WO1996022956A1

WO1996022956A1 - Selectively hydroxysubstituted triol

Info

Publication number: WO1996022956A1
Application number: PCT/SE1996/000056
Authority: WO
Inventors: Carl-Axel Edvard SJÖGREEN
Original assignee: Perstorp Ab
Priority date: 1995-01-23
Filing date: 1996-01-22
Publication date: 1996-08-01
Also published as: SE9500206L; TW318835B; SE504282C2; AU4593196A; SE9500206D0

Abstract

A process for production of a selectively alkoxylated triol, which process comprises two or more Steps including the Steps of a) reacting a cyclic triol formal having one reactive hydroxyl group with an alkylene oxide or correponding glycol, which reaction yields a corresponding alkoxylated cyclic triol formal; and b) acidic hydrolysis of the alkoxylated cyclic triol in the presence of a triol, which hydrolysis yields a selectively alkoxylated triol having one alkoxysubstituted and two unsubstituted hydroxyl groups and formaldehyde, which formaldehyde reacts with the triol yielding a cyclic triol formal, whereby in Step b) yielded cyclic triol formal can be used for alkoxylation in Step a). A further aspect of the invention relates to an acidic hydrolysis of a hydroxysubstituted cyclic triol formal. The hydrolysis is performed in the presence of a triol and the hydrolysis yields a selectively hydroxysubstituted triol having one substituted and two unsubstituted hydroxyl groups and formaldehyde, which formaldehyde reacts with the triol yielding a cyclic triol formal.

Description

SELECTIVELY HYDROXYSUBSTITUTED TRIOL

The present invention relates to a process for preparation of a selectively alkoxylated triol, whereby the start material is a cyclic triol formal. In a further aspect, the invention refers to an acidic hydrolysis of a hydroxysubstituted cyclic triol formal.

It is known from the European Patent 0 042 505 to produce for example selectively propoxylated glycerol. The reaction is carried out in three steps. Glycerol is in a first step reacted with a ketone, such as acetone, forming a ketal. The ketal is then in a second step reacted with propylene oxide yielding corresponding propoxylated ketal, which in a third step is hydrolysed by means of heating in a mixture of water, an acid, preferably hydrochloric acid or sulphuric acid, and a monoalcohol, such as ethanol.

Above disclosed reaction steps are subject to a number of drawbacks. Acetone is highly volatile and inflammable. Most lower monoalcohols are also highly volatile and/or highly inflammable, Equipment secured against explosions must hence be used. Simple and cost effective methods for recovery of acetone and/or added lower monoalcohols in the third step do presently not exist.

The European Patent Application 0 506 424 discloses an improved process for the hydrolysis and purification of an alkoxylated polyol containing a ketal protective functionality. The process comprises contacting an aqueous mixture of the protected polyol with an acid, adding a base and cause the mixture to form two phases, one containing the deprotected polyol and one water The disclosed procedure exhibits a number or disadvantages, including those of EP 0 506 424. A major disadvantage is that the process is limited to water insoluble polyols. A mixture containing a water soluble polyol and water will not form said two phases. This drawback is accentuated by the fact that an alkoxylated polyol normally is water soluble, completely or to a very high percentage.

There has, due to above discussed drawbacks and disadvantages, such as the use ketones, lower alcohols and a hydrolysis involving phase separation, in the production of selectively substituted polyols been a long felt need to use an aldehyde, preferably formaldehyde, instead of a ketone and a desire to be able to use a facilitated and cost effective recovery procedure. Aldehydes react with for instance a triol forming acetals, such as 1 ,3-dioxanes. Formaldehyde acetals are normally called formals. Cyclic formals can, due to the stable formal ring, which is difficult to decompose, not be hydrolysed in the presence of an acid and a lower monoalcohol.

The present invention supplies quite unexpectedly a process wherein said needs and desires in the production of selectively substituted polyols can be met. The process is especially suitable for production of selectively alkoxylated polyols, in particular triols. The process involves at least two steps and start material is a cyclic formal of a triol, such as a cyclic formal of trimethylolpropane, trimethylolethane or glycerol. Said cyclic formal can be produced by reacting a triol with formaldehyde, preferably in the presence of an acid catalyst, such as sulphuric acid, hydrochloric acid, methane sulphonic acid, and at a temperature of 20- 150°C, normally 20- 100°C. The reaction can, furthermore, optionally be carried out in the presence of a low-boiling solvent, such as benzene. Cyclic formals of triols is in certain triol processes yielded as by-products and can, thus, alternatively be obtained through recovery of said by-products.

