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Home , Boron trifluoride

Patented Feb. 27, 1951 2,543,312

UNITED STATES PATENT OFFICE 2,543,312 RESNOUS. ACE ALS AND PROCESS FOR, PRODUCING AND HYDROLYZING THE SAME TO PRODUCE UNSATURATED ALDEHYDEs John W. Copenhaver, Easton, Pa., assignor to General Aniline & Film Corporation, New York, N.Y., a corporation of Delaware No Drawing. Application November 13, 1948, Serial No. 59,978 6 Claims. (C. 260-3) 2 This invention relates to a method of preparing of 60-64 C. as it was formed. The residue Was ag-unsaturated aldehydes. then steam distilled until no more Water-insol I have discovered that when an aldehyde is uble material came over. reacted with a vinyl in the presence of a The organic layer was then separated and the Friedel-Crafts metallic halide, catalyst such as aqueous layer was extracted with and trifluoride, there is obtained a somewhat the combined organic layer and extract distilled. resinous reaction product of -an unknown com After removing the chloroform and unreacted position which is apparently an acetal since on benzaldehyde, there was obtained a good yield hydrolysis in solution, it yields an a 6-unsat (about 60% of theory) of cinnamic aldehyde urated aldehyde of two more carbon atoms than O (boiling point 127-128° C) at 14 mm., n25 16175. were present in the original aldehyde and an The product was further characterized as cin alcohol corresponding to the alkyl group of the namic aldehyde by conversion to the phenyl hy vinyl ether. In addition, smaller amounts of drazone ( 168-169° C.). A mixed somewhat higher molecular weight and more melting point with an authentic sample ShoWed highly unsaturated aldehydes containing two or no depression. more double bonds can be isolated from the prod lucts of the hydrolysis. While the exact mech Eacample II anism of the reaction is not understood, the over A mixture of 300 grams of diethylacetaldehyde, all reaction may be formulated as follows: 0.375 ml of BF3O (C2H5)2 at 5-10 C. Was treated BF's resinous acetal) hydrolysis 20 with 89 grams of . By treat mm) . m3 ment of the reaction mixture in a manner sim t H. B. RCHO--ROCH=CH RCs-C-CHO-ROH ilar to that described in Example I, there was E. isolated: RCH=CHCHO-RO CH=CH- RCH=C-CH=C-CHO, etc. CH-CH-CH-CH-CHO wherein R and R represent hydrocarbon radicals 25 (i. e., alkyl, aryl or aralkyl), R preferably being aryl or aralkyl and R' preferably being alkyl which was identified as its 2,4-dinitrophenylhy (i. e. methyl, ethyl, propyl, butyl or amyl). drazone (melting point 153-154 C.). The present invention may be most readily Analysis calculated for C14H8N4O4: described by first considering specific examples 30 (C 54.90; H 5.92; N 18.29 thereof. Found: C 54.71; H 5.77; N17.78 Eacample I In practicing the present invention, it has been 636 grams (6 mols) of benzaldehyde and 0.375 found that the best yields were obtained when ml. of boron trifluoride complex employing aromatic aldehydes, such as benzalde were charged to a 1-liter, 3-necked flask fitted hyde, o-, m- and p-nitrobenzaldehyde, o-, m with a sealed stirrer, thermometer and gas inlet and p-chlorobenzaldehyde, tolualdehyde, a- and tube. 148 grams (2.55 mols), of vinyl methyl B-naphthaldehyde, p-methoxybenzaldehyde, p ether were then slowly introduced through the bromobenzaldehyde, and the like, and therefore gas inlet tube, while stirring:the reaction mixture 40 the process of this invention appears of greatest and maintaining the temperature within the interest for the production of aromatic unsatu range of 20-30° C. by intermittent cooling. rated aldehydes such as cinnamic aldehyde and There is thus obtained a light brown resinous the like. However, the process is operative and product (boiling point 203° C-204° C./2 mm.), fair yields of a,3-unsaturated aldehydes have Calculated 1:1 adduct C10HiOa: C, 73.14; H, 7.37 45 been obtained when using aliphatic aldehydes Calculated dinner: 328 M. W. such as propionaldehyde, ethyl butyraldehyde, and the like. Found: C, 73.01, H, 7.49. While substantially any vinyl ether may be M. W.: 325 . . . employed in practicing the present invention, it which was transferred to a distillation flask at 50 is preferable to employ lower alkyl vinyl tached to a fractionating column and 