WO2001000552A1

WO2001000552A1 - Selective alkanol alkoxylations process

Info

Publication number: WO2001000552A1
Application number: PCT/US2000/017902
Authority: WO
Inventors: Mark Robert Bassett; Thomas Craig Bedard; Scott Patrick Christensen; Brian Terry Keen; Bradley Allen Sleadd
Original assignee: Union Carbide Chemicals & Plastics Technology Corporation
Priority date: 1999-06-30
Filing date: 2000-06-29
Publication date: 2001-01-04
Also published as: AU6201800A; WO2001000552A9

Abstract

The addition reaction of an epoxide and an organic compound containing an active hydrogen, in particular alkanols, is catalyzed by certain bismuth compounds represented by the formulas BiX3, BiOX, and X2BiOBiX2 wherein X is a weakly coordinating anion to obtain alkoxylation products having a desirable balance of selectivity, activity and by-product formation.

Description

SELECTIVE ALKANOL ALKOXYLATION PROCESS

Field of the Invention

This invention relates to the preparation of alkoxylate products by the catalyzed addition reaction of an epoxide with an active hydrogen containing organic compound and in particular to the production of alkylene glycol ethers by the alkoxylation of lower alcohols with an alkylene oxide.

Background of the Invention

Addition reactions of epoxides and organic compounds containing active hydrogen have been known for many years. A variety of catalysts have been proposed for promoting such addition reactions. For example, the use of compounds which are basic in nature and are soluble in the reaction medium such as soluble basic salts of the alkali metals of Group I of the Periodic Table, including sodium, potassium, rubidium and cesium, and of the alkaline earth metals of Group II of the Periodic Table, including calcium, strontium and barium are well documented in the literature. Sodium hydroxide has long been used in the commercial production of glycol ethers. In general, these basic catalysts provide acceptably low by-product formation but when used in amounts sufficient to provide acceptable activity, the selectivity, i.e. the amount of mono-alkoxylate produced as compared to the di- , tri- and higher alkoxylates produced is somewhat deficient and could desirably be increased to improve process economics.

It is also well known that compounds having a strong acidic nature which are soluble in the reaction mixture can be used to catalyze the addition reaction of alkoxides and hydroxylated compounds such as alcohols. For example, triflic acid and various soluble metal salts of triflic acid are described as catalysts for the addition reaction of alkanols and alkoxides in U.S. Patent No. 4,543,430 and Australian Patent No. 538,363. In general, the soluble acid catalysts are recognized as being highly active and providing excellent selectivity in producing mono-glycol ethers. However, corrosion and instability problems make certain of these catalysts difficult to use commercially and as a group they tend to promote side reactions leading to unacceptable levels of undesirable by-products being formed. Accordingly, industry continues to seek catalysts for the addition reaction of alkoxides and lower alcohols that will provide a combination of high activity, good selectivity and minimal by-product formation.

Summary of the Invention

According to the present invention, applicants have discovered that certain bismuth compounds represented by the formulas BLX3, BiOX, and X2BiOBiX2 wherein X is a weakly coordinating anion are effective in catalyzing the addition reaction of an epoxide and an organic compound containing an active hydrogen, in particular alkanols, to obtain alkoxylation products having a desirable balance of selectivity, activity and by-product formation.

Description of the Invention

The process of the present invention relates to the addition reaction of an epoxide with an active hydrogen containing compound carried out in the presence of a catalyst comprising one or more bismuth compounds soluble in the reaction medium and represented by the formulas B X3, BiOX, and X2BiOBiX2 wherein X is a weakly coordinating anion. Representative examples of weakly coordinating anions useful in preparing the bismuth catalysts of the present invention include, without being limiting, trifluoromethanesulfonate (triflate) CF3SO3-, perchlorate CIO4-, tetreaphenylborate BCCβHβ -, perfiourotetraphenylborate B CβFβ - and pentaflourotellurate (teflate) OTeFs-. Combinations of bismuth compounds with different weakly coordinating anions may be used. Particularly good results have been obtained using bismuth triflate.

The bismuth containing catalyst compositions used in the alkoxylation process of the present invention may be prepared by well known processes which include reacting an oxide, carbonate or hydroxide of bismuth (III) with the weakly coordinating acid of choice in the appropriate molar ratios.

Numerous epoxides including alkylene oxides and oxides of epichlorohydrin may be used as a starting material in the alkylation process of the present invention. Examples of suitable epoxides include, without limitation, ethylene oxide, propylene oxide, butylene oxides, glycidol, epichlorohydrin, cyclohexene oxide, cyclopentene oxide and styrene oxide. With the bismuth catalysts of the present invention, particularly useful results are achieved in alkylation reactions using ethylene oxide.

