- Email: [email protected]
The synthesis of chlorinated diphenyl ethers
Chemospbere So. ~, pp .305 - 312, 1976.
l'ergmaon l ~ e s s .
}h'inted i n Great B r i t a i n .
THE SYNTHESIS OF CHLORINATED DIPHENYL ETHERS G. S u n d s t ~
and O. H u t z i n g e r
L a b o r a t o r y o f Environmental Chemistry, U n i v e r s i t y o f Amsterdam, Nieuwe A c h t e r g r a c h t 166, Amsterdam, The N e t h e r l a n d s .
(Received i n UK for p u b l i c a t i o n 23 August 1976)
In o u r s t u d i e s on t h e c h e m i s t r y and environmental behaviour of I n d u s t r i a l
products s i m l l a r
t o compounds which have caused environmental problems, such as PCBs ( p o l y c h l o r l n a t e d b i p h e n y l s ] and PBBs ( p o l y b r o m l n a t e d b l p h e n y l s ) , we have surveyed the l i t e r a t u r e
on p o l y c h l o r l n a t e d d i p h e -
nyl e t h e r s (PDEs). PDEs have been t h e s u b j e c t o f a l a r g e number o f p a t e n t s and have been suggested f o r uses s i m i l a r t o those o f PCBs and PBBs. This i n c l u d e s use as flame r e t a r d a n t s , e l e c tric
insulators,
plastlclsers,
l u b r i c a n t s and as h y d r a u l i c f l u i d s
- a l t h o u g h we do n o t know t o
what e x t e n t c h l o r i n a t e d diphenyl e t h e r s e r e used o r manufactured a t p r e s e n t . The s t r u c t u r a l
similarity
between PDEs and PCBs o r PBBs i n d i c a t e s t h a t any leakage o f such
compounds i n t o t h e b i o s p h e r e may cause s i m i l a r problems as w i t h t h e lat-ker p r o d u c t s r e g a r d i n g btoaccumulation etc.
I t has r e c e n t l y been shown t h a t PDEs are p r e s e n t as i m p u r i t i e s in f u n g i -
c i d a l and h e r b i c i d a l c h l o r o p h e n o l p r e p a r a t i o n s which may t h e r e f o r e be a source o f c o n t a m i n a t i o n w i t h PDEs1-5. A certain toxicity Io,-chlorinated
p o t e n t i a l o f PDEs t o organisms is I n d i c a t e d by t h e suggestions t o use
diphenyl e t h e r s as a c a r i c i d e s 4, m i t i c i d e s 5 and a g a i n s t l i c e 6 . PDEs may a l s o be
used as s y n e r g l s t s t o g e t h e r w i t h p y r e t h r i n s 7 o r p e s t i c i d e s o f both phosphate and c h l o r i n a t e d hydrocarbon t y p e 8. The b l o c o n c e n t r a t i o n p o t e n t i a l o f diphenyl e t h e r dlphenyl e t h e r were i n v e s t i g a t e d by Neely e t e l .
and 2 , 2 w , 4 , 4 t - t e t r a c h l o r o -
by c a l c u l a t i o n o f p a r t i t i o n
coefficients
tween nzoctanol and w a t e r and by measuring uptake and c l e a r a n c e r a t e s in t r o u t 9 .
be-
The t e t r e c h l o -
r o compound showed a b l o c o n c e n t r a t t o n f a c t o r o f a value s i m i l a r t o t h e very p e r s i s t e n t compound hexachlorobenzene. Furthermore,
i t was r e c e n t l y shown t h a t h i g h l y t o x i c c h l o r i n a t e d d l b e n z o -
f u r a n s are formed upon p h o t o l y s l s o f PDEs and may be a r e a c t i o n o f environmental s i g n i f i cance10, 11 As is ev.|dent from above t h e r e is very l i m i t e d data on both b i o l o g i c a l , chemical p r o p e r t i e s on PDEs. To f a c i l i t a t e
toxicological
and
s t u d i e s on t h e environmental beheviour o f PDEs we
have s y n t h e s i s e d • number o f pure PDEs and c o l l e c t e d data on s y n t h e t i c r o u t e s useful f o r t h e p r e p a r a t i o n o f c h l o r i n a t e d dlphenyl e t h e r s o f known s t r u c t u r e .
3o5
T h i s work is summarlsed below.
