US3526672A - Process for the manufacture of 4-vinylcyclohexene - Google Patents

Description

United States Patent O1 fice 3,526,672 PROCESS FOR THE MANUFACTURE OF 4-VINYLCYCLOHEXENE Nicodemus E. Boyer, Parkersburg, W. Va., and Marvin P. Weaver, Belpre, Ohio, assignors to Borg-Warner Corporation, Chicago, [1]., a corporation of Delaware No Drawing. Filed Jan. 14, 1969, Ser. No. 791,182

Int. Cl. C07c 3/10 U.S. Cl. 260-666 11 Claims ABSTRACT OF THE DISCLOSURE A process for the dimerization of 1,3-butadiene to 4- vinylcyclohexene may be practiced to produce high yields by the use of certain catalyst systems which include (1) secondary aromatic amines, or (2) metal acetylacetonates, or (3) mixtures of (1) and (2), or (4) mixtures of (2) and triphenylphosphine.

BACKGROUND AND SUMMARY OF THE INVENTION This invention relates to a process for the production of dimers of 1,3-butadiene, specifically 4-vinylcyclohexene. More particularly, the invention is directed to an improved catalyst system which, in the presence of a conventional diluent and polymerization inhibitor, can produce 4-vinylcyclohexene with relatively high yields, for example, 84% to 91% based on the weight of reacted butadiene.

Conventional catalyst systems described in the prior art include oxides, complex carbonyl compounds, olefins, metal salts, secondary aliphatic amines, metals, as well as ultra-violet radiation. Of those listed herein, the most effective have been found to be dialkyl amines (discussed in US. Pat. No. 2,943,117), metal salts (discussed in US. Pat. No. 2,544,808), and metal, such as iron powder (discussed in German Pat. No. 949,466).

By the present invention, additional catalyst systems have been found in which the yields are consistently above 80%, are reasonably inexpensive, easy to handle, and very effective in the production of 4-vinylcyclohexene. Catalyst systems which may be employed are (1) secondary aromatic amines; (2) metal acetylacetonates; (3) mixtures of (1) and (2); or (4) mixtures of (2) and triphenylphosphine. The process is carried out in the presence of up to 60%, based on the weight of the 1,3- butadiene, or inert diluent, preferably 12 to 34% by weight, at a pressure of atmospheric to 650 p.s.i., preferably 220 to 410 p.s.i., and at a temperature of 100 to 170 0., preferably 120 to 150 C. The inert diluent may be an aromatic or halogenated aromatic solvent. A small 3,526,672 Patented Sept. 1, 1970 amount of a polymerization inhibitor, such as p-tert-butylcatechol, is also conventionally used.

DETAILED DESCRIPTION OF THE INVENTION In order to further illustrate the invention, reference will be made herein to certain specific examples which are intended to be illustrative, and not in any sense limitmg.

EXAMPLE I A one liter stainless steel autoclave, fitted with a nitrogen inlet and outlet and a thermocouple well, was charged with 5 g. (2.6% by weight based on butadiene charged) of N-phenyl-2-naphthylamine, 0.3 g. of p-tert.-butylcatechol (polymerization inhibitor) and 50 ml. g., 34% by weight) o-dichlorobenzene (diluent). After being flushed with nitrogen to remove all residual air and sealed, the autoclave was cooled in a Dry Ice-acetone bath and charged with 191.7 g. of 1,3-butadiene. The charged autoclave was heated at 130l40 C. for 8 hours. During this time, the maximum internal pressure was 300 p.s.i., and, after 8 hours, dropped to 220 p.s.i. After 8 hours, the autoclave was left to cool to room temperature overnight, after which time, unreacted butadiene was vented from the autoclave. The liquid residue which remained was fractionated through a glass column (23 x 2 cm.) filled with glass helices. The yield of 4-vinylcyclohexene (B.P. 127-130 C.) was 85.2% (based on reacted butadiene).

EXAMPLE II A one liter stainless steel autoclave, fitted with a nitrogen inlet and outlet and a thermocouple well, was charged with 10 g. (5.2% by weight) of di-2-naphthylaminc, 0.6 g. of p-tert.-buty1catechol, and 32.5 g. (17% by weight) of o-dichlorobenzene (diluent). After the autoclave was flushed with nitrogen to remove residual air and sealed, it was cooled in a Dry Ice-acetone bath, and charged with 193.4 g. of 1,3-butadiene. The charged autoclave was heated at 139-141" C. for 8 hours, during which time the internal pressure ranged from 390-270 p.s.i. The autoclave was left to cool to room temperature overnight, and the unreacted butadiene removed by venting. The liquid residue which remained was fractionated asin Example I, and an 88.3% yield of 4-vinylcyclohexene was obtained.

