CA1043795A - Aromatic bis(etherimide)s and method for making aromatic bis(ether anhydride)s therefrom - Google Patents

Abstract

Abstract of the Disclosure Aromatic bis(ether anhydride)s can be made by a nitro displacement of an N-substituted nitrophthalimide with ? alkali diphenoxide to produce an intermediate aro-matic bis(etherphthalimide). Hydrolysis of the aromatic bis(etherphthalimide) to the corresponding tetra-acid salt followed by acidification and dehydration, results in the production of the aromatic bis(ether anhydride). These anhydrides can be used as intermediates for making poly-imides. The intermediate aromatic bis(etherphthalimide) can be employed as a plasticizer in polyimide resins.

Description

379:~
RD - 5 7 2 0 .
AROMATIC BIS(ET~ERIMIDE)S A~ID METHOD FOR MAKING
` AROMATIC BIS (El~IER ANHYI)RIDE) S THI~REFROM _ ~ .
.
`~ The present invention relates to a method for JI making aromatic bis(ether anhydride)s from N-substi~uted nitrophthalimides by a nitro displacement reaction with :~
`~i bisphenolate, followed by phthalimide ring openings to the .:
~ 5- tetra acid salt, acidification, and subsequent dehydration.
; ,' The intermediate aromatic bis(etherimide) is also provided. `~
~ - The aromatic bis(ether anhydride)s which can be .; . .
made by the method of the present invention have the follow~
ing formula, .
.~: O
... " "

lC (I) O~ ~O-R-O~( O

:. . - .1. :
0 ;~
';, ~ .
; where R is a divalent aromatic radical having from 6-30 ` carbon:atoms.
In accordance with the present invention the -:
aromatic bis(ether anhydride)s of formula~(I) can be made :~ 15 by (1~ effecting nitro displacement of a nitrophthalimide ;~
of the formula, ~' . :
;II) N02~ _R1 6~ :
. . .
"'' ~b .

3`7~
RD-5720 - ~ :
with an alkali diphenoxide of the formuia, (III) M-0-R-0-M
to produce an intermediate aromatic bis(etherphthalimide),

(2) hydrolyzing the aromatic bis(etherphthalimide) with base to produce a tetra-acid salt, (3) acidifying the tetra-acid salt to produce the tetra-acid, and (4) dehydrating `.~ the tetra-acid to the aromatic bis(ether anhydride) where ....
R. is as~previously defined, M is a metal ion of an àlkali ~ :
~ metal selected from the class consisting of sodium, potas-`i 10 sium, lithium, etc., and Rl is a monovalent organo radical ':! selected from the class consisting of C(l 8) alkyl radicals,ar : organic radicals having from 6-20 carbon atoms,selected from the class conslsting of aromatic hydrocarbon radicals and ~
halogenated derivatives thereof. ~ ~ .
15 : Radicals included by R are more particularly -~
~Y 3 ~Br ~H3 Br Br , and -< O } C(CH3)2 . . . CH3Br Br CH3 Br Br . . .

''' Q~ ' '., , :, . . . ' , 7~?

and (b) divalent organic radicals of the general formula ' where X is a member selected from the class consisting of ~~
O :~
~,~ , .................................. .. .
divalent radicals of the formulas, -CyH2y~, -C-, -S-, -0-, O
and -S-, where m is 0 or 1, y is a whole number from 1 to 5.
Radicals included by R are, for example, phenyl, tolyl, xylyl, naphthyl, chlorophenyl, bromonaphthyl, etc., and alkyl radicals such as methyl, ethyl, etc.
The nitrophthalimides o formula II can be made ~i 10 by effecting reaction between substantially equal moles of J~ nitrophthalic anhydride of the formula, '~1 0 :-i~ 11 .