~o6
No. 5
SYNTHESIS OF CHLORINATEDDIPHENYL ETHERS. A. Direct c h l o r i n a t i o n of dlphenyi ether. The d i r e c t c h l o r l n a t l o n of diphenyl ether
have been Investigated by Welngarten and
Schisla using tetrachloron~thane as solvent with SnCl4, FeCI3 or AIBr5 as c a t a l y s t s or a c e t i c acid without c a ~ l y s t s 12. S u b s t i t u t i o n i n i t i a l l y
occurr in the 2- and 4 - p o s i t i o n s and unsub-
s t i t u t e d dlphenyl ether, 2 - c h l o r o - and 4-chlorodiphenyl ether give the 2,2 B-, 2,4 t- and 4,4 TM •d l c h l o r o compounds as major products. 2-Chloro- and 4-chlorodiphenyl ether also give traces of the 2 , 4 - d i c h l o r o Isomer and from the 2-chioro ~ o u n d
also traces of 2,6-dichiorodiphenyl
ether was detected. No traces of a 3p4-dichlorosubstituted ether was found as claimed by Brewster and Stevenson 13. Further c h l o r i n a t i o n of diphenyl ether give good y i e l d s of 2,2t,4,4W-tetrachlorodlphenyl 10 ether, unambiguously s t r u c t u r a l l y determined by Norstr~n e t a l . although o r i g i n a l l y being. claimed to be the 2 , 2 t , 6 , 6 t - t e t r a c h l o r o isomer 14. The c h l o r i n a t i o n reactions are usually performed in the presence of a solvent (CCI410"14'15 or HOAc13) and often without c a t a l y s t s when low-chlorinated dlphenyl ethers are to be synthesised. However, even in the preparation o f oct~-, and decachlorodipbenyl ethers solvents may be used, b o i l i n g tetrachloromethane16 and b o i l i n g t e t r a c h l o r o e t h y l e n e17. Decachlorodlphenyl ether can also be obtained by treatment of diphenyl ether with the ~
reagent (S02Cl2-AICl3-S2Cl2)18.
I n d u s t r i a l c h l o r i n a t i o n processes are mostly performed without solvent and except f or c h l o r i n e only s u i f u r y l c h l o r i d e seem to have used as c h l o r i n a t i n g agent 19.20. I t has been c l a i med t h a t the usual r a t i o of p a l l to ortho s u b s t i t u t i o n of 4:1 obtained upon monochlorinatlon of diphenyl ether can be increased to 9:1 by not using solvent or c a t a l y s t 21. Increased amounts o f meta ison~rs (64-80~) can be obtained by heating the c h l o r i n a t i o n mixture with alumlum chlorideZZ or by c h l o r i n a t i o n in the gas phase23. The rate of c h l o r i n a t i o n of diphenyl ether In chiorobenzene s o l u t i o n has been examined but no products were i d e n t l f i e d 24. A number of highly c h l o r i n a t e d ethers have been syntheslsed by d i r e c t c h l o r i n a t i o n but since no structures were assigned these compounds have not been included in Table 1 below 16~25 B. The Ullmann ether synthesis and m o d i f i c a t i o n s . The c l a s s i c a l UIImann ether synthesis -coupling of phenol s a l t s with halogenated benzenes in the presence of copper c a t a l y s t 26- have been used f o r the preparation of a number of chloro substituted diphenyl ethers (cf. Table 1). O r i g i n a l l y the reaction was performed without s o l vent but recent m o d i f i c a t i o n s successfully employ the use of h l g h - b o i l i n g solvents such as d i glyme 27,28 and dimethyl sulfox.ide29p30. In the former solvent Cu2CI2 and KI were used as c a t a l y s t s while no c a t a l y s t s were used when the reaction was performed in dimethyl s u l f o x i d e s o l u t i o n . Copper and mercury have been used as c a t a l y s t s in the synthesis of 4-chiorodlphenyl ether from 4-chlorobromobenzene and phenol in the absence of base31 • In the synthesis of two pentachlorodJphenyi ethers we used the m o d i f i c a t i o n of the Ulimann ether synthesis using diglyme as solvent to obtain 2 , 4 - d i n i t r o - 2 V , 4 t , S t - t r i c h l o r o - and 3,4-dinitro-2W,4t,5~-trichlolnodlphenyl ether whereafter the n i t r o groups were substituted f or
2,4-
/,-
2-
0
~'~r-O-w~, ClI,I~I ll~J
'LP 'LP
Cl ,?~,,~O ~
B O
D E
B
A
D E
C
B
13 15 (4/,) (/,S) 30 (39) 42 {43) this work 32
42 (/,3)
(39) 42 (/,3) 13 13 this work 32 (36)
Ref.
n251.5982 /,6 this work oil cont.
oil oil
146-50(7) 2~-5(760) 140-2(7) 133-9(5) 133-9(5) %9~2(8) 161-2(19) 160(20)
155-6(20)
m
43.5 152-3(15) ~6.7-47.5 47-8 142-6(12) oil oil
Table 1. Knownchlorinated diphenyl ethers. Compound synthetic m.p. method k F (ram)
"+:
3,3r-
0,.~0.~::[
3,+-c,icroyb
Compound
Table 1. continued.
