Decomposition of cumene hydroperoxide and recovery of boron trifluoride catalyst

Cumene hydroperoxide is decomposed to phenol and acetone using boron trifluoride or boron trifluoride complexed with an oxygen-containing polar compound as the decomposition catalyst. The boron trifluoride in the reaction product is then complexed with an amine such as trimethyl amine for recovery and reuse in the process.

FIELD OF THE INVENTION 
This invention relates to the catalytic cleavage of cumene hydroperoxide to 
equal molar portions of phenol and acetone using boron trifluoride as the 
catalyst, and more particularly it relates to a process for the catalytic 
cleavage of cumene hydroperoxide in the presence of boron trifluoride or a 
complex of boron trifluoride with an oxygen-containing polar compound in 
which the boron trifluoride in the product is deactivated by reaction with 
an amine. The boron trifluoride is recovered from the boron 
trifluoride.amine complex and is recycled to the process. 
DESCRIPTION OF THE PRIOR ART 
Cumene can be readily oxidized with air to form cumene hydroperoxide and 
the hydroperoxide can then be decomposed to form equal molar amounts of 
phenol and acetone. In the commercial process for producing phenol by this 
general method, a small amount of a mineral acid, generally sulfuric acid, 
is used as the decomposition or cleavage catalyst. Since phenol and 
acetone are the products of the cleavage reaction, the reaction solvent 
can conveniently be a phenol-acetone solution. In this process the cumene 
hydroperoxide instantaneously decomposes to phenol and acetone as it is 
slowly added in solution with cumene to the mineral acid solution. The 
highly exothermic reaction is controlled by the rate of cumene 
hydroperoxide addition and by acetone reflux. Water is substantially 
excluded from the reaction medium during the decomposition reaction to 
insure homogeneity. Since the mineral acid is neutralized in the product 
stream with an alkali solution to reduce tar formation during subsequent 
distillative separation of the phenol and acetone from the tars, the 
resulting alkali sulfate sludge by-product may be disposed of and new acid 
must be continuously supplied to the process. 
DESCRIPTION OF THE INVENTION 
The desired decomposition of cumene hydroperoxide is a cleavage to equal 
mols of phenol and acetone, that is, about 62 weight percent phenol and 38 
weight percent acetone. In using sulfuric acid as the decomposition 
catalyst, a selectivity to phenol of about 85 to 95 percent is generally 
obtained. The non-selective decomposition product particularly as 
catalyzed by a strong mineral acid includes cumyl alcohol, acetophenone, 
methylbenzofuran, several organic acids, mono- and dicumylphenol, 
diacetone alcohol, acetol, mesityl oxide, phorone, alpha-methylstyrene and 
various oligomers of alpha-methylstyrene which are tar-like substances. 
When the reaction product is distilled, these by-products remain in the 
residue which is collectively called "tar" or "tars". It has been reported 
that the main products in this "tar" are cumylphenol and dicumylphenol, 
the polymers of alpha-methylstyrene, acetophenone and diacetone alcohol. 
Since few of these by-products of the non-selective reaction can be 
economically recovered, this non-selective reaction represents a 
significant economic loss. 
A particular advantage in the use of the boron trifluoride and complexed 
boron trifluoride decomposition catalysts is that a selectivity greater 
than 95 percent, approaching 100 percent under optimum conditions, can be 
obtained. Another advantage of these catalysts in contrast with the strong 
mineral acid catalyst is that the boron trifluoride catalysts do not 
promote the alkylation of phenol product to cumylphenol nor the 
oligomerization of aromatic olefin to form tars. Furthermore, in the 
present process the major by-product, if any, alpha-methylstyrene, can be 
recovered and hydrogenated to cumene for recycle in the process. A further 
advantage in the use of the boron trifluoride catalysts instead of the 
mineral acid catalysts is that the corrosion problems of the latter are 
substantially avoided. 