~2 ~ \ ' ~` ' and an organic amine, R NH2, where R i5 as previously defined in the presence of refluxing acetic acid. Included ~s 15 by such organic amines are, for example, aniline, toluidine. ;;
etc., methylamine, ethylamine, etc. Nitrophthalimides in-., ~
cluded by formula (II) are, for example, N-phenyl-3-nitro~
, phthalimide, N-phenyl-4-nitrophthalimide, ~-methyl-3-nitro-phthalimide, N-butyl-4-nitrophthalimide, etc.

-3-' , : , ~ RD-5720 ; A signîficant feature of the present invention is that a nitrophthalimide of formula (II) and an alkali ' diphenoxide of formula (III) can be reacted at from 5C
'. . to 100C and preferably ambient to 70C to produce the corresponding aromatic bis(etherphthalimide) i~termediate.
This result is quite surprising in view of the teaching of Lyman R. Caswell in the Robert A. Welch Foundation Annual Report, Houston, Texas (1970), on page 58, which suggests a .~ significant difference between the reactivities o~ 3- and

4-nitro-N-substituted phthalimides with sodium methoxide.
; A further advantage of the present invention is demonstrated .. , , ~ .
.' by the teaching of German Offenlegungschrift 2,155,431, showing that temperatures o at least 150C arP required to couple N-substituted 4-chlorophthalimides with alkali metal ;~
dihydroxy cyclic compounds where as indicated above, ~he '~ method of the subject mvention allows for tempera~ures as low as 5CC.
Included ~y the aromatic bis(ether anhydride)s of formula (I), are compounds selected from : .
'. O O
.. . .

(IV) ~ o-~- ~ / ~

., .
' O O

' ~

~ RD-5720 .
, O O ::
~. " "

(V) \C/~ ~\C/
0-R- o ~` O O
.. ..
C C
~: , ,~J o~\ / ~ ~ ~

(VI) ,, 0 R C

where R is as previously defined. These dianhydrides can be employed to make polyetherimides which can be injection `~ 5 molded to useful products. "
~!; Included by the alkali metal salts of the above `~ described alkali diphenoxides of formula (I) are sodium ~ and potassium saIts of the following dihydric phenols :~
;3 :~ 2,2-bis-(2-hydroxyphenyl)propane;
2,4'-dih~droxydiphenylmethane;

bis-(2-hydroxyphenyl?methane;
2,2-bis-(4-hydroxyphenyl)propane hereinafter identified as "bisphenol-A" or "BPA";
bis-(4-hydroxyphenyl)ethane;
.~ . 15 1,1-bis-(4-hydroxyphenyl)propane;
2,2-bis-(4-hydroxyphenyl)pen~ane;
3~3_bis_(4-hydroxyphenyl)pentane;

4,4'-dihydroxybiphenyl;

-5-:

. ~ .

, .... ,. . . . . ~ _ .

7~3~
. RD-5720 4,4'-dihydroxy-3,3,5,5'-tetramethylbiphenyl;
2,4'-dihydroxybenzophenone;
4,4'-dihydroxydiphenylsulfone;
2,4'-dihydroxydiphenylsulfone;
4,4'-dihydroxydiphenyl sulfoxide;
4,4'-dihydroxydiphenyl sulfide; - :
hydroquinone;
resorcinol;
- . 3,4'-dihydroxydiphenylmethane;
`; 10 4,4'-dihydroxybenzophenone; ~
: and 4,4'-dihydroxydiphenylether. . ~ .
. In the practice of the invention, reaction is ~ :~
effected between the nitrophthalimide, or "nitroimide"
of formula II, and the alkali di.phenoxide or "diphenoxide"
15~ to produce an aromatic bis(etherphthalimide) or "bisimide".
,, i The bisimide is thereafter hydrolyzed with base to the tetra-:~ acid sal~, which is thereafter acidiried to the tetra-a¢id;
,,..................................................................... :
. the tetra acid can then be dehydra~ed to the corresponding ., aromatic bis(ether anhydride) or "bisanhydride" of formula I.
. 20 Reaction between the nitroimide and diphenoxide :
'! to produce the bisimide can be effected under an inert gas -~ atmosphere such as nitrogen at 5C to 100C under substan-:~ tially anhydrous conditions and in the presence of dipolar aprotic organic solvent such as dimethyl sulfoxide, N,N~
dimethylformamide, N-methylpyrrolidine, N,N-dimethyl- :
::`
.
~ -6- : .

