Note: Descriptions are shown in the official language in which they were submitted.
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The invention relates to a process for the preparation
of bis(hydroxyaryl) compounds, in particular to the
preparation of bis(hydroxyaryl)alkanes such as 2,2~di(4-hydroxy-
phenyl)propane3 often called diphenylolpropane or
Bisphenol A and 2,2-di(4-hydroxyphenyl)methane, also
called Bisphenol F.
The present invention mainly relates to the
preparation of diphenylolpropane, however, without
being restricted thereto. Bis(hydroxyaryl)alkenes
and especially diphenylolpropane are important chemicals
which can be used as starting compounds for various - :
resins, for instance epoxy resins.
The bis(hydroxyaryl) compounds according to
, .. . .
~ the present invention may be represented by the following
formula:
Rl ~ ,
HOAr - C - Ar'OH
:` ' ' R2 .,
wherein R and R2 may each represent hydrogen or
a saturated or unsaturated alkyl, cycloalkyl, aryl,
alkaryl, aralkyl or heterocyclic group and Ar and
Ar~ each represent a (substituted) aromatic nucleus.
If Rl and R2 are both methyl and Ar and Ar' both
represent a phenylene radical the formula represents
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diphenylolpropane.
As bis(hydroxyaryl)compounds are in general very
useful products it is not surprising that their preparatlon
has been thoroughly investigated. By far the most
extensively evaluated process for the preparation
of diphenylolpropane is the reaction between phenol
and acetone in the presence of an acid condensation
agent, for instance, hydrogen chloride, preferably
in the presence of a co-catalyst such as hydrogen
sulphide, methylmercaptan, beta-mercaptopropionic
acid and the like. Detailed descriptions of the prior
art can be found, for instance, in British Patent ~ -
Specifications Nos: 735,21~; 735,216 and 785,o79.
The reaction between phenol and acetone is normally
. ,.
carried out in a continuous system using a large
excess of phenol compared to the acetone to be reacted,
for instance an excess up to 15 moles per mole of
acetone. The reaction is generally effected at a
tempe~ature in the range of from 20C to 85C, preferably
in the range of from 45C to 65C, and at a pressure
of from autogeneous up to about 10 bar. The use of
suitable solvents has also been described.
The reaction as hereinbefore described is normally
carried out in the presence of an acid condensation
agent,~such as a hydrogen halide, e.g. hydrochloric
~` acid, preferably anhydrous hydrochloric acid, sulphuric
acid, a Lewis acid or an acidic cation-exchange resin. ~ ;
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Sulphur compounds, sometimes bound to the appropriate
acidic cation-exchange resin, are often used to accelerake
the condensation reaction.
Many working-up procedures for the crude reaction
product have been suggested in the literature and
some of them are commercially applied. For instance,
after flashing off most of the excess phenol, the
product, sometimes in the form of its phenol or cresol
adduct, is recovered from the reaction mixture by
~10 precipitation~ washing, recrystallization or any
other suitable technique.
Although the process as described hereinbefore
is advantageous in that rather simple and cheap starting
materials may be used, many proposals have been presented
in the literature in which compounds other than acetone
are used. For instance, the use of propyne as well
as propadiene has been described (British Patent
- Specification 974,982). It is also possible to start
with chloropropylene instead of acetone~ but all
the proposals mentioned hereinbefore may be considered
to be alternatives which are of little or no commercial `
importance -
The classical process for the preparation of
diphenylolpropane, which has proved to be of great
economical interest has been e~tensively evaluated
~` over the years so that a highly advanced process
` has been commercialized,
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However, even the advanced process has a number
of drawbacks which are inherent in the particular
reaction system applied.
For instance, the use of a mercaptan or other
sulphur-containing compound as a co-catalyst, which
in itself is an attractive way to accelerate the reaction,
automatically implies tha~ the product will contain
a certain (limited) amount of sulphur, which is very
difficult to remove. However, sulphur-free diphenylolpropane
is required as a starting material in the production
of polycarbonates. Pollution aspects, too, have to
be taken into account when use is made of a volatile
sulphldic co-catalyst, especially when the reaction
is carried out in a large-scale plant. It is possible,
of course, to circumvent the use of a sulphur compound,
but the alternative process for the production of
diphenylolpropane has to be carried out under super-atmos-
pheric HCl-pressure which has many drawbacks in itself.