The mineral acid in the crude decomposition product resulting from the 
mineral acid catalyzed cleavage reaction is deactivated by neutralization 
with a suitable basic substance prior to distillation of the crude mixture 
for the separation of the phenol and acetone product from the tar, 
otherwise the mineral acid will catalyze substantial additional tar 
formation during distillation. Thus, we have determined that distillation 
of a portion of a sulfuric acid catalyzed decomposition product resulted 
in 12 percent tar while only 4.4 percent tar resulted overall in another 
portion of the same decomposition product which was distilled after 
neutralization with sodium bicarbonate. But this neutralization procedure, 
which includes downstream caustic and acid washes, introduces water into 
the reaction product. This requires additional distillation equipment for 
water removal and requires additional treatment of the separated water for 
phenol removal prior to its disposal. A separator is also required for the 
removal of precipitated sodium sulfate. A substantial economic burden is 
superimposed onto the mineral acid-catalyzed decomposition process 
including capital, labor and energy costs as a result of the catalyst 
neutralization and associated procedures. 
In contrast, in the present procedure, the catalyst is deactivated for 
product distillation in a non-aqueous procedure by reacting the boron 
trifluoride catalyst with a tertiary amine to form a stable, high boiling 
amine-boron trifluoride coordination compound. As a result, neutralization 
and water removal problems are eliminated from the system and product 
separation is greatly simplified. And most advantageously the complex of 
the boron trifluoride and the amine is treated after product separation, 
to release both the amine and the boron trifluoride for recycle in the 
process. This recovery of boron trifluoride not only provides an economic 
saving, but it also substantially reduces environmental problems which 
would result from discharging it as a waste. 
The amines which we find to be suitable for the catalyst deactivation are 
the lower alkyl tertiary amines such as trimethyl amine, triethyl amine, 
tripropyl amine, tributyl amine; the lower alkyl secondary amines such as 
dimethyl amine, diethyl amine and dibutyl amine; mixed lower alkyl 
aromatic amines such as phenyl dimethyl amine, benzyl diethyl amine, and 
the like; aromatic amines such as aniline, N,N-dimethylaniline, naphthyl 
amine and the like; and heterocyclic amines such as pyridine, piperidine, 
piperazine, and the like. The primary requirement of this amine is that it 
produce a sufficiently strong complex with the boron trifluoride to retain 
the boron trifluoride in the residue resulting from the product 
distillation notwithstanding rigorous distillation conditions. 
When boron trifluoride gas is used as the catalyst, it can be bubbled into 
the reaction liquid or the desired quantity can be added to the free space 
in the reactor from which it will readily dissolve in the reaction liquid. 
We have found that catalyst concentration is an important reaction 
variable. That is, the higher the catalyst concentration, the more rapid 
the reaction until too much catalyst renders the exothermic reaction 
uncontrollable. On the other hand, the reaction is too slow with too 
little catalyst. Within these constraints the concentration of 
non-complexed boron trifluoride catalyst will generally be between about 
20 parts of boron trifluoride per million parts of total reaction liquid 
(ppm.), and about one percent, or even higher with appropriate control of 
reaction temperature and preferably its concentration will be between 
about 500 ppm. and about 0.5 percent. 
The complexed boron trifluoride catalyst is a liquid or solid which is 
readily dissolved in the reaction liquid. Suitable complexes can be formed 
with boron trifluoride and water or an appropriate oxygen-containing 
organic polar compound in which oxygen acts as the electron donor. These 
organic polar compounds include aliphatic alcohols having one to about 
four carbon atoms; aromatic alcohols such as benzyl alcohol; aliphatic 
ethers having from two to about eight carbon atoms; or mixed 
alkyl-aromatic ethers such as methylphenyl ether; aliphatic acids having 
from one to about four carbon atoms or aromatic acids such as phenol and 
benzoic acid; acid anhydrides such as acetic acid anhydride; esters formed 
from aliphatic acids having from one to about four carbon atoms esterified 
with an alkyl group containing one to about four carbon atoms or with an 
aromatic group such as phenyl and benzyl; an aliphatic ketone having from 
two to about eight carbon atoms, in aromatic ketone such as dibenzyl 
ketone or a mixed alkylaromatic ketone; aliphatic aldehydes having from 
two to about four carbon atoms or an aromatic aldehyde such as benzyl 
aldehyde; and the like. Also useful as a complexing agent for the boron 
trifluoride are suitable chlorine derivatives of the above such as 
chloroethyl alcohol, dichloroethyl alcohol, trichloroacetaldehyde, and the 
like. Free boron trifluoride, which is dissolved in the reaction liquid, 
readily complexes with phenol which is produced as the reaction proceeds. 