~(3~'7~ ~
~-5720 -~ acetamide, etc. Mixtures of such solvents with non-polar solvents such as toluene, chlorobenzene, etc. also can be employed. Reaction time can vary between one minute to 100 minutes or more depending upon temperature, degree of agitation, etc. A proportion of from 1.8 to 2 5 moles of nitroimide, per mole of diphenoxide can be used.
Hydrolysis of the bisimide to the tetra-acid salt ~ -can be effected under reflux conditions in the presence of ;i a base sùch as an a1kali hydroxide, for example, sodium hydroxide, etc. Reaction time can vary from 1 to 24 hours or more depending upon reactants, degree of agitation, tem-s perature, etc. The organic amine by-product can be removed by standard procedures, such as steam distillation, etc.
~ . .
In addition, the rate of hydrolysis is greatly accelerated by carrying out the reaction at above atmospheric pressures at temperatures in the range of from 100 to 220C.
The tetra-acid salt can thereafter be acidified - with a mineral acid, such as a dilute aqueous solution of t` hydrochloric acid, etc. The resulting tetra-acid can be dehydrated by s~andard techniques. For example, refluxing , with a dehydrating agent such as acetic~anhydride, etc. the dianhydride can be recrystallized by standard procedures.
In order that those skilled in the art will be better able to practice the invention, the following : 25 examples are given by way of illustration and not by way .. , ;~ -7-:: .
- ~ .

` ' ' ' ' ~ ' ' ' `

~ 3 ~ ~ RD-5720 of limitation All parts are by weight.
e 1 A mixture of 2.28g (0.01 mol) of bisphenol-A, 30 ml of dimethylsulfoxide, 10 ml of benzene, and 0 8 g ~ -of sodium hydroxide as a 50% aqueous solution was stirred ~
, ::
; and heated to reflux in a nitrogen atmosphere over a Dean Stark trap for 5 hours. The benzene was distilled until the temperature of the reaction mixture exceeded 145C and the mixture was cooled to 15C. Then 5.36g (0.02 mol) of N-phenyl-3-nitrophthalimide and 20 ml of dimethylsulfoxide were added. The solution was stirred for 30 minutes at room temperature and 30 minutes at 50C, cooled, and added ~ ~;
`~ to 600 ml of water. The gummy solid which separated was extracted into methylene chloride and the organic solution dried with sodium sulfate, filtered, and evaporated to leave an oil. The oil solidified when slurried with hot ethanol to give 5.6g (84% yield) of crude product. Recrys-tallization from acetonitrile gave fine white needles melt-ing at 187 188.5C. Anal. Calcd. for C43H30N2O6: C, 77.0;
H, 4.47; N, 4.18. Found:~C, 77.1; H, 4.6; N, 4.2. Based on the above preparation and elemental analysis, there was obtained 2,2-bis[4-(N-phenylphthalimid-3-oxy)phenyl]-., .
propane ~ A mixture of 81.5g of 2,2-bis[4-(N-phenylphthal-;i 25 imid-3-oxy)phenyl~propane, 200g of water and 160g of 50%
"' . .
: -8-: .
., ~ ' .

' , . ' .

