Vinyl acetylene is coupled with butadiene to selectively produce 1-octen-7-yne by reacting the vinyl acetylene with butadiene in the presence of formic acid or a salt thereof, optionally a solvent and a catalyst comprising palladium complexed with tertiary organophosphorus ligand.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to the production of 1-octen-7-yne by 
hydrocoupling butadiene and vinyl acetylene. 
2. Description of the Prior Art 
1-Octen-7-yne is a useful chemical intermediate. Since olefinic and 
acetylenic bonds have different reactivities, this subject compound is 
useful for synthesis of bifunctional compounds, particularly compounds 
having terminally distributed functional groups. Illustrative of such 
compounds are 1,2-epoxy-7-octyne, 6-heptynoic acid, 1,2-dibromo-7-octyne 
and 2-cyano-1,7-octadiene. 
Hydrodimerizing butadiene with formic acid and palladium catalyst is known. 
Wright in U.S. Pat. No. 3,732,328 issued May 8, 1973, prepares mixtures of 
octadienes by reacting butadiene in the presence of a palladium compound, 
a polar solvent, a reducing agent and a tertiary phosphine. Wright in U.S. 
Pat. No. 3,832,199, issued July 9, 1974, prepares mixtures of octadiene by 
reacting butadienes in the presence of a palladium compound, a non-polar 
solvent, a reducing agent and a tertiary phosphine. Wright in British Pat. 
No. 1,341,324 issued Dec. 9, 1973 discloses processes similar to above. 
Gardner et al, Tetrahedron Letters No. 2, pp. 163-164 (1972) discloses the 
production of mixtures of octadiene by reacting butadiene in the presence 
of palladium salts, or organic base, formic acid and a phosphine. Roffia 
et al, Journal of Organometallic Chemistry, 55 (1973) 405-407 utilizes a 
phoshpine-zero valent palladium complex catalyst in benzene in the 
presence of formic acid to dimerize butadiene. 
Hydrodimerization of vinyl acetylene is not a known process. 
SUMMARY OF THE INVENTION 
The process of this invention is directed to the cross hydrocoupling of 
vinyl acetylene and butadiene in the presence of formic acid and a 
catalyst comprising palladium complexed with a tertiary organo 
phosphorus-containing ligand. The formic acid may be present as the acid 
or as the salt of a base. The palladium is present in any of its possible 
valence states, with zero valence preferred. A suitable solvent is 
optionally used. The process of this invention predominately produces 
1-octen-7-yne rather than, as might be expected, mixtures of 
1-octen-7-yne, dimers of butadiene and dimers of vinyl acetylene. 
DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Solvents are not essential to the process of this invention, but a good 
organic solvent can promote the rate of reaction by a factor of two or 
more. 
Wright in above-cited U.S. Pat. No. 3,823,199 cites the use of non-polar 
solvents such as paraffinic, cycloparaffinic or aromatic which are also 
useful in the process of this invention. The solvent can be a paraffin or 
cycloparaffin containing 5 to 16 carbon atoms, such as hexane, dodecane, 
pentadecane, cyclohexane, methylcyclohexane and the like. Suitable 
solvents also include aromatic hydrocarbons such as benzene, lower alkyl 
substituted aromatic hydrocarbons such as toluene, m-, p- and o-xylene, 
halogenated aromatic hydrocarbons including chloro, bromo and iodo 
substituted, such as chlorobenzene and the like. Halogenated lower 
aliphatic compounds such as chloroform, methylene chloride, carbon 
tetrachloride and the like may be used, in particular chloroform is 
preferred. 
Further useful are amine solvents such as those cited by Wright in 
above-noted British No. 1,341,324. A wide range of amines are useful 
provided that they are liquid under reaction conditions. Tertiary amines 
are preferred to primary and secondary amines. Suitable amine solvents 
include alkylamines, cycloalkylamines, arylamines and heterocyclic amines 
such as morpholine, pyridine, piperazine and piperidine. Examples of these 
classes of amines are the lower alkylamines containing 2 to 6 carbon atoms 
in each alkyl group such as triethylamine; mono-cyclohexylamine, and 
N-alkyl-cyclohexylamines containing up to 12 carbon atoms; aniline and 
N-alkylanilines containing up to 12 carbon atoms and N-alkylmorpholines 
containing up to 12 carbon atoms. 
