WO2008048882A2

WO2008048882A2 - Process for preparing polyallyl ethers

Info

Publication number: WO2008048882A2
Application number: PCT/US2007/081207
Authority: WO
Inventors: Christian U. Oertli
Original assignee: Huntsman Advanced Materials Americas Inc.
Priority date: 2006-10-13
Filing date: 2007-10-12
Publication date: 2008-04-24
Also published as: WO2008048882A3

Abstract

The present invention provides a process for producing monohydroxy polyallyl ethers by reacting a polyol with allyl halide in an alkaline reaction medium until about 50-80 mol % of the allyl halide to be reacted, has reacted, then adding excess solid alkali metal hydroxide in a single addition to the reaction medium. The addition of the solid alkali metal hydroxide to the reaction medium creates a reaction medium having a substantially constant free hydroxy ion concentration in the aqueous phase allowing the monohydroxy polyallyl ether to be formed in high yields.

Description

PROCESS FOR PREPARING POLYALLYL ETHERS

CROSS-REFERENCE TO RELATED APPLICATION

This application is a new International Application which claims priority to U.S. Application No. 60/851,701 filed October 13, 2006. The noted application is incorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT Not Applicable.

FIELD OF THE INVENTION

The present invention relates to a process for producing polyallyl ethers in high yields by reacting a polyol having at least three hydroxy groups with an allyl halide in an alkaline reaction medium under conditions where the concentration of free hydroxy-ions in the aqueous phase of the reaction medium is maintained under constant control.

BACKGROUND OF THE INVENTION

As is generally known, polyethers of aliphatic alcohols can be prepared from alkali metal alcoholates and organic halides by the Williamson ether synthesis. Several improvements to this synthesis have been taught, for example: U.S. Pat. No. 2,924,621, which teaches the use of up to 3 moles of organic halide and hydroxide per mole of trihydric alcohol to produce a diether product; U.S. Pat. No. 3,634,522, which teaches the use of DMSO as a soivenτ in order to produce the fuiiy etherified produci; U.S. Par. No. 4,433,179, which teaches the use of phase transfer catalysts; US 2005/0215830, which teaches the removal of water from the reaction system after partial addition of the organic halide; and JP62223Ϊ41, which teaches the use of an allyl alcohol as a reaction accelerator.

Monohydroxy polyethers, prepared by etherifying all but one hydroxy group of the alcohol, are valuable specialty chemicals with broad market applications, such as in the paint, coatings and plastic industries. The difficulty in synthesizing these polyethers is developing a process which can be easily implemented to produce the monohydroxy polyether product at high yields while minimizing the production of the intermediate di-hydroxy, tri-hydroxy, etc. polyether products. Thus, it would be desirable to develop a process for producing such monohydroxy polyethers at higher yields than have already been obtained and which does not require the use of specialty starting materials, catalysts or the need for additional or specialized processing equipment.

SUMMARY OF THE INVENTION

The present invention is directed to a process for producing a monohydroxy polyallyl ether by reacting a polyol having at least three hydroxy groups with an allyl halide in an alkaline reaction medium until about 50-80 mol % of allyl halide, based on the total molar amount of allyl halide to be reacted, has reacted in the alkaline reaction medium then adding about 2-10 molar excess of solid alkali metal hydroxide in a single addition to the alkaline reaction medium.

In another embodiment, the present invention is directed to a process for preparing a monohydroxy polyallyl ether of the formula (I): {HO) - R - (O - CHz - CH = CHi)_n (I) where R is a linear or branched, aliphatic, cycloaliphatic, cycloaliphatic-aliphatic or heterocyclic-aliphatic group having between 2 to 20 carbon atoms and n is an integer of at least 2 by (i) reacting a polyol of formula (II):

R - ψH)z (II) where R is defined as in formula (I) and z is an integer of greater than 2 and less than 25, and preferably is equal to 3 to 11, and the OH groups are bonded to primary, secondary or tertiary aliphatic C atoms with (U) ally! halide in an alkaline reaction medium. The reaction progresses until about 50-80 mol % of the allyl halide, based on the total molar amount of allyl halide which is to be reacted (or z-1), has reacted, then about 2-10 molar excess of solid alkali metal hydroxide is added in a single addition to the alkaline reaction medium.

