Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~)39740
~ he present invention i~ concerned ~ith a process for
the preparation of aromatic carbonate~ having the general formula:
O
~ O_C_OR'
(1-5)
wherein R i9 an alkyl, alkoxy, aryl or aryloxy radicsl or a nitro
group and Rl is an alkyl group or a radical of the formula:
~ : '.
(1-5)
' '
in which R has the nforesaid meanings.
M~thod~ for the preparation of these compounds are known~
starting from the corresponding phenols through a reaotion with
phosgene or chloroformiates according to complex technologies.
These however, present several risks due to the toxioity of the
reagents employed and give rise to the formation of hydrochloric
aoid 8~ by-product. ~ ;
On the other hand, it i~ also known to react phenols and
alkyl carbonates in preeence of ~trong ba~es aa oataly~t, Such a
reaotion ha~ however the drawbaok of lo~ reaotion rate~ and the
~ormation of high amounts of phenol ether as by-products.
Aromatio carbonates ha~e a remarkable industrial applica-
t~on ~ince they can be employed as intermediates in the produ¢tion
~ . .
;~ Or aromatic polyoarbonates and in the synthesi~ of various isocy-
.
anate~.
It has no~ been found that it is possible to obtain, at
. ~
~ hi p yields and selectivities, aryl-alkyl carbonates and diaryl
: : ,
carbonates according to the present in~ention, these are obtained
by reacting the corresponding phenQls or acyl esters thereof with
;alkyl cyclic or aryl-alkyl carbonates, in the presence of suitable
~catalys~t~ he reaction i9 carried out in the liquid pha~e, ~ith
,;; ,.'.'. ;:,, ,~', ~"; ',"',''";."."'' ;
~)39740 - ~
or without a solvent, at a temperature of from 25 to 350C, pre-
ferably from 80 to 250~, and 8 pressure of from 0.1 to 100 atm "
pre~erably from 1 to 25 atm.
The molar ratio between the phenol and carbonate com-
pounds may range from 100:1 to 1:100, preferably ~rom 5:1 to t 100 ~.
Efficient catalysts are ~ewis acids and the metal ortransition metal compounds generating the same. ~he Iewis acids
may be employed as such or mixed with one another; use may also be
made of adducts thereof with organic molecules. Preferred catalysts
are compounds having the formulae AlX3, TiX3, UX4, TiX4, VoX3~ VX5,
ZnX2, ~eX3 and SnX4, wherein X is halogen, acetoxy, alcoxy or
aryloxy.
~ he process according to the in~ention may be utilized
for preparing aromatic derivatives other than those mentioned above,
for instance aromatio thlocarbonates or imido-carbonates starting
~rom the corresponding alkyl compounds. Moreover, it is possible,
to prepare polymeric carbonates contsining in the molecule repeating
units of the type ~A-O_C0_0~ in which A is a divalent radical con-
taining at least one aromatic ~unction. These polymeric carbonates
are obtained~ in accordance with a further aspect of the invention, ;~
by carrying out the aforesaid reaction while removing thQ alkyl
oarbonate,
~ he subJeob invention will now ~e further understood with
referonoe to the following non restrictive exam~les. In these
example~ the reagent3 and the catalyst were charged in a 2 1 ~lask
~itted with a 10 plate distilling column having a liquid-dividing
hsad5 th~ lo~ boiling aloohols were oontinuously distilled eithe~r
~ uch or in the form of azeotropes. ~he ~eactions w~re carried
out under an inert atmosphere, the reagents and solvent employed
~30 having been suitably rendered anhydrous.
E~ MPIE 1
Reaction between dimethylcarbona~e (DMC) and phenol (phen)
was carried out in presence of anhydrou~ AlCl~ in a DMC/Phen/cat
:
.
, .
1~)39740
molar ratio of 5/1/0.05. The temperature was 98C; a methyl
alcohol _DMC azeotro~e wa9 distilled at a reflux ratio of 10:1.
After 8 hours, a phenol conversion equal to 15.5% and a pheny-
lmethylcarbonate (PhMC) selectivity of 95% were obtained, the re_
maining 5% of phenol having been converted to anisole.
EX~MPIE 2
~ he reaction was carried out under the same conditions
as in example 1~ but the catalyst utiliæed was TiC13. After 5.5
hours~ a phenol conversion of 13% and a Ph MC sele¢ti~ity higher
than 99% were obtained.
. ~ .
EXAMPIE 3
The reaction was carried out as in example 1. ~iC14 wa~
u~ed as cataly~t. After 8 hours, conversion of 23% and a total
~ele¢tivity with rQspect to Ph MC were obtained.
