2,811,562 United States Patent Office Patented Oct. 29, 1957

1. temperatures in the range of 50-90° C. Thus, I have found it possible to carry out a mixed aldol condensation 2,811,562 of isobutyraldehyde with another in a tempera CONDENSATON OF SOBUTYRALDEHYDE WITH ture range such that no isobutyraldol is formed. If the LOWER ALPHATC reaction is carried out according to the process of the invention, and the aldehyde to be condensed with iso Hugh J. Hagemeyer, Jr., Longview, Tex., assignor to is added to a solution of hot isobutyralde Eastman Kodak Company, Rochester, N. Y., a corpo hyde containing the alkali metal carbonate catalyst, the ration of New Jersey sole product of the reaction is a 3-hydroxy-2,2-dimethyl No Drawing. Application June 28, 1954, 10 aldehyde. Serial No. 439,865 50-90°C. 7 Claims. (C. 260-602) (CH3)2CHCHO -- RCHO Macd. RCH(OH) C(CH),CHO This invention is concerned with an improved process wherein R is hydrogen or a 1-9 carbon alkyl radical. for the production of mixed aldols of isobutyraldehyde. 5 In producing the mixed aldol products, and particu It is concerned with a process wherein isobutyraldehyde larly in preparing hydroxypivalaldehyde, it is advan and lower aliphatic aldehydes are reacted in the form of tageous to use at least a one mole excess of isobutyralde mixed aldols by carrying out the condensation in the hyde so that a complete recovery of the hydroxypivalal presence of an alkali metal carbonate. It is specifically dehyde is realized in the organic layer. In the process concerned with a process for the production of hydroxy 20 of the present invention I have found that optimum re pivalaldehyde by reacting isobutyraldehyde and formal sults are obtained by employing molar excesses of iso dehyde at temperatures from 50-90° C. in the presence butyraldehyde ranging from 1 to 5. The catalyst is of an alkali metal carbonate. The invention is further usually a solution of potassium, sodium or lithium car concerned with a process wherein the lower aliphatic alde bonate in water and the weight of catalyst used varies hyde is added to a reaction vessel containing an excess of 25 with the particular aldehydes reacted. Thus, in making isobutyraldehyde and the alkali metal carbonate and hydroxypivalaldehyde and employing a one mole excess heated to a temperature of 50-90° C. It is further con of isobutyraldehyde, I have found it advantageous to use cerned with a process for producing mixed aldols of 4% potassium carbonate based on the weight of iso isobutyraldehyde which avoids the formation of other butyraldehyde charged to the reactor. aldol products, and of the usual Cannizzaro and Tis 30 Mixed aldols of isobutyraldehyde with , chenko reaction products. It is also specifically con acetaldehyde, and butyraldehyde are. cerned with a process for the production of hydroxy made according to the invention by adding the aldehydes pivalaldehyde wherein formaldehyde is reacted with at to a refluxing solution of isobutyraldehyde in the presence least a molar excess of isobutyraldehyde in the presence 35 of aqueous potassium carbonate. Although any soluble" of an alkali metal carbonate at a temperature in the range alkali carbonate may be used, potassium carbonate is of 50-90° C. Then substantially pure hydroxypivalalde usually preferred and the amount used can vary from hyde is obtained by separating the organic layer and 2-10% based on the weight of isobutyraldehyde charged stripping off unchanged isobutyraldehyde. to the reactor. The catalyst is preferably charged as a No prior art process has been reported in which the 20-50% aqueous solution in water. Reaction tempera mixed aldol of isobutyraldehyde and a lower aliphatic 40 tures varying from 50-90° C. have been used and I have aldehyde is substantially the sole product. Hydroxy found that the optimum results are usually obtained in pivalaldehyde has been prepared from isobutyraldehyde the temperature range 60-75° C. At temperatures be and formaldehyde in the presence of potassium carbonate low this broader range, aldol products other than the by Wesseley, Monatshefte 21, 216-234 (1900). Later 45 mixed aldol are formed and at temperatures above 90' experiments using this same procedure are reported by C., there is considerable yield loss due to the formation Fourneau et al., Bull. Soc. Chim. (4), 47, 871 (1930) and of the Tischenko