Process for the production of 1,2-bis (acyloxylates)

A process for the preparation of 1,2-bis(acyloxyates) comprises acylation of epoxides with carboxylic anhydrides in the presence of a catalytic composition containing a tertiary amine and a carboxylic acid. Preferably, the carboxylic acid is a conjugate acid of the carboxylic anhydride. The carboxylic acid acts as a co-catalyst and its use in conjunction with the tertiary amine significantly increases the rate of reaction and results in higher selectivity. The catalytic composition may be prepared prior to acylation or in situ providing application versatility.

TECHNICAL FIELD 
This invention relates to processes for acylation of epoxides with 
carboxylic anhydrides to produce 1,2-bis(acyloxyates). More particularly, 
this invention relates to catalysts for such processes. 
BACKGROUND OF THE INVENTION 
1,2-Bis(acyloxyates) are useful intermediates for organic synthesis. For 
example, 3,4-diacetoxy-1-butene is used in the production of vitamin A 
acetate, Paust, J., Pure and Appl. Chem., 63, 45 (1991). The 
1,2-bis(acyloxylates) are the bis-esters of 1,2-dihydroxy compounds, or, 
alternatively, 1,2-diol dicarboxylates. The general formula for such 
compounds is shown in structure (I). 
##STR1## 
The preparation of 1,2-bis(acyloxylates) may be by acetylation of epoxides 
with acetic anhydride in the presence of various forms or combinations of 
amine catalysts. For example, a study by Shvets and Al-Wahib discloses 
that 1,2-diacetoxyethane can be prepared from ethylene oxide with acetic 
anhydride in the presence of pyridine and that the reaction proceeds by 
the intermediacy of N-(.beta.-acetoxyethyl)pyridinium acetate. The 
reaction produces yields ranging from 45 to 93.5 percent. The yields 
decrease with increasing pyridine concentration at 0.05 to 1.00 M. Shvets, 
V. F. and Al-Wahib, Wahib, I., Kinet. Katal., 16(3), 785-8 (1975). 
In another study by Shvets and Al-Wahib the nucleophilic catalysis of 
ethylene oxide is disclosed. The reaction of ethylene oxide with acetic 
anhydride is catalyzed by (CH.sub.3 CH.sub.2).sub.4 N.sup.+X.sup.- (X=Cl, 
Br, I) and proceeds by attack of the halide anion on ethylene oxide to 
form the 2-haloethyl acetate and (CH.sub.3 CH.sub.2).sub.4 N.sup.+ 
OAc.sup.-. The latter product continues to catalyze the reaction of 
ethylene oxide with acetic anhydride and also reacts with the 2-haloethyl 
acetate so that both processes lead to 1,2-diacetoxyethane. Product yields 
are typically low when using tetraalkylammonium halides. Shvets, V. F. and 
Al-Wahib, Wahib, I., Kinet. Katal., 16(2), 425-30 (1975). 
As taught by Swindell, the nucleophilic catalysis of an epoxycyclooctane 
derivative with acetic anhydride catalyzed by 
1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and LiCl in tetrahydrofuran 
produces the corresponding 1,2-bis(acyloxyate) at a 70 percent yield, 
Swindell, C. S. and Patel, B. P., J. Org. Chem., 55, 3 (1990). Fraser-Reid 
discloses that the reaction of epoxypyranosides with acetic anhydride 
catalyzed by (CH.sub.3 CH.sub.2 CH.sub.2 CH.sub.2).sub.4 N.sup.+ OAc.sup.- 
opens the epoxy ring to prepare the corresponding 1,2-bis(acyloxyate), 
Fraser-Reid, B. and Rahman, Md. A., J. Amer. Chem. Soc., 107, 5576 (1985). 
Tetraalkylammonium acetates are produced by alkylation of a tertiary amine 
to form a quaternary ammonium salt in which the counterion is exchanged 
for acetate. Generally, this process requires isolation or purification of 
the intermediates. Thus, these types of catalysts are difficult to produce 
and costly. 
The acid catalyzed ring opening of epoxides in the presence of acetic 
anhydride is also well known. For example, the acetylation of 
3,4-epoxy-1-butene in the presence of acetic anhydride produces 
3,4-diacetoxy-1-butene as disclosed by Evans, R. M., Fraser, J. B. and 
Owen, L. N., J. Chem Soc., 248 (1949). A 70 percent yield is obtained when 
using hydrochloric acid as the catalyst, while only a 39 percent yield is 
obtained using anhydrous zinc chloride as the catalyst. Another example of 
a Lewis acid catalyzed ring opening of an epoxide is disclosed by Ali, S. 
and Bittman, R., J. Org. Chem., 53, 5547, (1988) which describes the 
diacylation of glycidyl tosylate in the presence of boron trifluoride 
etherate with a 76 percent yield. These Lewis acid catalyzed acylations 
give reasonable yields. However, in practice Lewis acid catalysts do not 
give good process economics on large scale due to catalyst costs and the 
need to use expensive, corrosion-resistant materials of construction. 
U.S. Pat. No. 5,189,199 to Godleski discloses the addition of oxygen 
nucleophiles to 3,4-epoxy-1-butene catalyzed by ligated Pd(O) to prepare 
1,4-disubstituted-2-butenes. However, applying this process for the 
production of 3,4-diacetoxy-1-butene using acetic anhydride requires 
additional separation because it predominately produces 
1,4-diacetoxy-2-butene. Its application is limited in scope since the 
substrate must be an epoxide in direct conjugation with a carbon-carbon 
double bond. 