In yet another embodiment, the present invention is directed to a process for producing a monohydroxy triallyl ether by reacting pentaerythritol with allyl chloride in an alkaline reaction medium until about 50-80 mol % of the allyl chloride, based on the total molar amount of allyl chloride which is to be reacted, has reacted and adding about 2-10 molar excess of solid sodium hydroxide in a single addition to the alkaline reaction medium. The remaining 20-50 mol % of the allyl chloride is allowed to react and the alkaline reaction medium is neutralized with acid. The monohydroxy triallyl ether may then be separated from the neutralized medium. DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a process for producing monohydroxy polyethers, in particular, monohydroxy polyallyl ethers, from polyols having at least three hydroxy groups and allyl halides in an alkaline reaction medium. During the synthesis of such polyallyl ethers, a significant amount of water of reaction is produced. This in turn causes the concentration of free hydroxy-ions (or [OH^"]) in the aqueous phase of the reaction medium to decrease as the synthesis progresses which impedes production of monohydroxy polyallyl ether. It has surprisingly been found that the dilution effects associated with such an increase in water can be eliminated by adding excess solid alkali metal hydroxide in a single addition to the reaction medium after synthesis has begun. Thus, as the synthesis progresses, water already present in the reaction medium and any water subsequently produced combines in- situ with the solid alkali metal hydroxide to provide a continuously saturated alkaline reaction medium. The [OH^"] of the reaction medium therefore remains substantially constant as the synthesis continues to completion. Yields of greater than 75% by weight of the monohydroxy polyallyl ether (based on the total weight of all ethers produced) can be achieved by the process.

Thus, the present invention generally relates to a process for producing a monohydroxy polyallyl ether comprising reacting a polyol having at least three hydroxy groups with allyl halide in an alkaline reaction medium until about 50-80 mol % of allyl halide, based on the total molar amount of allyl halide to be reacted, has reacted, and adding about 2-10 molar excess of solid alkali metal hydroxide in a single addition to the reaction medium. The addition of the solid alkali metal hydroxide creates a completely saturated reaction medium which is impervious to water dilution effects and therefore has a substantially constant [OH^"] throughout synthesis. The remaining allyl halide is then allowed to react in the completely saturated reaction medium before the reaction medium is neutral ized with acid .

The term "monohydroxy polyallyl ether" as used herein refers to an ether having one hydroxy group and at least two allyl groups.

The term "allylation" as used herein refers to the substitution of a hydrogen atom from a hydroxy group on a polyol by an allyl group. The term "[OH^"]" as used herein refers to the concentration of free hydroxy-ions in the aqueous phase of the alkaline reaction medium.

The term "alkaline reaction medium" as used herein refers to a medium comprising hyuroxiue.

In one embodiment, the monohydroxy polyallyl ethers, which may generally be represented by the formula (I): (HO) - R - (O - CHi - CH = CHi)_n (I) where R is a linear or branched, aliphatic, cycloaliphatic, cycloaliphatic-aliphatic or heterocyclic-aliphatic group having between 2 to 20 carbon atoms and n is an integer of at least 2, may be prepared by a process according to the present invention by reacting a polyol of formula (II):

R ~~ (OH)z (U) where R is defined as in formula (I) and z is an integer of greater than 2 and less than 25 and the OH groups are bonded to primary, secondary or tertiary aliphatic C atoms, with allyl halide in an alkaline reaction medium characterized in that the reaction progresses until about 50-80 mol % of the allyl halide, based on the total molar amount of allyl halide which is to be reacted, has reacted, then adding about 2-10 molar excess of solid alkali metal hydroxide in a single addition to the alkaline reaction medium. The remaining 20-50 mol % of allyl halide is then allowed to react in the reaction medium before the reaction medium is neutralized with acid, and the polyethers separated from the neutralized reaction medium by means well known to those skilled in the art, such as by distillation.