product of the mixed aldol. This is Stiller et al., J. Am. Chem. Soc., 62, 1785 (1940). In avoided in the present process by adding the aldehyde to the prior art references, relatively large amounts of po be reacted to isobutyraldehyde at reflux in the presence tassium carbonate were added to equimolar parts of iso of aqueous potassium carbonate, and after the addition butyraldehyde and formalin at low temperatures, 10-20 is complete the organic layer is separated from the aqueous C. Some of the disadvantages of this prior art method catalyst solution, the excess isobutyraldehyde is stripped were low yields, long reaction times, large catalyst re off and the product is then distilled at reduced pressure. quirements, and incomplete reaction of the formaldehyde. This method avoids yield loss due to other condensation I have found that mixed aldols of isobutyraldehyde may 5 5 reactions since the mixed aldol is heat stable in the ab be prepared, by a process in which a relatively small sence of the catalyst solution. amount of alkali metal carbonate is used, a fast reaction Table I contains comparative results obtained using time is obtained and complete reaction of the formalde the method described in the prior art and the process of hyde or other aldehyde used with isobutyraldehyde, is the present invention in preparing hydroxypivalaldehyde realized. In addition the formation of condensation 60 from isobutyraldehyde and formaldehyde. In addition products other than the mixed aldol is avoided by carry to the higher conversions and yields obtained by the proc ing out the reaction at or above the reflux temperature ess of the present invention, it is immediately obvious of isobutyraldehyde. It is an object of my invention to that there is no loss of reagents to the formation of higher provide such a process. condensation products and the aldehyde being added to The process of the present invention makes use of the 65 the isobutyraldehyde is substantially completely reacted. discovery that isobutyraldol is completely dealdolized This is particularly advantageous where hydroxypivalal at about 60° C. I have found that mixed aldols of iso dehyde is being made, since it avoids any of the difficulties butyraldehyde with formaldehyde and aldehydes con involved in destroying or removing residual traces of taining from 2-10 carbon atoms do not dealdolize at formaldehyde. ... 2,811,562

TABLE I Mole Ratio, Catalyst, Weight Reaction Reaction i-HBu, HOPA, Run No. i-HBuf Solvent Percent Temp., Time Percent Percent CHO o C. Conv. Yield

1:1 CEO.0.5 KOH 20-25 2 hours.----- 47 28 1:1 CEO. O.5 KOH- 20-25 24 hours 83 80 2:... i E20...... ist.0K i60-702 hours...... 9. 90 2:l, 60-70 ----- do------86 97 2: 60-70 ----do 82 91. 2:1. ". 93 94 2:1 No reaction "2: 112 73 2: 09 9 23------. 2: 84.96 7074 In Table I, the isobutyraldehyde percent conversion represents the amount of isobutyraldehyde reacted under distilled off thereafter is returned to the reaction con the conditions employed. Runs Nos. 1, 2, 34, and 37 tinuously, the reaction being operated at 62-64° C. show the results using alcoholic and aqueous alkali at Example 2 lower temperatures. Here the isobutyraldehyde reacted Eight hundred seventy-six grams of normal butyralde was considerably more than the hydroxypivalaldehyde hyde was added to 1,150 grams of isobutyraldehyde at re yield due to the formation of other products. In run. 22 flux in the presence of 46 grams of potassium carbonate the reaction temperature was allowed to go to 100 and dissolved in 90 grams of water over a one-hour period. in this run a considerable amount of the hydroxypivalalde The reaction temperature was maintained at 60-70° C. hyde was converted to the glycol ester by the Tischenko O and at the end of the addition the mixture was heated an reaction. In run 23 only a tenth mole excess of isobutyral additional two hours at 70 C. The reaction mixture was dehyde was employed and again a yield loss was experi cooled to 40 C. and the organic layer decanted. Excess enced due to a cross Cannizzaro reaction between hydroxy isobutyraldehyde was distilled off at atmospheric pres pivalaldehyde and formaldehyde to form the pentaglycol. Sure and the residue was distilled through a 10-plate Table II summarizes the results obtained in the prepara 5 column at reduced pressure to yield 1,061 grams of 3 tion of