 95 (19 ^ 0), a partially lactonized poly-o? * Hydroxyacrylic acid which, depending on the method of preparation or the degree of chain crosslinking, correspondingly, it is more or less, but generally poorly soluble, so that it can be separated in a simple manner, for example by filtration.

Alkali salts obtained by neutralizing poly-Of-hydroxy acrylic acid with equivalent amounts of alkali are very soluble in water and are preferred for use as complexing agents.

Example 1 a) In a round beaker equipped with a stirrer and a reflux condenser, a mixture of 100 g of o-chloroacrylic acid, 100 ml of benzene and 1 g of benzoyl peroxide was boiled under a nitrogen atmosphere for three hours. The precipitated polymer was separated and dried in vacuo at U0 ° C. The yield of poly-of-chloroacrylic acid was 100% of theory.

b) A saturated aqueous solution of poly (o-chloroacrylic acid) was prepared at 30 ° C and this solution was boiled for 2 hours. The precipitated hydrolyzate was washed free of chlorides and dried in vacuo at 60 ° C. The yield of about a third of lactonized poly-hydroxyacrylic acid was 77%. g or 100% of theory The hydrolyzate had the following properties: 5 57427

The content of free, lactonized COOH groups was 55.2% by weight

Calcium complexability 160 mg Ca / g

Lime tower capacity 265 mg Ca / g logK _ ++ (measured at ionic strength 0.1) 7.0

SuSlD ΛΘ ·

Molecular weight 2800 c) Neutralization of 25 g of the poly-o-hydroxyacrylic acid obtained in b) in 25 g of 50- $ sodium hydroxide solution and evaporation to dryness gave poly-hydroxyacrylic acid n atr ium.su Ola.

Example 2

In a round-bottomed flask equipped with a stirrer and a reflux condenser, 180 g of polyacrylic acid having a molecular weight of 6,000 to 3,000 g were dissolved in 3000 g of glacial acetic acid at 80-95 ° C. After the addition of 10 g of PCl 2 and 5 g of iodine, U00 g of bromine was added dropwise and the temperature was slowly raised to 105 ° C. This was when the strong evolution of hydrogen bromide began. After the addition of bromine was complete, the mixture was heated to reflux until the excess brommi had evaporated, and then 1000 g of glacial acetic acid was distilled off. in a short time a poly-orbromoacrylic acid precipitate formed which was separated and dissolved in 3 liters of water. The solution was filtered and then evaporated to dryness. 170 g of poly-of-hydroxyacrylic acid were obtained as a residue. The hydrolyzate had the following properties:

Calcium complexability 78 mg Ca / g

Lime binding capacity 18U mg Ca / g logKsta ^ £ a ++ (measured at ionic strength 0.1) 6.85

Claims (1)

A process for the preparation of polyphenyl hydroxyacrylic acid having a molecular weight of about 800 to 30,000, characterized in that polyacrylic acid dissolved in glacial acetic acid or a mixture of glacial acetic acid or trichloroacetic acid and carbon tetrachloride is reacted with a stoichiometric amount of chlorine gas or bromine in the presence of a small amount of phosphorus trichloride and a very small amount of iodine at a temperature of about 80-110 ° C, after completion of the reaction chlorine or vast, the excess bromine is separated off by heating the reaction mixture to reflux, and part of the solvent is then evaporated to give poly (chloro or acrylic acid to precipitate, after which the precipitated poly-α-chloro- or vast-bromoacrylic acid is separated and dissolved in water, the solution is filtered and the poly-OH-hydroxyacrylic acid is recovered by evaporating the solution to dryness.