Method for producing monohydroxypolyalkylene oxides

Abstract

The present invention relates to a process for the preparation of monohydroxypolyalkylene oxides (MPAO) which are substantially free of diols, comprising the reaction of at least one monoalcohol as a starter with at least one alkylene oxide in the presence of at least one basic catalyst, the catalyst being used as a solution in water or alcohol or in solvent mixtures which comprise water and/or alcohol.

Claims

1. A processes for producing a monohydroxypolyalkylene oxide (MPAO), the process comprising: combining at least one starter and at least one basic catalyst, to obtain an initial mixture; distilling the initial mixture until at least 0.1% by weight of the at least one starter is distilled off; and adding at least one alkylene oxide to the at least one starter and at least one basic catalyst immediately after the distilling, and then reacting the at least one starter with the at least one alkylene oxide in the presence of at least one basic catalyst in solution, to obtain a monohydroxypolyalkylene oxide (MPAO), wherein: the monohydroxypolyalkylene oxide (MPAO) obtained from said reacting comprises not more than 10,000 ppm of a diol, water is present during said reacting of at least one starter with at least one alkylene oxide in the presence of at least one basic catalyst in solution, and the water is present during said reacting in an amount of greater than 1,000 ppm, each of said at least one starter is a compound represented by formula (I):
R.sup.1(OCH.sub.2CHR .sup.2).sub.kOH (I); R.sup.1 is an aliphatic or an aromatic radical; R.sup.2 is hydrogen or an aliphatic or an aromatic radical; k is an integer from 1 to 15; and the basic catalyst solution comprises an alkali metal hydroxide or an alkali metal methylate and an alcohol other than the starter as the solvent of the basic catalyst solution.

2. The process of claim 1, wherein, in formula (I): R.sup.1is a C.sub.1 to C.sub.13-alkyl radical; R.sup.2 is hydrogen or a C.sub.1- to C.sub.4-alkyl radical; and k is an integer from 1to 5.

3. The process of claim 1, wherein the each starter is diethylene glycol monomethyl ether.

4. The process of claim 1, wherein the alkylene oxide is ethylene oxide.

5. The process of claim 1, wherein the monohydroxypolyalkylene oxide (MPAO) obtained from said reacting comprises not more than 6,000 ppm of a diol.

6. The process of claim 1, wherein the MPAO comprises from 5 to 200 alkylene oxide units.

7. The process of claim 1, carried out in a reactor comprising an initial amount of up to 2% by weight of a maximum reactor content of MPAO, before the reacting.

8. The process of claim 1, wherein each of the at least one starter is obtained by a process comprising reacting at least one monoalcohol with at least one alkylene oxide in the presence of at least one basic catalyst.

9. The process of claim 1, wherein the monohydroxypolyalkylene oxide (MPAO) obtained from said reacting comprises not more than 4,000 ppm of a diol.

10. The process of claim 1, wherein alcohol other than the starter is a linear or branched alcohol having from one to five carbon atoms.

11. The process of claim 1, wherein the monohydroxypolyalkylene oxide (MPAO) obtained from said reacting comprises not more than 2,000 ppm of a diol.

12. The process of claim 1, wherein water is present during said reacting of at least one starter with at least one alkylene oxide in the presence of at least one basic catalyst in solution, and the water is present during said reacting in an amount of greater than 1,000 ppm to 5,000 ppm.

Description

EXAMPLES

(1) The following examples are intended to illustrate the properties of this invention, but without limiting it.

(2) Parts, percent or ppm are understood in this document as meaning proportions by weight, unless stated otherwise.

(3) The determination of the diol content was effected by liquid chromatography by HPLC. For this purpose, the free OH groups of the products were derivatized by reaction with an excess of phenyl isocyanate. The chromatographic separation is then effected by means of an HPLC pump of the Varian 9012 type on a silica gel column of the Intersil ODS-3 type (5 m, 150 4 mm). The detection was effected with a UV detector of the Varian 9050 type.

(4) The OH number was determined according to DIN 53240 by esterification of the OH groups with acetic anhydride and back-titration of the unconsumed acetic acid. The molar mass was calculated from the OH number thus determined.