B
B
E
B
A,C
B
synthetic method
-10 113(0.5)
12 313(760)
31 170-/,(8) oil
377(76/,)
160-3(7)
306-7(762)
b.pm'~m)
cont.
28 28
27 27
2"/ (39) this work (36)
(36)
30
13
30
Ref.
%,,I D
2'/,'~" C l ~
Cl
Compound
I
0
0
"]3),C!
Table 1. continued.
F
B C
E
B
synthetic method 13 13 15
3O 168-72(7) ~-1~(760)
51 5&-5 183 51 51-2
oil
180-5(6)
oil
cont
38 10
(39) 37
this work
(36)
(39)
this
(20) 150-3(3) 310-2(760) (20) 30 27 30 (34 30
(19)
Ref.
b.;' ml
2~,~50
~"~Ci
0"~
I
0
0
.Fo.iF f ,
Cl" ~
22'kL O b
Compound
Table 1. continued.
132-3
oil
oil
oil n
68 70 205-7(12} 72 73-3.5 70-2
86-8
B~E oil a B~ B--E 65-6
B
D
c
D
B B~,E B~C
A
synthetic mefhod
cont.
32 33
29
this work
this work
this work
10 1/, (48) (~ (39) (~) (3/,)
Ref.
0 30
S,~. 5
309
Table 1. continued synthetic method
Compound 2,31k~5-
0
E[-"~ C[
m.p b.F (mm)
Ref
B-"E
oil a
32
B
36
139)
vii
2,Zt+,4:,6-
Q"+'~'f'Ct
v
EL
II ;I II :1 13~ (]."'~" deca- C I ~ O
~.,_.0
A
II . ' I I I
216
17
22t,.-5
18
n solidifies around roomtemperature.
c h l o r i n e by the Ponomarenko reaction (see below] 32. Two japanese groups synthesised diphenyl ethers with n i t r o and chloro substituents by coupling of chlorophenol s a l t s with 2 , 5 - d i c h l o ~ nltrobenzene whereby S l b s t l t u t i o n occurrs in the 2 - p o s i t i o n 33"34. C. The Sanda~yer reaction. A number of mainly low-chlorinated dlphanyl ethers have been synthesised by exchange of amino groups f o r c h l o r i n e via the Sandmeyer reaction (cf. Table 1). I t may be pointed out t h a t attempts in t h i s laboratory t o exchange amino groups in the p o s i t i o n ortho to the ether linkage f o r c h l o r i n e have been unsuccessful although the corresponding deaminatlon reaction via d l a z o t a t i o n have given good y i e l d s of products (see below). D. Deamlnatlon reactions. We have synthesised a number of c h l o r i n a t e d diphenyl ethers f r =
~rclally
available
amlno-chlorosubstltuted diphenyl ethers (Aldrich Cheen, Co.) by deamination v ia treatment with amyl n i t r i t e
in b o i l i n g tetrahydrofuran 35.
E. Miscellaneous s u b s t i t u t i o n reactions. Chlorine have been introduced Into the dlphenyl ether system by d i r e c t s u b s t i t u t i o n of n i t r o or sulfonyl groups. The 2 - c h l o r o - , 4-chloro-~ 2 , 2 t , 4 j 4 1 , 5 - t e t r a c h l o r o- and 2,314,4v5 -
310
~'~. 3
- t e t r a c h l o r o d l p h e n y l ethers were syntheslsed by the Ponomarenko reaction which involves treal~nent of n i t r o compounds with tetrachloromethane a t elevated temperatures. Deactivated aromatic compounds u s u a l l y give high y i e l d s of products and the reaction may be used f or the synthesis of a number of s p e c i f i c a l l y c h l o r i n a t e d aromatic systems 32. Natsui e t a l . substt~ruted n i t r o and sulfur~/I groups f o r c h l o r i n e treal~nent with t h io n y l c h l o r i d e a t high temperatures33. F i n a l l y , exchange of n i t r o groups f or c h l o r i n e by the use of c h l o r i n e gas a t high temperatures have been described in a patent 36. Refs. 37-~9 contain data on a number of n i t r o - c h l o r o substituted diphenyi ethers which may be used In any of the above reactions f o r the synthesis of PDEs of known structure. F. Miscellaneous couplln Q reactions. The aryl ether synthesis described by Crowder et a l . 4 0 have been used f o r the synthesis of 2,4,4W-trlchlorodiphenyl ether by coupling of sodium 2~4-dichlorophenolate with 4 , 4 t - d i chloroblaryliodonlum c h l o r i d e l O . F l n a l l y , an octachlorodlphenyl ether of unknown structure were obtained when diphenyl sulphate was c h l o r ln a t e d in the presence of Iron In an attempts to synthesise 4 , 4 t - d i c h l o r o d l p h e n y l sulphate41.
In Table 1 is summarised data on c h l o r i n a t e d diphenyl ethers of known structure. Referantes t h a t give l i m i t e d information on synthetic procedures are given In parentheses. I f two synthetic methods have been used In a sequence t h i s Is Indicated with an arrow (A~B) while t~o Independent routes are separated by a comma (A,B). Acknowledgements. The technical asslstance by Mr. F. van der Wlelen and Mr. J. van der Steen i s gratefu I I y acknowl edged. REFERENCES. t. Firestone, D., Ressp J . , Brown, N.L., Barron, R.M. and Damico, J.N., J. Ass. Off. Anal. C.hemists, 5_~5, 85 (1972). 2. NIIsson, C.A. and Renberg, L., J. Chrornatog., 8_~9, 325 (1974). 3. Buser, H.R., J. ChromatoQ., 107p 295 (1975). 4. Hetcalf, R.L., J. Econ. Entomol., 41, 875 (1948). 5. Cross, H.F. and Snyder, F.M.,
Soap
Sanit. ChemLcals, 2__55, 135 (1949).
6. Blan#on, F.S.p J. N. Y. Entomol. Soc., 6..~1, 217 (1953). 7. Gersdorff, W.A. and Schechter, M.S.,
Soap Sanlt.
Chemlcal~, 24, 155 (1948).
8. Yana, A., Doc. Techn. Inst. Nat. Rech. A~ron. T u n l s l c . , No. 24, 1966. {Chem. Abstr., 70, 27933d (1969) }. 9. Neely, W.B., Branson, D.R. and Blau, G.E., Environ. Sci. Technol., 8, 1113 (1974). 10. NorstriSm, ~. , Andersson, K. and Rappe, C., Chemosphere, 1976, 21.
No. 5
311
11. Choudry, G., SundstrOm, G. and Hutzinger, 0., in preparation~ 12. Weingarten, H. and Schlsla, R.M., J. Or~. Chem., 27, 4103 (1962). 13. Brewster, R.Q. and Stevenson, G., J. Amer. Chem. Soc., 62, 3144 (1940). 14. Get. 1,139,847, Nov. 22, 1962. {Chem. Abstr., 58, P 11277c (1963)}. 15. Mailhe, A. and Murat, M., Compt. Rend., 154, 601 (1912). 16. D.R.P. 705,530, March 27, 1941. {Chem. Abstr., 36, 1946 (1942)}. 17. Denivelle, L., Fort, R. and Van 14oi, P., Bull. Soc. Chlm. France, 1960, 1538. 18. Hutzlnger, 0., Jamleson, W.D.J., Safe, S. and Zltko V.Z., J. A.ss. Off. Anal. Chemists, 5~6, 982 (1973). 19. U.S.S.R. 170,525, April 25, 1965. {Chem. Abstr., 63, P 13155e (1965.)}. 20. Voronkova, Z~V., Bessudnova, G.M. and Khvostov, J.V., Metody Pollychenlya Khlm. Reaktivov i Preparatov, 13, 49 (1965). {Chem. Abstr., 65, 5390e (1966)}. 21. U.S. 3,022,252, Feb. 20, 1962. {Chem. Abstr., 58, 7174e (1962)}. 22. Brit. 917,950, Feb. 13, 1963. {Chem. Abstr., 59, 5078d (1963)}. 23. Engelsma, J.W. and Y ~ l j ~ n ,
E.C., Rec. Trav. Chlm., 80, 526 (1961).
24. Roberts, R.E. and Soper, F.G., J. Chem. Soc., 1932, 1979. 25. Babln, E.P., Skavlnskll, Y.P., Andrukhov, N.A., Sedlove, L.N., Lltoshenka, N.A. and Rudavskil, V.P., Khlm. Tekhnol. (Kiev), 1973, 48. {Chem. Abstr., 7_~9, 78259s (1973)}. 26. Ulln~nn, F. and Sponagel, P., Bar., 38, 2211 (1905). 27. Netb. Appl. 6,512,264, March 22, 1966. {Ch.em. Abstr., 65, PC I0530f (1966)}. 28. Neth. Appl. 6,512,286, March 22, 1966. {Chefn. Abstr., 65, PC 7104h (1966)}. 29. Fr, 1,514,721, Feb. 23, 1968. {Chem. Abstr., 70, I~ 77449f (1969)}. 30. Fr. 1,576,298, July 25, 1969. {Chem. Abstr., 722, P 79667r (1970)}. 31. Brit. 912,340, Dec. 5, 1962. {Chem. Abstr., 5_~8, 11280b (1963)}. 32. Sundstr~m, G., Chemosphere, 1976, 191. 33. Matsul, K., Oda, K. and Seino, J . , Yuki Gosei Ko~aku Kyokal Shl, 1_~4, 401 (1956). {Chem. Abstr., 51, 10415f (1957)}. 34. Wakabayashi, S. and Matsubara, Y., Nippon Kagaku Zasshi, 80, 1179 (1959). {Chem. Abstr.,
55_, 4420e (1961)}. 35. Cadogan, J . I . G . and Molina, G.A., J. Chem. So<;. Perkln Trans. I . , 1973, 541. 36. U.S. 3,072,728, Jan. 8, 1963. {Chem. Abstr., 58, P 11277a (1963)}. 37. Groves, L.G., Turner, E.E. and Sharp, G . I . , J. Chem. Soc., 1929, 512.
38. Raiford, L.C., Thlessen, G.W. and Werner-r, I . J . J .
Amer. Chem. Soc., 52, 1205 (1930).
39. Dahl9ard , Iq. and Brewster, R.Q, J. /~e.r . Chem.. Soc., 80, 5861 (1958). 40. Crowder, J.R., GIover, E.E., Grunden, M.F. and Kaempfen, H.X., J. Ch.em.. Soc., 1963, 4578. 41. B o l l l n g e r , J . L . , B u l l . Soc. Chim. France, 1948, 156. 42. Surer, C.M. and Green, F.O., J. Amer. Chem. 5oc., 59, 2578 (1937). 43. Sanesi, M., Gazz. Chim. I t a l . ,
86, 1246 (1956).
44. Sperry , J . A . , U.S. Dept. Corn.r O f f i c e Tech. Ser~., PB Rep?. 145, 953 (1959). {Chem. Abs?r., 58, 45924 (1963)}. 45. U.S. 3,110,08}, Nov. 12, 196}. {Chem. A b s t r . , 60, 28469 (1964)}. 46. Fr. 1,327,189, May 17, 196}. {Chem. A b s t r . , 59, P 12709b (1963)}. 47. Le F~vre, R.J.W., Saunders, S.L.M. and Turner', E.E., J..Chem. ' Soc., 1927, 1168. 48. D.R.P. 673,522, March 25, 19}9. (Chem. A b s t r . , 33, 6342 (1939)}.
l'ergmaon l ~ e s s .
}h'inted i n Great B r i t a i n .
THE SYNTHESIS OF CHLORINATED DIPHENYL ETHERS G. S u n d s t ~
and O. H u t z i n g e r
L a b o r a t o r y o f Environmental Chemistry, U n i v e r s i t y o f Amsterdam, Nieuwe A c h t e r g r a c h t 166, Amsterdam, The N e t h e r l a n d s .
(Received i n UK for p u b l i c a t i o n 23 August 1976)
In o u r s t u d i e s on t h e c h e m i s t r y and environmental behaviour of I n d u s t r i a l
products s i m l l a r
t o compounds which have caused environmental problems, such as PCBs ( p o l y c h l o r l n a t e d b i p h e n y l s ] and PBBs ( p o l y b r o m l n a t e d b l p h e n y l s ) , we have surveyed the l i t e r a t u r e
on p o l y c h l o r l n a t e d d i p h e -
nyl e t h e r s (PDEs). PDEs have been t h e s u b j e c t o f a l a r g e number o f p a t e n t s and have been suggested f o r uses s i m i l a r t o those o f PCBs and PBBs. This i n c l u d e s use as flame r e t a r d a n t s , e l e c tric
insulators,
plastlclsers,
l u b r i c a n t s and as h y d r a u l i c f l u i d s
- a l t h o u g h we do n o t know t o
what e x t e n t c h l o r i n a t e d diphenyl e t h e r s e r e used o r manufactured a t p r e s e n t . The s t r u c t u r a l
similarity
between PDEs and PCBs o r PBBs i n d i c a t e s t h a t any leakage o f such
compounds i n t o t h e b i o s p h e r e may cause s i m i l a r problems as w i t h t h e lat-ker p r o d u c t s r e g a r d i n g btoaccumulation etc.