The process of the present invention may be used in the alkylation of a wide variety of organic compounds containing active hydrogen. Such organic compounds may include alcohols, phenols, carboxylic acids and amines. By way of illustration which is not intended to be limiting, suitable alcohols which may be alkoxylated using the process of the present invention include primary and secondary straight and branched chain alcohols containing up to 30 carbon atoms, cycloaliphatic alcohols, glycols, polyethylene glycols, polypropylene glycols and polyhydric alcohols such as pentaerythritol and glycerol. Alkylation of primary and secondary alcohols containing 1 to 6 carbon atoms represent a preferred embodiment of the process of the present invention. Particularly useful results have been demonstrated using the process of the present invention in the ethoxylation of a lower alkanol such as butanol to prepare ethylene glycol mono-alkyl ethers.

Because of its high activity, the amount of bismuth compound used as catalyst in the process of the present invention is relatively small and will vary depending on a number of factors including the particular catalyst species, temperature and other process conditions, the ratio of reactants and the desired balance of activity, selectivity and impurity formation sought by the skilled process operator. In general, the amount of bismuth catalyst used may be in the range of 5 to 500 ppm, based of the weight of the reactant organic compound containing active hydrogen, and more typically in the range of 50 to 100 ppm.

The temperature at which the process of the present invention may be carried out will also vary depending on a variety of factors such as equipment considerations, other process conditions such as catalyst concentration and reactor pressure and the desired balance of activity, selectivity and impurity formation targeted by the process operator. Acceptable process operations may be conducted at a reactor temperature in the range of 80 to 180 °C, more preferably in the range of 100 to 120 °C.

The alkylation process of the present invention is further illustrated by the following examples.

EXAMPLE 1

A two liter autoclave equipped with a stirrer, cooling coil, pressure transducer, vapor and liquid phase thermocouples and sampling port is charged with 900 grams of butanol in which is dissolved 65.5 ppm of bismuth triflate catalyst. Once charged, the butanol is degassed three times with 50 psig of nitrogen and 10 psig of nitrogen is left in the reactor. Heat is then applied to the reactor to achieve a desired reaction temperature of 160 °C. After a GC sample is taken, 90 grams of ethylene oxide is charged to the reactor through an oxide injector which is pressurized with 400 psig of nitrogen. The reaction half life was determined by monitoring the pressure drop in the reactor and is shown in Table 1 below. The reaction run time is six times the reaction half life time. At the end of the reaction time, heat is removed from the reactor and the reaction mixture is cooled to room temperature. The contents of the reactor are then removed and sampled for analysis. 989.7 grams of glycol ether product are recovered having the selectivity and impurities content shown in Table 1.

EXAMPLE 2

Example 1 was repeated using a reaction temperature of 100 °C. 988.7 grams of glycol ether product were recovered. Reaction half life and the selectivity and impurities content of the product are shown in Table 1.

TABLE 1

Example Temperature Half Life(l) Selectivitv(2) Impurities(3)

1 160°C 2.75 8.81 1.23

2 100 °C 22.75 7.52 0.41

(1) Minutes

(2) ratio of one mole adduct to two mole adduct

(3) Impurities as weight percent of product

The data in Table 1 clearly shows the advantageous balance of activity, selectivity and minimal impurities production obtained by the bismuth catalyzed process of the present invention. The glycol ether product produced by the process of the present invention has a ratio of mono- alkoxylate to di- alkoxylate of at least 7 to 1 and contains less than 1.5 weight percent impurities based on the total weight of the product.

Claims

What is claimed is:

1. A process for the alkoxylation of organic compounds containing an active hydrogen, said process comprising reacting said organic compound with an epoxide in the presence of a catalyst comprising one or more bismuth compounds soluble in the reaction medium and represented by the formulas BIX3, BiOX, and X2BiOBiX2 wherein X is a weakly coordinating anion.

2 The process of claim 1 wherein said catalyst is bismuth triflate.

3. The process of claim 1 wherein the reaction is carried out at a temperature in the range of 80 to 180 °C.

4. The process of claim 1 wherein said bismuth catalyst is present in an amount in the range of 5 to 500 ppm based on the weight of said organic compound.

5. The process of claim 1 wherein said organic compound is a straight or branched chain alkanol containing up to 30 carbon atoms.

6. The process of claim 5 wherein said alkanol contains from 1 to 6 carbon atoms.

7. The process of claim 1 wherein said epoxide is an alkylene oxide.

8. The process of claim 7 wherein said alkylene oxide is ethylene oxide.

9. An alkylene glycol monoalkyl ether prepared by the process of claim 1.

10. An alkylene glycol monoalkyl ether prepared by the process of claim 2.

11. An alkylene glycol monoalkyl ether prepared by the process of claim 3.

12. An alkylene glycol monoalkyl ether prepared by the process of claim 4.

13. An alkylene glycol monoalkyl ether prepared by the process of claim 5.

14. An alkylene glycol monoalkyl ether prepared by the process of claim 6.

15. An alkylene glycol monoalkyl ether prepared by the process of claim 7.

16. An alkylene glycol monoalkyl ether prepared by the process of claim 8.