(5) Preparation of Polyethylene Glycol Monomethyl Ether Having an Average Molar Mass of 1990 g/mol (MPAO 1)

(6) 1744 kg of diethylene glycol monomethyl ether and 55.3 kg of a 45% strength solution of potassium hydroxide in water were initially taken in a stirred reactor. The mixture was heated to 125 C. in 30 min under reduced pressure (90 mbar) and the reduced pressure was subsequently eliminated with nitrogen. Thereafter, 24 137 kg of ethylene oxide were metered in at a temperature of 150 C. at a pressure of not more than 5.2 bar. After metering was complete, the reactor content was neutralized by addition of 27.1 kg of acetic acid and the reactor was then emptied.

(7) Preparation of Polyethylene Glycol Monomethyl Ether Having an Average Molar Mass of 2900 g/mol (MPAO 2)

(8) 1211 kg of diethylene glycol monomethyl ether were initially taken simultaneously with 50.1 kg of 45% strength by weight potassium hydroxide solution in a reactor. The mixture was heated to 125 C. in 30 min under reduced pressure (90 mbar) and the reduced pressure was subsequently eliminated with nitrogen. Thereafter, 24 669 kg of ethylene oxide were metered in at a temperature of 150 C. at a pressure of not more than 5.6 bar. After metering was complete, the reactor content was neutralized by addition of 26.5 kg of acetic acid and the reactor was emptied. During the emptying, 2.2 kg of 2,6-di-tert-butyl-4-methylphenol were metered into the product stream behind the bottom outflow of the reactor.

(9) Preparation of Polyethylene Glycol Monomethyl Ether Having an Average Molar Mass of 4700 g/mol (MPAO 3)

(10) 796 kg of diethylene glycol monomethyl ether were initially taken simultaneously with 36.5 kg of a 45% strength by weight potassium hydroxide solution in a reactor. The mixture was heated to 125 C. in 30 min under reduced pressure (90 mbar) and the reduced pressure was subsequently eliminated with nitrogen. Thereafter, 25 698 kg of ethylene oxide were metered in at a temperature of 150 C. at a pressure of not more than 5.1 bar. After metering was complete, the reactor content was neutralized by addition of 27.1 kg of acetic acid and the reactor was emptied.

Example 1

(11) The polyethylene glycol monomethyl ethers MPAO 1 to 3 described above were carried out in the same reactor in the sequence stated in table 1. The reactor was not cleaned between the individual experiments. The analytical values stated in table 1 were achieved:

(12) TABLE-US-00001 TABLE 1 OH number Diol content Example Product [mg KOH/100 g] [% by wt.] 1.1 MPAO 2 19.7 0.1 1.2 MPAO 2 19.8 0.2 1.3 MPAO 2 19.1 0.2 1.4 MPAO 1 27.1 0.2 1.5 MPAO 3 12.3 0.3

Example 2

(13) The polyethylene glycol monomethyl ethers MPAO 1 to 3 described above were carried out in the same reactor in the sequence stated in table 2. The reactor was not cleaned between the individual experiments. The analytical values stated in table 2 were achieved:

(14) TABLE-US-00002 TABLE 2 OH number Diol content Example Product [mg KOH/100 g] [% by wt.] 2.1 MPAO 1 28.2 0.1 2.2 MPAO 1 28.0 0.5 2.3 MPAO 1 28.4 0.4 2.4 MPAO 1 29.0 0.6 2.5 MPAO 3 11.4 0.3

Example 3

(15) MPAO 2 was prepared five times in the same reactor. The reactor was not cleaned between the individual experiments. The analytical values stated in table 3 were achieved:

(16) TABLE-US-00003 TABLE 3 OH number Diol content Example Product [mg KOH/100 g] [% by wt.] 3.1 MPAO 2 19.3 0.1 3.2 MPAO 2 19.4 0.3 3.3 MPAO 2 19.3 0.2 3.4 MPAO 2 19.9 0.3 3.5 MPAO 2 19.1 0.3

Example 4

(17) MPAO 1 to 3 were prepared in random order 136 times altogether in the same reactor, the sequence of the MPAO batches being interrupted by altogether 94 cleaning operations with water and/or steam and in random order so that between one and eight batches of MPAO were prepared in succession without interruption. The following average analytical values and variations were achieved:

(18) TABLE-US-00004 TABLE 4 Diol (Diol OH number (OHN) content content) Product [mg KOH/100 g] [mg KOH/100 g] [ppm] [ppm] MPAO 1 28.61 1.38 3950 2206 MPAO 2 19.22 0.42 2807 1735 MPAO 3 12.15 1.75 3000 1788