7~ RD-5720 ; sodium hydroxide was stirred at reflux for 12 hours. The mixture was steam distilled for 3 hours and then 250g of water were added and steam dis~illation was continued for 2 hours. Acidification of the homogeneous residue with S hydrochloric acid caused the product to precipitate. The material was isolated by filtration and dried There was obtained 66.7g of crude product. Anal. Calcd. for C31H2401o: C, 66.9; H, 4.3. Found: C, 64 4; H, 4.5.
` Based on the above method of preparation and elemental analysis, there was obtained 2~2-bis[4-(2,3-dicarboxyphenoxy)-i phenyl]propane.
A mixture of 45.9g of 2,2-bis[4-(2,3-dicarboxy-' phenoxy)phenyl]propane, 400 cc of glacial acetic acid and 25 cc of acetic anhydride was stirred at reflux for 3 hours. There was obtained 34.2g of an off-white solid ~,~ when the mixture was filtered. The product was recrystal-.~.. . . .
-~; lized from toluene/acetic acid to give 30.0g of white needles; m.p. 186-187.5C. Anal. Calcd. for C31H2008:
C, 71.5; 8, 4.1. Found: C, 71.4; H, 3.8. Based on method 2Q of preparation and elemental analysis, the product was 2,2-bis[4 (2,3-dicarboxyphenoxy)phenyl]propane dianhydride.
Example 2 ., :
A mixture of 29 8g (0 131 mol) of bisphenol-A, `
10 44g of sodium hydroxide in the form of a 50% aqueous solution, 250 cc of dimethylsulfoxide, and 66 cc of toluene ~ - .
:; _9 _ .
.; ~ ,.

r ~ , , .

~ 3~

; was stirred in a nitrogen atmosphere at reflux for 7 hours.
Final drying was effected by refluxing the toluene over a recirculating trap filled with calcium hydride The toluene was removed by distillation and the reaction mix-ture was cooled to 60C. Then 70.0g (0 26 mol) of N-phenyl-4-nitrophthalimide and 250 cc of dimethylsulfoxide were added; the resulting solution was stirred at 60C for 45 minutes. There was added 25 cc of glacial acetic acid;
the reaction mixtùre was then diluted with 1400g of water.
A fine solid separated; it was isolated by filtration, washed with water, and dried After recrystallization from acetonitrile and rom benzene there was obtained 44.4g , . .
of white needles, m.p. 214C Anal. Calcd. for C43H30N206:
C, 77.0; H, 4.51; N, 4.18. Founcl: C, 76 7; H, 4.5; N, 4.1.
S .Ba~ on method of prepara~ion and elemental analysis ~he ,:. .: . ' . .
product was 2,2-bis~4-(N-phenylphthalimid-4-oxy)phenyl~-propane.
~` A mixture of 60 2g of 2~2-bis~4-(N-phenylphthal- ~`
Xi - imid-4-oxy)phenyl~propane, 57.37g of an aqueous 50% sodium i ~
hydroxide solution, and 350 cc of water was heated for 25 ~; -hours at 160-175C under 150 psi pressure The mixture was then steam distilled for 45 minutes The aqueous residue was acidified with hydrochloric acid. A product separa~ed from the aqueous solution, which was washed with water and recrystallized from 50% acetic acid. There was obtained . .

:' ' 32 9g of product; m.p. 208 216C Anal Calcd..for C31H2401o: C, 66.9; ~I, 4.3. Found: C, 66 5; H, 4.4.
Based on method of preparation and elemental analysis, there was obtained 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl~
propane A mixture of 24 7g (0 05 mol) of 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane, 250 cc of glacial acetic acid, and 12 8g of acetic anhydride was stirred at reflux -for 2 5 hours The solution was concentrated on a rotary evaporator A white crystalline product separated on cool-. ing The product was isolated by filtration, washed with cold acetic acid, and dried in VclCUO. The material was recrystallized from a toluene/acetic acid mixture to give , j 20g of product, m.p. 187-190C. Anal Calcd. for C31H2008:
C, 71.5; H, 4.1. Found: C, 72.0; H, 3 8 Based on method of preparation and elemen~al analysis, the product was ;~ 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride.
Example 3 ~ A mixture of l.lOg (0.01 mol) of hydroquinone, ;:j 20 0.8g of sodium hydroxide as a 50% aqueous solution, 30 ml of dimethylsulfoxide, and 10 ml of benzene was stirred in t. a nitrogen atmosphere at reflux over a Dean Stark trap for ` 3 hours The benzene was removed by distillation until ,, the temperature of the reaction mixture exceeded 140C; the mixture was then cooled to 15C There were added 5 36g .~