I t has r e c e n t l y been shown t h a t PDEs are p r e s e n t as i m p u r i t i e s in f u n g i -
c i d a l and h e r b i c i d a l c h l o r o p h e n o l p r e p a r a t i o n s which may t h e r e f o r e be a source o f c o n t a m i n a t i o n w i t h PDEs1-5. A certain toxicity Io,-chlorinated
p o t e n t i a l o f PDEs t o organisms is I n d i c a t e d by t h e suggestions t o use
diphenyl e t h e r s as a c a r i c i d e s 4, m i t i c i d e s 5 and a g a i n s t l i c e 6 . PDEs may a l s o be
used as s y n e r g l s t s t o g e t h e r w i t h p y r e t h r i n s 7 o r p e s t i c i d e s o f both phosphate and c h l o r i n a t e d hydrocarbon t y p e 8. The b l o c o n c e n t r a t i o n p o t e n t i a l o f diphenyl e t h e r dlphenyl e t h e r were i n v e s t i g a t e d by Neely e t e l .
and 2 , 2 w , 4 , 4 t - t e t r a c h l o r o -
by c a l c u l a t i o n o f p a r t i t i o n
coefficients
tween nzoctanol and w a t e r and by measuring uptake and c l e a r a n c e r a t e s in t r o u t 9 .
be-
The t e t r e c h l o -
r o compound showed a b l o c o n c e n t r a t t o n f a c t o r o f a value s i m i l a r t o t h e very p e r s i s t e n t compound hexachlorobenzene. Furthermore,
i t was r e c e n t l y shown t h a t h i g h l y t o x i c c h l o r i n a t e d d l b e n z o -
f u r a n s are formed upon p h o t o l y s l s o f PDEs and may be a r e a c t i o n o f environmental s i g n i f i cance10, 11 As is ev.|dent from above t h e r e is very l i m i t e d data on both b i o l o g i c a l , chemical p r o p e r t i e s on PDEs. To f a c i l i t a t e
toxicological
and
s t u d i e s on t h e environmental beheviour o f PDEs we
have s y n t h e s i s e d • number o f pure PDEs and c o l l e c t e d data on s y n t h e t i c r o u t e s useful f o r t h e p r e p a r a t i o n o f c h l o r i n a t e d dlphenyl e t h e r s o f known s t r u c t u r e .
3o5
T h i s work is summarlsed below.
~o6
No. 5
SYNTHESIS OF CHLORINATEDDIPHENYL ETHERS. A. Direct c h l o r i n a t i o n of dlphenyi ether. The d i r e c t c h l o r l n a t l o n of diphenyl ether
have been Investigated by Welngarten and
Schisla using tetrachloron~thane as solvent with SnCl4, FeCI3 or AIBr5 as c a t a l y s t s or a c e t i c acid without c a ~ l y s t s 12. S u b s t i t u t i o n i n i t i a l l y
occurr in the 2- and 4 - p o s i t i o n s and unsub-
s t i t u t e d dlphenyl ether, 2 - c h l o r o - and 4-chlorodiphenyl ether give the 2,2 B-, 2,4 t- and 4,4 TM •d l c h l o r o compounds as major products. 2-Chloro- and 4-chlorodiphenyl ether also give traces of the 2 , 4 - d i c h l o r o Isomer and from the 2-chioro ~ o u n d
also traces of 2,6-dichiorodiphenyl
ether was detected. No traces of a 3p4-dichlorosubstituted ether was found as claimed by Brewster and Stevenson 13. Further c h l o r i n a t i o n of diphenyl ether give good y i e l d s of 2,2t,4,4W-tetrachlorodlphenyl 10 ether, unambiguously s t r u c t u r a l l y determined by Norstr~n e t a l . although o r i g i n a l l y being. claimed to be the 2 , 2 t , 6 , 6 t - t e t r a c h l o r o isomer 14. The c h l o r i n a t i o n reactions are usually performed in the presence of a solvent (CCI410"14'15 or HOAc13) and often without c a t a l y s t s when low-chlorinated dlphenyl ethers are to be synthesised. However, even in the preparation o f oct~-, and decachlorodipbenyl ethers solvents may be used, b o i l i n g tetrachloromethane16 and b o i l i n g t e t r a c h l o r o e t h y l e n e17. Decachlorodlphenyl ether can also be obtained by treatment of diphenyl ether with the ~
reagent (S02Cl2-AICl3-S2Cl2)18.