Nevertheless, we have found that the reaction proceeds more rapidly when 
free boron trifluoride is used as the catalyst than when this boron 
trifluoride complex with phenol is initially used as the catalyst since 
the free boron trifluoride is a much more active catalyst. 
The boron trifluoride complex can be either a 1:1 or a 2:1 molar complex of 
the complexing agent with the boron trifluoride provided that the complex 
can be produced and is stable at the conditions of the decomposition 
reaction. The concentration of the boron trifluoride in the reaction 
liquid depends, in part, on the properties of the complex. For example, 
some complexes are active at very low concentrations, while other 
complexes require substantially higher amounts for a suitable rate of 
reaction. The more active complexes of boron trifluoride, such as the 1:1 
complex with diethyl ether, are similar in activity to free boron 
trifluoride. The concentration range for free boron trifluoride in the 
reaction liquid, as specified above, also applies to the complexes of 
boron trifluoride. 
Since the cleavage reaction is highly exothermic, temperature control of 
the reaction liquid is generally provided. This temperature control can be 
accomplished by controlling the amount of catalyst used or by controlling 
the rate at which the catalyst is mixed with the cumene hydroperoxide. But 
with the highly active catalysts one or both of the following techniques 
for temperature control is desirably utilized. Temperature control can be 
effected, in part, by maintaining appropriate means for the positive 
cooling of the reaction liquid during the reaction such as by solvent 
reflux or by submerged cooling coils. Another effective and useful method 
of temperature control is the employment of sufficient inert solvent to 
serve as a heat sink. The reaction can be carried out within the range of 
between about 25.degree. to about 110.degree. C. and preferably a range of 
between about 60.degree. to about 80.degree. C. At the lower temperatures 
the reaction becomes quite slow although highly selective, while 
undesirable tar formation can result at higher temperatures due to the 
effects of thermal decomposition of the cumene hydroperoxide. 
The pressure within the reactor is not a critical factor during the 
decomposition reaction. Generally, the pressure will range from a pressure 
moderately below to moderately above atmospheric pressure. Since boron 
trifluoride gas is highly soluble in the reaction liquid, the boron 
trifluoride gas pressure need only be moderately elevated above 
atmospheric pressure to obtain its solution in the liquid reaction medium. 
The cumene hydroperoxide can desirably be prepared by oxidation of cumene 
with air in the conventional manner. In this process a solution of at 
least about 10 weight percent cumene hydroperoxide in cumene is desirably 
produced, although a product containing less than 10 weight percent cumene 
hydroperoxide can be utilized. Since it is not particularly desirable to 
use an excessive amount of cumene in a continuous process as a reaction 
solvent due to subsequent handling and separation problems, it is 
preferred that a more concentrated solution of cumene hydroperoxide be 
prepared. In this oxidation reaction the maximum concentration of cumene 
hydroperoxide that can conveniently be produced is about 30 percent. 
The cumene hydroperoxide to be used in the decomposition reaction can be 
further concentrated by flashing off sufficient cumene to form a feed 
solution of between about 60 to about 90 percent, preferably about 65 to 
about 80 percent, cumene hydroperoxide. Although pure cumene hydroperoxide 
can be used, it is not desirable to obtain it in this final stage of 
purity for economic reasons and also for safety reasons since the presence 
of some cumene tends to stabilize the cumene hydroperoxide. The 
decomposition reaction can suitably be carried out with as little as about 
0.1 weight percent cumene hydroperoxide in the reaction liquid, with at 
least about 0.5 percent being preferred and at least about 1.0 percent 
being most preferred. The maximum amount of cumene hydroperoxide in the 
cleavage reaction liquid will suitably be about 20 weight percent, 
preferably about 10 percent and most preferably about 5 percent. Since 
explosions have in the past resulted from cumene hydroperoxide reactions 
which have run away, it is generally desired to carry out the reaction 
with substantial diluent as a safety measure, resulting in a concentration 
of cumene hydroperoxide in the reaction liquid much below the upper limit. 
