DE974767C - Process for the production of polyglycol ethers of higher alcohols - Google Patents

Description

The invention relates to the production of a new class of polyglycol ethers of higher, saturated, aliphatic, monohydric alcohols. These ethers have such properties that they stand for particularly suitable for use as effective non-ionic wetting agents. The invention relates to in particular a process for the production of polyethylene glycol ethers higher secondary alkanols with 10 to 17 carbon atoms. The compounds obtained have a network effect that is up to three times stronger than the effect of compounds that, hitherto starting from these alkanols, by the known one-step process, i. H. through treatment these alkanols with ethylene oxide in the presence of alkaline catalysts were obtained.

So far, the polyethylene glycol monoalkyl ethers produced and sold as wetting agents have with regard to the surface activity effect is the alkylphenoxy polyethylene glycol compounds not reached. The aliphatic polyglycol ethers were generally made by reacting a higher straight chain or branched, primary or secondary alkanols with 6 to 20 moles of ethylene oxide per mole of alkanol and prepared in the presence of caustic alkali or alkali metal alcoholates at temperatures of about 100 to 180 ° C.

Although the substances produced in this way are powerful surfactants, there is nevertheless there is an increasing demand for an improvement in the network efficiency of the connections this kind.

109 574/6

The invention is based to an essential part on the observation that under corresponding Reaction conditions the rate at which ethylene oxide with the hydroxyl group of the higher Alcohols, the molecular weight of which is about 160 or higher, react in the presence of an alkali catalyst has approximately the following order of magnitude: monoalkyl ethers of polyoxyethylene glycols: 40; primary Alcohols: 30; secondary alcohols: 1. Many of the inevitable higher molecular weight condensation products of ethylene oxide with these alcohols, which are obtained in the presence of an alkali catalyst, but like the low molecular weight products are not very effective surface-active agents, especially with regard to their wetting effect. It was also found that in the reaction of ethylene oxide with these higher secondary or primary alkanols in the presence of an acidic catalyst, z. B. boron trifluoride, a much larger proportion of the ethylene oxide with the original alkanol instead of reacting with the monoalkyl glycol ether formed first, as does the alkali-catalyzed Reaction is the case.

For example, the reaction of equimolar amounts of purified 2,6,8-trimethyl-4-nonanol and ethylene oxide in the presence of an acidic catalyst at 50 ⁰ C leads to a 42% reaction of the alkanol with the ethylene oxide, a mixture of monotrimethylnonyl ether compounds of the mono- , Di-, tri- and tetraethyl glycols with an average molecular weight of 290 is obtained. In a similar experiment, but using a sodium alcoholate catalyst and higher reaction temperatures, only 10% of the alkanol reacted with all of the ethylene oxide, which shows that the rate of reaction of the oxide with the glycol monoalkyl ether products compared to the rate at which the oxide with reacting to the original alcohol was extraordinarily large. In the acid-catalyzed process, therefore, four times as much secondary alcohol was converted to the monoalkyl ether of ethylene monoglycol and polyglycol than was the case in the one-stage, hitherto customary alkali-catalyzed reaction. The mixture of monoalkyl ethers of the glycols mentioned, which was prepared in the presence of an acidic catalyst, had a much narrower molecular weight range than when it was obtained using an alkaline catalyst. According to the invention, secondary and primary alkanols with 10 to 17 carbon atoms can now be prepared in good yields to the corresponding monoalkyl ether compounds of ethylene glycol and polyethylene glycols with a narrower molecular weight range and with very effective surface-active properties in two stages by the fact that in the first stage alkanol and ethylene 'Oxide are reacted with one another in the presence of an acidic catalyst under conditions which promote the initial reaction of the ethylene oxide with the alkanol and keep the reaction of the ethylene oxide with the mono- and polyethylene glycol ethers as low as possible as soon as these are formed, which then follows in the second stage Removal of the acidic catalyst and all of the unreacted alkanol, the mixture obtained with ethylene oxide in the presence of an alkali metal alcoholate of the original alkanol or preferably the corresponding alcoholate of the herge in the first process stage provided monoalkyl ethers of mono- or polyethylene glycol is reacted. The catalysts of the second stage can be prepared in situ by reacting the purified product of the first reaction stage with an alkali metal, an alkali metal oxide or hydroxide, which will be described in more detail below.