Other processes are commonly used to prepare 1,2-bis(acyloxyates) such as 
the acetylation of 1,2-diols with acetic anhydride or acetyl chloride. 
However, when using acetic anhydride, acetic acid is co-produced and must 
be removed or recycled in the process. With acetyl chloride, an excess of 
an organic base is generally needed to remove the corrosive hydrochloric 
acid that is co-produced in the process. In most cases, 
1,2-bis(acyloxyates) are prepared from epoxides by acid catalyzed 
hydrolysis of epoxides to form the corresponding 1,2-dihydroxy derivative 
followed by acylation of the hydroxyl groups with an equivalent amount of 
carboxylic anhydride and organic base, such as pyridine or 
4-(N,N-dimethylamino)pyridine. This overall process requires two chemical 
steps and isolation of intermediates. 
Thus, there exists a need whereby 1,2-bis(acyloxyates) may be produced from 
epoxides in a single step process with increased rates of reaction and 
higher selectivities using relatively inexpensive catalysts, without the 
need to use corrosion resistant equipment, without the added costs of 
separating co-products and recovering by-products of the process and 
without the waste associated with the loss of catalysts. Accordingly, it 
is to the provision of such improved processes for the preparation of 
1,2-bis(acyloxyates) that the present invention is primarily directed. 
SUMMARY OF THE INVENTION 
A process for the preparation of a 1,2-bis(acyloxyate) comprises acylation 
of an epoxide with a carboxylic anhydride in the presence of a catalytic 
composition containing a tertiary amine catalyst and a carboxylic acid 
co-catalyst. Preferably, the carboxylic acid is a conjugate acid of the 
carboxylic anhydride. The carboxylic acid in conjunction with the tertiary 
amine significantly increase the rate of reaction. The catalytic 
composition may be prepared prior to acylation or in situ providing 
application versatility.

DETAILED DESCRIPTION OF THE INVENTION 
In the preparation of 1,2-bis(acyloxyates) by the catalytic acylation of 
epoxides with carboxylic anhydrides, the use of catalytic compositions of 
tertiary amines with carboxylic acids has now been discovered to provide 
an improved process which increases the rates of reaction with minimal 
processing concerns. The catalytic species are believed to be tertiary 
ammonium carboxylate salts formed by the combination of the tertiary 
amines and the carboxylic acids either in a separate step or in situ. In 
the conversion of the epoxides to the 1,2-bis(acyloxyates), the epoxide 
rings are believed to be cleaved with the carboxylates of the catalytic 
species forming incipient alkoxides. The incipient alkoxides are 
concomitantly acylated by the carboxylates of the carboxylic anhydrides 
thereby producing 1,2-bis(acyloxyates). 
The substituted 1,2-bis(acyloxyates) produced in accordance with the 
present invention have the formulas: 
##STR2## 
wherein the R and R' substituents are defined below with respect to the 
epoxide and carboxylic arthydride reactants, respectively. 
The substituted epoxide reactants contain from 2 to about 20 carbon atoms, 
preferably from 3 to 8 carbon atoms. Examples of the substituted epoxide 
reactants include compounds having the structural formula: 
##STR3## 
wherein each R is independently selected from hydrogen, alkyl or alkenyl 
of up to about 8 carbon atoms, carbocyclic, aryl or heterocyclic aryl of 
about 5 to 10 carbon atoms or any two R substituents collectively may 
represent an alkyl or alkenyl forming a ring, e.g., alkyl containing in 
the main chain 4 to about 6 carbon atoms. The preferred epoxide reactants 
comprise compounds of formula (II) wherein the R substituents individually 
represent hydrogen, lower alkyl of up to about 4 carbon atoms, or 
collectively represent a straight or branched chain alkyl or alkenyl of 2 
to about 8 carbon atoms, especially compounds of formula (II) wherein 2 or 
more of the R groups represent hydrogen. Exemplary compounds contemplated 
for use in the practice of the present invention include 1,2-epoxybutane, 
2,3-epoxybutane, 3,4-epoxy-1-butene, ethylene oxide, propylene oxide, 
styrene oxide, cyclohexene oxide, and the like. The epoxide reactant of 
primary interest is 3,4-epoxy-1-butene. 
The preferred carboxylic anhydride reactants comprise compounds of formula 
(R'CO).sub.2 O wherein R' is independently selected from alkyl or alkenyl 
of up to about 15 carbon atoms or carbocyclic, aryl or heterocyclic aryl 
of about 5 to 10 carbon atoms. The carboxylic anhydrides are preferably 
reacted in an amount of at least 1 molar equivalent of the carboxylic 
anhydride to the epoxide. In excess amounts the carboxylic anhydrides act 
not only as reactants, but also as solvents. 
The tertiary amine components of the catalytic compositions having the 
formula R".sub.3 N contain from about 3 to about 36 carbon atoms. The 
tertiary amines are preferably linear chain or non-aromatic cyclic amines 
and contain R" substituents independently selected from alkyl of up to 
about 12 carbon atoms or aryl or carbocyclic of about 5 to 15 carbon 
atoms. Exemplary compounds contemplated for use in the practice of the 
present invention include triethylamine, tributylamine, 
diisopropylethylamine, N,N-dimethylaniline, 4-methylmorpholine, 
1-methylpyrrolidine, 1-methylpiperidine, 
1,8-diazabicyclo[5.4.0]undec-7-ene, 1,4-diazabicyclo[2.2.2]octane and the 
like. The use of tertiary amines with low boiling points, especially 
triethylamine, allow the 1,2-bis(acyloxyates) to be readily separated from 
the catalysts since the tertiary amines can be distilled away from the 
products and recycled. The tertiary amines may also be supported in the 
form of resins or other solid supports. 