5 grams Such as methyl vinyl ether, , of p- sulfonic acid and 100 ml. of water propyl vinyl ether, isopropyl vinyl ether, n-butyl were added thereto, and the mixture gradually vinyl ether, isobutyl vinyl ether, amyl vinyl ether, heated. Methanol was formed in the reaction and the like, since the alcohol corresponding to and was removed by distillation at a temperature 55 the alcohol of the vinyl ether is formed in the 2,548,812 ... } 3 hydrolysis reaction. Accordingly, the lower alkyl ployed. Too large an amount of water, however, vinyl ethers, especially methyl and ethyl vinyl is preferably avoided, since it constitutes only an ethers which are less expensive than the higher unnecessary load on the System. vinyl ethers, are to be preferred in practicing I claim:. . . . -- ...... this invention. 5 i. The process of producing a 5-unsaturated It has been found that in order to obtain a aldehydes which comprises reacting a vinyl ether good yield of the desired unsaturated aldehyde, of the formula, R-O-CH=CH2 wherein R. some excess of aldehyde should be employed in represents a hydrocarbon radical selected from the reaction with vinyl ether. When the ratio of the group consisting Of alkyl, aryl and ai'alkyl aldehyde to vinyl ether is within the range of O with an aldehyde in the presence of the metallic 2:1 to 4:1, the best yield of the product has been halide Friedel-Crafts catalyst at a temperature of obtained. While boron trifluoride and its ether from 0-50° C. and then hydrolyzing the thus ob complex are preferred as catalysts in the initial tained primary reaction product in an acidic reaction of aldehyde and vinyl ether, other aqueous medium at a temperature in excess of Friedel-Crafts type metallic halide catalysts such ls 50° C. to obtain an ag-unsaturated aldehyde of as gallium trichloride, stannic chloride, bismuth two more carbon atoms than the original trichloride, antimony trichloride, aluminum aldehyde. chloride, and the like, may be used if desired. 2. The process as defined in claim 1, wherein This initial reaction of aldehyde and vinyl ether the aldehyde employed is an aromatic aldehyde. may advantageously be carried out at tempera 20 3. The process as defined in claim 1, wherein tures of from 0-50° C. the metallic halide catalyst employed is boron The hydrolysis of the primary reaction product trifluoride. of aldehyde and vinyl ether may advantageously 4. The process as defined in claim 1, wherein be carried out at the reflux temperature of the the vinyl ether specified is a lower alkyl vinyl reaction mixture, in order to remove the alcohol 25 ether. -- formed in the reaction. However, somewhat 5. The process as defined in claim 4, wherein lower temperatures may be employed if desired, the metallic halide catalyst specified is boron satisfactory reaction rates being obtained attem trifuoride. . peratures above about 50° C. 6. A resinous product comprising the reaction Substantially any acid reaction compounds 30 product, formed in the presence of a Friedel may be employed during the hydrolysis. As ex Crafts catalyst, of a vinyl ether of the formula amples of acidic Substances which may be used R-O-CH=CH2 wherein R represents a hydro may be mentioned mineral acid, such as hydro Carbon radical selected from the group consisting chloric, sulfuric or phosphoric acid, Organic of alkyl, aryl and aralkyl With a member of the carboxylic such as acetic acid, organic 35 class consisting of an aromatic and aliphatic Sulfonic acids and acid reacting inorganic Salts, aldehyde. . . . . Such as zinc chloride, ammonium chloride, JOHN W. COPENHAVER. Sodium acid sulfate and the like, Such acids need not be present in large amounts, amounts of REFERENCES CITED from .1 to 1% by weight of the reaction mixture -40 having been found satisfactory, although larger The following references are of record in the amounts up to 5% may be employed. Without file of this patent: - - - - adverse effect. UNITED STATES PATENTS Preferably, Some excess of water over the amount theoretically required for hydrolysis of Number Name Date the primary reaction product is employed during 45 2,104,000 Reppe ------Dec. 28, 1937 the hydrolysis, approximately double the theo 2,223,171 Gaylor ------Nov. 26, 1940 retical quantity of water being preferably en