3,655,735 United States Patent Office Patented Apr. 11, 1972 1. 2 Suitable basic compounds include, in addition to in 3,655,735 organic bases such as sodium hydroxide, barium hydrox PRODUCTION OF 3.NETHYLBUT-2-EN-1-OLOR ide or ammonia and in addition to the salts of strong bases 3-METHYLBUT-2-EN-1-YLACETATE and weak acids such as sodium carbonate or ammonium Horst Pommer, Ludwigshafen, Herbert Mueller, Franken carbonate, particularly nitrogenous basic compounds such thal, Dietrich Mangold, Neckargemuend, and Hermann Overwien, Ludwigshafen, Germany, assignors to as alkylamines or arylamines and also compounds which Badische Anilin- & Soda-Fabrik Aktiengesellschaft, are capable of splitting off bases, such as piperidine ace Ludwigshafen (Rhine), Germany tate or acid amides such as acetamide or urea. Basic com No Drawing. Filed Dec. 9, 1968, Ser. No. 782,420 pounds of phosphorus, such as alkyl and aryl phosphines, Claims priority, application Germany, Mar. 22, 1968, O for example triphenyl phosphine, are also suitable. - P 77 68 023.8 Hexamethylenetetramine (urotropine) is preferred as Int, C. C07c 29/00, 67/00 the basic compound. U.S. C. 260-491 2 Claims The presence of basic compounds causes a more rapid and more specific isomerization in the desired direction, 5 i.e. from the 3-ene compound to the isomeric 2-ene com ABSTRACT OF THE DISCLOSURE pound. Since there is one more possibility of isomerization Production of 3-methylbut-2-en-1-ol and 3-methylbut with the free alcohol than with the acetate (namely to 2-en-1-yl acetate by isomerizing 3-methyl-3-buten-1-ol or isovaleraldehyde), the addition of base is particularly ad 3-methyl-3-buten-1-yl acetate with a catalytic amount of a vantageous in the rearrangement of 3-methylbut-3-en-1-ol carbonyl compound of a metal of subgroups 6 to 8 of 20 to 3-methylbut-2-en-1-ol. the Periodic System. The basic compound is generally used in an amount of from 0.01 to 20%, preferably from 1 to 10%, by weight with reference to the compound to be isomerized. The present invention relates to a new process for the Hydrocarbons which are liquid under the reaction con production of 3-methylbut-2-en-1-ol or 3-methylbut-2-en 25 ditions concerned, as for example hexane, heptane, ligroin, 1-yl acetate. benzene, toluene or xylene, are especially suitable as sol It is known that these compounds (also known as vents. Moreover, high boiling point ether such as diphenyl prenol and prenyl acetate) can be prepared in a multi ether, 2,2'-dimethoxydiethylether and 2,2'-diethoxydiethyl stage synthesis. This method is troublesome however and ether are also suitable. gives only unsatisfactory yields. 30 Since both the starting compounds and the products of We have now found that 3-methylbut-2-en-1-ol or 3 the process are sensitive to oxygen, it is advisable to carry methylbut-2-en-1-yl acetate can be obtained in a simple out the reaction while exluding oxygen, for example under way and in high yields by treating 3-methylbut-3-en-1-ol nitrogen or argon. When readily decomposable carbonyl or 3-methylbut-3-en-1-yl acetate with a catalytic amount compounds are used as isomerization catalysts, it may be of a carbonyl compound of a metal of subgroups 6 to 8 35 advantageous to use carbon monoxide. of the Periodic System. When the isomerization is over, the reaction mixture The starting compounds are known and obtainable par may be worked up by conventional methods, preferably ticularly advantageously by reaction of isobutene with by distillation. formaldehyde followed if necessary by acetylation. The products of the process are valuable intermediates Suitable compounds which act as isomerization cata 40 for organic synthesis, particularly for the production of lysts are particularly those of zerovalent metals in accord compounds of the carotenoid and vitamin A series and of ance with the definition, more particularly, complexes hav perfumes. ing one or two central atoms such as chromium hexacar The invention is illustrated by the following examples. bonyl, iron pentacarbonyl, diron nonacarbonyl, and nick EXAMPLE 1. el tetracarbonyl. Compounds in which some of the car 45 bonyl groups have been replaced by other ligands, as in A mixture of 50 g. of 3-methylbut-3-en-1-yl acetate and dihydrogen iron tetracarbonyl or hydrogen cobalt tetra 3.5 g. of iron pentacarbonyl is heated for fifteen hours at carbonyl, are also suitable. 