Recyclable boron trifluoride catalyst and method of using same

Provided by PatentStorm, http://www.patentstorm.us Provided by PatentStorm, http://www.patentstorm.us Provided by PatentStorm, http://www.patentstorm.us Provided by PatentStorm, http://www.patentstorm.us Provided by PatentStorm, http://www.patentstorm.us Provided by PatentStorm, http://www.patentstorm.us United States Patent [19] [11] 4,209,654 Booth et ml. [45] Jun. 24, W80 [54] RECYCLABLE BORON TRIFLUORIDE [56] References Cited CATALYST AND METHOD OF USING SAME U_S_ PATENT DOCUMENTS 2,425,839 8/1947 Schulze et al. ................. .. 260/671 P [75] Inventors; Robert E, Booth; Francis E, Evans, 2,836,634 5/1958 Lee et al. ....... .. 260/671 P both of Hamburg; E. Eibeck’ . . . . . . . . . . . .. Orchard park; Marfiu A. Robinson, 3,855,342 12/1974 Huang et al. 585/726 East Amherst all of N.Y. 4,032,591 6/1977 Cupples et al. .................... .. 585/644 Prfmaty Examiner—George Crasanakis Attorney, Agent, or Firm—Alan M. Doernberg; Jay P. Friedenson [57] ABSTRACT When saturated with boron trifluoride, certain poly- hydric alcohols form adducts which catalyze reactions for which boron trifluoride is catalytic. The adduct is [22] Filed: Oct 16’ 1978 recovered from the reaction mixture and recycled, greatly reducing boron and fluoride values in the prod- uct and in any effluent. Examples include propylation of [73] Assignee: Allied Chemical Corporation, Morris Township, NJ. [21] App]. No.: 951,911 [51] Int. «C13 ......................... .. C07C 3/56; C07C 3/18 toluene in the presence of a recycled adduct of boron [52] US. «Cl. ................................... .. 585/465; 585/525 trifluoride with mannitol or sorbitol. [58] Fielrl of Search ......... .. 260/671 C, 671 P, 671 R; 585/465, 525, 644, 726 12 Claims, No Drawings Provided by PatentSt0rm, http://WWW.patentst0rm.us 4,209,654 1 RECYCJLABLE BORON TRIFLUORIDE CATALYST AND METHOD OF USING SAME BACKGROUND OF THE INVENTION Boron trifluoride has found wide use as a catalyst for various reactions and has been proposed as a catalyst for additional reactions. Such reactions include hydrocar- bon transfers (alkylations, cracking, isomerizations, polymerizations) and reactions involving functional groups (dehydration of alcohols, cyanation of olefins, conversion of aniline to diphenylamine, conversion of methylol to 4-methoxy-2-methyb1-butene, reaction of ammonia and acrolein to form pyridine and reaction of sodium acetate and acetylene to form vinyl acetate). A drawback of the use of boron trifluoride is that it de- composes during reaction, preventing reuse and con- tributing boron and fluoride to either the product or an effluent stream, necessitating extra purification or re- covery. While attempts have been made to fix boron trifluo- ride to a polymer or inorganic support, these attempts have not produced a reusable boron trifluoride catalyst system practical for the wide variety of catalytic uses. For many particular reactions, a cocatalyst is provided with boron trifluoride to cause or enhance catalytic activity. Such cocatalysts have not, however, been used to retain the boron and fluoride values. BRIEF DESCRIPTION OF THE INVENTION It has been discovered that certain polyhydric alco- hols form stable complexes or adducts with boron triflu- oride which can catalyze reactions for which boron trifluoride is a catalyst and which can be separated from the reaction mixture with minimum loss of activity or boron and fluoride values. Accordingly, the present invention includes an im- provement in a method of reacting at least one unsatu- rated hydrocarbon in an alkyl transfer reaction of the type catalyzed by boron trifluoride. In the improve- ment, the reaction is conducted in the presence of a catalytic amount of a polyhydric alcohol saturated with boron trifluoride to form an adduct and the adduct is recovered from the product of the reaction and is recy- cied. In one form of the invention the polyhydric alcohol is selected from the group consisting of linear compounds of the formula CI-I201-I——(CHOH),.