EX~MPIE 4
~ he same conditions as in example 1 were retained, except
that ~i(0-isopropyl)4 was employed as catalyst. After 8 hours, a
conversion ef 11% and a practically total selectivity ~ith respect
to Ph MC were obtained.
'.
E MPIE ~
The same condition~ a~ in example 1 were retained, except
that ~i(od)4 Wa9 employed as employed as cataly~t. After 24 hours~
a eonver~ion of 41.5% and a ~electivity with respeot to Ph MC of
95% were obtained~ the remaining part consisting of diphenylcarbonate
(Dpha). Anisole was present only as traces, ~hich could not be
evsluated from an analytical point of view. ~ ;
~ ~ .
XAMPIE 6
Under the same conditions as in example 1, VC14 was
utllized a8 oatalyst. A conversion of 3% and a total selectivity
with respect to phenylmethylcarbonate ~ere obtained.
-3~
, : , . .' ' - ,:
EXAMPIE ~ 1039740
VOC13 was employed as cataly~t in the reaction conditions
of example 1. After 5 hours, a phenol conversion o~ 5~ and a
total selectivity with respect to phenylmethylcarbonate were - -
obtained. ~
- .
E-X~MPIE 8 ~ -
~ he same conditions as in example 6 ~ere retained, except
that use was made of a DMC/Phen/Ti(00)4 molar ratio of 10/1/0.05.
After 8 hours, a phenol conversion of 21% and a practically total
~electivity with re~pect to Ph~lC were obtained.
,
EX~MPIE g --
The reaotion ~as carried out with mixture formed by DMC/
Phen/~iCl in a molar ratio of 1/4/0.05, in presence of n-hexane
~n an a-mount corresponding to 35 g per m~le of D~C. A mixture
consisting of hexane/DMC/Methyl alcohol na9 distilled at a reflux ~-
ratio of 10/1 and added a mixture of hexane/DMC was continuously
added ~u¢h a~ to reinstate the portion ~emoved by distillation.
The reaction temperature was 135C. After 8 hours, a phenol con-
- vereion of 9%~ a Phen MC selectivity of 78% and a D Phen C ~electi-
vity o~ 22% were obtained.
;. . ~
EXA~MPI~ 1
~ he reaotion was carried out at 130C with a mixture
oonsisting of p-cresole/DEC (diethylcarbonate)/~i(0-iC3E7)4 in a
molar ratio of 1/5/0.05~ over a period of 3 hours, A conver~ion
o~ 25% and a total selectivity ~ith respeot to tolyl-ethyl-car-
bonate were obtained.
- , , -
EXAUEIE 11
A mixture of ~EC/hydroquinone-mo-nomathylether/~i(O_i C3H7)4
in a molar ratio of ratio 5/1/0.05 were reacted at 130C over a
~30 perlod of 3 hours. A oonvffrsion of 36~ and a practically total
_4_
~: f
1~39740
electivity with respect to p-methoxiphenylcarbonate were obtained
XAMPIE 12
Phenylethylcarbonate wa3 reacted with phenol in the
presence of Ti(00)4, in a molar ratio of 1~0.8/0.04, at 180C, and
in heptane. A mixture consisting of n-hept~ne-ethyl alcohol and
n-heptane was continuou~ly distilled and wa~ added to the reaction
medium for replacing the distilled fraction~ After 4 hours, a
phenol conversion of 42% and a total selectivity with respect to
diphenylcarbonate were obtained.
E~AMPIE 13
Use was made of a stainless steel reactor having a volume
of 2,4 1, which was fitted with a steel ~istillation column having
1" in diameter and 1 m in length and packed with glass rascings.
~he reaction was carried out at 180C and at 6.6 Atm by continuous-
ly distilling the methyl alcohol, _DMC azeotrope and renewing the
DMC removed throuth distillation. ~he DMC/Phen/Ti(00)4 molar ratio
Wa9 5/1/0.5. After a reaction period of 7 hours, a phenol conver-
~ion of 53%, a sele¢tivity with respect to PhMC of 95% and a
~electivity ~ith respect to DPhC of 5% were obtained
EXAMPIE 14
~he ~ame conditions as in example 1 were retained, except
that SnC14 was employed as catalyst, ~he conversion obtained was
8%~ the selectivity ~ith respect to phen~lmethylcarbonste wa~ 85%
and with respect to phenylmethylether 15%.