As water will invariably be formed when phenol -
.
and acetone are reacted to diphenylolpropane, c.orrosion
problems will arise as well, the more so as large
amounts of hydrochloric acid ha~e necessarily to
be ùsed, especially when the process is carried out ~`
in the absence of a sulphur compound. It should be
noted that one of the biggest problems in a commercial
diphenylolpropane plant always relates to the working-up
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of the aqueous hydrochloric acid obtained. An amount of equipment out of
all proportion is necessary to ensure that the environment will not be
contaminated by the plant effluents. The same can be said with respect to
the use of a volatile sulphidic co-catalyst.
Another disadvantage of the classical process is the highly
unfavourable phenol/acetone molar ratio to be used, which normally exceeds
10:1, and is sometimes as high as 15:1. Hence, up to 13 moles of phenol
have to be separated from the product and are subsequently to be recycled
to the reactor.
It has now surprisingly been found that bis(hydroxyaryl) com-
pounds, and, in particular, diphenylolpropane can be prepared without almost
any of the above-mentioned drawbacks by reacting a phenolic compound with an
acetal and/or a ketal in the presence of an acidic catalyst. The expressions
"acetal" and"Ketal" as used in the present description comprise the reaction
products of compounds containing one or more hydroxylic groups with compounds
., , -
containing a carbonyl function such as aldehydes (the condensation products
may be mentioned acetals) and ketones (the condensation produ~ts may be
mentioned ketals).
The invention provides a process for the preparation of bis
~hydroxyaryl) compounds by reacting a phenolic compound with an oxygen com-
pound in the presence of an acidic condensation catalyst wherein the oxygen
compound has the general formula:-
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~) R'2 \ 0 - C - R'5
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~ wherein R'l and R'2 may each represent hydrogen or a saturated or unsaturated
3;''~ alkyl group and R'3 to R'6 may each represent hydrogen or a saturated or
~i, unsaturated alkyl, cycloalkyl, aryl, alkaryl or aralkyl group.,?l
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The invention relates in particular to the preparation of
Bisphenol A from phenol and the cyclic ketal 2,2-dimethyl-1,3-dioxolane and
of Bisphenol F from phenol and the cyclic acetal 1,3-dioxolane in the
presence of an acidic condensation catalyst.
The invention also relates to a preferred process for the
preparation of (substituted) 1,3-dioxolanes, which can suitably be used as
starting materials for the preparation of bis~hydroxyaryl) compounds
according to the present invention.
The use of acetals and/or ketals and especially of the preferred
class of (substituted~ 1,3-dioxolanes instead of acetone in the preparation
of bis(hydroxyaryl) compounds has a number of advantages which are discussed
hereinafter in an arbitrary sequence.
` In the first place, the process according to the present
invention can be carried out in the absence of a volatile sulphur compound
as a co-catalyst whilst maintaining an economically very acceptable reaction
rate. This implies that the product ~oes not necessarily contain any sulphur
impurities and can be suitably applied for sophisticated purposes, for ;
instance in the preparation of polycarbonates. It is also noted that
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environmental problems connected with
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the use of volatile sulphur compounds are no longer
relevant. , ,
It has further been found that under the prevailing
reaction conditions the amount of phenol required '
to maintain an economically acceptable recycle process
can be lowered to some extent, for instance phenol/dioxolane ;
ratios not exceeding 10:1 or even as low as 8:1 can
suitably be applied, which implies a considerable ''
decrease of the amount of phenol to be ~lashed off -
in the w,orking-up procedure and subsequently recycled ~, ,
to the reactor. It is without doubt that any reduction ,'' :
o~ the phenol/reactant ratio to be achieved offers ' ,
great economical advantages. , ~ -
In the third place it should be noted that when ~ ,
use is'made of a (substituted) 1,3-dioxolane for ~ ' ` '-
, the production of bis(hydroxyaryl) compounds, (substitutedj
~ ethylene glycol is obtained as a by-product, thus
; ~ diminishing the corrosion problems inherent in the
,~ water/hydrochloric acid system invariably present ~ ,
'20 to a considerable extent in the classical process. ~'
.. . .. .
'' This also implies that a considerable amount of the -~
, hydrochloric acid may be recycled to the reactor.