-—-CH2OH where n is 1 to 5, pentaerythritol, crystalline cellulose and non- adjacent diols of 5-10 carbons of the formula R1-—- CHOH—-—Cll-lz-—CHOH-—R2 where R1 and R2 are each alkyl of 1-6 carbons. In another form of the invention the reaction is con- ducted in the presence of a catalytic amount of an ad- duct formed by saturating with boron triflouride a poly- hydric alcohol selected from the group consisting of glycerine, tetritols, pentitols, hexitols, heptitols, penta- erythritol, crystalline polysaccharides, polyvinyl alco- hol and non-adjacent diols of 4-10 carbons; the reaction is conducted at an elevated temperature at which the adduct is stirrable; the reaction mixture is cooled to a temperature at which the adduct becomes viscous; and the adduct is recovered from the reaction mixture and recycled. The present invention also includes stable, recyclable catalyst adducts formed by the saturation with boron trifluoride of a polyhydric alcohol selected from the group consisting of glycerol, tetritols, pentitols, hex- 5 10 15 20 25 30 35 40 45 50 55 60 65 2 itols, heptitols, pentaerythritol, polyvinyl alcohol, crys- talline polysaccharides and non-adjacent diols of 4-10 carbons. DETAILED DESCRIPTION OF THE INVENTION The stable catalyst adducts of the present invention are formed by saturation of polyhydric alcohols with BF3. The product is referred to herein as an “adduct” without limitation as to its actual structure which, be- cause of the observed ratio of one mole of BF3 to two moles of hydroxyl in some cases, may be a chelate of the formula I I H H‘-‘C O\ H-C ON %BF2 or (WE; H-‘C O H— O I \ I H H The polyhydric alcohols of the present invention include linear members of the formula CH2CH—-(- CIi[OH),,——CH2OH where n is 1 to 5, branched poly- hydric alcohols having 3-6 hydroxyls such as penta- erythritol, polyvinyl alcohol and certain polysaccha- rides. The linear polyhydric alcohols include glycerin; the tetritols erythritol and threitol (D or L or racemic); the pentitols ribitol, xylitol and arabitol (D or L or racemic); the hexitols dulcitol, sorbitol, mannitol (D or L of racemic), iditol (D or L or racemic), talitol (D or L or racemic) and allitol; and the heptitols which in- clude perseitol and sedoheptitol. Preferred are the hex- itols and especially preferred are mannitol and sorbitol. The polyhydric alcohols of the present invention also include diols with non-adjacent hydroxyls of 4-10 car- bons such as 2,4-pentane diol. Preferred in this group are diols of the formula R1—CHOH—CH2—- CI-IOH—Rz where R1 and R2 are each alkyl of 1-6 carbons and together have 2-7 carbons. Branched polyhydric alcohols having 3-6 hydroxyls are also suitable, and preferred in this group is penta- erythritol C(CH2OH)4. Some, but not all sugars, both pentoses and hexoses, are suitable. Crystalline polysaccharides are also suit- able, such as crystalline cellulose and some starches; while non-crystalline polysaccharides such as cellulose fiber and sucrose are generally unsuitable. The first criterion for polyhydric alcohols suitable in the present invention is that they absorb BF3 gas in substantial proportions. It appears that a minimum of about 0.3 moles BF3 absorbed per mole of hydroxyls is required. Many but not all polyhydric alcohols tested which absorb such substantial quantities of BF; are active for one pass of alkylation or similar reaction. The second criterion for the polyhydric alcohol-BF3 adduct is that it be separable from the product mixture of alky- lation or similar reaction, either by distillation, decant- ing or some other technique, preferably