Relative to the total amounts of tertiary amines and epoxides in the 
reactions, the tertiary amines are present in amounts ranging from about 
0.1 to 40 mole percent and the epoxides are present in amounts ranging 
from about 99.9 to 60 mole percent. Preferably, the tertiary amines are 
present in amounts ranging from about 1 to 10 mole percent and the 
epoxides are present in amounts ranging from about 99 to 90 mole percent. 
The carboxylic acid components of the catalytic compositions preferably 
contain from about 2 to 16 carbon atoms. More preferably, the carboxylic 
acids are conjugate acids of the carboxylic anhydrides. Thus, the 
carboxylic anhydride conjugate carboxylic acids having the formula R'COOH 
comprise R' substituents as defined above for the carboxylic anhydrides. 
The catalytic compositions comprise the tertiary amines present in amounts 
ranging from about 0.1 to 50 mole percent and the carboxylic acids present 
in amounts ranging from about 99.9 to 50 mole percent, based on a total 
amount of tertiary amine and carboxylic acid. Preferably the tertiary 
amines are present in amounts ranging from about 1 to 15 mole percent and 
the carboxylic acids are present in amounts ranging from about 99 to 85 
mole percent. 
The tertiary amines act as catalysts by themselves and catalyze the 
reactions in the absence of the carboxylic acids. The carboxylic acids, 
however, do not function to catalyze the reactions in the absence of the 
tertiary amines. Rather, the carboxylic acids act as co-catalysts with the 
tertiary amines to increase the rates of reaction beyond that which either 
catalyst component alone would produce. In the case of disubstituted 
epoxides, the addition of the conjugate carboxylic acids significantly 
increases the reaction rates, as well as the degree of conversion. With 
terminal epoxides, the dependence on the carboxylic acid concentrations 
has been observed to give reaction orders of less than 1 and to enhance 
the selectivity. 
The use of the conjugate carboxylic acids in excess relative to the 
tertiary amines provides an improvement to the process that would 
otherwise be unexpected. The carboxylic acids neutralize the tertiary 
amines forming the tertiary ammonium carboxylates at equivalent amounts. 
Thus, any excess carboxylic acid would be expected to react the same as if 
the carboxylic acid was the sole catalyst. Such is shown in Example 1 
wherein the use of acetic acid as the sole catalyst results in a very slow 
reaction rate with low yield and selectivity. However, in the presence of 
tertiary ammonium carboxylates the addition of excess carboxylic acid 
unexpectedly increases the rate of reaction and produces higher yields and 
selectivity as shown in Example 9-11. 
The significance of using the conjugate carboxylic acids is demonstrated in 
the conjugated epoxyalkene system of 3,4-epoxy-1-butene by the 
regioselective addition process of acetic anhydride in the presence of a 
tertiary ammonium acetate to prepare 3,4-diacetoxy-1-butene, a key 
intermediate in the manufacture of Vitamin A Acetate. Preferably, the 
tertiary ammonium acetate is triethylammonium acetate. Such acetylations 
of 3,4-epoxy-1-butene conducted under moderate temperatures of 50.degree. 
to 200.degree. C. at atmospheric pressure or under moderate pressure of an 
inert gas, such as nitrogen, give 88 to 94 mole percent 
3,4-diacetoxy-1-butene and 1 to 5 mole percent 1,4-diacetoxy-2-butene. 
As compared to pyridine or tetraalkylammonium acetates of the prior art, 
the tertiary ammonium acetates differ significantly in their chemical 
reactivity. The active catalytic species of the present invention are salt 
complexes of tertiary amines and carboxylic acids. The active species is 
created when the carboxylic acid protonates the basic amine function 
rendering the tertiary amine non-nucleophilic. Evidence supporting the 
involvement of the active species is the lack of reaction between the 
epoxides and tertiary amines in the absence of the carboxylic anhydrides 
and carboxylic acids. The epoxides are relatively stable to most 
carboxylic acids and carboxylic anhydrides in the absence of strong acids 
such as hydrochloric acid or sulfuric acid. The ammonium carboxylate anion 
of the tertiary ammonium carboxylates functions as a soluble form of 
nucleophilic carboxylate ion which initiates the cleavage of epoxides. 
The use of the catalytic composition of the present invention also provides 
advantages over the prior art catalysts. A wide variety of carboxylic 
anhydrides and carboxylic acids may be used with tertiary amines to form a 
variety of acyloxy functional groups without multi-step preparation as is 
required for tetraalkylammonium carboxylates. The lower chain tertiary 
ammonium carboxylates, such as triethylammonium acetate, may also be 
recovered from the reaction mixture since this activated complex has a 
reasonably low boiling point. The tetraalkylammonium carboxylates, 
however, are non-volatile salts which decompose upon heating. Thus, the 
catalytic compositions of the present invention are more convenient to use 
and offer a significant cost advantage over the prior art. 
The acylation conditions of temperature and pressure may vary depending on 
the reactants and catalysts employed. The acylation is generally conducted 
from about 50.degree. to 200.degree. C. The preferred temperature of 
operation is in the range of 100.degree. to 125.degree. C. The process may 
be carried out under atmospheric pressure or under moderate pressures of 
50 to 250 psig (4.6 to 35.5 bar) which is advantageous when low boiling 
catalysts or reactants are employed. As noted above, the optimum 
combination of temperature and pressure depends on other process variables 
but can be readily ascertained by those skilled in the art. 