- A small amount of the hydrochloric acid present will
dissolve in water which may be present in the reaction ',
system (e.g. as a contaminant of the phenolic compound ~ ~
~;J to be reacted) and the aqueous hydrochloric acid ',
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solution obtained has consequently to be worked up
but only a fraction of the equipment normally required
to treat the effluent will be necessary.Moreover
the presence of, for instance, ethylene glycol obtained
in an amount substantially equal to the molar amount
of DMDO converted has the advantage that it may act
as a solvent for diphenylolpropane formed, thus facilitating
the separation steps which have to be carried out
after flashing off the major amount of excess phenol.
Thus, for the production of diphenylolpropane
from phenol and DMDO according to the present invention
the following reaction scheme can be given:
2 ~ OH ~ C~c~ Cl acidic catalyst~
. (DMDO)
,
HO ~ - C ~ OH ~ H2C - OH
\ J C H2C - OH :~
~,.
. The phenolic compounds which may be reacted
with an acetal and/or a ketal, for instance, with
~, 15 a (substituted) dioxolane, in accordance with the . , -;
.~ process of the present invention comprise the broad
class of phenolic compounds having at least one replaceable
: ~ hydrogen atom directly bound to a nuclear carbon ~ :
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atom of the phenolic radical. By the term phenollc
~; 20 compoundsl' are meant those organic compounds which ~ . :
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contain an aromatic radical and at least one hydroxyl
group, linked directly to a carbon atom contained
in the nucleus of the aromatic radical. The phenolic
compounds used as starting material comprise the
simplest members o~ the class, phenol, and its homologues
as well as substitution products containing at least
one replaceable hydrogen atom directly attached to
a nuclear carbon atom of the phenolic radical; they
include those compounds wherein hydrogen atoms of
the aromatic nucleus have been substituted by hydrocarbon
radicals, such as alkyl, cycloalkyl, aryl, alkaryl
and aralkyl groups. ~`
The following examples of phenolic compounds
may be given: phenol, ortho-cresol, meta-cresol,
~ 15 para-cresol, the xylenols, thymol, carvacrol, cumenol,
:
2,3-diethylphenol, 2-methyl-3-ethylphenol, 2,3-di-tert.butyl-
phenol, 2,4-dimethyl-3-ethylphenolj 3,5-diethylphenol,
4-ethylphenol, 2-ethyl-4~methylphenol, 2,3,6-trimethyl-
`,
i' phenol, 2-methyl-4-tert.butylphenol, 2,4-di-tert.butyl-
phenolg 2-tert.butyl-4-methylphenol, 2,3,5,6-tetra-
methylphenol, o-phenylphenol, p-phenylphenol, alfa-naphthol,
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beta-naphthol, phenantrol and their homologues. The
~; phenolic compounds also comprise those compounds
-; which contain more than one hydroxyl group in the
nucleus as well as polynuclear compounds having one
or more hydroxyl groups in each nucleus. Mixtures
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of phenolic compounds may also serve as the phenolic
starting material.
The acetals and/or ketals as defined hereinbefore
which are reacted with the phenolic compounds according
to the process of the present invention may be represented
by the general formu.la
R1\ - ~v ~ R43
C R5 (I~
R2 ~ C \ R6
wherein R1 to R8 may each represent hydrogen or a .`
saturated or unsaturated alkyl, cycloalkyl, aryl, ~ `~
alkaryl, aralkyl or heterocyclic group with the proviso
that one of the groups R3, R4 or R5 together with
i oné of the groups R6, R7 or R8 may be replaced by
a carbon-carbon bond (thus giving a (substituted) ~-
. ~ 1,3-dioxolane compound). It should be noted that ;. ~
compounds of the general formula (I) wherein at least ~ ..
~ 15 one of the groups R1 and R2 represents a hydrogen . :
`!, atom belong to the class of the acetals. .. :
. Preference is gi~en to compounds in which the . .
above-mentioned carbon-carbon bond is present, i.e.
. compounds of the (substituted) 1,3-dioxolane type ; .
.j 20 which are represented by the general formula
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1 / C R 4
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R'2 ~ C - R~6
wherein R'1 to R'6 ~ay each represent hydrogen or
a saturated or unsaturated alkyl, cycloalkyl, aryl,
alkaryl, ralkyl or heterocyclic group.
As suitable compounds of formula (I) may be `
mentioned 2,2-dimethoxypropane, 2,2-diethoxypropane,
dimethoxymethane, diethoxymethane, 2-methoxy-2-ethoxypropane
and methoxy ethoxymethane.