The solvent used in this process can be the cumene associated with the 
cumene hydroperoxide as described above. However, since phenol and acetone 
are the desired reaction product, a phenol-acetone solvent is generally 
desirable in order to simplify product separation. Since a solution of 
cumene hydroperoxide and cumene is usually added to the reactor, the 
solvent system will therefore include cumene as a component, generally a 
minor component. The solvent can conveniently be the 1:1 molar phenol to 
acetone product of the cumene hydroperoxide cleavage reaction, however, 
variations in the relative proportions can be used. Thus, although there 
is no particular advantage to using an excess of phenol, an excess of 
acetone may be desirable, particularly if the acetone is to be utilized 
for temperature maintenance during reaction by means of acetone reflux or 
boil-off. Therefore, the mol ratio of acetone to phenol as the solvent in 
the reaction mixture can be as high as about 10:1 and preferably no higher 
than about 3:1. Other usable solvents include aromatic solvents such as 
benzene, toluene, and the like; ethers such as diethyl ether and 
tetrahydrofuran, or any other solvent which is compatible with the 
reactant and catalyst and can be conveniently separated. 
Phenol is not inert when used as a solvent for cumene hydroperoxide in its 
decomposition. Rather phenol, by virtue of its acid nature, has been found 
to be a catalyst for the decomposition of cumene hydroperoxide in a 
reaction which is significantly slower than the above-described mineral 
acid catalyzed reaction. Moreover, the selectivity of this phenol 
catalyzed decomposition of cumene hydroperoxide is very poor, being less 
than 80 percent selectivity to phenol as determined by a study of the 
reaction. It is readily apparent that the presence of solvent phenol in 
the mineral acid catalyzed reaction of the commercial processes is not 
noticeably detrimental because the great speed of the mineral acid 
catalyzed decomposition effectively eliminates the detrimental effect on 
selectivity of the relatively slow phenol catalyzed reaction. In our 
reaction we can avoid a significant adverse effect on product selectivity 
from the phenol catalyzed reaction, particularly when phenol is present as 
an added solvent, by appropriate catalyst selection and/or concentration 
to obtain a suitably rapid reaction. 
When operating under the general conditions described herein, particularly 
within a temperature range between about 60.degree. and 80.degree. C., the 
decomposition reaction to substantial completion, as a batch or as a 
continuous process, will take place in about two minutes to about two 
hours, and preferably will take place in about five to about 45 minutes. 
The process can also be carried out in a semi-continuous manner in which 
the reactant, solvent and catalyst are continuously added to a stirred 
tank reactor at a rate coinciding with the withdrawal rate, sufficient to 
provide a suitable average reaction rate within the above time ranges for 
substantially complete reaction. Since a significant quantity of unreacted 
cumene hydroperoxide in the final reaction product can undesirably 
interfere with the distillative separation procedure, it is preferred that 
there be a substantially complete decomposition of the cumene 
hydroperoxide in the reaction stage. 
After the cumene hydroperoxide decomposition reaction is completed, the 
product solution is treated with the amine in order to bind the boron 
trifluoride with the amine in the stable, high boiling coordination 
compound. If the catalyst is boron trifluoride itself, the amine directly 
reacts with the boron trifluoride to form the complex. If the catalyst is 
a coordination compound of boron trifluoride and the oxygen-containing 
polar compound, the amine will react with the complex displacing and 
freeing the oxygen-containing polar compound. The amine is able to 
displace the oxygen-containing polar compound from its complex with the 
boron trifluoride because the complex of the amine with the boron 
trifluoride is much stronger and more stable than the complex with the 
oxygen-containing polar compound. Sufficient amine is added to form a 1:1 
molar complex with the boron trifluoride and preferably a sufficient 
excess of the amine is added to insure the complexing of all of the boron 
trifluoride with the amine so that there is no carry-over of boron 
trifluoride into the distillate. Therefore, it is preferred to use a mol 
ratio of the amine to the boron trifluoride of between about 1.2:1 and 
about 2:1, although higher amounts can be used such as a mol ratio of 
10:1 or higher. 