., ., - - - ,~ ,"

~ 3 7~ ~ R~-5720 (0,02 mol) of N-phenyl-3-nitrophcllalimide, and 20 ml of dimethylsulfoxide, The solution was stirred for 20 minutes ; at 15-20C, 20 minutes at 30~C and for 20 minutes at 40C, After cooling the reaction mixture, there was added thereto 400 ml of water, A crude product was isolated by filtration, The crude product was dissolved in 700 ml of boiling ethyl-ene glycol and separated from the cold solution as fine white needles, The recrystallized product was dried in vacuo at 110C, There was obtained 3,8g (70% yield) of product9 m,p, 312 313C, Anal, Calcd, for C34H20N206: C, 73,9; H, 3,62; N, 5.07, Found: C, 73,8; H, 3,9; N, 5,0, . .; . .
~ Based on method of preparation and elemental analysis the :! product was 1,4-bis(N-phenylphthalimid-3-oxy)benzene.
A mixture of 54,2g of 1,4 bis(N-phenylphthalimid-,~ 15 3-oxy)benzene, 54,4g of a 50% aqueous sodium hydroxide ~h~ solution, and 100 cc of water was stirred at reflux for 24 hours, There was added with stirring at reflux an addi-~, tional 200g of water, The mixture was stirred for 2 more ,~ ~ days. The mixture was steam distilled, A product separated ~ 20 when the aqueous solution was acidified, The crude material '~ was isolated by filtration to give 46,4g of product. The product was then mixed with 55g of 50% sodium hydroxide and , 500g of water. It was heated at 180C for 2 hours under sealed conditions. Acidification of the cooled solu~ion 25 with concentrated hydrochloric acid gave 41,1g of crude ' ~ ' ' . . .
, ~ , .

Rl)-5720 '7~ ~
product. Recrystallization ~rom a 50/50 mixture of water-acetic acid gave 39.3g of white powder; m.p. 305-315C

The product was found to be the acetic acid adduct of 1,4-bis(2,3-dicarboxyphenoxy)benzene. Anal. Calcd. for ~ -C22H1401o 2CH3CoOH: C, 55 92; H, 3.97. Found: C, 56.0; -~

H, 4.1. Acid number: Calculated, 10.74 meq/g; Found, 10 4 meq/g A mixture of 39.3g (0.0901 mol) of 1,4-bis(2,3- -~ dicarboxyphenoxy)benzene, 400 cc of glacial acetic acid, i~ 10 and 25 cc of acetic anhydride was stirred at reflux for ~ 3 hours The solution was cooled and fil~ered. Based on ; ~ . . . ~
method of preparation, the product was 1,4-bis(2,3-dicarboxy-~ ~ phenoxy)benzene dianhydride.

;; Exampie 4 ~ 15 A series of bisimides were prepared in accordance -~i with the present invention by effecting the nitro-displace-ment of a nitrophthalimide of formula II, with an alkali diphenoxi~e of formula III. The bisimides were included by the foilowing-formula, .
', O O ~.:
C C '''' :~ 20 (VII) R N ~ ORO ~ / R

., " " .
,, O

~.

If ~

~ 3~ 79~ RD-5720 : where R and R are as previously defi.ned.
The ~ollowing tables show the bisimides prepared where R and Rl are as defined in Table 1 and the calculated values for the elemental analysis are shown in Table 2.