Preferred 1,3-dioxolane compounds according
to formula (II) are those in which R'l and R'2 both
; 10 represent a methyl group, R'3 to R'6 being hydrogen
and/or lower alkyl groups. Most preference is given
to the use of 2,2-dimethyl-1,3-dioxolane (R'l and -~
~ R~2 each being methyl and R'3 to R'6 representing
- hydrogen radicals) which leads to the formation of
diphenylolpropane whe reacted with phenol in the ~ -
presence of an acidic catalyst accordin~ to the process
of the present invention.
It will be clear that the structure of the alkyl
,. . .
radical which links together the two hydroxyarl groups
~ 20 in the bis(hydroxyaryl) compounds depends on the
;;l groups (Rl) R'l and (R2) R'2 present in the acetal
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and/or ketal compound according to formula (I) or
~II). In other words, a change in the groups (Rl) ~
R'l and ~R2) R'2 will cause the formation of a different ;`
type of bis(hydroxyaryl) compounds. When, for instance,
(Rl)R7l and ~R2) R~2 are both hydrogen radicals the
product of the condensation reaction, regardless the
nature of (R3) R'3 to (R8) R'6, will be a bis(hydroxyalkyl)
methane compound. When phenol is thus reacted with
1,3-dioxolane according to the process of the present
invention the product will be 4,5'-bishydroxyphenyl-
methane, also called Bisphenol Fo Starting with an
asymmetrical dioxolane, (Rl) Rll being different from
~R2) R~2, the product will be an asymmetrical bis(hydroxy-
aryl)alkane.
It is also possible to prepare mixtures of bis- ~
(hydroxyaryl) compounds, for instance, mixtures of ~ -
Bisphenol A and Bisphenol F, by reacting a phenolic com- ~
". . .
;~ pound (e.g. phenol) with a mixture of (substituted) 1,3-
dioxolanes (e.g. 2,2-dimethyl-1,3-dioxolane and 1,3-
dioxol~ane). It should be noted that, for instance in the i-
; preparation of a mixture of Bisphenol A and Bisphenol F, ;
instead of 1,3-dioxolane to be reacted, also its precursor -
` formaldehyde, for instance in the form of trioxane, can ~
be used, in combination with 292-dimethyl-lj3-dioxolane ~ -
Reference is made in this respect to United States
Patent NoO 3,920,5730
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in whicha preferred method ~or the preparation of
a mixture of Bisphenol A and Bisphenol F has been
described~nd claimed.
It is appreciated that in~tead of the acetal
and/or ketal, and preferably o~ the (substituted)
1,3-dioxolane according to the present invention,
bis(hydroxyaryl) compounds may also be prepared by
reacting a phenolic compound with a (substituted)
thioacetal and/or a (substituted) thioketal compound.
When applying a thioacetal and/or a thioketal compound,
one should bear in mind, however, that the incentive
of a sulphur-free process is no longer present. The
use of rather large amounts of volatile sulphur compounds
would impair the product quality and also cause environmental
problems. The same arguments are true for the addition
of a volatile mercapto compound as a co-catalyst
to the phenol/DMDO system.
~ The acetals, and~or ketals, and especially the ;~-
;i dioxolanes to be used in the process according to
the present invention may be prepared by any suitablè
method. For instance, acetone and ethyleneglycol
may be reacted in the presence of an acidic catalyst
such as p-toluene-sulphonic acid (J. Chem.Eng.Data
.. . .
;~ 7 (19629 p, 578~. The use of acidic cation-exchange
resins has also been reported in condensation reactions
between ketones and monovalent alcohols such as -~
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methanol or ethanol.
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It has been found that the ~substituted? dioxolanes
to be used together with a phenolic compound according
to the process of the present invention, can be suitably
prepared by the following ~echnique, which is reported
with respect to the preparation of 2,2-dimethyl-1,3-dioxolane
but which is certainly not restricted to the preparation
of this compound.
2,2-Dimethyl-1,3-dioxolane ~DMD0) may be produced ~ ~
by reacting acetone and ethyleneglycol at room temperature ~-
in the presence of an acidic catalyst, in particular ;
an acidic cation exchange resin, for instance Amberlyst* -
15 H . After neutralization, the reaction product ~
, . :;
is distilled, preferably in three steps: ~a) removal
of acetone, ~b) removal of reaction water, using ;~
, for example, cyclohexane as an auxiliary distillation
I agent and ~c) removal of DMD0 product; the acetone
removed in the first step and the bottom product -~
of the third step being recycled to the reactor.