The product solution is then distilled under appropriate conditions of 
temperature and pressure to drive off the volatile components in the 
solution including acetophenone without distilling off or dissociating the 
boron trifluoride.amine complex. Under these conditions of operation the 
only materials remaining in the still are the complex of the boron 
trifluoride with the amine and the polymeric tar solids, which are 
produced during the decomposition of the cumene hydroperoxide or during 
product distillation. It may be desirable in certain instances to distill 
off the volatile compounds, including acetophenone, in the decomposition 
reaction product at a reduced pressure and temperature to improve the 
separation of the acetophenone without dissociating the amine complex or 
tar solids. For these reasons this distillation can be carried out at a 
temperature as low as about 150.degree. C. and a pressure of about one 
millimeter of mercury, but it is preferred to use distillation conditions 
of at least about 160.degree. C. and a pressure of at least about 30 mm 
Hg. If distillation is carried out at about atmospheric pressure (760 mm 
Hg.), the temperature must be at least as high as the boiling point of 
acetophenone (201.7.degree. C.). A pressure higher than atmospheric 
pressure can be used in the distillation but there is no advantage to 
using such elevated pressures. The distillation can be effected at a 
temperature up to about the temperature at which the boron 
trifluoride.amine complex begins to dissociate, but preferably it should 
be maintained substantially below this temperature to avoid any 
dissociation of the complex and carry-over of boron trifluoride into the 
distillate. 
After this distillation is completed, the residue containing the 
coordination compound and the polymeric tar solids is further heated to 
volatilize and separate the boron trifluoride.amine complex from the tar 
solids. This stream of the volatilized complex, together with any free 
amine and boron trifluoride resulting from the dissociation of the complex 
at the distillation temperature, is passed through a heat zone, such as a 
bed of inert ceramic beads heated to about 400.degree.-500.degree. C., in 
order to cause a rapid dissociation of the complex. The dissociated amine 
and boron trifluoride are separately condensed out in cold traps at 
appropriate temperatures for reuse in the process. Each specific boron 
trifluoride.amine complex possesses not only a particular boiling point 
but it also possesses a temperature at which dissociation of the complex 
into boron trifluoride and amine is initiated. For example, the 
coordination compound with trimethylamine begins to dissociate at a 
temperature somewhat above its boiling point of about 230.degree. C., 
while the coordination compound with pyridine does not begin to dissociate 
until its boiling point of about 300.degree. C. is exceeded. If the 
distillation of the complex causes a partial decomposition and 
distillation of the polymeric tar solids, then the complex may be 
separately recovered in another vessel and dissociated at appropriate 
conditions as described.

DESCRIPTION OF PREFERRED EMBODIMENTS 
In the following examples, the hydroperoxide was analyzed by iodometric 
titration with sodium thiosulfate. The boron analysis was carried out by 
converting the boron to a water soluble acid or salt and then 
quantitatively measuring it by atomic absorption. The decomposition 
product resulting from the boron trifluoride, both free and complexed, 
catalyzed reactions was light yellow in color and transparent, indicating 
very slight tar, while the sulfuric acid catalyzed product liquid was 
black and opaque. Both the residue and the product distillate were 
analyzed. Many of the analyses in the following examples add up to 100 
percent due to product averaging because the actual "tar" value was less 
than one percent as indicated where specific tar analyses were made. The 
analyses for compounds other than hydroperoxide and boron were 
accomplished by gas chromatography or by high performance liquid 
chromatography. 