The acidic catalyst used in the first stage of the process can be a Friedel-Crafts catalyst be e.g. B. the chloride or fluoride of boron, aluminum, iron, tin or titanium or a complex these halides with ethyl ether. Sulfuric acid and phosphoric acid are also effective.

The ethylene oxide may be several hours under stirring in a mixture of secondary alkanol containing 0.02 to 0.05% of ^{0 <i it} more acidic catalyst, based on its weight contains, are introduced. The reaction mixture is kept at a temperature of 0 to 80 ° C., preferably about 50 ° C., and at a pressure of 1 to 3.5 atm. This reaction is carried out until all of the ethylene oxide added has reacted with the alkanol. So much ethylene oxide is introduced into the alkanol that it reacts with it in a molar ratio of 0.2: 1 to 4: 1, preferably 0.8: 1 to 1.5: 1. A molar ratio of 1: 1 gives excellent results.

The reaction mixture is then neutralized, generally with a 10% strength methanolic Sodium hydroxide solution, the neutralized reaction mixture is fractionally distilled in vacuo and not yet separated off converted secondary alkanol.

The distillation residue consists of a mixture of monoalkyl ethers of ethylene glycol and the lower polyethylene glycols and normally has an average molecular weight of 200 to 400.

This residue from monoalkyl ethers of ethylene glycol and polyethylene glycols is then with about 0.5 to 75 mole percent, preferably with about 4 mole percent, of an alkali metal alcoholate des Monoalkyl ethers of one of the glycols mentioned, preferably mixed with an ether compound, which corresponds to an ether obtained in this residue from the first process stage.

The alcoholate can be prepared in situ by treating this residue with a powdered caustic alkali or with an alkali metal or an alkali metal alcoholate of a lower molecular weight alcohol, e.g. Can as the methanol react while heating the mixture to 80 to 200 ⁰ C. The desired reaction is carried out under a nitrogen atmosphere, water or low molecular weight alkanol, as soon as it occurs in the reaction, being removed until essentially all of the alkali metal, caustic alkali or other corresponding compounds have reacted with the glycol monoether.

Ethylene oxide is then slowly introduced with stirring into the mixture of monoalkyl ethers of ethylene glycol: and the di- or tri- or higher polyethylene glycols, while the temperature between 80 to 2oo ° C _{1 is} preferably kept at about 125 ⁰ C ₁ until an o , 5 percent strength by weight aqueous solution of the product obtained shows turbidity at 10 to 100 ° C. The more ethylene oxide reacts, the more water-soluble the product and the cloud point

ίο increases in the same direction. The cloud point is the temperature at which the product precipitates from a 0.5 ° / _o aqueous solution due to an inverse solubility. In these surface-active products obtained in this way, the molar ratios of converted ethylene oxide to converted alkanol are in the range from 4: 1 to 20: 1.

For simplicity, the invention is illustrated by examples in which branched secondary alkanols having 10 to 17 carbon atoms, such as 2,6,8-trimethyl-4-nonanol, is illustrated. One can but of course other branched or straight chain secondary alkanols are also effective in that Use procedure. Primary alkanols with 10 to 17 carbon atoms are also suitable for this if the process also offers somewhat fewer advantages in the case of the primary alkanols.

The alkanols which have been found to be useful in the new process include, inter alia. the following compounds: 2-methyl-7-ethyl-4-nonanol; 2,7-dimethyl-4-decanol; 2-butyloctanol; 2,6,8-trimethyl-4-nonanol; i-dodecanol; 3,3-dipentyl-i-propanol; Tridecanol- (i); 3-ethyl-6-undecanol; 2-methyl-ethyl-4-undecanol; s.a.-diethyl-ö-undecanol and 3, g-diethyl-6-tridecanol.

In the following some experiments are described which are intended to explain the invention in more detail.

example 1

50 moles of 97 ° / _o sodium a.öjS-trimethyl - ^ - nonanol containing 0.05 percent by weight boron trifluoride was charged to an autoclave which was equipped with a stirrer. The batch was ^{heated to 50 °} C., the autoclave was then flushed through with nitrogen and 50 mol of ethylene oxide were introduced into the mixture with stirring at such a rate that a pressure of 0 to 0.2 atmospheres was maintained.