Examples of polyol compounds which may be used in the present invention include polymethylolalkanes such as trimethylolethane, trimethylolpropane, trimethylolbutane, substituted trimethyolalkanes such as trimethylolphenylmethane, tri-(hydroxymethyl)- nitromethane, glycerol, hexane-l,2,64riol, adducts obtained by adding an alkylene oxide onto these triols, erythritol, xylitol, sorbitol, arabitol, mannitol, pentaerythritol, dipentaerythritol, glucose, fructose, maltose, sucrose, lactose, and 1,2,5-tris-hydroxyethyl isocyanurate.

Examples of allyl halides which may be used include allyl chloride and allyl bromide. The total amount of polyol and allyl halide employed in the process may range from a ratio of about 1 mole of polyol to about 2 to 20 moles of allyl halide. In one embodiment, the polyol and allyl halide are reacted at a ratio of about 1 mole of polyol to about 3-6 moles of allyl halide, and preferably at a ratio of about 1 mole of polyol to about 4.5-5.5 moles of allyl halide.

Examples of solid alkali metal hydroxide which may be used include sodium hydroxide, potassium hydroxide and mixtures thereof. In another embodiment, sodium hydroxide, potassium hydroxide or a mixture thereof is further combined with a carbonate, such as sodium carbonate or potassium carbonate or a mixture thereof, to maintain a substantially constant [OH^"] throughout synthesis.

The total amount of solid alkali metal hydroxide employed in the process ranges from about 240 molar excess. In another embodiment, the alkali metal hydroxide employed ranges from about 3-6 molar excess, preferably from about 4.5-5.5 molar excess.

In one embodiment, the polyol may be added to an aqueous solution of an alkali metal hydroxide, such as a 20-90% aqueous solution of sodium or potassium hydroxide, to form the corresponding alkali metal alcoholate in the alkaline reaction medium. The alkali metal hydroxide is employed in such quantities so that the alkaline reaction medium initially contains about 2-4.5 moles of hydroxide per mole of polyol. The allyl halide may then be added continuously or intermittently to the alkaline reaction medium. The alkali metal alcoholate may also be formed in the presence of the allyl halide.

Thus, in another embodiment, the polyol is added to an aqueous solution of an alkali metal hydroxide at a ratio of about 1 mole of polyol to about 2-4.5 moles of hydroxide to form an alkaline reaction medium. About 1-3 moles of allyl halide per mole of the polyol may then be continuously added to the reaction medium under agitation. A single addition of about 2-10 moles of solid alkali metal hydroxide may then be added to the reaction medium.

The addition of the solid alkali metal hydroxide allows the concentration of free hydroxy-ions in the reaction medium to remain substantially constant while the remaining allyl halide (about 1-3 moles) is continuously or intermittently added to the reaction medium. The process may be carried out in any type of reaction vessel having adequate agitation and heating and cooling means. In one embodiment, the process may be carried out in an open vessel under reflux at a temperature ranging from about 50⁰C to about 15O⁰C₃ preferably from about 7O⁰C to about 110⁰C, and even more preferably from about 80⁰C to about 100⁰C.

The monohydroxy polyallyl ethers obtained by the process according to the present invention are valuable monomers which, alone or as a mixture with other polymerizable monomers, can be converted into crosslinked monomers. The monohydroxy polyallyl ethers may also be used as starting materials for the preparation of epoxide compounds by an epoxidation process.

The present invention will be further illustrated in more detail with reference to the following example, which is not however to be interpreted as limiting the invention thereto.

EXAMPLE 1

212 g (1.6 mol) of pentaerythritol and 525 g (6.5 mol) of 50% aqueous sodium hydroxide were introduced into a vessel, equipped with an agitator, reflux condenser and thermometer, and stirred and heated to about 9O⁰C. Approximately 335 g (4.4 mol) of allyl chloride was then introduced into the vessel at a rate of about 0.35-0.45 g/min over a 7 hour period and a reflux temperature of about 90⁰C. A sample of this reaction medium was then taken and determined to be 50/50 mixture of diallyl ether and triallyl ether products

30O g (7.5 mol) of solid sodium hydroxide was then added in a single addition to the reaction medium which was followed by the addition of 167 g (2.2 mol) of allyl chloride at a rate of about 0.4-0.75 g/min at a reflux temperature of about 90⁰C. The reaction medium was then neutralized with acid. Distillation of the volatiles from the yellowish product mass produced a colorless clear liquid. The colorless, clear liquid was then analyzed by GC/TIC using relative peak area integration and its composition was determined to be as follows: pentaerythritol monoallyl ether: 0.0%, diallyl ether: 8.3%, triallyl ether 80.1%, and tetraallyl ether: 1 1.4%.