Metal acetylacetonates alone and in combination with either secondary aromatic amines or triphenylphosphine are also effective catalysts in producing high yields of 4- vinylcyclohexene (4-VC).

By following the procedures of Examples I and II with different catalyst systems, the table below groups together additional examples.

TABLE I.DIMERIZATION OF 1,3-BUTADIENE Inert diluent Re- Catalyst action Internal Percent Cone, wt. Cone, wt. time, Temp., pressure, yield,

Example No. Name percent Name percent hours C. p.s.i. 4-VC III 1 Pi eridine 2.6 Toluene 16. 6 8 135-140 270-420 11. 9 IV N- phenyl-lnaphthylami 5. 2 O-dichlorobenzene 13. 8 8 120-150 310-370 84 8 V Ferric actitylacetonaiienan 2 do 13. 8 8 138-141 220-410 85 4 N-pheny -1-naphthy am ne 6 I VI "{gerric acezyiacezona? 2} 8 8 130 150 3304390 84 1 err e ace y ace ona e.

VII {Triphenylphosphme 13.8 s 130 140 270- 91 3 VIII N -phenyl-1-naphthylami 7. 8 8 -145 240-360 83. 9 IX 1 Diethanolamine 2.6 8 128-138 260-330 35. 8 X N-phenyl-l-naphthylamine 3. 7 8 134-168 340-600 88. 8 XI Di-2-naphthylamine 15. 0 48 100-120 50-220 81. 5 XII- Di-l-naphthylamine 10.0 3 -150 440-550 83. 2 XIIL. N-phenyl-l-naphthylamine 0. 3 Ohlorobenzen 12 130-150 350-450 80, 5 XIV.. N-phenyl-2-naphthylamine 5 0 Xyl 6 -170 500-650 90. 3

1 Piperidine and diethanolamine belong to the class of secondary aliphatic amines which are claimed to be effective catalysts in this process in the prior art. Our experiments have shown that the yields of ii-vinylcyclohexene (4-VC) are much higher when the novel catalysts of this invention (secondary aromatic amines, triphenylphosphlne, and/or ferric acetylacetonate) are used.

The examples in Table I clearly show that secondary aromatic amines are superior to secondary aliphatic amines for use in such catalyst systems. In the absence of any catalyst, no 4-vinylcyelohexene is formed from 1,3-butadiene at similar conditions.

While this invention has been described in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not by way of limitation; and the scope of the appended claims should be construed as broadly as the prior art will permit.

What is claimed is:

1. The process of dimerizing 1,3-butadiene to produce 4-vinylcyclohexene which comprises maintaining 1,3-butadiene in contact with a catalyst selected from the group consisting of (1) secondary aromatic amines; (2) fern'c acetylacetonate; (3) mixtures of (l) and (2); and (4) mixtures of (2) and triphenylphosphine.

2. The process as defined in claim 1, wherein the concentration of said catalyst is from 0.3 to 15% by weight, based on the weight of said butadiene.

3. The process as defined in claim 2, wherein said reaction is maintained for at least 3 hours.

4. The process as defined in claim 3, wherein said reaction mixture is maintained at 100 to 170 C.

5. The process as defined in claim 4, wherein said reaction mixture is maintained at a pressure of atmospheric to 650 p.s.i.

6. The process as defined in claim 5, wherein said reaction mixture is maintained in the presence of an inert diluent in a concentration of 0 to by weight (based on the weight of said butadiene).

7. The process as defined in claim 6, wherein said inert diluent is an aromatic or halogenated aromatic solvent.

8. The process as defined in claim 1, wherein said secondary aromatic amine is N-phenyl-Z-naphthylamine.

9. The process as defined in claim 1, wherein said secondary aromatic amine is dinaphthylamine.

10. The process as defined in claim 1, wherein said secondary aromatic amine is N-phenyl-l-naphthylamine.

11. The process as defined in claim 1, wherein said catalyst is a mixture of N-phenyl-l-naphthylamine and ferric acetylacetonate.

References Cited UNITED STATES PATENTS 2,504,016 4/ 1950 Foster. 2,943,117 6/ 1960 Gleason. 2,964,575 12/ 1960 Sekul. 2,991,317 7/ 1961 Sellers. 3,187,062 6/ 1965 Shechter. 3,457,319 7/ 1969 Olechowski. 3,446,862 5/ 1969 Menapace.

DELBERT E. GANTZ, Primary Examiner V. OKEEFE, Assistant Examiner UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,526,672 September 1, 1970 Nicodemus E. Boyer et a1.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 49, "or" should read of Signed and sealed this 23rd day of March 1971.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. WILLIAM E SCHUYLER, JR.

Attesting Officer Commissioner of Patents