The reaction between a triol and formaldehyde can be exemplified Formula I disclosing the reaction between trimethylolpropane and formaldehyde yielding the cyclic triol formal 5-ethyl-5-hydroxymethyl- l ,3-dioxane

Formula I .

The process according to the present invention involves the Steps of a) reacting a cyclic triol formal having one reactive hydroxyl group with an alkylene oxide, preferably ethylene oxide and/or propylene oxide, or a glycol yielding corresponding alkoxylated cyclic triol formal; and b) acidic hydrolysis of yielded alkoxylated cyclic triol in the presence of an added amount of triol, the triol is preferably the same as the one included in said cyclic triol formal and said alkoxylated cyclic triol formal, which hydrolysis yields an alkoxylated triol having one substituted and two unsubstituted hydroxyl groups and formaldehyde, which formaldehyde reacts with the added triol yielding a cyclic triol formal, whereby the in Step (b) yielded cyclic triol formal can be used for alkoxylation in accordance with Step (a). A suitable molar ratio between alkoxylated cyclic triol formal yielded in Step (a) and triol is in the range of 1 0 5 to 1 5 or preferably 1 1 5 to 1 .3

A suitable process for alkoxylation, according to Step (a), of a cyclic formal can be disclosed as follows The formal is charged in a reaction vessel equipped with a stirrer, temperature control and inlet of inert gas An alkaline compound, such as sodium or potassium hydroxide, is thereafter charged as catalyst The reaction mixture is heated to 100- 1 80°C and a pressure of 100- 1000 kPa is applied Alkylene oxide is then, in an amount, preferably 0 5-30 moles/mole cyclic formal, resulting in the desired degree of addition, slowly pumped into the reaction vessel The obtained product is optionally neutralised to pH 6-8 by addition of for instance sodium hydrogenphosphate, acetic acid or the like optionally together with a small amount of water and/or a filter aid The product is finally if necessary filtered at for instance 100°C and optionally stabilised by addition of an antioxidant, such as butylhydroxytoluene

Alkoxylation of a cyclic triol formal can be exemplified by Formula II disclosing ethoxylation (ethylene oxide addition) of 5-ethyl-5-hydroxymethyl- l ,3-dioxane yielding corresponding ethoxylated cyclic triol formal

Formula II

The alkylene oxide can if so is desired be replaced by equivalent glycol Addition to a cyclic formal is in such a case performed by means of an etherification

The hydrolysis of the present invention, which hydrolysis is equal to Step (b) of the process, is an acidic hydrolysis performed at a vacuum of 0-0 15 kPa, preferably 0-665 Pa and most preferably 0-400 Pa, and in the presence of a triol The hydrolysis yields an alkoxylated or otherwise substituted triol having one substituted and two unsubstituted hydroxyl groups and formaldehyde, which formaldehyde reacts with the triol yielding a cyclic triol formal The amount of triol added is preferably at least equal to the amount of yielded alkoxylated or otherwise hydroxysubstituted cyclic triol formal The temperature is preferably raised until yielded cyclic triol formal evaporates, whereby any excess of added triol can be removed, by evaporation or distillation, and the alkoxylated or otherwise hydroxysubstituted triol can be recovered.

The acidic hydrolysis according to the present invention, including Step (b) of the process, can be exemplified by Formula III disclosing hydrolysis of ethoxylated 5-ethyl-5-hydroxymethyl- l ,3-dioxane in the presence of trimethylolpropane, whereby ethoxylated trimethylolpropane and the cyclic triol formal 5-ethyl-5-hydroxymethyl- l ,3-dioxane are yielded

Formula III

Hydroxysubstituted cyclic triol formals can be exemplified by Formula IV and Formula V disclosing a hydroxysubstituted 1 ,3-dioxane and a hydroxysubstituted 1 ,3-dioxolan

Formula IV Formula V

1 2 wherein R is oxygen, alkanyloxy or alkenyloxy, R is alkanyl, alkenyl, alkynyl, aryl, alkanylaryl, alkenylaryl or alkynylaryl and R is hydrogen, alkanyl, alkenyl, alkynyl, aryl, alkanylaryl, alkenylaryl or alkynylaryl. The hydrolysis of the present invention, which is as previously disclosed, performed in the presence of a triol, preferably the same triol as the base triol in the cyclic triol formal, gives substantial advantages The most important advantages are that

♦ a safe and with regard to the yield satisfactorily hydrolysis is obtained,

^♦ the cyclic triol formal yielded during the hydrolysis can be used in the reaction resulting in a hydroxysubstituted cyclic triol formal, which compound can be hydrolysed according to the invention yielding said cyclic triol formal etc

♦ optional excess of triol can be recovered and reused for production of a cyclic triol formal, and

^♦ volatile and/or inflammable solvents or the like not are used

These and other objects and the attendant advantages will be more fully understood from the following detailed description, taken in conjunction with appended embodiment examples, which disclose

Example 1 Preparation of a cyclic triol formal

Example 2 and 4 Alkoxylations of the cyclic triol formal of Example 1

Example 3 and 5 Hydrolysis of the alkoxylated cyclic triol formal of Example 2 and 4, respectively Example 6 Comparative example disclosing a hydrolysis of the alkoxylated cyclic triol formal of Example 2, which hydrolysis is outside the scope of the invention

Example 1

400 g of trimethylolpropane, 243 2 g of formaldehyde (37% by weight), 1 8 g of /7-toluenesulphonic acid as catalyst and 3 1 of benzene were charged in an autoclave provided with a reflux condenser and a thermometer The reaction mixture was refluxed at 100°C until 209 g of reaction water was collected The reaction mixture was now cooled and extracted, using 3 x 100 ml of an aqueous sodium formate solution (30% by weight) to remove the catalyst The obtained organic phase was dried and benzene removed by evaporation, whereby remaining product was vacuum distilled

381 g of the cyclic trimethylolpropane formal 5-ethyl-5-hydroxymethyl- l ,3- dioxane, having a boiling point of 100- 120°C at 399 Pa, was yielded Example 2

292 g of 5-ethyl-5-hydroxymethyl- l ,3-dioxane, obtained in Example 1 , and 0.61 g of KOH were charged in an autoclave. 716 g of ethylene oxide was now pumped into the autoclave. The temperature in the autoclave was 150°C and the pressure 500 kPa. The obtained reaction mixture was, following the charging of ethylene oxide, neutralised by addition of 0.66 g of acetic acid.

892 g ethoxylated 5-ethyl-5-hydroxymethyl- l ,3-dioxane, having an average of 6.9 moles of ethylene oxide added to the hydroxyl group of said 5-ethyl-5-hydroxy- methyl- l ,3-dioxane, was obtained.

Example 3

599.3 g of the ethoxylated 5-ethyl-5-hydroxymethyl- l ,3-dioxane obtained in Example 2, 273 g of trimethylolpropane and 4.4 g of H₂SO₄ (96% by weight) were charged in a reaction flask provided with a stirrer, a thermometer, a cooler and a receiver. The flask was placed in an oil bath and a reduced pressure of « 130 Pa was applied, whereby 5-ethyl-5-hydroxymethyl-l ,3-dioxane began to evaporate. The reduced pressure was kept at » 130 Pa and the temperature was allowed to raise to 145°C. The hydrolysis was allowed to continue for 2.4 hours. 1.2 mole of 5-ethyl-5-hydroxymethyl-l ,3-dioxane had whereby evaporated and been collected. The collected 5-ethyl-5-hydroxymethyl- l ,3-dioxane could be used for alkoxylation in accordance with Example 2 or 4.

The reaction mixture remaining in the flask was now neutralised and the temperature raised to 165°C. The reduced pressure was still kept at « 130 Pa. The temperature was now gradually raised to 180°C and excess of trimethylolpropane was distilled off. The thus recovered trimethylolpropane could be used for reaction with formaldehyde, in accordance with Example 1 , yielding 5-ethyl-5-hydroxy- methyl- l ,3-dioxane.

The reaction flask now contained 580 g of ethoxylated trimethylolpropane, having one ethoxylated hydroxyl group and two unsubstituted hydroxyl groups. The content of trimethylolpropane was 2%.