EXAMPLE 1 
The catalytic activity of sulfuric acid for the decomposition of cumene 
hydroperoxide was observed. A 57.3 percent solution of cumene 
hydroperoxide in cumene was added dropwise into 100 ml. of a two percent 
solution of sulfuric acid in acetone in a 300 ml. round bottom flask open 
to the atmosphere. Each drop instantly decomposed as it contacted the 
solution. Since no positive cooling of the reaction liquid was provided, 
the temperature of the solution rose from room temperature (about 
25.degree. C.) at the beginning of the addition to 44.degree. C. upon the 
completion of the addition. A total of 35.2 g. of the cumene hydroperoxide 
was added over 60 minutes. Analysis of the product showed that 99.9 
percent of the cumene hydroperoxide had reacted at a selectivity of 93 
percent to phenol. 
EXAMPLE 2 
The following reactions were carried out in a glass reactor equipped with a 
magnetic stirrer and operated at a pressure within the reactor slightly 
above atmospheric pressure. The reactor was cooled by a cold finger in the 
liquid. Small samples of the reaction liquid (about 1 ml.) were 
periodically withdrawn to monitor the reaction. 
Phenol was tested as a decomposition catalyst for cumene hydroperoxide at 
several temperatures. About 20 g. of a solution consisting of 5 parts 
phenol, 3 parts acetone and 1 part cumene were placed in the reactor. 
About 2 ml. of a solution consisting of 55 percent cumene hydroperoxide in 
cumene were injected into the reactor in each experiment. Table I 
summarizes the results of these experiments. 
TABLE I 
______________________________________ 
Minutes Cumene Hydroperoxide Decomposed, % 
Temp. 10 20 50 100 
______________________________________ 
40.degree. C. 
trace trace trace 
trace 
60.degree. C. 
-- 8 19 39 
80.degree. C. 
18 34 60 85 
______________________________________ 
The experiment at 80.degree. C. was allowed to run for four and one-half 
hours at which time the cumene hydroperoxide was completely decomposed. 
Analysis of this product mixture disclosed that it contained 77 percent 
phenol, 8 percent alpha-methylstyrene, 4 percent acetophenone, 4 percent 
dimethylbenzyl alcohol, and 7 percent of a residuum consisting of aromatic 
carbonyls, aromatic alcohols, substituted phenols, substituted benzofurans 
and methylstyrene oligomers. 
EXAMPLES 3-5 
A 200 ml. glass reactor partially immersed in a heated oil bath at 
60.degree. C. and equipped with a magnetic stirrer and a cold finger was 
used in these experiments. The cold finger was cooled with tap water and 
was only used when necessary to prevent excessive temperatures. A series 
of three experiments was carried out using different amounts of boron 
trifluoride gas as the catalyst. The reactor was charged with 22 g. of a 
20 percent solution of cumene hydroperoxide (CHP) which heated to 
60.degree. C. Boron trifluoride gas in a predetermined amount was bubbled 
into the liquid to initiate the decomposition reaction. One ml. samples 
were taken at intervals to monitor completion of the reaction. The results 
of these experiments, after greater than 99 percent decomposition of the 
cumene hydroperoxide, are set out in Table II. 
TABLE II 
______________________________________ 
Example 3 4 5 
______________________________________ 
CHP solution, g. 22 22 22 
BF.sub.3 conc., ppm. 
340 136 27 
Time, min. &lt;5 30 60 
Final Temp, .degree.C. 
100 72 64 
Selectivity 
phenol 92 90 98 
alpha-methylstyrene 
3 4 1 
acetophenone 3 4 1 
dimethylbenzyl alcohol 
2 2 -- 
______________________________________ 
EXAMPLES 6-8 
A second series of three experiments was conducted using the same reactor 
and 22 g. of a 20 percent solution of cumene hydroperoxide. In these 
experiments different amounts of a solution of the 1:1 complex of boron 
trifluoride with diethyl ether in acetone, at a concentration of one ml. 
per liter of acetone, were added, after the cumene hydroperoxide solution 
had reached 60.degree. C., to initiate the decomposition reaction. One ml. 
samples were taken at intervals to monitor the reaction. The results of 
these experiments are set out in Table III. 
TABLE III 
______________________________________ 
Example 6 7 8 
______________________________________ 
CHP solution, g. 22 22 22 
BF.sub.3 . O(Et).sub.2, conc., ppm. 
200 100 50 
Time, min. &lt;3 5 8 
Final temp., .degree.C. 