150 C. and the desired product (3-methylbut-2-en-1-yl, Other suitable ligands in such compounds are those B.P. 110 to 112 C. at 200 mm.) is isolated from the which bear basic nitrogen or phosphorus atoms. Exam mixture in the usual way by fractional distillation. The ples of such carbonyl compounds are bistriphenylphos yield of pure products is 86% at a conversion of 42%. phine iron tricarbonyl and tripyridine diron tetracar EXAMPLE 2 bonyl. A mixture of 2000 g. of 3-methylbut-3-en-1-ol and 10 Iron pentacarbonyl is particularly preferred as the cata 55 g. of iron pentacarbonyl is heated for four hours at 140 lyst. C. and from the mixture the desired product is isolated in The amount of carbonyl compound required for the the usual way by fractional distillation (3-methylbut-2- isomerization is from 0.01 to 20% by weight, preferably en-1-ol, B.P. 102° to 105° C. at 200 mm.; n24=1.4408). from 1 to 5% by weight, with reference to the amount of The yield of pure product is 63% at a conversion of 34%. starting material to be isomerized. It is possible however 60 to use larger or smaller amounts of these catalysts, the EXAMPLE 3 isomerization merely being accelerated or retarded there A mixture of 1000 g. of 3-methylbut-3-en-1-ol, 10 g. of by. iron pentacarbonyl and 50 g. of urotropine is heated for The reaction may be carried out at temperatures of ninety minutes at 200° C. and the desired product is iso from about 100 to 300° C., preferably from 150° to 65 lated from this mixture in the usual way by fractional dis 200 C. at atmospheric pressure or at superatmospheric tillation. The yield of pure 3-methylbut-2-en-1-ol (B.P. pressure up to about 50 atmospheres with or without a sol 102” to 105 C. at 200 mm.; n24=1.4408) is 75% at a vent and batchwise or continuously. conversion of 50%. We have further found that particularly good results are EXAMPLE 4 obtained in the process by carrying out the reaction in the 70 presence of catalytic amounts of a base or a compound A mixture of 150 g. of 3-methylbut-3-en-1-ol, 22 g. of having a basic reaction. iron pentacarbonyl and 9 g, of urotropine is heated for 3,655,735 3 4 thirty minutes at 200° C. and 3-methylbut-2-en-1-ol is iso 1-yl acetate at a temperature of about 100° C. to 300 C. lated in the usual way by fractional distillation. The yield with a catalytic amount of iron pentacarbonyl and in the of pure product is 89% at a conversion of 31%. presence of a catalytic amount of a basic reacting com pound selected from the class consisting of sodium hy EXAMPLE 5 droxide, barium hydroxide, ammonia, sodium carbonate, A mixture of 1000 g. of 3-methylbut-3-en-1-ol, 15 g. of ammonium carbonate, piperidine acetate, acetamide, urea, iron pentacarbonyl and 60 ml. of liquid ammonia is heated alkyl and aryl amines and phosphines. at 175 C. in an autoclave for two hours and the 3-methyl 2. A process as claimed in claim 1 wherein said basic but-2-en-1-ol is then isolated by fractional distillation. The reacting compound is hexamethylenetetramine. yield of pure product is 73% at a conversion of 40%. O EXAMPLE 6 References Cited A mixture of 1500 g. of 3-methylbut-3-en-1-ol, 20 g. of UNITED STATES PATENTS iron pentacarbonyl and 65 g. of piperidine acetate is heat 3,344,191 9/1967 Chappell et al. ------260-586 ed for two and a half hours at 210 C., after which the 2,837,577 6/1958 Blaser et al. ------260-491 3-methylbut-2-en-1-ol formed is isolated by fractional dis 5 tillation. The pure product is obtained in a yield of 70% LORRAINE A. WEINBERGER, Primary Examiner at a conversion of 60%. V. GARNER, Assistant Examiner We claim: 1. An isomerizing process for the production of 3-meth U.S. C. X.R. ylbut-2-en-1-ol or 3-methylbut-2-en-1-yl acetate which comprises treating 3-methylbut-3-en-1-ol or 3-methyl-3-en 260-488 H, 632 R, 642 3: UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,655,735 Dated-April ll, 1972 Inventor(s) Horst Pommer et al It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below: column 1, lines 10 to ill, "Claims priority, application. Germany,- Mar. 22, 1968, P 77 68 O23.8" should read -- Claims priority, applications Germany, Dec. 8, 1967, P 16 43 7 O9.5; Mar. 22, 1968, Pl7 68 O25.8 --. Column 3, line 22, claim l, "3-methyl-3-en-' should read - - - 5-methylbut-3-en- - -.

Signed and sealed this 21st day of November 1972.

(SEAL) Attest: EDWARD M.FLETCHER, JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents