PALI-SK 69-0827
301
Palit & Tripath)': SYllthesis of Benzoic Acid from Clt/oroh.en::el1C' IIl1def Pressure
References
'l' P '1
III :
ellf:.
(1)
t. I
11'1
' Illl f,
11
Ilc:
If,
lit f'
/I I\:
" iloski Aoki, J. clectrachell/. Soc. Japan , 1967, 35, 137 ; Warne,
A., & Hayfield, P. C. S., Trans. fllSt. Metal Finish., 1967,
-'5,83
,\damson, A. F., Lever, B. G ., & Stanes, 'N. F., J. appl. Chem.,
Lonc/., 1963, 13,483
, Greeson. H.E., to be published
• c\ yres, G. H., & Meyer, A. S., Analyt. Chem., 1951, 23, 299
• 11>1. N., & Landolt , D., J. £'Iectmchelll. Soc., 1968,115,713
' Antler, M., & Butler, C. A., Electrachem. Technol., 1967,5, 126
,,1.
I-I oare, J. Poo 'The Elec trochemistry of Oxygen', 1968 (New
York: Intersciencc)
8 Anson, F. c., & Lingane, J. J., J. Am. chern. Soc., 1957, 79,
4901
• Breiter, M. W., & ¥leininger, J. L., J. electrochem. Soc., 1962,
109, 1135
10 Suzuk, Coo Yoshida, Moo Onoue, H., & Matsumo, T., J. electrochem. Soc. japan, 1966.34, 165
I I Flisskii, M. M., Electrokhimiya, 1966,2,860
7
SYNTHESIS OF BENZOIC ACID
FROM CHLOROBENZENE UNDER PRESSURE
By S. K. PALIT and N. TRlPATHY*
Conversions as high as 76'26 % and 80 ·85 % of chlorobenzene to benzoic acid were obtained when chlorobenzene
was carboxylated with ca rbon monoxide and water at high pressure with nickel iodide-silica gel catalyst (Ni:Si0 2
= 50: 50) and without any ca talyst (therma l) respectively, at the opt imum temperature and pressure; these optima
were much higher for the latter than for the former process. The lower yield in the catalytic process could be
improved to some extent if the catalytic reacti on was carried out at a pressure, reached by introdlicing nitrogen
in addition to the usual input of carbon monoxide, almost equal to the optimum pressure of the thermal process.
I·r.
tI/
·i·
c
..
6
he
en
a
~e
Introduction
The possibility of synthesising various aromatic carboxylic
acids, esters etc. of industrial importance by the carbonylation (or carboxylation) of aryl halides under pressure with
mainly nickel carbonyl as catalyst, has been disclosed in
various patents.l In one such patent, Kroper et al. 2 have
claimed that benzoic acid and its esters can be synthesised
from bromo- and chloro-benzenes in a similar way. Romanovskii & Artemev 3 in a paper on carbonylation of dichlorobenzene, have also claimed to have obtained benzoic acid by
the same procedure. However, as both these papers are
lacking in detail and because of the industrial importance of
benzoic acid and the superior catalytic activIty of nickel
iodide-silica gel catalyst (Ni : Si0 2 = 50 ; 50) to the carbonyls,4 a detailed study of the synthesis of benzoic acid
from chlorobenzene, carbon monoxide and water with and
without this catalyst has been carried out.
Thermodynamics of the reaction
The effects of temperature and pressure on the equilibrium
constant of this reaction are given in Table I.
d
e
TABLt I
Equilibrium constant of the reaction (a) at mrious temperatures and a pressure of 1 atm. and (b) at various pressures
for a constant tempera ture 200 'c
Standard free energy change for the' reaction at 25"c and 1 atm = -15-83 kcal
(a) Temperature, °c
K "p·
(b) Pressure, atm.
K*
K'p· x 10- 5
100
150
8'l3x10 7 1·51 x 10'
100
0·7789
2·34
200
1·236
1'47
200
250
300
1·82xI0' 4-78 x 10J 5·88 X 10 '
350
9·77 x 10
400
2·607
0-698
3-627
0-501
300
1·516
1·201
500
3·716
0 '-l99
600
450
5-91
700
3·621
0·503
KOp = equilibrium constant at I atm; K'p = equilibrium constant for diO"erent pressures at
Kv
constant temperature and K,. =
YC f, .. , r OOIl X '(IICI
and Y = _pi where I is the fugacity of the gas and y is the
·K',
= KO•• where
400
2'31 x 10
YC6I"CI X
Yeo X Y.. ,o
·Present addre s: Dept. of Chemistry, Regional Engineering College, Rourkela, Orissa. India.
J. appl. Chern .. 1969, Vol. 19, October
302
Palil & Tril'olhy: SYlllhesi.\· of Bell::oic Acid from Chlorohel1::el1c Illlder Pressure
As values of the free energy and heat of formation of benzoic
:ll:iti in the gaseous sta te anti the heat capacities of benzoic
a ' id and chlorobenzene \\ere not availabh:, these were calculated by the group contribution method. s.
For the calculation of the clrcct of pressure 011 the equilibrium con tant at 200 ', the fugacit y co-etllcients of the
various compounds were evaluated -from the chart proposed
by Lydersen ('/ al. 6 and corrected for the dilTercnt critical
com pre. si bilities. 7 The temperature of 200-' was selected so
as to avoid the unreliable reduced temperature range of 0,81·2 at reduced pressures above I '2.7 From Table I(b), it is
seen that the equilibrium constant contrary to expectalion,
fluctuated in value. This could be due to the influence of
pressure on the fugacity co-enicients of the various compounds, but as the reaction proceeds with volume decrease
it is obvious that the equilibrium conversion would increase
with pressure.
Experimental
A high-pressure rocking autoclave of 270 ml capacity at
25"c and I atm pressure having an angular play of 15° with
45 oscillations per min was used. The product release assembly
and other experimental set-up were similar to those described by Bhattacharyya and co-workers. 8 ,9
Very pure carbon monoxide was prepared in the laboratory
by the same method and the same precautions were taken as
in the earlier work. 8 ,9 All other chemicals used were of
analytical grade.
The catalyst, nickel iodide supported on silica gel containing 84'16 % of nickel iodide (Ni : Si0 2 = 50 : 50), used
in this work, was prepared according to the method of
Bhattacharyya & Sourirajan. 9
Liquid products
The liquid products of the reaction consi sted of benzoic
acid, formic acid and benzaldehyde (in a few cases under
non-catalytic conditions only), together with the unconverted
chlorobenzene and watef'. Occasionally minute traces of
hydro hloric acid, nickel and iron salts were also present.
lndi\ idual components were identified by their melting
points and mixed melting points wherever possible, by
forming suitable derivatives and 'by paper and gas chromatography.
The liquid product mixture was cooled to abou t 0° and
filtered. The residue, containing benzoic acid and other
solid impurities, was treated with alcohol and subsequently
titrated with standard alkali to estimate benzoic acid. A
quantity of the filtrate was steam-distilled to eliminate the
impUrities. In the distillate, benzaldehyde was estimated
by the 2: 4 dinitrophenyl hydrazine method; formic acid
by titration with alkaline potassium permanganate and then
subtracting the amount consumed by benzaldehyde (if
present) from the above titration value; and finally benzoic
acid was determined by subtracting the acidity due to formic
acid from the total free acidity of the distillate. As the
amount of hydrochloric acid or the chlorides, determined
by Volhard's method after acidifying a part of the filtrate
with nitric acid, was almost negligible, it did not interfere
with the analyses of the other products.
Gaseous products
The gaseous product was found to contain carbon dioxide,
hydrogen and saturated hydrocarbons (methane was the
chief con titucnt) together with carbon monoxide. Analysis
was carried out with a standard Orsat gas analyser and the
results ,,"ere confirmed when nece sary by gas chromatography.
Results and disclission
As some preliminary iI1\estigations revealed that benZOl,
acid was produced even when the experiments were can,
ducted in the absence of any catalyst (thermal), the uek-r.
mination of the optimum reaction conditions at which thl'
yield of benLoic acid would be a maximum was carried 0 111
for both the catalytic and non-catalytic conditions. The result,
are recorded in Figs 1--4 and Tables ll- JV. Since the P:lr.
ticular reactions by which carbon dioxide and saturated
hyd rocarbons were formed during the synthesis reaction,
could not be represented by balanced equations, the yields of
these gases were calculated on the ba is of the percentage of
total input carbon (from chlorobenzene and carbon mono
oxide) that could be accounted for by the carbon of th ~
respective gas and have been given as 'percentage carbon
conversion'. Similarly the yield of gaseous hydrogen has
been expressed as 'percentage hydrogen conversion.'
Effeet of presslire
The influence of pressure at different temperatures \.\ a,
studied under both catalytic and non-catalytic condition,
by varying the input of all the reactants by the same pro·
portion so that their mole ratio remained constant in all the:
experiments (Fig. 1). When the temperature was changcd
by 90° (220- 3) 0°) in experiments with catalyst, the opti·
mum pressure did not increase to the extent that was notcd
by only a 50° rise (310--360°) under non-catalytic conditions.
This was probably because the temperature (360°) was vcry
close to the critical temperatures of water and chloro·
benzene. With increasing pressures the yields of benzaltk·
hyde, formic acid and the gaseous decomposition product';
increased steadily in all cases. However under catalyt ic
conditions the yields of formic acid and gaseous decomposition products were higher than those under non-catalytic
conditions (Fig. 2).
Effect of temperature
The optimum temperature of 295 ° under catalytic conditions was much lower than 360 ~ for non-catalytic COil'
ditions (Fig. 3). rn both cases, the yields of benzaldch) lk
and gaseous decomposition products increased with rise r
temperature whereas the yield of formic acid decreased. Of
the decomposi tion products the yields of carbon dioxide,
sa'lUrated hydrocarbon and hydrogen, increased steadily fro l11
12 ·9--42'8%, 4 ·7- 6 ·7 % and 0 ·5-30·3 % respectively for
catalytic conditions, whereas for the non-catalytic condition,.
the corresponding values were respectively 19 ·2-31 ·2",.
0- 11·6 % and 0- 11,6 % over the temperature ranges inve,lIgated.
EtTeet of residence time
With increase in residence time the yield of benzoic a.:id
passed through an optimum at three hours in both ca~c~ .
However in the catalytic synthesis the yield of benzoic ali ll
was Jess affected by residence time than when under no n·
catalytic conditions. The yicId of formic acid increased ;1'
residence time wa increa ed for catalytic synthesis \\llIk
the reverse was true for non-ca talytic synthesis. The yield, .,1
gaseous decomposition products increased steadily \\l lh
residence time and their yields increased almost by the sail"
amounts in the two different syn thetic conditions 1'01' tI l<'
same variation in residence lime.
J. appI. Chent., 1969, Vol. 19, Oc(()hl'f
-ta
u
<
u
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N
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CD
u.
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a
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Fig. 1.
With
Fig. 3
Me
In
CO
2·33
2' 15
1·97
~
J.
:pl
...·teem
..
Palit & TripathJ' ,' Synthesis oj Ben::oic A tid frOI/l ChlorobeJI::ene linder Pressure
n •
:;
BO
30
_-cr-------o
Q.
c:
f-
a
0
",,,,..,...,...,...,.
0
...
u
0-
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u
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N
t
Z
Id .
cD
(',
.h
W
0
0
40
=>
w
~1O
;;
0
0
UJ
apt, (-,
O~
____________
o
fin'·
I thl'
ngl'd
~
8000
-
/
~'--/-----6
___
lr=·!:==-=::'=="-~
••------~*r-------~.~~
____________- L_ _ _ _- - - '
4000
O~-------------J--------------~------~
4000
PRESSURE,lb/in'
h.,
\I ,1\
-
>=
m,l:,
~
0-----
...J
If II,
rbI"
...
.... -- --- ..... ---/
u.
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0"'"
Q:
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u.
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t'
vi
I-
4:
303
BODO
6000
PRESSURE,lb/in'
Fig. I. Eifect of pressure all yields of bellzoic acid ill both catalytic
and thermal processes
With catalyst: _O- - -O 5 mlat 31O' c; . - - - - - . 10 m l at 220°c
:-Jon-calalytic: 0 - - 0 at 360°c; 11-----. at 310°c
~lole ratio of reacta nts: CO : H 2 0: C.H,C1 = 1 : 1·29: 0 ·0114
Residence time = 3 h
vpll ·
Fig. 2. Eifect of pressure on yields of gaseous decolI/positioll producls al 310 ' c ill bOlh catalytic {Jlld therll/al processes
With catalyst: 0 - -0 CO 2 ; 0 - - 0 H 2 ; 6, - - 6 ,
saturated hydrocarbon
Non-catalytic: . - - . CO 2 ; 11--. H , ; 4.--,A.
saturated hydrocarbon
Reaction conditions are same as in Fig. 1
BO
Ot~d
ion,.
o
\ er~
0-
o
oroIde·
u
<
'!£F -
u
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u 80
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ron;onIyde
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om
for
'ns,
. .,. ,'.