85 82 80 
CHP decomp., % 99 99 99 
Selectivity 
phenol 97 98 98 
alpha-methylstyrene 
2 1 1 
acetophenone 1 1 1 
______________________________________ 
EXAMPLE 9 
A charge of 22 g. of the 20 percent solution of cumene hydroperoxide was 
placed in the reactor. After the solution had reached 60.degree. C., one 
ml. of a solution of the 1:1 complex of boron trifluoride with isopropanol 
in acetone, at a concentration of 14 ml. per liter of acetone, was added 
to provide a concentration of 400 ppm. of the catalyst in the reactor. 
Complete decomposition of the cumene hydroperoxide occurred in about 
thirty minutes at a final temperature of 69.degree. C. Analysis of the 
product disclosed a selectivity to phenol of 97 percent, to 
alpha-methylstyrene of 1.8 percent, to acetophenone of 0.7 percent and to 
dimethylbenzyl alcohol of 0.5 percent. 
EXAMPLE 10 
Another 22 g. charge of the 20 percent cumene hydroperoxide solution was 
placed in the reactor. After the solution had been warmed to 60.degree. 
C., a sufficient quantity of a solution of the 1:2 complex of boron 
trifluoride with methanol in acetone, at a concentration of two ml. per 
liter of acetone, was added to provide a concentration of 104 ppm. of the 
boron trifluoride dimethanol complex in the reactor. Complete 
decomposition of the hydroperoxide was obtained in 45 minutes at a final 
temperature of 74.degree. C. The selectivity to phenol was 97.5 percent, 
to alpha-methylstyrene two percent and to acetophenone 0.5 percent. 
EXAMPLE 11 
After a 22 g. charge of 20 percent cumene hydroperoxide had heated to 
60.degree. C., a 1:1 complex of boron trifluoride and phenol was 
introduced in sufficient amount to provide 435 ppm. of the catalyst 
complex. A maximum temperature of 67.degree. C. was reached and complete 
decomposition occurred in 60 minutes at a selectivity of 97 percent to 
phenol, two percent to alpha-methylstyrene and one percent to 
acetophenone. 
EXAMPLE 12 
A 20 g. charge of a solution consisting of phenol, acetone and cumene in 
the weight ratio of 5:3:1, respectively, was placed in the reactor. After 
adding 1.83 g. of concentrated (80-82 percent) cumene hydroperoxide to the 
solution, it warmed to 60.degree. C. One ml. of a solution of the 1:1 
complex of boron trifluoride with diethyl ether in acetone, at a 
concentration of two ml. of the complex per liter of acetone was added to 
provide a concentration of the complex of 90 ppm. based on the total 
solution. Complete decomposition of the cumene hydroperoxide occurred in 
ten minutes. 
EXAMPLE 13 
A continuous flow reaction was carried out in a one liter flask equipped 
with a reflux column and a magnetic stirrer. About 300 ml. of acetone were 
added to the flask and warmed to 60.degree. C. The catalyst, a solution of 
boron trifluoride monodiethyletherate complex in acetone, was pumped into 
the flask at a rate of about 350 ml. per hour, which provided a 0.3 
percent concentration of the complex in the reaction liquid. Concentrated 
(80-82 percent) cumene hydroperoxide in cumene was added at a rate of 750 
ml. per hour. Product was continuously removed at a rate to maintain the 
liquid volume constant. Acetone was continuously distilled off and 
returned to the flask by reflux to maintain a flask temperature between 
60.degree. and 70.degree. C. By analysis of the product stream, there was 
found to have been better than 99 percent conversion at a selectivity of 
about 98 percent to phenol, about two percent to alpha-methylstyrene and 
about one percent to acetophenone. 
EXAMPLE 14 
A comparison of tar production by the process of Example 13 with a sulfuric 
acid catalyzed reaction, both with and without catalyst deactivation was 
made. The sulfuric acid catalyzed reaction was carried out as a continuous 
reaction using a concentration of 0.3 percent sulfuric acid. All 
separations were made under identical conditions. A sample of each crude 
product was distilled and another sample of each was distilled after 
catalyst deactivation. The sulfuric acid was neutralized with sodium 
bicarbonate and the boron trifluoride diethyletherate was deactivated with 
tributylamine. 