by decanting based upon immiscibility or insolubility or solidification of the catalyst adduct on cooling. The third criterion is that the adduct be catalytically active for at least one additional pass of alkylation or similar reaction and preferably for at least four additional passes. Most pre- Provided by PatentSt0rm, http://WWW.patentst0rm.us 4,209,654 3 ferred are adducts formed from polyhydric alcohols such as mannitol, sorbitol, glycerin, crystalline cellulose and pentaerythritol which give substantially constant activity on succeeding passes of alkylation. The quantity of BF3 absorbed varies, even among isomers such as mannitol (which absorbed about 3 moles BF3) and sorbitol (which absorbed about 2 moles). Optical isomers such as D-mannitol and L—man- nitol and mixtures thereof such as racemic mannitol would be expected to behave similarly. It is postulated that the stereochemical differences between, for exam- ple, sorbitol ‘and mannitol cause one pair of adjacent hydroxyls to be good BF3 acceptors in mannitol but poor BF3 acceptors in sorbitol. The behavior of glyc- erin and xylitol in absorbing more BF3 moles than the number of hydroxyl pairs suggests that the odd hy- droxyl is also somewhat active. The resistence of the inositol used suggests a conformational arrangement which prevents BF3 absorption, but does not necessarily indicate that other stereoisomers are inactive. The cate- chol adduct only lasted one run, at least for the cymeme reaction, because it failed to be easily separable from the alkylation product mixture in which it dissolved. Cate- chol and other polyhydric aromatics such as resorcinol are not, therefore, excluded provided that a suitable separation technique is used. Of the polysaccharides tested, crystalline cellulose, starch and sucrose all gave absorption of at least about 0.3 moles BF3 per mole and all three were active on the first pass. Sucrose and starch would be regarded, how- ever, as unsuitable because of failure to retain activity after separation. Cellulose fiber failed to absorb BF3 and could thus be rejected on the first criterion. The reactions for which the present catalysts may be used are not limited to alkylations. Other hydrocarbon transfer reactions involving at least one unsaturated reactant, such as isomerizations, cracking and polymeri- zations for which boron trifluoride is catalytically ac- tive, may be conducted in the presence of the catalyst adducts. In addition, reactions involving functional groups such as cyanation of olefins, formation of pyri- dine and formation of vinyl acetate, may be practised with the catalyst adducts. Reaction conditions may be similar to those used for the same reaction with boron trifluoride alone as cata- lyst. Because many of the catalyst adducts solidify at moderate temperatures, it is frequently desirable to maintain the reaction mixture at slightly elevated tem- peratures such as 40°—120° C. with agitation. Ceasing agitation, cooling or both frequently causes separation of catalyst adduct from the reaction mixture, enabling recovery and recycling by phase separation. With some reactions, it may be more convenient to distill the prod- uct from the reaction mixture, leaving the catalyst ad- duct for reaction with fresh reactant. The ratio in each pass or in a continuous system at one time of catalyst adduct to reagent (monomer in the case of oligomerizations, the limiting reagent in the case of alkylations or other reactions between reagents) is not critical, but may be in the range of about 0.0001 to 10:1 with about 0.001 to 1:1 being preferred and about 0.005 to 01:1 being more preferred. EXAMPLE 1 Propylation of Toluene with Mannitol-BF3 Adduct BF3 gas was passed into a stirred slurry of mannitol (50 g, 0.276 mole) and toluene (207 g) (dried of excess moisture by azeotropic distillation) at