Solvents of moderate coordinating ability are quite useful and include 
nitriles such as lower alkyl nitriles, hydrocarbon aromatic nitriles 
including acetonitrile, benzonitrile and the like, amides including 
benzamide, acetamide, mono- and di-substituted amides where the 
substitutent is preferably lower alkyl. Suitable substituted amides 
include N-methyl acetamide, N,N dimethyl acetamide and dimethylformamide. 
Dialkyl sulfoxides such as dimethyl sulfoxide and sulfones such as 
sulfolane and alkyl-substituted sulfolane are satisfactory. By dialkyl it 
is meant that the sulfur and nitrogen atoms are connected to two different 
carbon atoms. They may be separate alkyl groups or the same, i.e., a ring 
alkyl group, e.g. tetramethylene sulfoxide and N-methyl pyrrolidinone. The 
alkyl moieties have carbon numbers ranging from 1 to about 6. Simple 
ethers such as the dilower alkyl ethers including dimethyl ether, 
diethylene, and the like function satisfactorily. Hydrocarbon aromatic 
ethers such as the lower alkyl phenyl ethers may be also used. In 
addition, the cyclic diethers such as 1,4-dioxane are also suitable 
solvents. 
Simple lower alkyl esters of lower alkanoic acids such as ethyl acetate, 
methyl acetate, methyl butyrate and the like as well as cyclic diesters 
such as ethylene carbonate are also suitable solvents of moderate 
coordinating ability. Ketones, including lower aliphatic ketones such as 
methyl ethyl ketone and hydrocarbon aromatic ketones such as acetophenone 
are also satisfactory solvents. Lower mono- and di-alkanols such as 
isopropanol, ethylene glycol and the like may be used if desired. The 
preferred solvents of moderate coordinating ability include nitriles, 
formamides, such as dimethylformamide, dilower alkyl ethers, lower alkyl 
phenyl ethers, simple lower alkyl esters of lower alkanoic acids, ketones 
and lower alkanols. 
The particularly preferred solvents utilized in this invention include 
benzene, dimethylformamide, chlorobenzene, anisol, N,N-dimethylacetamide, 
nitromethane, ethyl acetate, isopropanol, benzonitrile, chloroform, methyl 
ethyl ketone, acetonitrile, diethylether, acetophenone, toluene, ethylene 
glycol, ethylene carbonate, propylene carbonate and sulfolane. 
Particularly desired solvents are nitromethane, ethylene carbonate and 
propylene carbonate. 
The preferred organic solvents will have carbon numbers ranging from 1 to 
about 20. Particularly desired solvents are those which give two-phase 
systems which allow easy product separation such as, for example, 
nitromethane, ethylene carbonate and propylene carbonate. 
The amount of solvent added should be sufficient to dissolve the palladium 
compound-tertiary phosphine complex. 
The formic acid is utilized as a source of hydrogen for the process. It is 
present in the reaction mixture as an acid or as a salt of a base. When 
the salt is used, it is thought that dissociation of the formic acid-base 
salt provides a suitable amount of formic acid necessary to provide the 
required hydrogen. 
It is desirable that some formic acid or the salt, be present during the 
entire course of the reaction. When operating the process batch-wise, this 
can be accomplished by adding a stoichiometric amount of formic acid 
initially, 1 mole of formic acid for every 2 moles of butadiene, or by 
continuously or periodically adding additional amounts of formic acid. 
A base when used must be one which can neutralize formic acid according to 
the reaction: 
EQU HCOOH+B.fwdarw.HCOO.sup.- HB.sup.+. 
The base may be organic or inorganic. Suitable organic bases typically have 
dissociation constants greater than 10.sup.-8 and include tertiary amines 
such as triethyl amine, tributyl amine, dimethylethyl amine, lutidine, 
tripropyl amine, N-methyl morpholine, isoquinoline. 
N-methyl-2,2,6,6-tetramethyl piperidine, 2,8-(dimethylamine) naphthalene 
and the like. 
Suitable inorganic bases include ammonia, the hydroxide bases such as 
sodium hydroxide, potassium hydroxide, calcium hydroxide; ammonium 
hydroxide; the carbonates and bicarbonates such as sodium carbonate, 
sodium bicarbonate, potassium carbonate, potassium bicarbonate, calcium 
carbonate and the like; the weak bases such as sodium acetate, potassium 
acetate, ammonium carbonate, ammonium acetate and the like. When the 
inorganic bases are utilized, small amounts of water may be present. 
Preferred moles of water are at least equal to the moles of formate salts. 
When organic bases are utilized, excess base may be utilized as a solvent 
or the amine-base salt may be used as the solvent. 