The process of this invention optionally may be carried out in the presence 
of an inert, organic solvent. Examples of such solvents include aliphatic 
and aromatic hydrocarbons such as cyclohexane, heptane, toluene, xylene 
and mixed xylene isomers, ethers such as tetrahydrofuran, and amides such 
as N,N-dimethyl formamide and N-methyl-2-pyrrolidone. The preferred 
solvent system is the carboxylic anhydride that is used both as a solvent 
and reactant. The carboxylic anhydride is generally present in amounts of 
1.0 molar equivalent to a large molar excess of anhydride relative to 
epoxide. 
The process may be carried out in a batch, semi-continuous or continuous 
mode of operation. For example, batch operation may comprise agitating a 
tertiary amine, acetic acid, 3,4-epoxy-1-butene and acetic anhydride in a 
pressure vessel for a time sufficient to acylate essentially all of the 
3,4-epoxy-1-butene to 3,4-diacetoxy-1-butene. The catalyst being a 
tertiary amine and conjugate carboxylic acid may be separated from the 
acylated mixture by washing with water and the components of the organic 
phase separated by distillation or preferably by fractional distillation 
of the reaction mixture. 
The process provided by the present invention is further illustrated by the 
following examples which are intended to be exemplary of the invention. 
Gas chromatographic (GC) analyses were performed on a Hewlett-Packard 
5890A gas chromatograph with a 30 meter, DB-5, 0.5 mm inside-diameter, 
capillary column with a 1.2 micron film thickness. Diglyme was used as an 
internal standard to reference composition percentages. The temperature 
program was 35.degree. C. at 5 minutes, 20.degree. C. increase per minute 
to 240.degree. C., and hold 14.75 minutes. The identities of the products 
obtained were confirmed by nuclear magnetic spectrometry and gas 
chromatography-mass spectrometry. .sup.1 H NMR were recorded on a Gemini 
300 MHz spectrometer and .sup.13 C NMR were recorded at 75 MHz. 
EXAMPLE 1 
A 300-mL autoclave was charged with 40 mL (0.50 mol) of 3,4-epoxy-1-butene, 
67.3 g (0.66 mol) acetic anhydride, 5.82 g (0.097 mol) of acetic acid and 
4.2 mL of diglyme. The autoclave was purged with nitrogen twice, then the 
vessel was pressurized to 8 bars (100 psig) with nitrogen. The agitator 
was started and an initial sample was taken. The mixture was heated to 
125.degree. C. During the course of 2.5 hrs, samples were taken every 15 
min for analysis by GC. GC analysis of the crude mixture after 2.5 hrs 
revealed 11% yield of 3,4-diacetoxy-1-butene with a 13% selectivity, 21% 
3,4-epoxy-1-butene and numerous high boiling components. The reaction was 
observed to be first order in 3,4-epoxy-1-butene with a first order rate 
constant (Kfirst) of 0.0025 min.sup.-1 (Table A). This example illustrates 
low yield and selectivity in the absence of a tertiary amine and the 
inefficient catalysis of the reaction in the presence of the carboxylic 
acid alone. 
EXAMPLE 2 
A 300-mL autoclave was charged with 40 mL (0.50 mol) of 3,4-epoxy-1-butene, 
63.2 g (0.62 mol) acetic anhydride, 4.06 g (0.041 mol) of triethylamine 
and 4.2 mL of diglyme. The autoclave was purged with nitrogen twice, then 
the vessel was pressurized to 8 bars (100 psig) with nitrogen. The 
agitator was started and an initial sample was taken. The mixture was 
heated to 125.degree. C. During the course of 2.5 hrs, samples were taken 
every 15 min for analysis by GC. GC analysis of the crude mixture after 
2.5 hrs revealed a 92% yield of 3,4-diacetoxy-1-butene with a 92% 
selectivity and 0.36% 3,4-epoxy-1-butene. The reaction was observed to be 
first order in 3,4-epoxy-1-butene with a first order rate constant of 
0.037 min.sup.-1 (Table A). This example demonstrates the catalytic effect 
of the tertiary amine alone. 
EXAMPLE 3 
A 300-mL autoclave was charged with 40 mL (0.50 mol) of 3,4-epoxy-1-butene, 
62.2 g (0.61 mol) acetic anhydride, 1.8 g (0.018 mol) of triethylamine, 
1.1 g (0.018 mol) acetic acid and 4.2 mL of diglyme. The autoclave was 
purged with nitrogen twice, then the vessel was pressurized to 8 bars (100 
psig) with nitrogen. The agitator was started and an initial sample was 
taken. The mixture was heated to 125.degree. C. During the course of 2 
hrs, samples were taken every 15 min for analysis by GC. GC analysis of 
the crude mixture after 2 hrs revealed an 87% yield of 
3,4-diacetoxy-1-butene with an 89% selectivity and 1.8% 
3,4-epoxy-1-butene. The reaction was observed to be first order in 
3,4-epoxy-1-butene with a first order rate constant of 0.024 min.sup.-1 
(Table A). This example demonstrates the catalytic effect of the tertiary 
amine with acetic acid as the co-catalyst (Table B). 
EXAMPLE 4 
A 300-mL autoclave was charged with 40 mL (0.50 mol) of 3,4-epoxy-1-butene, 
60.0 g (0.59 mol) acetic anhydride, 3.7 g (0.02 mol) of tributylamine, 
0.72 g (0.012 mol) acetic acid and 4.2 mL of diglyme. The autoclave was 
purged with nitrogen twice, then the vessel was pressurized to 8 bars (100 
psig) with nitrogen. The agitator was started and an initial sample was 
taken. The mixture was heated to 125.degree. C. During the course of 2 
hrs, samples were taken every 15 min for analysis by GC. GC analysis of 
the crude mixture after 2 hrs revealed a 79% yield of 
3,4-diacetoxy-1-butene with a 90% selectivity and 12% 3,4-epoxy-1-butene. 
The reaction was observed to be first order in 3,4-epoxy-1-butene with a 
first order rate constant of 0.017 min.sup.-1 (Table A). This example 
shows the catalytic effect of another tertiary amine with acetic acid as 
the co-catalyst. 
EXAMPLE 5 
A 100-mL autoclave was charged with 57.2 g (0.44 mol) propionic anhydride, 
1.62 g (0.016 mol) of triethylamine and 3.44 g of diglyme. The autoclave 
was purged with helium twice, then the vessel was pressurized to 6.2 bars 
(75 psig) with helium followed by agitation. The reaction mixture was 
heated to 125.degree. C., then 31.35 mL (0.40 mol) of 3,4-epoxy-1-butene 
was introduced to the reactor via syringe pump over 10 seconds. A first 
sample was taken at 1 min, then sequential samples were obtained every 15 
min during the course of 2 hrs for analysis by GC. GC analysis of the 
crude mixture after 2 hrs revealed an 84% yield of 
3,4-dipropionyloxy-1-butene with a 94% selectivity and 11.2% 
3,4-epoxy-1-butene. The reaction was observed to be first order in 
3,4-epoxy-1-butene with a first order rate constant of 0.017 min.sup.-1 
(Table A). This example shows the use of another carboxylic anhydride with 
triethylamine and no carboxylic acid co-catalyst. 
EXAMPLE 6 
A 100-mL autoclave was charged with 57.2 g (0.44 mol) propionic anhydride, 
1.62 g (0.016 mol) of triethylamine, 1.2 g (0.016 mol) of propionic acid 
and 3.44 g of diglyme. The autoclave was purged with helium twice, then 
the vessel was pressurized to 6.2 bars (75 psig) with helium followed by 
agitation. The reaction mixture was heated to 125.degree. C., then 31.35 
mL (0.40 mol) of 3,4-epoxy-1-butene was introduced to the reactor via 
syringe pump over 10 seconds. A first sample was taken at 1 min, then 
sequential samples were obtained every 15 min during the course of 2 hrs 
for analysis by GC. GC analysis of the crude mixture after 2 hrs revealed 
a 90% yield of 3,4-dipropionyloxy-1-butene with a 91% selectivity and 6% 
3,4-epoxy-1-butene. The reaction was observed to be first order in 
3,4-epoxy-1-butene with a first order rate constant of 0.017 min.sup.-1 
(Table A). This example shows the use of another carboxylic anhydride with 
its conjugate carboxylic acid. 
EXAMPLE 7 
A 300-mL, 3-necked flask fitted with a thermocouple, condenser and stopper 
was charged with 47.5 g (0.21 mol) benzoic anhydride, 16 mL (0.2 mol) 
3,4-epoxy-1-butene and 1.4 mL (0.008 mol) of diisopropylethylamine. The 
flask was purged with nitrogen then heated to reflux. The reaction was 
discontinued after 1.5 hr when the temperature reached 160.degree. C. GC 
analysis revealed a mixture of about 1% starting material, 10-15% 
monocarboxylates (confirmed by GC-MS), 4% 1,4-bis(acyloxyate) and about 
80% of the desired 1,2-bis(acyloxyate). The reaction mixture was diluted 
with ether, washed with dilute HCl, washed twice with water, and then 
dried over Na.sub.2 SO.sub.4. The ether was removed under vacuum, and the 
residue was distilled at 0.15 mm Hg. Three fractions were obtained with 
the last two fractions containing the 1,2-bis(acyloxyates) for a combined 
yield of 62%. Fraction 2 results were 36.5 g of 95% 
3,4-dibenzoyloxy-1-butene and 5% monocarboxylates with bp of 
155.degree.-165.degree. C. Fraction 3 results were 21.5 g of 93% 
3,4-dibenzoyloxy-1-butene and 7% 1,4-dibenzoyloxy-2-butene with bp of 
165.degree.-170.degree. C. .sup.1 H NMR (CDCl.sub.3) .delta.8.08 (dd, 
J=0.7, 6.3, 4 H), 7.45 (m, 6 H), 5.98 (m, 2 H), 5.51 (d, J=17 Hz, 1 H), 
5.35 (d, J=10.4 Hz, 1 H) 4.56 (m, 2 H); .sup.13 C NMR (CDCl.sub.3) 
.delta.170.3, 73.6, 30.0, 23.3, 21.0. This example demonstrates the use of 
a very reactive carboxylic anhydride with a hindered tertiary amine (Table 
A). 
EXAMPLE 8 
A 300-mL, 3-necked flask fitted with a thermocouple, condenser and stopper 
was charged with 47.5 g (0.21 mol) benzoic anhydride, 0.49 g (0.004 mol) 
benzoic acid, 16 mL (0.2 mol) 3,4-epoxy-1-butene and 1.4 mL (0.008 mol) of 
diisopropylethylamine. The flask was purged with nitrogen then heated to 
reflux. The reaction was discontinued after 3 hrs of maintaining the 
temperature at 130.degree. C. GC analysis revealed a mixture of about 1% 
starting material, 10% monocarboxylates, 2% 1,4-bis(acyloxyate) and about 
87% of the desired 1,2-bis(acyloxyate). This example shows the use of a 
very reactive carboxylic anhydride and a hindered tertiary amine with the 
conjugate carboxylic acid (Table A). 
EXAMPLE 9 
A 100-mL autoclave was charged with 45.25 g (0.44 mol) acetic anhydride, 
1.62 g (0.016 mol) of triethylamine, 1.94 g (0.032 mol) acetic acid and 
3.44 g of diglyme. The autoclave was purged with helium twice, then the 
vessel was pressurized to 6.2 bars (75 psig) with helium followed by 
agitation. The reaction mixture was heated to 125.degree. C. Then 31.35 mL 
(0.40 mol) of 3,4-epoxy-1-butene was introduced to the reactor via syringe 
pump over 10 seconds. A first sample was taken at 1 min, then sequential 
samples were obtained every 15 min during the course of 2.25 hrs for 
analysis by GC. GC analysis of the crude mixture after 2.25 hrs revealed a 
93% yield of 3,4-diacetoxy-1-butene with a 95% selectivity and 1.9% 
3,4-epoxy-1-butene. The reaction was observed to be first order in 
3,4-epoxy-1-butene with a first order rate constant of 0.029 min.sup.-1 
(Table A). This example demonstrates the catalytic effect of a tertiary 
amine with two molar equivalents of acetic acid as a co-catalyst (Table 
B). 
EXAMPLE 10 
A 300-mL autoclave was charged with 40 mL (0.50 mol) of 3,4-epoxy-1-butene, 
56.2 g (0.55 mol) acetic anhydride, 2.0 g (0.02 mol ) of triethylamine, 
3.6 g (0.06 mol) acetic acid and 4.2 mL of diglyme. The autoclave was 
purged with nitrogen twice, then the vessel was pressurized to 8 bars (100 
psig) with nitrogen. The agitator was started and an initial sample was 
taken. Then the mixture was heated to 125.degree. C. During the course of 
2.5 hrs, samples were obtained every 15 min for analysis by GC. GC 
analysis of the crude mixture after 2.5 hrs revealed a 96% yield of 
3,4-diacetoxy-1-butene and 1.4% 3,4-epoxy-1-butene. The reaction was 
observed to be first order in 3,4-epoxy-1-butene with a first order rate 
constant of 0.037 min.sup.-1 (Table A). This example demonstrates the 
catalytic effect of a tertiary amine with three molar equivalents of 
acetic acid (Table B). 
EXAMPLE 11 
A 100-mL autoclave was charged with 45.25 g (0.44 mol) acetic anhydride, 
1.62 g (0.016 mol) of triethylamine, 9.6 g (0.16 mol) acetic acid and 3.44 
g of diglyme. The autoclave was purged with helium twice, then the vessel 
was pressurized to 6.2 bars (75 psig) with helium followed by agitation. 
The reaction mixture was heated to 125.degree. C., then 31.35 mL (0.40 
mol) of 3,4-epoxy-1-butene was introduced to the reactor via syringe pump 
over 10 seconds. A first sample was obtained at 1 min, then sequential 
samples were obtained every 15 min during the course of 2.25 hrs for 
analysis by GC. GC analysis of the crude mixture after 2.25 hrs revealed 
94% 3,4-diacetoxy-1-butene with no 3,4-epoxy-1-butene remaining. The 
reaction was observed to be first order in 3,4-epoxy-1-butene with a first 
order rate constant of 0.058 min.sup.-1 (Table A). This example shows the 
catalytic effect of a tertiary amine with ten molar equivalents of acetic 
acid (Table B). 
TABLE A 
__________________________________________________________________________ 
Moles 
RXN of 3,4- 
Moles 
Moles 
% 3,4- 
% 1,4- 
Time 
Epoxy-1 
of of Diacyloxy- 
Diacyloxy- 
Kfirst 
Ex. 
(Min.) 
Butene 
Amine 
Acid 1-Butene 
1-Butene 
(min-1) 
__________________________________________________________________________ 
1 150 0.5 0.00 
0.097 
11 1 0.0025 
2 150 0.5 0.041 
0 92 0.2 0.037 
3 120 0.5 0.02 
0.02 87 1 0.024 
4 120 0.5 0.02 
0.012 
79 0 0.017 
5 120 0.4 0.016 
0 84 5 0.017 
6 120 0.4 0.016 
0.016 
90 3 0.023 
7 90 0.2 0.008 
0 80 4 -- 
8 180 0.2 0.008 
0.004 
87 1 -- 
9 135 0.4 0.016 
0.032 
93 1.4 0.029 
10 150 0.5 0.02 
0.06 96 1 0.037 
11 135 0.4 0.016 
0.16 94 4 0.058 
__________________________________________________________________________ 
Kinetic Effect of Acetic Acid Co-catalyst 
The effect of acetic acid co-catalyst in the rate of addition of acetic 
anhydride to 3,4-epoxy-1-butene to form 3,4-diacetoxy-1-butene was 
demonstrated in Examples 3, 9-11 and is set forth in Table B. The 
dependence of the acetic acid concentration charged to the reactor was 
correlated with the rate constant by plotting the natural logarithm (ln) 
of the first order rate constant versus in of the acetic acid 
concentration as shown in FIG. 1. The dependence on acetic acid 
concentration is expressed as the slope of the line shown in FIG. 1. The 
slope is 0.38 indicating a dependence that is less than first order. This 
reaction order suggests that the acid catalyst plays a significant role in 
a complex mechanism and may be involved in more than one step of the 
mechanism. A linear correlation of 0.977 indicates a very good correlation 
in the range of one molar equivalent of acetic acid to 10 molar 
equivalents relative to triethylamine. The acetic acid is observed to 
enhance the rate and selectivity, but is not first order in acetic acid. 