It was ensured that the temperature did not rise during the 4-hour introductory period of Äthylenoxyds and another 2 hours after more than 55 ⁰ C, had reacted until all the ethylene oxide. The crude reaction mixture was then profiled with a neutra io ° / ₀ methanolic sodium hydroxide solution until the Phenolphthaleinumschlag was evident. The neutralized mixture was then fractionally distilled in vacuo and 1. the methanol passing over, 2. unconverted starting alcohol and 3. the reaction products which up to the boiling point of the 2,6,8-triniethyl-4-nonyl monoether of ethylene glycol (up to 171 ⁰ C at a pressure of 50 mm Hg) distilled over, collected separately. The residue remaining in the distillation vessel consisted of 20.5 mol of a mixture of the triethylnonyl monoethers of monoglycol and low molecular weight polyethylene glycols. It had an average molecular weight of 290 and an average of 2.36 moles of bound ethylene oxide per mole of ether compound.

4 mol (1160 g) of this residue consisting of glycol ethers were introduced into a stirred autoclave. Then 13 g of powdered potassium hydroxide, which had been aufgesehlämmt with a portion of the mixture were added and the mixture heated to 165 ⁰ C, the autoclave was flushed with nitrogen, which was free of oxygen, and acid gases such as carbon dioxide.

When the temperature of the mixture had reached 165 ^° C., the pressure in the autoclave was increased to 0.35 atmospheres with the aid of nitrogen. Then approximately 24 moles of ethylene oxide gas were introduced into the steam space of the autoclave at a constant rate over the course of 5 hours. The pressure reached a maximum of 0.56 atm. The reaction mixture samples were taken frequently, and as soon as the cloud point was an o, 5gewichtsprozentigen aqueous solution at 35 ⁰ C, the introduction of Äthylenoxyds was interrupted. The average molecular weight of the product thus obtained was 444.

The crude product was mixed with phosphoric acid up to a pn of 8.5, treated with 0.5 percent by weight magnesium hydrosilicate ^{at 100 ° C. for 5 hours and then filtered.} The filtrate consisted of a viscous, light yellow, slightly smelling liquid, which was homogeneous at temperatures above 50 ⁰ C. At room temperature, waxy, high molecular weight components tended to crystallize out. However, it was possible to stabilize the product against the precipitation and crystallization of these substances up to temperatures of 10 ^° C. by adding 5 to 10 percent by weight of water.

Example 2

6 moles of 2-methyl-7-ethyl-4-undecanol containing 0.05 percent by weight boron trifluoride was charged in a vessel with stirring and the mixture cooled to 10 ⁰ C. Then quickly 6 moles of ethylene oxide were introduced into the alcohol and the mixture heated at Ätmosphärendruck within 2 hours at 50 ⁰ C, whereupon the temperature was maintained at 50 ⁰ C, had reacted until all ethylene oxide.

The reaction mixture was neutralized with a methanolic sodium hydroxide solution until it had become phenolphthalein. The neutral mixture was then fractionally distilled under reduced pressure and the methanol passing over, the unconverted starting alcohol and the reaction products which up to the boiling point of the mono-2-methyl-7-ethyl-4-undecyl ether of ethylene glycol, ie up to 158 ⁰ C ₁ distilled over at a pressure of 10 mm, collected separately. The residue remaining in the distillation vessel consisted of 2.6 moles of a mixture of the monotetradecyl ethers of ethylene glycol and polyethylene glycols and had an average molecular weight of 315. It contained an average of 2.3 moles of bound ethylene oxide per mole of ether.

ι Mol (315 g) of this residue and 1 g of metallic sodium were placed in an autoclave and ^{heated to 165 °} C. with stirring, the autoclave

purged with nitrogen that was free of oxygen and acid gases. While the mixture was kept at 165 ⁰ C, 7,4MoI Äthylenoxyddampf were then introduced at a uniform rate under the atmospheric pressure in the vapor space above the liquid in the autoclave. The discharge was stopped when the cloud point was an o, 5gewichtsprozentigen aqueous solution of the reaction mixture at 35 ⁰ C.

The alkaline catalyst was neutralized with phosphoric acid until the mixture had a pn value of 7 to 8. The mixture was then filtered in order to remove the inorganic salts and the filtrate, a light yellow viscous liquid, was ^{stabilized against precipitations at temperatures of up to 10 °} C. by adding 10 percent by weight of water.