The catalyst used in the process of this invention is palladium or a 
palladium compound complexed with a trisorgano phosphorous-containing 
ligand. The palladium may be in any of its possible valence states, e.g. 
0, +2, etc. Suitable palladium compounds include the palladium 
carboxylates, particularly palladium carboxylates derived from alkanoic 
acids containing up to six carbon atoms such as palladium acetate (OAC), 
complexes such as palladium acetylacetonate (AcAc), bis-benzonitrile 
palladium (II) and lithium palladous chloride as well as the palladium 
halides, nitrates and sulfates such as palladous chloride and palladium 
nitrate (Pd(NO.sub.3).sub.2 (OH).sub.2) and palladium sulfate. Suitable 
reduced palladium-phosphine complexes are Pd(R.sub.3 P).sub.2 or 
Pd(R.sub.3 P).sub.3. The palladium is present in the reaction mixture in 
catalytic amounts; preferably from about 1 to about 10.sup.-6 molar and 
more preferably from about 10.sup.-1 to about 10.sup.-4 molar. 
The palladium compounds complexed with a trisorgano phosphorous-containing 
ligand are typically prepared by reacting the tertiary phosphorous ligand 
with the appropriate palladium compound as, for example represented by the 
following equations: 
EQU 2R.sub.3 P+(PhCN).sub.2 PdCl.sub.2 .fwdarw.(R.sub.3 P).sub.2 PdCl.sub.2 
EQU (R.sub.3 P).sub.2 PdCl.sub.2 +Ag.sub.2 CO.sub.3 .fwdarw.(R.sub.3 P).sub.2 
PdCO.sub.3 
EQU (R.sub.3 P).sub.2 PdO.sub.2 +SO.sub.2 .fwdarw.(R.sub.3 P).sub.2 PdSO.sub.4 
EQU (R.sub.3 P).sub.2 PdO.sub.2 +N.sub.2 O.sub.4 .fwdarw.(R.sub.3 P).sub.2 
Pd(NO.sub.3).sub.2 
where R.sub.3 P is a trisorgano phosphine of the invention, or may be made 
in situ by adding the palladium compound and the phosphine directly to the 
reactor. 
Any tertiary organo phosphorous ligand which can be dissolved in the 
reaction mixture may be used. Suitable ligands are represented by the 
formula: 
EQU (RO).sub.a P R.sub.b 
wherein R generally is hydrocarbyl and maybe the same or different and is 
selected from aryl, alkyl, aralkyl and alkaryl groups which contain less 
than about 20 carbon atoms, preferably less than about 12 carbon atoms, O 
is oxygen, a is an integer from 0 to 3 and b is 3-a. Suitable examples of 
R are phenyl, p-tolyl, o-tolyl, m-tolyl, m-chlorophenyl, p-anioly, 
m-anisoyl, ethyl, propyl, butyl and the like. It is also suitable for the 
organic radical R to contain functional groups or to satisfy more than one 
of the valences of the phosphorus atom, thereby forming a heterocyclic 
compound with the phosphorus atom. Preferably R represents aryl, alkyl, 
aralkyl, alkaryl or a mixture thereof having carbon numbers from 1 to 
about 20, preferably 1 to about 12 carbon atoms and need not be the same, 
e.g. R.sub.1 R.sub.2 R.sub.3 P,(R.sub.1 O)PR.sub.2 R.sub.3, (R.sub.1 
O)(R.sub.2 O)PR.sub.3, etc. Preferably R is alkyl or aryl and is the same. 
Alternatively the formula for the ligand can be expressed as R.sub.c.sup.1 
R.sub.d.sup.2 R.sub.e.sup.3 P(OR.sup.4).sub.f (OR.sup.5).sub.g 
(OR.sup.6).sub.h where c, d, e, f, g and h individually equals 0 or 1, 
c+d+e+f+g+h equals 3 and R is as defined above. The most preferred 
tertiary organo phosphorus ligands have at least one R as benzyl or 
branched alkyl, aralkyl, alkenyl, and cycloalkyl having from 3 to about 10 
carbon atoms with branching occurring at a carbon atom no more than two 
carbon atoms from the phosphorus or oxygen atom, This preferred R provides 
a steric hinderance to the catalyst complex which enhances selectivity. 