It will be appreciated that the above-mentioned
process for the preparation of DMD0 can be suitably
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incorporated in an integrated diphenylolpropane ~`~
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,~, exists to use ethyleneglycol precursors, for instance
ethylene oxide. The use of ethylene oxide would even
substantially prevent the formation of reaction ~ ;
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water which would facilitate the recovery procedure.
However, this possibility is not attractive in that
large amounts of reaction heat obtained would have
to be dissipated.
The process for the preparation of DMD0, and
in general of the (substituted) dioxolanes may be
carried out at a temperature in the range of from
0C to 120~9preferably in the range of from 10~
to 90C and most preferably at 40C. The reagents
are fed over an acidic cation exchange resin. The
molar ratio of the reagents to be applied is by no
means critical; for instance an acetone/ethyleneglycol
.
moIar ratio of 10:1 can be suitably applied as well
as a molar ratio of 1:10. Preference is given to
i15 a molar ratio ethyleneglycol/acetone of from 2~
to 1:2. Excellent results were obtained using a molar
ratio of 2:1.
;; ~ The crude reaction mixture is first neutralized
with an appropriate base such as sodium bicarbonate
or c~austic soda or an aqueous solution of said compound(s). -~
;i It has been found very suitable to carry out the
'i subsequent distillation in three steps. In the first
:~ step acetone is substantially removed, which may
be recycled to the reactor. In the second step water
produced during the reaction is removed preferably
with the aid of a water-immiscible hydrocarbon as
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an auxiliary distillation agent such as cyclohexane,
hexane or benzene. In the third step DMD0 may be
distilled off and sent to storage or to a subsequent
diphenylolpropane reactor when produced in an integrated ;~
process. The bottoms of the third distillation step,
mainly consisting of ethylene glycol are recycled -
to the DMD0-reactor.
In the process for the preparation of bis(hydroxyaryl)compounds
according to the present invention the phenolic compound
may be reacted with the acetal and/or the ketal,
for instance with a (substituted) 1,3-dioxolane compound,
in stoichiometric proportions. It is preferred, however,
to use higher proportions of the phenolic compound,
which may serve as a diluent, thus keeping the process
in the liquid state~ The molar ratio of the phenolic
compound to the acetal and/or the ketal, for instance
to the (substituted) 1,3-dioxolane compound in the
- reaot;on may range, for example from 20:1 to 2:1,
preferably between 15:1 and 8:1 and most prererably
between 12:1 and 10:1.
The reaction is carried out in the presence
` of an acidic catalyst-, preferably a strong mineral
acid, which may be added continuously or incrementally
,'l during the course of the operation. All of the acid
` 25 employed may be introduced directly into the reaction `-
` zone or it may be admixed, in part or entirely, with
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one or more of the components prior to their introduction into
the reactor.
As acidic catalysts may be employed, for exampleJ hydrochloric
acid, sulphuric acid, acetic acid, p-toluenesulphonic acid, alkane-
sulphonic acids, hydrofluoric acid, boron trifluoride complexes and
other acid-acting condensing agents, such as acidic cation-exchange
resins, for example Amberlyst* 15 H~. The acidic cation-exchange
resins may also contain additional fixed sulphur compounds. The use
of hydrochloric acid and especially of anhydrous hydrochloric acid is ;~
preferred. Materials capable of liberating an acidic agent in situ ~ -
under the reaction conditions may also be employed.
Relatively small amounts of the acidic agent generally ~ -
suffice to speed up materially the reaction. The amount of acidic
agent required to obtain optimum results will vary to some extent
~, in accordance with the specific acidic agent, reactants and operating
conditions employed. The use of the acidic agent in an amount
~ between 0.1% and 30% by weight, and preferably between 0.2% and
;~~ 20% by weight, based on the phenolic reactant, is generally satis-
factory. Excellent results have been obtained using hydrochloric
acid in an amount of from 2.5% to 7.5% by weight based on the molar
phenol intake. When employing a normally gaseous acidic agent such
as hydrogen ~;
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chloride, attainment of the desired concentration
thereof in the reaction mixture, particularly at
higher temperatures, is facilitated by the use of
superatmospheric pressures.
