The present invention relates to production of alkenediols by reaction of an alkenol with aqueous formaldehyde.
The alkenediols which are produced can be hydrogenated to alkanediols, which are in general useful in known processes for the production of polymers, resins, plasticizers and synthetic lubricants. Also, citric acid and other tertiary hydroxy polybasic acids can be produced from alkenediols containing methylene groups, as taught in Belgian Pat. Nos. 784,238 and 792,076.
U.S. Pat. No. 3,692,848 is directed to production of alkenediols by reaction of an alkenol with an aldehyde at a temperature from 235.degree. to 400.degree. C. (455.degree. to 750.degree. F.) and in the presence of a base selected from alkaline hydroxides, carbonates and bicarbonates, ammonia and hexamethylenetetramine. U.S. Pat. No. 3,574,773 is closely related to U.S. Pat. No. 3,692,848. U.S. Pat. No. 3,574,773 is directed to the reaction of an olefin with an aldehyde at a temperature from 235.degree. to 400.degree. C. and in the presence of a base such that the starting materials have a pH between 7 and 11, preferably 7.5 to 9. According to U.S. Pat. No. 3,574,773, the amount of base should be such that a sample of the reaction mixture after cooling has a pH value of from 6.5 to 10, preferably 7 to 9.
According to the examples in U.S. Pat. No. 3,692,848, 3-methylpentene-3-diol-1,5 is produced by reacting 3-methyl-3-buten-1-ol with formaldehyde in aqueous solution. U.S. Pat. No. 2,789,996 discloses the production of 3-methylene-1,5-pentanediol by reaction of 3-methyl-3-buten-1-ol with formaldehyde under anhydrous conditions and at a temperature between 200.degree. and 350.degree. C., and in the absence of a catalyst. Reaction pH conditions are not disclosed in U.S. Pat. No. 2,789,996, but it is stated that the reaction does not take place when the formaldehyde is in the form of aqueous formaldehyde.