the mixed aldols of isobutyraldehyde with acetalde hydroxy-2,2-dimethylhexaldehyde, boiling point 125 C. hyde, propionaldehyde and normal butyraldehyde. Al at 14 mm. though comparative data on operations outside of the in vention is not given, the advantages of this method of pre Example 3 paring mixed aldols of isobutyraldehyde over that wherein 20 Using the procedure of Example 2, 8 moles of acetalde an alkali metal hydroxide is used at low temperature hyde were reacted with isobutyraldehyde using a molar should be immediately obvious to those skilled in the art. excess of isobutyraldehyde and a 91% yield of 3-hydroxy Thus, the only product obtained is the mixed aldol of iso 2,2-dimethylbutyraldehyde, boiling point 90° C. at 22 butyraldehyde and the added aldehyde, and no isobutyr mm. was obtained. aldol or aldol of the added aldehyde is formed. 25 Example 4 TABLE II Using the same procedure as in Example 2, 8 moles of propionaldehyde were reacted with a molar excess of No. of Mixed isobutyraldehyde and a 96% yield of 3-hydroxy-2,2-di Added Moles, KaCO3, Reaction. Reaction i-HBu, Aldol, Aldehyde Excess Weight Temp. Time, Conv. Yield 30 methylvaleraldehyde, boiling point 98 C. at 20 mm. was i-EBu Percent o C. hours Percent Percent obtained. Sodium carbonate can also be used in the above ex

I '4.0. 60-75 2 9. 90 amples. - 2. 2.0. 60-70 2 88 96 I claim: . 5 2.0 60-62 2. 97. 97 4.0 '60-70 4. 93 91 1. A process for the preparation of hydroxypivalalde 4.0 60-70 4 92 96 4.0 60-70 3 90 92 hyde wherein said aldehyde is produced in extremely high n-Bu----- 2. 3.0 60-70 4. 96 '97 yield and is substantially the sole aldol product, which comprises, adding formalin to excess isobutyraldehyde maintained at 50-90 C. in contact with aqueous potas The invention is further illustrated by the following sium carbonate. specific examples. 40 2. A process for the preparation of an aldol product Example 1 of the formula Eleven hundred fifty grams of isobutyraldehyde and 56 grams of potassium carbonate dissolved in 90 grams of wherein the said aldol is produced in extremely high yields water were-added to a stirred three-necked flask and heated 60 and is substantially the sole aldol reaction product in each to reflux. Six hundred fifty grams of a 37% formalin case, comprising adding an aliphatic aldehyde of the solution was added over a period of 30 minutes and the formula RCHO to a solution of isobutyraldehyde main reaction temperature was held below 70° C. by cooling tained at 50-90° C. and containing 2-10% aqueous alkali as necessary. The reaction mixture was stirred at 65 metal carbonate based on the quantity of isobutyralde 70 C. for two hours and at the end of this time the mixture 65 hyde used, the isobutyraldehyde being present in sub was allowed to cool to 40 C. and the organic layer stantial molar, excess over the quantity of aliphatic decanted. Unchanged isobutyraldehyde was distilled off aldehyde added, the symbol R being selected from the and the residue was distilled at reduced pressure. Seven group consisting of H and C1-Co alkyl radicals, and said hundred ninety grams of hydroxypivalaldehyde, boiling isobutyraldehyde solution being maintained at 50 to 90 point 78-85 C. at 4 mm. was obtained. The hydroxy 70 C. during the reaction. pivalaldehyde dimerized on standing and formed a white 3. A process according to claim 2 wherein the iso crystalline dimer, melting point 92-94. C. butyraldehyde is present in a 1-5 mole excess, the alkali. This reaction runs, very well on a continuous basis by metal carbonate being aqueous, potassium carbonate. passing the reaction products through a condenser and 4. A process according to claim 2 wherein the added then to a decanting step. The isobutyraldehyde which is 75 aldehyde is formaldehyde. 2,811,562 5 6 5. A process according to claim 2 wherein the added OTHER REFERENCES alty.articly to claim 2 wherein the added agensteiner: Monat, fur Chemie, vol. 22, pages 14 algly is propically laim 2 wherein the added "E. Monat. fur Chemie, vol. 22, pages 23 and 24. ld h FE E. E. calm 2. Wherein the added 5 Lieben: Monat. fur Chemie, vol. 22, pages 291-98. aldehyde is n-butyraldehyde. Wessely: Monat. fur Chemie, vol. 21, pp. 216-220 Reft 8 O ten (1900).Stiller et al.: J. Am. Chem. Soc. 62, p. 1787 (1940). 2,468,710 Hull ------Apr. 26, 19490 2,684,385 Biribouer et al. ------July 20, 1954