Illustrative of the preferred R moiety are, for alkyl, isopropyl sec-butyl, 
tert-butyl, isobutyl, neopentyl, sec-pentyl, tert-pentyl, 2-methylbutyl, 
sec-hexyl, tert-hexyl, 2,2-dimethylpropyl; for aralkyl, 
alpha-methylbenzyl, alpha, alpha-dimethylbenzyl, 
alpha-methyl-alpha-ethylbenzyl, phenylethyl, phenylisopropyl, 
phenyl-tert-butyl; for alkenyl allyl, crotyl, methallyl, 1-methyl-ethenyl, 
1-methyl-2-propenyl, 2-methyl-2-propenyl, 1,1-dimethyl-2-propenyl, 
1-methyl-3-butenyl and, for cycloalkyl, cyclopropyl, cyclobutyl, 
cyclopentyl, cyclohexyl, cycloheptyl, and the like. 
Two or more of the instant phosphorus ligands may be used in the same 
reaction. The mole ratio of tertiary phosphorus ligand to palladium is at 
least 1. Preferably the mole ratio of ligand to palladium ranges from 
about 1:1 to about 1:20 and preferably from about 2:1 to about 5:1. The 
use of the tertiary phosphorus ligands of the invention provides extremely 
high selectivities to 1,7-octadiene. 
Alternatively, the palladium compound and tertiary phosphorus ligand may be 
bound onto a crosslinked synthetic resin instead of being dissolved in the 
reaction medium. Acceptable crosslinked synthetic resins include 
crosslinked polystyrene, poly(alpha-alkyl) acrylates, polycarbonates, 
polyamides and the like. In the generic sense, the bound ligand will have 
the generic formula Z-P(RO).sub.i R.sub.j wherein R is as defined above, i 
is an integer from 0 to 2, j is 2-i and Z is the crosslinked synthetic 
resin. 
The bound tertiary phosphine may have the general formula: 
##STR1## 
wherein R, i and j are defined previously, and R.sub.6 represents the 
repeating unit of the synthetic resin and where m is a positive integer, n 
is 0 or a positive integer, m+n equals the total number of repeating units 
in resin and the percentage of the repeating units substituted with the 
tertiary phosphine is represented by the formula: 
##EQU1## 
The number of repeating units substituted with the tertiary phosphine is 
not critical. When less than 5% of the repeating units contain a phosphine 
substitute, large quantities of the resin must be used to form the bound 
catalyst. Accordingly, it is desirable to have at least 10% of the 
repeating units substituted with a tertiary phosphine. It is preferred, 
however, that from 20 to 40% of the repeating units contain a phosphine 
substituent. The substituent can be introduced into the resin using 
well-known techniques, such as those described by Smith et al in the 
Journal of the American Chemical Society, 97 (7) 1749 (1975) and by 
Pittman et al in Ann. N.Y. Academy of Sciences, 239, 76 (1974). In 
accordance with those techniques, the palladium compound is complexed with 
the phosphorus-substituted resin by admixing in a solvent for palladium 
acetate. 
The catalyst may be pretreated to enhance reactivity by contacting it with 
a reducing agent at a temperature of from about 20.degree. to about 
90.degree. C. for from about 0.1 to about 5 hours. The reducing agent may 
be gaseous, solid or liquid. Examples of gaseous agents are hydrogen, and 
carbon monoxide. Examples of liquid or solid reducing agents are 
hydrazine, NaBH.sub.4, NaOCH.sub.3, (isopropyl).sub.3 P, Cu, Na, and Al 
alkyls, etc. The reduction may be carried out in a separate autoclave or 
preferably is carried out in the hydrodimerization reactor prior to the 
introduction of the butadiene. The palladium compound-triorganophosphorus 
complex may be dissolved in the solvent used in this invention prior to 
reduction. 
The process can be either continuous or batch. The reaction temperature of 
the process is not critical, however, it is preferred to maintain the 
reaction between about 0.degree. to about 100.degree. C. preferably 
between about 20.degree. to about 70.degree. C. The process is conducted 
under a sufficient pressure to maintain liquid phase conditions at the 
reaction temperature. Typically the pressure is autogeneous. 
The process of this invention is particularly useful when a BBB stream from 
an oil pyrolysis unit is utilized to provide the butadiene. These BBB 
streams are the C.sub.4 cut from a thermal cracking unit typically 
containing 30-40% butadiene, 20-35% isobutene and 20-30% n-butenes and 
many minor components including about 1/2% of vinylacetylene.

The process of this invention will be further described by the following 
illustrative embodiments which are provided for illustration and are not 
to be construed as limiting the invention. 