Example 3

4 moles of 2-butyl-i-octanol, containing 0.05 weight percent of boron trifluoride were charged in a round bottom flask and cooled to 10 ⁰ C. Then 4 mol of ethylene oxide were passed rapidly into the alkanol with stirring in the manner described in Example 2, the reaction being carried out ^{at 50 ° C.} The reaction mixture was neutralized with a methanolic sodium hydroxide solution and the neutralized mixture was then fractionally distilled to remove methanol and unreacted butyloctanol, leaving a residue consisting of 2.26 mol of a mixture of mono- (2-butyl-i-octyl) -ethers of ethylene glycol and polyethylene glycols and had an average molecular weight of 264. The mixture contained an average of 1.77 moles of bound ethylene oxide per mole of monoether compound.

1 mole (246 g) of this product was poured together with 1 g of metallic sodium into a round-bottom flask with a stirrer device and the mixture was ^{heated to 165 °} C., the flask being flushed with nitrogen which was free of oxygen and carbon dioxide. Then, at constant speed and atmospheric pressure, while the mixture was kept at 165 ^° C., approximately 6.5 mol of ethylene oxide was passed into the vapor space. The Äthylenoxydeinleitung was interrupted when the cloud point of the mixture was at 50 ⁰ C a o, 5gewichtsprozentigen aqueous solution.

After neutralizing the reaction mixture with phosphoric acid in that described in Example 2 Way and filtering the neutralized mixture to remove inorganic salts was the non-ionic surfactant obtained as a clear light yellow viscous liquid.

The following table now contains comparative values for the wetting efficiency of non-ionic ones surfactants made by the process of the present invention and go of products made from the same secondary alcohols by one-step process with the ethylene oxide were obtained.

Table I.

Alkanol Molar ratio
of ethylene oxide
to alkanol Middle
Molecular weight
of the glycol
monoether product catalyst Wetting
efficiency
of
Product *} 2,6,8-trimethyl-4-nonanol
the same
the same
2-methyl-7-ethyl ~ 4-undecanol
the same
the same
5-ethyl-2-nonanol
6-dodecanol 8.3
8.5
10.5
9.7
ii, 5
12.2
8.3
8.5
9.1
ii, 4
12.8 550
560
650
640
720
750
505
560
600
730
820 A.
NaOR **)
BF ₃ **)
A.
NaOR **)
BF ₃ **)
A.
A.
A.
A.
A. 0.23
0.70
O, 6o
0.25
0.65
o, 55
0.26
0.23
0.23
0.29
0.42 3-ethyl-6-undecanol
3,9-diethyl-o-undecanol
3, g-diethyl-6-tridecanol

*) The wetting efficiency is equal to the amount of surface-active substance per liter of water at 25 ° that is necessary is to obtain a wetting time of 20 seconds according to the Draves method (Year Book of Am. Ass. of Textile Chemists and Colorists [1943], vol. 20, p. 226).

**) Comparison test. One step reaction.

In Tables I and II, catalyst "A" means

a two-step reaction according to the invention,

boron trifluoride as a catalyst in the first stage and in the second stage the sodium alcoholate

Starting alkanol compound or the corresponding

Monoalkyl ether of an ethylene glycol was used.

The method according to the invention is suitable

also for the production of polyethylene glycol monoether compounds with a high wetting effect, in which one uses primary straight-chain or branched alkanols with 10 to 17 carbon atoms as shown in Table II. The monoalkyl ethers of the polyethylene glycols were with the exception of the compounds for which it was stated otherwise, by using the two-stage Method according to the invention using

Tabel II catalyst Wetting
efficiency
of
Product *) Alkanol
5 Molar ratio
of ethylene oxide
to alkanol Middle
Molecular weight
of the glycol
monoether product A.
A.
A.
A.
NaOR **) 0.26
0.20
0, l8
0.21
0.24 i-decanol 5.3
7.9
7.7
8, o
8.2 Ol Oi Ol Ol OJ
ON Ol Φ- OJ VO
O O O Ol O 2-butyl-i-octanol
io 3- (2 ', 2'-dimethylpropyl-
5,5-dimethylhexanol- (i)
Tridecanol- (i)
the same

*) For determination of the wetting efficiency see table

**) Comparison test. A one step process using the sodium salt of the indicated alkanol as
Catalyst.

Table III

Comparison of the properties of various polyoxyethylene derivatives of alcohols
having 12 to 17 carbon atoms