The process according to the present invention
may be carried out in the absence but preferably
in the presence of a solventO It should be noted
that the excess of phenolic compound normally used
(e.g. phenol exceeding a 2-3 molar ratio towards
dioxolane reactant, depending on the way of precipitating
the product) is considered to behave as a solvent. -
A number of solvents which may each, or in combination,
replace partially or even totally the excess of phenolic
compound normally applied are for instance, primary -
alcohols, such as methanol, ethanol and propanol;
glycols such as ethyleneglycol, the propylene glycols, ~-
butyIene glycols, ethers, for instance di-isopropylether,
tetrahydrofuran, dioxan, dichloroethane and the like.
~ . .
The use of ethyleneglycol in the production of diphenylolpropane
is especially preferred in that this compound acts
as a very good solvent for diphenylolpropane. Ethyleneglycol
will also be ~ormed in situ when 2,2-dimethyl-1,3-di- -~
^ oxolane is used in the preparation of diphenylolpropane.
The use of ethylene~lycol in an amount of from 1
to 10 moles per mole of dioxolane compound to be
; reacted has proved to be satisfactory, amounts in
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the range of from 2 to 3 moles per mole of dioxolane
compound - in addition to an excess of phenol also
applied - have given very satisfying results.
The process according to the present invention
may be carried out at temperatures between 20C
and 150C, and preferably at temperatures between
40C and 85C. The process may be carried out under
atmospheric, subatmospheric or superatmospheric pressure.
In general the use of pressures offrom atmospheric ~ -
up to 10 bar is preferred.
The process according to the present invention ~
may be carried out batchwise, or in a semi-continuous -
or a continuous manner. It is preferred to carry
out the process of the present invention continuously
which implies that the excess phenolic compound presènt
as well as the amount of acidic catalyst can substantially
be recycled to the reactor, which is very advantageous
in that use can be made of rather simple equipment. ~ ~`
It is also possible to use more than one reactor
and to recycle the excess phenolic compound to several~
reactors. For instance, when preparing diphenylolpropane
from phenol and DMD0, excess phenol as well as hydrochloric
acid may be recycled to the reactor(s) and also ethyleneglycol,
~; either formed from DMD0 or originally present as
solvent, may be recycled to the reactor(s) or~ if ~ ~
~` desired, to the reactor used in the production of -
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DMD0 from acetone and ethylene glycol when employing
an integrated diphenylolpropane process.
The reactants may be introduced into the reaction
zone in separate streams, and such separated streams
may be independently preheated. All or part of the
individual components charged to the reaction zone
may also be combined, and all or a part of the resulting
mixture may be preheated before introduction into
the reaction zone.
i 10The time of contact between the reagents may
vary and depends to some degree on the specific operating
conditions employed and the nature of the charge.
Contact times between 10 minutes and 10 hours, and
preferably between 15 minutes and 2 hours are generally ~ -
satisfactory~ although shorter or longer contact
times may be employed, if desired.
The crude bis(hydroxyaryl) compounds obtained
by the process according to the present invention
may be purified by a number of methods depending
on whether the bis(hydroxyaryl3 compound is obtained
....
as such or in the form of an adduct. .!.
`In general it has proved to be advantageous
to remove the acidic catalyst, if employed in anhydrous
form, as quickly as possible in order to prevent
or to diminish corrosion problems. This can be effected,
~; for instance, by stripping with the aid of inert
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hydrocarbons such as cyclohexane.
One of the working-up procedures general'y applied
involves the separation of the phenolic adduct of :
the bis(hydroxyaryl) compound formed by lowering ~-
the temperature. After filtration of the adduct, the
mother liquor containing - in the production of diphenylol-
propane - phenol, ethyleneglycol and impurities is
distilled in order to obtain phenol and/or ethylene
glycol, which may be recycled to the appropriate
reactor(s). If desired, the adduct crystals may be
combined with heated phenol and water in amounts
sufficient to produce a single-phase liquid mixture -~
~:, at approximately 60C. The mixture may be cooled
with gentle stirring to ambient temperature in a
; 15 :~ew hours. The adduct crystals formed are separated ::
~; by centrifuging and may be rinsed with aqueous phenol
to remove entrained liquid prior to the conversion
. into product. The conversion can be carried out,
for instance, by heating the adduct crystals under
diminished pressure to a final temperature of approximately
200C to strip the phenol component, the purified
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respect to ~ritish Patent Specification No. 1,274~798.
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.~ o~ the desired compound(s) as well as higher condensation
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products are invariably formed. Thus, during the
production of 2,2-di(4-hydroxyphenol)propane, also
called para,para-diphenylolpropane certain amounts
of ortho30rtho - as well as ortho,para-diphenylolpropane
are formed.