Example 4

13.9 kg of 5-ethyl-5-hydroxymethyl- l ,3-dioxane, obtained in accordance with Example 1 , and 45 kg of KOH were charged in an autoclave. 32.4 kg of ethylene oxide was now pumped into the autoclave. The temperature in the autoclave was 150°C and the pressure 500 kPa. The obtained reaction mixture was, following the charging of ethylene oxide, neutralised by addition of 49 kg of acetic acid.

75 kg ethoxylated 5-ethyl-5-hydroxymethyl- l ,3-dioxane, having an average of 14 6 moles of ethylene oxide added to the hydroxyl group of said 5-ethyl-5-hydroxy- methyl- l ,3-dioxane, was obtained.

Example 5

75 kg of the ethoxylated 5-ethyl-5-hydroxymethyl- l ,3-dioxane obtained in Example 4, 19.9 kg of trimethylolpropane and 4.7 kg of H₂SO₄ (96% by weight) were charged in an autoclave provided with a stirrer, a thermometer, a cooler, a receiver and a vacuum pump. A reduced pressure of 130-260 Pa was applied, whereby 5-ethyl-5-hydroxymethyl- l ,3-dioxane began to evaporate. The reduced pressure was kept at 130-260 Pa and the temperature was allowed to raise to 145°C. The hydrolysis was allowed to continue for 3 hours. 76 moles of 5-ethyl-5- hydroxymethyl- l,3-dioxane had whereby evaporated and been collected. The collected 5-ethyl-5-hydroxymethyl- l ,3-dioxane could be used for alkoxylation in accordance with Example 4 or 2.

The reaction mixture remaining in the autoclave was now neutralised and the temperature raised to 165°C. A reduced pressure of approx. 130-140 Pa was applied. The temperature was now gradually raised to 1 80- 185°C and excess of trimethylolpropane was distilled off. Steam was during the final phase of the distillation blown into the reaction mixture in a total amount of 3 kg in order to facilitate the distillation of trimethylolpropane. The recovered trimethylolpropane could be used for reaction with formaldehyde, in accordance with Example 1 , yielding 5-ethyl-5-hydroxymethyl- 1 ,3-dioxane.

The autoclave now contained 72 kg of ethoxylated trimethylolpropane, having one ethoxylated hydroxyl group and two unsubstituted hydroxyl groups. The content of trimethylolpropane was < 0.5%.

Example 6 - Comparative Example

5 g of ethoxylated 5-ethyl-5-hydroxymethyl- l ,3-dioxane, obtained in Example 2 and having a hydroxyl number of 128 mg KOH/g, was dissolved in ethanol and IN HCL. The weight ratio between said three components was 2: 1 : 1. The reaction mixture was heated to 80°C and kept at this temperature for 4 hours. All volatile components were after the 4 hours evaporated and the remaining product analysed with regard to its hydroxyl number.

The hydroxyl number was 128 mg KOH/g, which is very close to the hydroxyl number of used ethoxylated 5-ethyl-5-hydroxymethyl- l ,3-dioxane. A complete hydrolysis yielding ethoxylated trimethylolpropane would have resulted in a hydroxyl number of _* 380 mg KOH/g

This Example clearly shows that a hydroxysubstituted cyclic triol formal, or for that matter a cyclic triol formal, under disclosed conditions not or only to a minor extent can be hydrolysed yielding a selectively hydroxysubstituted triol, or a triol

While particular embodiments of the invention have been shown, it will be understood, of course, that the invention is not limited thereto since many modifications may be made, and it is, therefore, contemplated to cover by the appended claims any such modifications as fall within the true spirit and scope of the invention.

Claims

1. A process for production of a selectively alkoxylated triol c h a r a c t e r i s e d i n, that the process comprises two or more Steps including the Steps of a) reacting a cyclic triol formal having one reactive hydroxyl group with an alkylene oxide or corresponding glycol, which reaction yields a corresponding alkoxylated cyclic triol formal; and b) acidic hydrolysis of the alkoxylated cyclic triol formal in presence of an triol, which hydrolysis yields a selectively alkoxylated triol, having one alkoxysubstituted hydroxyl group and two unsubstituted hydroxyl groups, and formaldehyde, which formaldehyde reacts with the triol yielding a cyclic triol formal, whereby in Step (b) yielded cyclic triol formal can be used for alkoxylation in Step (a).