TABLE B 
______________________________________ 
Kfirst AcOH ln ln AcOH 
Example (min-1) Molarity Kfirst 
Molarity 
______________________________________ 
3 0.024 0.171 -3.730 
-1.766 
9 0.029 0.396 -3.540 
-0.926 
10 0.037 0.586 -3.297 
-0.534 
11 0.058 1.81 -2.847 
0.593 
______________________________________ 
EXAMPLE 12 
A 300-mL, 3-necked flask fitted with a thermocouple, condenser and stopper 
was charged with 181 mL (1.6 mol) acetic anhydride, 62.7 mL (0.8 mol) 
3,4-epoxy-1-butene, 7.2 mL (0.04 mol) of diisopropylethylamine and 2.4 g 
(0.04 mol) of acetic acid. The flask was purged with nitrogen then heated 
to reflux. The reaction was complete after 48 hrs. GC analysis revealed 
only the desired 3,4-diacetoxy-1-butene. The reaction mixture was washed 
with dilute HCl and water, then dried over Na.sub.2 SO.sub.4. Distillation 
at 2.0 mm Hg (bp 66.degree.-68.degree. C.) gave 101.4 g for a combined 
yield of 74%. .sup.1 H NMR (CDCl.sub.3) .delta.5.78 (m, 1 H), 5.46 (m, 1 
H), 5.33 (dd, J=1.1, 17.3 Hz, 1 H), 5.25 (dd, J=1.1, 10.3 Hz, 1 H), 4.22 
(dd, J=3.7, 12.0 Hz, 1 H), 4.07 (dd, J=7.1, 12.0 Hz, 1 H), 2.07 (s, 3 H), 
2.04 (s, 3 H); .sup.13 C NMR (CDCl.sub.3) .delta.170.4, 169.7, 132.1, 
118.5, 71.8, 64.5, 20.8, 20.5. This example shows that even when using 
acetic acid as a co-catalyst a hindered tertiary amine is slow to react 
(Table C). 
EXAMPLE 13 
A 300-mL autoclave was charged with 35 mL (0.50 mol) of propylene oxide, 95 
mL (1.01 mol) acetic anhydride and 2.8 mL (0.02 mol) of triethylamine. The 
autoclave was purged with nitrogen twice, then the vessel was pressurized 
to 8 bars (100 psig) with nitrogen followed by agitation. The reaction was 
conducted for 4 hrs at 120.degree. C. After 4 hrs, GC analysis revealed 
complete conversion to 1,2-diacetoxypropane with greater than 99% 
selectivity. The reaction mixture was washed three times with dilute HCl 
then distilled through a short Vigreux column at 4 mm Hg, bp 
75.degree.-77.degree. C. A total of 50.3 g was obtained with a combined 
yield of 63%. .sup.1 H NMR (CDCl.sub.3) .delta.5.04 (m, 1 H) , 4.09 (dd, 
J=6.6, 11.8 Hz, 1 H), 2.00 (s, 3 H), 1.98 (s, 3 H), 1.17 (d, J=6.5 Hz, 3 
H); .sup.13 C NMR (CDCl.sub.3) .delta.170.6, 170.3, 68.1, 65.9, 21.0, 
20.6, 16.3. This example shows the production of a 1,2-bis(acyloxyate) 
from another type of an epoxide (Table C). 
EXAMPLE 14 
A 300-mL autoclave was charged with 43 mL (0.50 mol) of 1,2-butylene oxide, 
95 mL (1.01 mol) acetic anhydride and 2.8 mL (0.02 mol) of triethylamine. 
The autoclave was purged with nitrogen twice, then the vessel was 
pressurized to 8 bars (100 psig) with nitrogen followed by agitation. The 
reaction was conducted for 4 hrs at 120.degree. C. After 4 hrs, GC 
analysis revealed complete conversion to 1,2-diacetoxybutane with greater 
than 99% selectivity. The reaction mixture was washed two times with 
dilute HCl then distilled through a short Vigreux column at 3 mm Hg, bp 
83.degree.-85.degree. C. A total of 72.9 g was obtained with a combined 
yield of 84%. .sup.1 H NMR (CDCl.sub.3) 64.95 (m, 1 H), 4.18 (dd, J=3.4, 
11.9 Hz, 1 H), 3.98 (dd, J=6.6, 11.9 Hz, 1 H), 2.00 (s, 3 H), 1.99 (S, 3 
H), 1.55 (q, J=7.5 HZ, 2 H), o.aa (t, J=7.5 Hz, 3 H); .sup.13 C NMR 
(CDCl.sub.3) .delta.170.6, 170.4, 72.6, 64.6, 23.6, 20.8, 20.6, 9.3. This 
example demonstrates the production of a 1,2-bis(acyloxyate) from another 
type of epoxide without an acid co-catalyst (Table C). 
EXAMPLE 15 
A 300-mL, 3-necked flask fitted with a thermocouple, condenser and stopper 
was charged with 49.5 mL (0.53 mol) acetic anhydride, 43 mL (0.5 mol) 
1,2-butylene oxide, 2.8 mL (0.04 mol) of triethylamine and 2.2 mL (0.02 
mol) of acetic acid. The flask was purged with nitrogen then heated to 
reflux. The reaction was complete after 5 hrs. GC analysis revealed the 
desired 1,2-diacetoxybutane plus another side-product. The reaction 
mixture was washed with dilute HCl and water, then dried over Na.sub.2 
SO.sub.4. The side-product was no longer present after the aqueous workup. 
Distillation at 3.5 mm Hg (bp 84.degree.-85.degree. C.) gave 74 g for a 
combined yield of 85%. This example shows the production of a 
1,2-bis(acyloxyate) from another epoxide using acetic acid as a 
co-catalyst (Table C). 