I n d u s t r i a l c h l o r i n a t i o n processes are mostly performed without solvent and except f or c h l o r i n e only s u i f u r y l c h l o r i d e seem to have used as c h l o r i n a t i n g agent 19.20. I t has been c l a i med t h a t the usual r a t i o of p a l l to ortho s u b s t i t u t i o n of 4:1 obtained upon monochlorinatlon of diphenyl ether can be increased to 9:1 by not using solvent or c a t a l y s t 21. Increased amounts o f meta ison~rs (64-80~) can be obtained by heating the c h l o r i n a t i o n mixture with alumlum chlorideZZ or by c h l o r i n a t i o n in the gas phase23. The rate of c h l o r i n a t i o n of diphenyl ether In chiorobenzene s o l u t i o n has been examined but no products were i d e n t l f i e d 24. A number of highly c h l o r i n a t e d ethers have been syntheslsed by d i r e c t c h l o r i n a t i o n but since no structures were assigned these compounds have not been included in Table 1 below 16~25 B. The Ullmann ether synthesis and m o d i f i c a t i o n s . The c l a s s i c a l UIImann ether synthesis -coupling of phenol s a l t s with halogenated benzenes in the presence of copper c a t a l y s t 26- have been used f o r the preparation of a number of chloro substituted diphenyl ethers (cf. Table 1). O r i g i n a l l y the reaction was performed without s o l vent but recent m o d i f i c a t i o n s successfully employ the use of h l g h - b o i l i n g solvents such as d i glyme 27,28 and dimethyl sulfox.ide29p30. In the former solvent Cu2CI2 and KI were used as c a t a l y s t s while no c a t a l y s t s were used when the reaction was performed in dimethyl s u l f o x i d e s o l u t i o n . Copper and mercury have been used as c a t a l y s t s in the synthesis of 4-chiorodlphenyl ether from 4-chlorobromobenzene and phenol in the absence of base31 • In the synthesis of two pentachlorodJphenyi ethers we used the m o d i f i c a t i o n of the Ulimann ether synthesis using diglyme as solvent to obtain 2 , 4 - d i n i t r o - 2 V , 4 t , S t - t r i c h l o r o - and 3,4-dinitro-2W,4t,5~-trichlolnodlphenyl ether whereafter the n i t r o groups were substituted f or
2,4-
/,-
2-
0
~'~r-O-w~, ClI,I~I ll~J
'LP 'LP
Cl ,?~,,~O ~
B O
D E
B
A
D E
C
B
13 15 (4/,) (/,S) 30 (39) 42 {43) this work 32
42 (/,3)
(39) 42 (/,3) 13 13 this work 32 (36)
Ref.
n251.5982 /,6 this work oil cont.
oil oil
146-50(7) 2~-5(760) 140-2(7) 133-9(5) 133-9(5) %9~2(8) 161-2(19) 160(20)
155-6(20)
m
43.5 152-3(15) ~6.7-47.5 47-8 142-6(12) oil oil
Table 1. Knownchlorinated diphenyl ethers. Compound synthetic m.p. method k F (ram)
"+:
3,3r-
0,.~0.~::[
3,+-c,icroyb
Compound
Table 1. continued.
B
B
E
B
A,C
B
synthetic method
-10 113(0.5)
12 313(760)
31 170-/,(8) oil
377(76/,)
160-3(7)
306-7(762)
b.pm'~m)
cont.
28 28
27 27
2"/ (39) this work (36)
(36)
30
13
30
Ref.
%,,I D
2'/,'~" C l ~
Cl
Compound
I
0
0
"]3),C!
Table 1. continued.
F
B C
E
B
synthetic method 13 13 15
3O 168-72(7) ~-1~(760)
51 5&-5 183 51 51-2
oil
180-5(6)
oil
cont
38 10
(39) 37
this work
(36)
(39)
this
(20) 150-3(3) 310-2(760) (20) 30 27 30 (34 30
(19)
Ref.
b.;' ml
2~,~50
~"~Ci
0"~
I
0
0
.Fo.iF f ,
Cl" ~
22'kL O b
Compound
Table 1. continued.
132-3
oil
oil
oil n
68 70 205-7(12} 72 73-3.5 70-2
86-8
B~E oil a B~ B--E 65-6
B
D
c
D
B B~,E B~C
A
synthetic mefhod
cont.
32 33
29
this work
this work
this work
10 1/, (48) (~ (39) (~) (3/,)
Ref.