room temperature 10 15 20 25 30 35 40 45 50 55 765 4 for seven hours. The adduct had separated as a gummy mass that could be agitated only at elevated tempera- tures. BF3 addition was continued at 60°—70° for 16 hours, and 50°—60° for seven hours (viscosity had de- creased somewhat). The mannitol absorbed 57.7 g BF3, 0.851 mole, which is 3.1 moles BF3 per mole of manni- tol, and 0.51 mole BF3 per hydroxyl group. The toluene was decanted from the adduct (an immo- bile gum at room temperature) and fresh toluene (about 200 g) was stirred with adduct at about 60° with a N2 purge to strip unreacted BF3. When gas chromatogra- phy analysis of the toluene phase showed no BF3, the toluene was again replaced, and propylene passed into the toluene-adduct mixture agitated at 62° for 3 hours. Gas chromatography analysis of the liquid phase showed it to contain 20.5% p-cymene. (The chromato- gram has peaks that are probably attributable to o- cymene, and dipropyl-toluenes, but proof and quantita- tive determinations were not available for these.) The product mixture (200 g), decanted from the catalyst, was extracted twice with 200 ml water; analysis of the combined extracts showed the toluene-cymene product had 248 ppm boron and 590 ppm fluoride. The catalyst was washed by stirring at 60° with fresh toluene to remove cymenes. Fresh toluene was added to the catalyst and stirred 2 hours at 60'’; it now showed 0.8% p-cymene extracted from the catalyst. Propylene was passed in with agita- tion at 60°—80° for three hours. Analysis showed the toluene phase to be 44.5% p-cymene, or a gain of 43.7%. Water extraction and analysis showed that the toluene phase contained 87 ppm boron and 221 ppm fluoride. In like manner the catalyst performed through two additional cycles. The conditions and results of all four cycles are displayed in Table 1. Table 1 Cycle 1 2 3 4 Propylation (hrs) 5 3 3 3 Temperature (“C.) 62 60-80 65-86 60-63 Initial p-cymene (vol. %) O 0.8 0.8 2.0 Final p-cymene (vol. %) 20.5 44.5 4-4 40 Gain in p-cymene 20.5 43.7 43.2 38 Boron content of 248 87 — 20 product (ppm) Fluoride content of 59 221 149 99 product (ppm) Other batches of mannitol-boron lrifluoride adduct were used over ten and five cycles. EXAMPLE 2 Propylation of Toluene With Sorbitol—BF3 Adduct In a procedure like that described in Example 1, BF3 was added to sorbitol (50 g., 0.276 mole) at tempera- tures up to 85° (whatever temperature was required to preserve mobility through the gummy stages) over a 19 hour period. 40.7 g. BF3 (0.600 mole) was absorbed, (equivalent to 2.17 moles per mole sorbitol or 0.36 per hydroxyl). Propylation of toluene by this catalyst was conducted as detailed in Example 1, but, as shown below, the run time was shortened. In the first cycles, the p-cymene content had leveled off, but the toluene content was about 20%, and dipropyl toluenes showed prominently, indicating that ‘cymeme was being propylated more than toluene. Provided by PatentSt0rmi http://WWW.patentst0rm.us 4,209,654 5 6 Consequently, the third, fourth and fifth runs were shortened to two, one and one hour. The conditions and EXAMPLE 4 results are displayed in Table 2. Propylation of Toluene with Xylitol-BF3 Adduct Table 2 Following the procedure of Example 1, BF; (26.0 g, Cycle 1 2 3 4 5 5 0.383 mole) was added to xylitol (25.3 g, 0.166 mole) at m Mon (hours) 3 3 2 1 1 4-0°—50°. '1‘ he xylitol absorbed 2.30 moles BF; per mole, Texxlgerature (°c.) 77—94° 91-98’ 70—86'‘ 80-83“ 75—81° 01' 0-46 P31’ hYd1'0XY1- and PTODYI-filed 1011181“? 85 Shown p-Cymene - 0.15 o.o3 o.l 0.5 0.01 in Table 4. initial % T bl 4 p-Cymene - 34 40 46.5 30.5 30 10 3 3 final % Cycle 1 2 3 p-Cymene— 33.8 40 46.5 30 30 _ increase % Time — hours 3 3 3 Boron _ ppm 263 99 214 7 137 Temperature 52—61° 5l—57° 52-64° Fmoride _ ppm 5“ 244 47; 28 472 p-Cymene - initial %