It may be advantageous - in order to increase
the yield of the desired isomer - to subject a mixture
relatively rich in unwanted isomers to an isomerization
treatment. This isomerization treatment can be carried
out at any suitable stage in the process for the ;
production of diphenylolpropane. For instance, the
mother liquor obtained after filtration of the para,para-diphe-
nylolpropane product, being predominantly rich in
the unwanted ortho9para-isomer can be subjected to
an isomerization treatment in the presence of an
acidic isomerization catalyst, for instance in a
separate isomerizer.
If desired, the product obtained may be subjected
to physical treatments such as prilling in order
; 20 to increase the mechanical strength. ~ `
Bis(hydroxyaryl) compounds or reaction products
comprising them, are o~ value as starting or intermediate
materials in the production of, ~or instance, chemical
derivatives, resins, plastics, paints, lacquers,
varnishes, adhesives and textile printing compounds.
~` The bis(hydroxyaryl) compounds and in particular
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diphenylolpropane may easily be converted into bis(epoxyalkyl)
ethers, for instance by reacting diphenylolpropane
with an epoxy haloalkane such as epichlorohydrin
at temperatures in the range of from 50C to 150C,
preferably in the presence of a base.
The following examples are illustrative of the
present invention.
EXAMPLE I
Pre~aration of 2l2-dimeth~ 3-dioxolane (DMD0) -~
DMD0 was prepared using a continuous flow reactor
containing a bed of 100 ml (measured in dry condition)
of hmberlyst 15 H~ wetted with acetone. At ambient
temperature a mixture of acetone (DMK) and ethyleneglycol
(EG) having a fixed molar ratio EG/DMK of 2 was pumped~
over the Amberlyst catalyst bed at liquid hourly
space velocity (LHSV) of 10 l feed per l catalyst
per hour. The water content of the feedstock was -
below 0.2%w. The reaction was carried out at atmospheric
pressure. Even after 400 hours of operation no catalyst
activity decline was observed. An acetone conversion
of 36 mole.~ was obtained.
The reactor effluent was made alkaline by the
~` addition of 0.02%w of sodium hydroxide (added as
a 10%w aqueous solution), the resulting pH of the
effluent being 8.8. After removal of unconverted acetone
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by distillation, which was recycled to the reactor,
DMD0 was recovered as the hetero-azeotrope DMD0/H20
boiling at 78.5C. The organic phase obtained, mainly
consisting of DMD0 and also containing a small amount
of water was dried by three additions of 1%w of potassium
acetate and subsequently removing the aqueous layer
thus formed. DMD0 obtained in a quantitative yield
with respect to acetone converted contained only
0.3%w H20. The boiling point at atmospheric pressure
' 10 was 93C.
EXAMPLE II
Pre~aration of 2~_-dimeth~ 3-dioxolane (DMD0) in
the ~resence_of di~hen~lol~ro~ane
DMD0 was prepared using a continuous flow reactor
containing a bed of 150 ml (measured in dry condition)
of Amberlyst 15H wetted with acetone. At 40C a
mixture of DMK and EG having a fixed molar ratio
of 1035 was pumped over the catalyst bed at a liquid -
~-~ hourly space velocity of 5 1 feed per 1 catalyst per
`~ hour. The EG used contained 5 %w of diphenylolpropane. ~-~
The water content of the feedstock was well below -~
0,2 %w. The reaction was carried out at atmospheric -~ ;
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pressure. A steady EG conversion of 29 mole% was
obtained during a 400 runhours life test. No catalyst
activity decline was observed in this run time.
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The reactor effluent was made alkaline by the
addition of 0.01 %w of sodiumhydroxide (added as-
a 10 %w aqueous solution), the resulting pH of the
effluent beng 8.5.
The alkaline reaction product was distilled in
a continuous distillation column. Unconverted DMK
was taken overhead for recycle to the DMD0-producing;
reactor. Via a side-stream the DMD0/water hetero-azeotrope
was collected, the two phase system obtained was
separated into an organic layer which was returned
to the continuous distillation column, and an aqueous
phase which was distilled separately for recovery
:. . of DMD0-dissolved in the water - in the form of the
DMD0/water hetero~azeotrope which was returned to
the continuous distillation column.
The bottom stream of the continuous distillation ~-:
. column.consisting of dry DMD0 in EG and also containing
the initial diphenylolpropane was sent to the diphenylolpropane
, manufacturing section.