10 /
:sl i-
o
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>=
O~------------'L-------------'
200
400'
300
TEMPERATURE,oc
RESIDENCE TIME, h
Fig. 3. Effect of tempera lure 01/ yields of bel/zoic acid ill both
catalytic alld thermal processes
Mole ralio of reactants CO:I-I,O:C.H,C1 = 2· 15:2·77:0·0246
With catalyst: 0 - -0 5 ml a t 5700- 9'+00 Ib/in.>
Non-catalytic: 0 - - 0 at 4000-9600 Ib/in.'
Fig. 4. Eflect of residence time all yields of bell=oic acid ill b011r
calalytic alld tlrerma! processes
Reacta nts ratio as in Fig. 3
With catal yst: 0 -----0 10 ml at 295°c and 6700Ib/in.>
Non-catal ytic: 0 - - 0 at 360 c and 9 100 Ib/ in.'
TABLE ](
Effect of ,-ar ia lion of reactant ratio
cid
es.
Input of reactant.
moles
-id
nas
ik
of
'Ih
lC
hI!
Press.rre. Ib/in 1
CO
11 ,0
C.H,C1 Catalytic
2·33
2' 15
1·97
2· 15
2·M
1'66
2·77
3-89
2·77
3·33
0 ·0246
0'0:!-l6
0 ·0246
O'M92
0·0-+92
6500
6750
6900
Yield of
benzoic acid,
0 /
/ 0
Percentage of carbo n converted to
Sat. hydrocarbon
CO ,
Percen tage of inrllt
hydroge n converted
to gaseolls hyd roge n
Thcrmal
Catalytic
Thermal
Catalytic
Therma l
Ca ta lytic
Thermal
Ca talytic
Thermal
8200
9100
9150
!!800
4 1·2 1
74·94
66 ·6 1
64-47
RO 'R5
5-+-95
67 ·11
18 ·7
23-8
26 ·30
17·9
27·5
30·8
19 ·9
3·0
·9 ' 3
10-4
7-9
9 '8
12·3
6 ·0
23 ·0
9·2
6·0
7 ·5
10·5
7·0
9 ·6
6700
3 1' 17
21·8
3·7
11 ,8
Reac ti o n conditions: catalytic- with 101111 nicl..cI iodide:sil ica gel cata lys t at 295"c for 3 h ; thermal (n o n-catalytic)- at .160 c for 3 h.
rr
J.
~ppl.
ChCIll., 1969, Vol. 19, October
• 304
Palit & Tripath.\': Sy!!ti1esis (If BCI1::oic Acid/rom Ch/oroben;:cl1c under Pr('.uure
Effect of changc in reactant ratio
As is e\'ident frol11 Table II, the optimum yield for both
eatalyti\.: and non-catalytic sy ntheses was obtained when the
input of carbon monoxide, water and chlorobenzene were
2'15,2'7 and 0 ·0246 moles respect ive ly. With increase in the
input and mole ratio of water and carbon monoxide, the
yields of c3rbon dioxide and methaile increased stea di ly for
both conditions whereas hyd rogen did not foll ow any particular trend. With increasi ng amounts of water the yield
of formic acid increased for catalytic reactions whereas for
the non -ca talytic reaction there was little change.
Elfect of the quantity of catalyst
It is c\'idcnt from Table III that an increase in the amount
of catalyst beyond 10 ml (13 g) did not have any appreciable
effcct on the yield of benzoic acid or gaseo us decomposition
products. The yield of formic acid (not presented in Table III)
was hi ghes t with 15 1111 of the catalyst, which incidentally
also gave the optimum yields of benzoic acid.
TABLE
III
Effect of catalyst amount
Catalyst volume, ml
Yield of benzoic acid, %
Amount of carbon converted, %
(i) to CO 2
(ii) to sa turated hydrocarbon
Amount of hydrogen converted to
gaseous hydrogen, %
5
10
15
Conclusions
In the systems studied it was found that ni cke l iodide lin
silica gel (Ni : SiOl = 50 : 50) is an cOicient catalyst gi\ in ~
a much lower optimum rea ction pre s ure and temperat urt:.