Although making and using various embodiments of the present invention have been described in detail above, it should be appreciated that the present invention provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention, and do not delimit the scope of the invention.

Claims

What is claimed is: L A process for producing a monohydroxy polyallyl ether comprising: (i) reacting a polyol having at least three hydroxy groups with an allyl halide in an alkaline reaction medium until about 50-80 mol % of allyl halide, based on the total molar amount of allyl halide to be reacted, has reacted in the alkaline reaction medium; and (ϋ) adding about 2- 10 molar excess of solid alkali metal hydroxide in a single addition to the alkaline reaction medium.

2. The process according to claim 1, wherein the polyol is a polymethylolalkane a substituted trimethyolalkane, glycerol, erythritol, xylitol, sorbitol, arabitol, mannitol, pentaerythritol or dipentaerythritol.

3. The process according to claim 2, wherein the polyol is pentaerythritol.

4. The process according to claim 1, wherein the alϊyl halide is allyl chloride or allyl bromide.

5. The process according to claim 1, wherein the solid metal alkali hydroxide is sodium hydroxide.

6. The process according to claim 5, wherein the sodium hydroxide is added at an amount of about 4-6 molar excess.

7. The process according to claim 5, wherein the sodium hydroxide is added after about 60-70 mo! % of the allyl halide, based on the total molar amount of allyl halide to be reacted, has reacted in the alkaline reaction medium.

8. The process according to claim 1, wherein the monohydroxy polyallyl ether is

9. A process for preparing a monohydroxy polyallyl ether of the formula (I):

(HO) -R - (O-CHi - CH = CHi)_n (I) where R is a linear or branched, aliphatic, cycloaliphatic, cycloaliphatic-aliphatic or heterocycHc-aliphatic group having between 2 to 20 carbon atoms and n is an integer of at least 2 comprising reacting a polyol of formula (II):

where R is defined as in formula (I) and z is an integer of greater than 2 and less than 25 and the OH groups are bonded to primary, secondary or tertiary aliphatic C atoms with ally] halide in an alkaline reaction medium, allowing the reaction to progress until about 50-80 mol % of the allyl halide, based on the total molar amount of allyl halide which is to be reacted (or z-1), has reacted, then adding about 2-10 molar excess of solid alkali metal hydroxide in a single addition to the alkaline reaction medium.

10. The process according to claim 8, wherein the polyol is a polymethyolalkane or pentaerythritol.

11. The process according to claim 8, wherein n is three and z is four.

12. The process according to claim 8, wherein the solid sodium hydroxide is added at an amount of about 4.5-5.5 molar excess.

13. The process according to claim 8, wherein the polyol of formula (II) and the allyl halide are reacted at a ratio of about 1 mole of polyol to about 5 moles of allyl halide.

14. The process according to claim 13, wherein the allyl halide is allyl chloride.

15. A process for producing a monohydroxy triallyl ether consisting essentially of: (A) reacting pentaerythritol with allyl chloride in an alkaline reaction medium until about until about 50-80 mol % of the allyl chloride, based on the total molar amount of allyl chloride which is to be reacted, has reacted;

(B) adding about 2-10 molar excess of solid sodium hydroxide in a single addition to the alkaline reaction medium; (C) allowing the remaining 20-50 mol % of the allyl chloride to react; (D) neutralizing the alkaline reaction medium with acid; and

(E) separating the monohydroxy triallyl ether from the medium.

16. The process according to claim 15, wherein the monohydroxy triallyl ether is produced from the process in a yield of at least 75%.

17. The process according to claim 15, wherein the monohydroxy triallyl ether is produced from the process in a yield of at least 80%.

18. The process according to claim 15, wherein the alkaline reaction medium has a substantially constant concentration of free hydroxy-ions in the aqueous phase after the addition of the solid sodium hydroxide.

19. The process according to claim 15, wherein the reaction is carried out at a temperature of about 80°- 100⁰C.