EXAMPIE 15
A mixture of rEC/Phen/UCl4 wa9 reacted, in a molar ratio
of 5/1/0.075~ at 130C and over a period of 4 hour~. A phenol con-
~r~ion of 38% was obtained with selecti~ities with respect to Phen
EC of 98% and to ~EC of 2%.
:: :: :
1~)39740
E MPIE 16
A mixture of IEC/p-nitrophenol/Ti(00)4 in a molar ratio
of ratio 5/1/0.05 wa9 reacted at 130C and over a period o~ 4
hours. A p-nitrophenol conversion of 10% and a total selectivit~
with respect to p-nitrophenyl-carbonate were obtained.
E MPIE 17
Use wa~ made of a 250 cc flask provided with a distilla-
tion column having 20 plates and equipped with a liquid-dividing
head; 68 g of phenyl acetate, 60 g of diethylcarbonate and 2 g o~
titanium phenate were charged therein, at 145C. ~y continuously
head distilling ethyl acetate, 68% by mole of diphenyl carbonate
nnd 30% by mole of phenyl-ethyl-carbonate at a total 3electivity
higher than 98% and a conver~ion of phenyl acetate of 95% were
obtained after a reaction period of 4 hour3.
.~ .
E MPIE 18
~ In the apparatu~ of example 17, at 145C, were charged
; 74 g of phenol acetate and, gradually, 90 g of dimethyl carbonate
and 1 g of titanium tetramethoxide. Methyl acetate wa~ continuous-
ly di3tilled and, after 4 hours~ BO~o by mole of diphenyl carbonate
;~20 and 18% by mole o~ ph~nol m~thyl oàrbonate n~re obtainQd, at a
eeleotivity higher than 9~% and a oonYer~ion of methyl acetat~ o~
~` 97%-
BX~MPIæ 19
. .
~; In thQ same apparatu~ described in example 17 were charged,
at 150C, 68 g of phenyl a¢etate, 80 ~ of phenyl methyl carbonate
and 25 cc of n-heptane with 1.5 g of aluminium ethylate. Methyl
aoetate ~a3 continuou~Iy distilled and, after 4 hours, a conversion
~ ... ..
of ;90~0 and a ~electivity with respect to diphenyl carbonate. `
EXA~PIE 20
;~ 150 g of bisphenol A bis acetate and 3 cc of titanium
6-
.
1~39740
tetrai~opropylate ~ere charged, at 140-150C, in the apparatus of
example 17, then 130 cc of diethylcarbonate were gradually added
while ethyl ~cetate was continuouslg distilled from the system.
After 10 hours, a total conversion of bisphenol acetate to bi- _
sphenol A - bis ethyl carbon~te wa~ obtained. -~
EXAMPIE 21
In the same apparatus described in example 17 were charged
150 g of bisphenol A bis~cetate ~nd 3 g of aluminium tetraiso-
propylate, at 150-170C, and there were gradually added 110 cc of
demethyl carbonate~ methyl acetate being continuously distilled.
After 8 hours, a complete conversion t bisphenol bis methyl car-
bonate was obtained.
. '.
EXAMPIE 2~
190 g o~ bi~phenol A bis-aceta~e and 2.5 g of ~i(0-i~o
C ~7)4 were charged into a 250 cc flask fitted with a distilling
column having 30 plates and equipped with a liquid - dividing
hesd. ~he mixture ~as heated at 150-170C~ and was then gr~duaily
added with 160 cc of dimethylcarbonate. In the same time methyl
aoetate wa~ formed, which distilled off when the reaction was
completed~ the system was brought under ~aouum and the temperature
rai3ed up to 270QC. Dimeth~lcarbonate~ which distilled during the
reaction~ ~a~ recovered by means of a cold trap. After 4 hours,
a polymer ha~ing an average molecular weight of 17~000 and a
~truoture corre~ponding to oommercial aromatic polycarbonates wa~
obtained.
.
.
E~ MPIES 23-24
wo tests were carried out according to the procedure of
:, .. ::: ;!:
the precedin~ e~ample. ~he amounts Or the compounds employed and
the re3ults obtained are reported in the following table.
, .
~ 30 ` ~ -
. ~. .
~ 7_ ~
,. ~ . .
~;)3~740 -
Alkyl carbonate Catalyst ~isphenol PolymRr molecular ~eigh~
diethylcarbonate ~i(O0)4 acetate
1S0 cm 2.5 g 150 g 14,000 ~ -
dimethylcarbonate Al(0_~ec butyl)3 .
150 cm3 3 g 150 g 5~600 -
.
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