67501b/ in 2 and 295 - respectively, compared with the vulut"
9100 Ib/ in 2 and 360 ' re pectively, under non cntalytic Con.
diti ons (Table I V) with only about 4 % loss in the ben7ol.
acid yield.
When the optimum inpu \ pressu re of 2500 Ib/i n 2 at 25
in the catalytic study was boosted with nitrogen to an input
press ure of 35001b/ in 2 at 25 ° so that the final reaction
pressure of 9700 Jb/ in2 was almost identic31 with the opti.
mum pressure under non-catalytic conditions, the percenta l!t'
con ersion of chlorobenzene to b;:nzoic acid increased
nearly the same va lue as th.1t under non-catalytic condition
(Table IV), indicating the pressure dependence of the rea ction
Production of formic acid, probably by the interaction (It
carbon monoxide with water, was favoured to a grcah:r
extent in the presence of the cataly t. Similarly decompo.
sition or other side reactions leading to the formation of
various gaseous products, were more favoured in presence of
the ca talyst.
til
20
Acknowledgment
72 ·26 74·94 76·26 75 ·89
23·7
4·8
23·8
9·3
24 ·4
9·4
25-8
9·5
2·8
9·2
9·2
9·5
The authors wish to thank Prof. S. K. Bhattacharyya for
his helpful suggestions and keen interest in the work.
Department of Applied Chemistry,
Indian Institute of Technology,
Kharagpur, India
Reacti on condiiions : Press ure 67501b/in at 295°c for residence
period of 311; mole ratio of reactants CO; H 2 0 : C 6 H,C1 =
2·15 : 2·77 : 0 '0246; 10 ml of catalyst weighs 13 g.
2
TABLE
Received 9 May, 1909
lV
Comparative yields under optimum conditions for the catalytic and thermal processes
Reaction temperature, °c
Input pressure, Jb/in'
Reaction pressure, Ib/in 1
Yield of benzoic acid, %
Amount of carbon converted to:
(i) CO 2 , %
(ii) saturated hydrocarbon, %
Amount of hydrogen converted to gaseous hydrogen, %
Thermal
Catalytic
Catalytic (reaction pressure
raised by nitrogen)
360
2500
9100
80·85
295
2500
6750
76·26
295
3500·
9700
79 · 14
26·1
10·3
10·2
24·4
9 ·4
9·2
17·8
0 ·7
0·2
*3500 Ib/ in 2 initial pressure was built up by an input of 2500 Ib/in 2 carbon monoxide and 1000 Ib/in' nitrogen.
Reaction conditions: mole ratio of reactants and residence time as in Table Ill ; volume of catalyst 15 ml.
Referenccs
Bird, C. W. , 'Transition Metal Intermediates in Organic Synthesis', 1967, p. 192 (London: Logos Press & Elek Books)
2 Kroper, H., Wirth. F., & Huckler, O. H ., Ger. P. 1,074,028;
Chelll. Abslr., 1961,55, 12364f
3 Romanovski i, V. I. , & Artemev, A. A., Zh. vses. khilll. Obshch.,
1960,5.476; Chem. Abslr., 1961,55, 1506 d, 3511g
" Bhallacharyya, S. K., J. iledian deelll. Sac., 1968, 45, 1151
, Hougen, O. A., Watson, K . M., & Ragatz, R. A. , 'Chemical
Process Principles', 2nd Edn, 1959, Part 11, p. 100.:1 (New
York : John Wiley)
I
• Houge n, O. A., V';also n, K. M., & Ragatz. R. A. , 'Chcll1i, .li
Process Principles Charts', 2nd Edn, 1960, Figs ]42:1, I·C I.
(New York: John Wiley)
.
7 Hougen, O. A., Watson, K . M., & Ragatz, R. A., 'ChcI111.:.11
Process Principles', 2nd Edn, 1959, Part II, p. 574 ( ,'\'
York: John Wiley)
8 BhatLacharyya, S. K ., & Sen, A. K., J. appl. Chelll., LOlld.
1963, 13, 498
• Bhattncharyya, S. K., & Sourirajan, S., J. appl. Clcelll., LIIII.I.
1956,6,442
J. appl. Chcm., 1969, Vol. 19, Odobt·r