No. Alkanol Molar ratio
of ethylene
oxide
to alkanol Middle
Molecular
weight of the
Glycol mono-
ether product catalyst Cloud point
one
0.5 »/» igen
aqueous
Solution ( ⁰ C) *) Wetting
Degree**) 1
2
3
4th
5
6th
7th
8th
9
10
11th
12th
13th
14th
15th
16 2,6,8-trimethyl-4-nonanol ..
the same
the same
the same
the same
the same
2-methyl-7-ethyl-4-undecanol
the same
the same
the same
the same
5-ethyl-2-nonanol
6-dodecanol
3-ethyl-6-undecanol
3, a.-diethyl-6-undecanol ...
Sg-diethyl-o-tridecanol ... 6: 1
7.7: i
8.3: i
8.3: 1
8.5: i
I0.5: i
9.7: i
9.7: i
9.6: i
II, 5: i
I2.2: i
8.3: 1
8.5: i
9, i: i
II, 4: i
I2.8: i 450
525
550
550
560
650
640
640
635
720
750
505
560
600
730
820 A.
A.
A.
BF ₃
NaOR
BF ₃
A.
BF ₃
NaOR
NaOR
BF ₃
A.
A.
A.
A.
A. <I.
31
33
<I.
<I.
<I.
35
<I.
<I.
<I.
<I.
36
35
30th
46
35 0.17
0.23
0.23
0.41
0.70
O, 6o
0.25
O, 6o
0.75
0.65
o, 55
0.26
0.23
0.23
0.29
0.42

*) A measure of the inverse water solubility (see page 3, lines 10 to 13). **) Draves method (see footnote in Table I).

of boron trifluoride catalyst in the first stage and of sodium alcoholates of the glycol ether products first stage used as catalysts in the second stage.

When this method according to the invention is used, non-ionic surface-active substances are produced Obtain 1.5 to 3 times the wetting power and the degree of effectiveness with corresponding surface-active Have phenomena that are similar to secondary alkanol ethers of monoethylene glycol and the polyoxyethylene glycols occur through the reaction of ethylene oxide and secondary Alkanol in a one-step process with

using an acidic or an alkaline catalyst.

Claims (8)

PATENT CLAIMS: i. Process for the production of polyglycol ethers of higher alcohols by reacting a saturated monohydric primary or secondary alkanol having 10 to 17 carbon atoms with ethylene oxide in the presence of acidic or alkaline catalysts, characterized in that the reaction is first carried out in the presence of an acidic catalyst, the resulting reaction 109 57Φ / 6 tion mixture is neutralized, unreacted alkanol is reacted removed therefrom and then the neutralized mixture with additional ethylene oxide at a temperature between ⁰ and 200 8o C in the presence of an alkali metal alcoholate. 2. The method according to claim 1, characterized in that that in the first stage 0.2 to 4 moles, preferably 1 mole, of ethylene oxide with 1 mole of alkanol lets react. 3. The method according to claim 1 or 2, characterized in that the reaction of the first stage at a temperature between 0 and 80 ⁰ C is carried out. 4. The method according to claim 1 to 3, characterized in that the acidic catalyst of the first stage is a Friedel-Crafts catalyst, preferably in an amount of 0.02 to 0.05 ° / ₀ , based on the weight of the alkanol, used. 5. The method according to claim 1 to 4, characterized in that in the second stage the Alkali metal alcoholate catalyst, preferably a monoalkyl ether of ethylene or poly • Ethylene glycol, used in an amount of 0.5 to 75 mole percent. 6. The method according to claim 1 to 5, characterized in that the reactants are heated ^{to a temperature of about 125 0 C in the second stage.} 7. The method of claim 1 to 6, characterized in that one brings in the second stage of the neutralized reaction mixture with further ethylene oxide to the reaction until a o, 5 ° / ₀ aqueous solution of the resulting impure reaction product has a cloud point within the temperature range of 10 to 100 ⁰ C. 8. The method according to claim 1 to 7, characterized in that in the second stage so a lot of ethylene oxide can react until the molar ratio of ethylene oxide to alkanol residue in the reaction product is 4: 1 to 20: 1. Considered publications:
German patents No. 605 973, 667 744, 694178; U.S. Patent Nos. 1,970,578,226,213; British Patent Nos. 271169, 354 357, 664992;
French patent specification No. 664 261. © 509 600/39 12.55 (109.57Φ / 6 5.61)