; 20 This example clearly demonstrates that DMD0
can be suitably prepared in the presence of diphenylolpropane
: which ls highly advantageous for the production of
. diphenylolpropane in an ntegrated process starting
.~ with the production o~ DMD0.
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EXAMPLE III
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_rep_r t_on _f diphenylolpropane_fro_ ~h_n_l_a_d D D0
Into a 300 ml stirred-tank reactor made of Hastelloy* B
were introduced at room temperature 600 grams per hour of a liquid
feedstock containing phenol, DMD0 and ethyleneglycol in a molar `
ratio of 10:1:2.4. Separately, gaseous anhydrous HCl was
introduced into the reactor via a dip-pipe at an amount of 30
grams per hour. The reaction was carried out at substantially
atmospheric pressure, the reactor being operated liquid full.
The reactor contents were stirred with a flat turbine stirrer C650
rpm). The reactor was electrically heated to mamtain a reaction
temperature of 60C.
After three hours running-in, stable operation was ~ -
reached and samples of the reactor contents were analysed. The -~ ~
conversion of DMD0 proved to be 90%. The diphenylolpropane ~;
produced contained 10%w of the ortho-para isomer.
EXAMPLE IV :
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The experiment of Example III was repeated, except that
; the hourly throughput of the feed was 300 grams and that of gaseous
20 HCl 15 grams respectively.
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The Dl~0 conversion proved to be 95.4~ and the diphenylpropane
product contained 1 o.8~ of ortho-para isomer.
EXAMPL~ V
The experiment of Example III was repeated,
except that the hourly throughput of the feed was
1200 grams and that Or gaseous HCl 60 grams. The
DMD0 conversion proved to be 76.7% and the diphenylol-
propane product contained 11.4% of ortho-para isomer.
EXAMPL~ VI
Pre~aration o~ di~hen lolmethane from ~henol and
~- .
The experiment of Example III was repeated, except
that a liquid feedstook containing phenol, dioxolane-
1,3 (formaldehyde-glycol) and ethylene glycol in a molar
ratio o~ 10:1:2,4 was processed. The dioxolane-1,~
conversion proved to be >99%. The selectivity to
` - diphenylolmethane isomers was 84~ and the isomer
. . .
distribution towards para, para-~ orthoJ para- and ortho, ~
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ortho-diphenylolmethane, respectively was close to 1:2 1.
~XAMPL~ VII ~ ~
In a 100 ml all glass reactor a catalyst bed o~ 90 ml
Amberlyst 15 H was installed. The reactor heating mantle
~i was set at 60C. A liquid feedstock containing phenol,
'~ dioxolane~ and ethylene glycol in a molar ratio o~
10-1:1,6 was pumped through the catalyst bed at a liquid~
hourly space velocity (LHSV) of 1 l (l cat hr 1)~
~l The reactor effluent obtained showed a dioxolane-1,3 conversion
rl o~ 97$ for the first 24 hours. The isomer distribution
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towards para~ para~ h~, para- and ortho) ortho- -~
diphenylol methane~ respectively, was 36:42:22.
EXAMPLE VIII
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Isomerization of ortho, para-diphen~lol~ro~ane into
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Into a ~00 ml stirred tank made o~ Hastelloy B
were introduced at room temperature ~00 grams o~ a
liquid feedstock containing phenol (77%w),ethyleneglycol ~ -~
(15~) and diphenylolpropane (8~ow)~ The weight ratio
ortho, para- to para, para-diphenylolpropane was ~ -
2 6/7 4 ~ r
Separately, gaseous HCl was introduced into the
reactor via a dip-pipe just above the stirrer at an
amount of 15 grams per hour. The isomerization reaction
was carried out at 60C under atmospheric pressure.
The reactor contents were stirred with a flat turbine
stirrer at 650 rpm, the reactor being operated liquid
full.
After three hours running-in the e~luent of the
:
reactor was anaLyzed to determine the ortho, para-/para
para-diphenylolpropane ratio. A constant value of 12/88
w/w was ~ound ~or several hours indicating that thermo-
dynamic equilibrlum at 60C (ratio 9/91) was nearly
reached.
A similar experiment ~ras carried out, except that a
residence time of thirty mlnutes was used. The ortho, ~para-/
para, para-diphenylolpropane ~reight ratio was 16.5/83.5 w/w. `;~
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