ILLUSTRATIVE EMBODIMENTS 
Illustrative Embodiment I 
To an 80 milliliter glass-lined autoclave were charged 2.7.times.10.sup.-5 
moles of palladium as a 10% water solution of Pd(NO.sub.3).sub.2 
(OH).sub.2, 5.4.times.10.sup.-5 moles (isopropyl).sub.3 phosphine, 5 ml of 
pyridine, vinyl acetylene, butadiene and triethylamine formic acid salt 
(Et.sub.3 N.HOOCH) in the amount indicated in column 2 in Table I. The 
stirred reactor was heated to 60.degree. C. for the time indicated in 
column 2, cooled and the product was analyzed by gas chromatography and 
mass spectrography. The results are shown in Table I. 
Table I 
__________________________________________________________________________ 
Reactants 
Vinyl Time 
Test Acetylene, g 
Butadiene, g 
Et.sub.3 N . HOOCH, g 
Hours 
__________________________________________________________________________ 
1 0.7 0 2.52 5 
2 1.2 0 1.26 1 
3 1.2 1 1.26 1 
4 0.20 1 1.26 1 
__________________________________________________________________________ 
Product Analysis 
Test 1-Octen-7-yne, % 
1,7-Octadiene, % 
Vinyl acetylene, % 
Butadiene, % 
__________________________________________________________________________ 
1 6 0.3 65 27 
2 2 0 96 2 
3 60 0.3 22 18 
4 25 65 0 5 
__________________________________________________________________________ 
Test 1 shows that with a large excess of Et.sub.3 N.HOOCH and a long 
reaction time, some 1-octen-7yne is produced because considerable 
butadiene is generated from the hydrogenation of vinyl acetylene. No dimer 
from vinyl acetylene and very little 1,7-octadiene was produced. 
Test 2 shows that decreasing the Et.sub.3 N.HOOCH and reducing the reaction 
time has decreased the butadiene and the 1-octen-7-yne. Little reaction 
was noted and no vinyl acetylene dimer or 1,7-octadiene was produced. 
Test 3 with nearly equal amounts of vinyl acetylene and butadiene gave a 
fairly rapid reaction to 1-octen-7-yne with very little 1,7-octadiene 
produced. No vinyl acetylene dimer was found. 
Test 4 was run with a small amount of vinyl acetylene and excess butadiene. 
The reaction most probably yields 1-octen-7-yne initially, followed by 
rapid formation of 1,7-octadiene and the vinyl acetylene is exhausted. 
Illustrative Embodiment II 
To an 80 milliliter glass-lined autoclave were charged 2.7.times.10.sup.-5 
moles of the palladium compound listed in Table II, 5.4.times.10.sup.-5 
moles of (isopropyl).sub.3 phosphine, 5 ml of pyridine or 4 ml of 
dimethylformamide (DMF) solvent, 1 gram of butadiene, vinyl acetylene and 
formic or its salts in the amount listed in Table II. The stirred reactor 
was heated to 60.degree. C. for 1 hour, cooled and the product was 
analyzed by gas chromatography and mass spectrography. The results are 
shown in Table II. 
Table II 
__________________________________________________________________________ 
Palladium Vinyl Formate 
Test Solvent Compound Acetylene, g 
Compound, g 
__________________________________________________________________________ 
5 DMF Pd(AcAc).sub.2 
0.8 Formic acid, 0.38 
6 DMF Pd(AcAc).sub.2 
0.8 NH.sub.4 Formate, 0.58 
7.sup.(a) 
DMF Pd(AcAc).sub.2 
0.8 Na Formate, 0.63 
8 DMF Pd(AcAc).sub.2 
0.8 Na Formate, 0.63 
9.sup.(b) 
Pyridine Pd(NO.sub.3).sub.2 (OH).sub.2 
1.0 Et.sub.3 N . HOOCH, 
__________________________________________________________________________ 
1.26 
Product Analysis 
Test 1-Octen-7-yne, % 
1,7-Octadiene, % 
Vinyl Acetylene, % 
Butadiene, % 
__________________________________________________________________________ 
5 40 0.7 10 50 
6 35 0.5 12 52 
7 2 0 44 54 
8 10 0 40 50 
9 47 0.3 26 27 
__________________________________________________________________________ 
.sup.(a) 0.5 ml of water added 
.sup.(b) 5.4 .times. 10.sup.-5 moles of (tertbutyl).sub.2 POCH.sub.3 
instead of (isopropyl).sub.3 P 
.sup.(c) 2 hours at 75.degree. C.