2. A process according to Claim 1 c h a ra c t e r is ed i n, that the alkylene oxide is ethylene oxide and/or propylene oxide.

3. A process according to Claim 1 or 2 c h a r a c t e r i s e d i n, a molar ratio between cyclic triol formal and alkylene oxide of 1:0.5 to 1:30 in Step (a).

4. A process according to any of the Claims 1-3 c h a r a c t e r i s e d i n, an alkaline compound, such as sodium or potassium hydroxide, is used as catalyst in Step (a)

5. A process according to any of the Claims 1-4 c h a r a c t e r i s e d i n, that Step (a) is performed at a reaction temperature of 100-180°C and at a pressure of 100-1000 kPa.

6. A process according to any of the Claims 1-5 c h a ra c t e r i s e d i n, that the cyclic triol formal and the alkoxylated cyclic triol formal are formals of trimethylolpropane, trimethylolethane or glycerol.

7. A process according to any of the Claims 1-6 c h a ra cterised i n, that the triol used in Step (b) is the same triol as the one being base triol in said cyclic triol formal and said alkoxylated cyclic triol formal.

8. A process according to any of the Claims 1-7 c h a r a c t e r i s e d i n, that the triol used in Step (b) is added in an amount being at least equivalent to yielded amount of alkoxylated cyclic triol formal of Step (a).

9. A process according to any of the Claims 1-8 cha racterised i n, that the triol used in Step (b) is added at a molar excess giving a molar ration between alkoxylated cyclic triol formal and triol of 1.1.05 to 1:5, preferably 1:1.5 to 13

10. A process according to any of the Claims 1-9 c h a r a c t e r i s e d i n, that the acidic hydrolysis of Step (b) is performed at a vacuum of 0-0.15 kPa, preferably 0-665 Pa and most preferably 0-400 Pa.

11. A process according to any of the Claims 1-10 c h a ra c t e ri s ed i n, that the cyclic triol formal yielded in Step (b) is evaporated by means of a raised temperature, followed by an evaporation or distillation of optional excess of triol, whereby the alkoxylated triol can be recovered.

12. A process according to any of the Claims 1-11 c h a ra c t e ris ed i n, that the cyclic triol formal yielded in Step (b) is used for alkoxylation in Step (a).

13. An acidic hydrolysis of a hydroxysubstituted cyclic triol formal c h a ra ct e ri sed i n, that the hydrolysis is performed in the presence of a triol, which hydrolysis yields a selectively hydroxysubstituted triol having one substituted and two unsubstituted hydroxyl groups and formaldehyde, which formaldehyde reacts with the triol yielding a cyclic triol formal

14. An acidic hydrolysis according to Claim 13 c h a r a c t e r i s e d i n, that the substituted hydroxyl group is alkanyl, alkenyl, alkynyl, aryl, alkanylaryl, alkenylaryl or alkynylaryl substituted

15. An acidic hydrolysis according to Claim 13 or 14 c h a ra c te rised i n, that the hydroxysubstituted cyclic triol formal is a hydroxysubstituted cyclic formal of trimethylolpropane, trimethylolethane or glycerol.

16. An acidic hydrolysis according to any of the Claims 13-15 c h a ra c t e ri s e d i n, that the triol is the same triol as the one being base triol in said hydroxysubstituted cyclic triol formal

17. An acidic hydrolysis according to any of the Claims.13-16 c h a r a c t e r i s e d i n, a molar ratio between triol and hydroxy¬ substituted cyclic triol formal of 1 :0.5 to 1:5, preferably 1:1.5 to 1:3.

18. An acidic hydrolysis according to any of the Claims 13-17 c h a ra c te ri s e d i n, that the hydrolysis is performed at a vacuum of 0-0.15 kPa, preferably 0-665 Pa and most preferably 0-400 Pa.

19. An acidic hydrolysis according to any of the Claims 13-18 c h a ra c t e r i sed i n, that yielded cyclic triol formal is evaporates by means of a raised temperature, followed by an evaporation or distillation of optional excess of triol, whereby the selectively hydroxysubstituted triol can be recovered.