The tar analyses are set out in Table IV. 
TABLE IV 
______________________________________ 
Sample, g. 
Tar, g. Tar, wt % 
______________________________________ 
H.sub.2 SO.sub.4, crude 
42.8 5.13 12 
.sup.a H.sub.2 SO.sub.4, neutralized 
44.2 1.94 4.4 
BF.sub.3 . OEt.sub.2, crude 
45.0 3.2 7.1 
.sup.b BF.sub.3 . OEt.sub.2, deactivated 
40.9 0.29 0.7 
______________________________________ 
.sup.a average of two runs 
.sup.b average of three runs 
This example shows that the deactivation of the boron trifluoride catalyst 
complex with the tertiary amine results in a substantial reduction in the 
amount of tar. The following example shows that this deactivation of the 
boron trifluoride catalyst complex with the tertiary amine also results in 
a much higher retention of the boron in the residue. This is advantageous 
since it permits the quantitative removal of boron from the product and 
simplifies its recovery for recycling. 
EXAMPLE 15 
A solution containing 0.16 g. of the 1:1 complex of boron trifluoride and 
diethylether was heated to 60.degree. C. and 20.46 g. of 80 percent cumene 
hydroperoxide was added slowly to control the temperature. After 
completion of the reaction, the boron trifluoride catalyst complex was 
then reacted with triethylamine. A 2.62 g. sample was taken for boron 
analysis and the remainder of the solution was distilled at about 100 mm. 
Hg. pressure at a temperature ranging from 45.degree. to 160.degree. C. 
The distillate and tar were analyzed for boron. This data is compared in 
Table V with data obtained from catalyst deactivation using tributylamine 
and with a run in which there was no catalyst deactivation, all carried 
out at similar conditions. 
TABLE V 
______________________________________ 
Deactivating Agent 
Et.sub.3 N 
(C.sub.4).sub.3 N 
None 
______________________________________ 
B in crude sol'n, mg. 
10.1 10.6 18.1 
B in distillate, mg. 
0.9 0.5 14.3 
B recovered, % 
&gt;98 &gt;99 &gt;99 
B in tar, mg. 9.0 10.1 4.3 
B in tar, % 90.0 95.3 23.8 
______________________________________ 
EXAMPLE 16 
An 80 percent solution of cumene hydroperoxide in cumene is slowly added to 
0.16 gram of the 1:1 complex of boron trifluoride with diethylether in 
14.2 grams of acetone at about 60.degree. C. until 20.6 grams of the 
concentrated hydroperoxide solution have been added. The product solution 
is treated with 3.60 grams of triethylamine and heated for about 30 
minutes at 60.degree. C. to insure that the boron trifluoride complexes 
with the amine. The temperature is then raised to 160.degree. C. and the 
pressure is reduced from atmospheric to about 100 mm. Hg. After the 
acetone, the phenol and the distillable by-products including acetophenone 
have been taken overhead, the temperature applied to the residue is 
elevated to volatilize and separate the boron trifluoride.amine complex 
from the tar solids. This volatilized complex is passed through a bed of 
glass beads heated to about 400.degree. C. by an external heater element 
and the resulting mixture of boron trifluoride and triethylamine vapors is 
passed through a trap cooled to -78.degree. C. to condense out the amine. 
The boron trifluoride is then condensed out at -196.degree. C. in a 
subsequent trap and is saved for reuse. 
The effectiveness of the deactivation of the boron trifluoride catalyst 
complex both in preventing the formation of tars during product recovery 
and in directing the boron to the residue depends, in part, on the 
complexing strength of the deactivating amine and the conditions at which 
the distillation is carried out. It is therefore possible by appropriate 
correlation and control of these variables to optimize boron recovery and 
minimize tar formation during product separation. 
It is to be understood that the above disclosure is by way of example and 
that numerous modifications and variations are available to those of 
ordinary skill in the art without departing from the true spirit and scope 
of the invention.