EXAMPLE 16 
A 300-mL, 3-necked flask fitted with a thermocouple, condenser and stopper 
was charged with 76 mL (0.8 mol) acetic anhydride, 45.5 mL (0.4 mol) 
stryrene oxide and 2.25 mL (0.016 mol) of triethylamine. The flask was 
purged with nitrogen then heated to reflux. The reaction was complete 
after 2 hrs. GC analysis of the crude reaction product revealed the 
desired diacetate in 95% assay. The reaction mixture was washed with 
dilute HCl and water, then dried over Na.sub.2 SO.sub.4. Distillation of 
the product at 2.2 mm Hg (bp 110.degree.-112.degree. C.) gave 74.5 g of 
1,2-diacetoxy-1-phenylethane for a combined yield of 84%. .sup.1 H NMR 
(CDCl.sub.3) .delta.7.34 (m, 5 H) , 6.03 (dd, J=3.5, 7.7 Hz, 1 H) , 4.33 
(m, 2 H), 2.12 (s, 3 H), 2.06 (s, 3 H); .sup.13 C NMR (CDCl.sub.3) 
.delta.170.5, 169.9, 136.4, 128.6, 128.5, 126.6, 73.2, 66.0, 21.0, 20.7. 
This example shows the production of a 1,2-bis(acyloxyate) from another 
epoxide without a co-catalyst (Table C). 
EXAMPLE 17 
A 300-mL, 3-necked flask fitted with a thermocouple, condenser and stopper 
was charged with 76 mL (0.53 mol) acetic arthydride, 45.5 mL (0.4 mol) 
styrene oxide, 2.25 mL (0.016 mol) of triethylamine and 0.9 mL (0.016 mol) 
of acetic acid. The flask was purged with nitrogen then heated to reflux 
for 1.5 hrs. The reaction mixture was washed with dilute HCl and water, 
then dried over Na.sub.2 SO.sub.4. Distillation of the product at 0.25 mm 
Hg (bp 100.degree.-102.degree. C.) gave 71.4 g of 
1,2-diacetoxy-1-phenylethane with a yield of 80%. This example shows the 
production of a 1,2-bis(acyloxyate) from another epoxide with acetic acid 
as a co-catalyst (Table C). 
EXAMPLE 18 
A 25-mL round-bottomed flask was charged with 10 mL (0.052 mol) acetic 
anhydride, 5 g (0.1 mol) cyclohexene oxide and 0.14 mL (0.002 mol) of 
triethylamine. The flask was purged with nitrogen then heated to reflux. 
The reaction was monitored as a function of time by GC analysis. After 16 
hrs, the reaction was only 50.6% complete in the absence of acetic acid 
co-catalyst. This example shows the production of a 1,2-bis(acyloxyate) 
from another epoxide and that the reaction is slow with a disubstituted 
epoxide in the absence of acetic acid co-catalyst (Table C). 
EXAMPLE 19 
A 300-mL, 3-necked flask fitted with a thermocouple, condenser and stopper 
was charged with 49 mL (0.52 mol) acetic anhydride, 25 g (0.26 mol) 
cyclohexene oxide, 1.4 mL (0.01 mol) of triethylamine and 0.6 mL (0.01 
mol) of acetic acid. The flask was purged with nitrogen then heated to 
reflux for 16 hrs. The reaction mixture was washed with dilute HCl then 
distilled at 1.6 mm Hg (bp 99.degree.-102.degree. C.) to give 42 g of 
1,2-diacetoxycyclohexane with a yield of 81%. .sup.1 H NMR (CDCl.sub.3) 
.delta.4.75 (m, 2 H), 2.01 (m, 2 H), 1.98 (s, 6 H), 1.69 (m, 2 H), 1.32 
(brm, 4 H); .sup.13 C NMR (CDCl.sub.3) .delta.170.3, 73.6, 30.0, 23.3, 
21.0. This example shows the production of a 1,2-bis(acyloxyate) from a 
disubstituted epoxide with acetic acid as a co-catalyst which results in 
higher conversions as compared to without acetic acid (Table C). 
TABLE C 
__________________________________________________________________________ 
RXN % Isolated 
Time Dicarboxylate 
Ex. 
(Hrs.) 
Epoxide 
Anhydride 
Amine Acid 
Ester 
__________________________________________________________________________ 
12 48 3,4-Epoxy-1- 
Acetic 
(i-Pr)2NEt 
AcOH 
74 
butene 
13 4 Propylene 
Acetic 
NEt3 None 
63 
oxide 
14 4 Butylene 
Acetic 
NEt3 None 
84 
oxide 
15 5 Butylene 
Acetic 
NEt3 AcOH 
85 
oxide 
16 2 Styrene 
Acetic 
NEt3 None 
84 
oxide 
17 1.5 Styrene 
Acetic 
NEt3 AcOH 
80 
oxide 
18 16 Cyclohexene 
Acetic 
NEt3 None 
51 
oxide (Unisolated) 
19 16 Cyclohexene 
Acetic 
NEt3 AcOH 
81 
oxide 
__________________________________________________________________________ 
As thus seen, the catalytic composition of the present invention produces 
1,2-bis(acyloxyates) from the acylation of epoxides with carboxylic 
anhydrides with improved process results. The tertiary amine and 
carboxylic acid catalytic compositions are relatively inexpensive because 
preparation is minimal. The rates of reaction are increased and higher 
selectivity is obtained, thus reducing the need for extensive separation 
and by-product recovery equipment. 
The invention has been described in detail with particular reference to 
preferred processes thereof, but it will be understood that variations and 
modifications can be effected within the spirit and scope of the 
invention.