0 30
S,~. 5
309
Table 1. continued synthetic method
Compound 2,31k~5-
0
E[-"~ C[
m.p b.F (mm)
Ref
B-"E
oil a
32
B
36
139)
vii
2,Zt+,4:,6-
Q"+'~'f'Ct
v
EL
II ;I II :1 13~ (]."'~" deca- C I ~ O
~.,_.0
A
II . ' I I I
216
17
22t,.-5
18
n solidifies around roomtemperature.
c h l o r i n e by the Ponomarenko reaction (see below] 32. Two japanese groups synthesised diphenyl ethers with n i t r o and chloro substituents by coupling of chlorophenol s a l t s with 2 , 5 - d i c h l o ~ nltrobenzene whereby S l b s t l t u t i o n occurrs in the 2 - p o s i t i o n 33"34. C. The Sanda~yer reaction. A number of mainly low-chlorinated dlphanyl ethers have been synthesised by exchange of amino groups f o r c h l o r i n e via the Sandmeyer reaction (cf. Table 1). I t may be pointed out t h a t attempts in t h i s laboratory t o exchange amino groups in the p o s i t i o n ortho to the ether linkage f o r c h l o r i n e have been unsuccessful although the corresponding deaminatlon reaction via d l a z o t a t i o n have given good y i e l d s of products (see below). D. Deamlnatlon reactions. We have synthesised a number of c h l o r i n a t e d diphenyl ethers f r =
~rclally
available
amlno-chlorosubstltuted diphenyl ethers (Aldrich Cheen, Co.) by deamination v ia treatment with amyl n i t r i t e
in b o i l i n g tetrahydrofuran 35.
E. Miscellaneous s u b s t i t u t i o n reactions. Chlorine have been introduced Into the dlphenyl ether system by d i r e c t s u b s t i t u t i o n of n i t r o or sulfonyl groups. The 2 - c h l o r o - , 4-chloro-~ 2 , 2 t , 4 j 4 1 , 5 - t e t r a c h l o r o- and 2,314,4v5 -
310
~'~. 3
- t e t r a c h l o r o d l p h e n y l ethers were syntheslsed by the Ponomarenko reaction which involves treal~nent of n i t r o compounds with tetrachloromethane a t elevated temperatures. Deactivated aromatic compounds u s u a l l y give high y i e l d s of products and the reaction may be used f or the synthesis of a number of s p e c i f i c a l l y c h l o r i n a t e d aromatic systems 32. Natsui e t a l . substt~ruted n i t r o and sulfur~/I groups f o r c h l o r i n e treal~nent with t h io n y l c h l o r i d e a t high temperatures33. F i n a l l y , exchange of n i t r o groups f or c h l o r i n e by the use of c h l o r i n e gas a t high temperatures have been described in a patent 36. Refs. 37-~9 contain data on a number of n i t r o - c h l o r o substituted diphenyi ethers which may be used In any of the above reactions f o r the synthesis of PDEs of known structure. F. Miscellaneous couplln Q reactions. The aryl ether synthesis described by Crowder et a l . 4 0 have been used f o r the synthesis of 2,4,4W-trlchlorodiphenyl ether by coupling of sodium 2~4-dichlorophenolate with 4 , 4 t - d i chloroblaryliodonlum c h l o r i d e l O . F l n a l l y , an octachlorodlphenyl ether of unknown structure were obtained when diphenyl sulphate was c h l o r ln a t e d in the presence of Iron In an attempts to synthesise 4 , 4 t - d i c h l o r o d l p h e n y l sulphate41.
In Table 1 is summarised data on c h l o r i n a t e d diphenyl ethers of known structure. Referantes t h a t give l i m i t e d information on synthetic procedures are given In parentheses. I f two synthetic methods have been used In a sequence t h i s Is Indicated with an arrow (A~B) while t~o Independent routes are separated by a comma (A,B). Acknowledgements. The technical asslstance by Mr. F. van der Wlelen and Mr. J. van der Steen i s gratefu I I y acknowl edged. REFERENCES. t. Firestone, D., Ressp J . , Brown, N.L., Barron, R.M. and Damico, J.N., J. Ass. Off. Anal. C.hemists, 5_~5, 85 (1972). 2. NIIsson, C.A. and Renberg, L., J. Chrornatog., 8_~9, 325 (1974). 3. Buser, H.R., J. ChromatoQ., 107p 295 (1975). 4. Hetcalf, R.L., J. Econ. Entomol., 41, 875 (1948). 5. Cross, H.F. and Snyder, F.M.,
Soap
Sanit. ChemLcals, 2__55, 135 (1949).
6. Blan#on, F.S.p J. N. Y. Entomol. Soc., 6..~1, 217 (1953). 7. Gersdorff, W.A. and Schechter, M.S.,
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No. 5
311
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