TABLE 1.
Properties of Bisimides m.p.
.~ R Rl I.S.* (C) . . ~
-~ (1) 1,4-Benzene n-Butyl 3 187.5 ,`1. ' ~ ' ', ~ (2~ 1,3-Benzene Phenyl 3 272 s 10 (3) 4,4'-Biphenyl Phenyl 3 34 5 ;i ~4) 4j4'-Biphenyl Phenyl 4 (5) 4~4l-Diphenylether Phenyl 3 239 5-4,4'-Diphenylether Phenyl 4 358 5 sulfide Phenyl 3 285 (8) 4,4'-D phenyl- Phenyl 4 230 (9) 2,2-Bis(4-phenyl)- n-Butyl 3 95-98 propane , 20 (10~ 2,2-Bis(4-phenyl)- n-Butyl 4 88-90 :
-~ propane ~ (llj 4,4'-Benzophenone Phenyl 3 236 5- ` ~ :

si propane Methyl 3 209 ~'J, 25 (13) 2~2-Bis(4-phenyl)- Methyl 4 129- ~ :
. propane ,. . .
* Isomeric Structure .
' ~ ,, ~.' . " . . . . , , , . . . ~

L~ 5 TABLE 2, Elemental Analysis of the Above Bisimides C H N S
(Calcd,) .
- 70.4 5.5 5.9 (1~ (70,3) (5,5) (5.5) ` (2) (73 9) (3 6) 5 0 ' 76,4 4.0 4,4 ^! (3) (76,4) (3,8) (4,5) ` (~) (76,4) (3,8) (4.5) `-~
5) 73,5 3,8 4,2 ~
(74.5) (3,8) (4-4) ~ ;
~' 10 (6) (774 5) (3 8) (44 4) 7 72,5 3,5 3,8 4.8 ( ) (72,7) (3,6) (4,2) (4.9) 8 72,7 3,8 4,3 ~.0 ( ) (72.7) (3.6) (4,2) (4.9) ;

(9) (74 3) (6 0) (~ 4) , (10) (74 3) (6,0) (4,4) (11) (75 o) (3 79 . ~ .
(12) (7722 6) (4 7) (5 1) (13) (722 56) (44 78) (5 1) The above bisimides can be employed as plasticizers for organic polymers such as polyvinylchloride, polyimides, `~f 20 etc; these bisimides can withstand oxidation at high temper-atures, '. "

'7aC~i~
Although the above examples are limited to only ~` a few of the very many bisimides which are provided by the ` present invention, it should be understood that the bis-imides provided by the invention are broadly shown by formula VII.
In addition to the dianhydride shown by the above .. ~ . . .
. examples, lt should be understood that the method of the invention broadly provides dianhydride shown by formula I, ~^?, `' ' ~ ' ` .... ,.:

~; ~
' ' ' ~'', s,- . :'~ :'' .~ , ~;.
. .

.

. ,~

,'~, ~' .

Claims (23)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method for making an aromatic-bis ether which comprises effecting the nitro displacement of a nitro-phthalimide of the formula, with an alkali diphenoxide of the formula, M-O-R-O-M
to produce a bis ether having the formula, in which formula R is a divalent aromatic radical having from 6-30 carbon atoms, M is an alkali metal ion, and R1 is a monovalent organo radical selected from the class con-sisting of organic radicals having from 6 20 carbon atoms selected from the class consisting of hydrocarbon radicals and halogenated derivatives thereof, and C(1-8) alkyl radicals.

2. A method in accordance with claim 1 where the alkali diphenoxide is selected from the diphenoxide of bisphenol-A and hydroquinone.

3. A method in accordance with claim 1 where R1 is selected from phenyl and methyl.

4. A method in accordance with claim 1 where M
is sodium.

5. A method in accordance with claim 1 wherein the nitrophthalimide is selected from N-phenyl-3-nitro-phthalimide, N-phenyl-4-nitrophthalimide, and mixtures thereof.

6. A method in accordance with claims 1, 2 or 3 including the step of hydrolyzing the bisimide with a base to produce the corresponding tetra acid salt.

7. a method in accordance with claim 4 or 5 including the steps of hydrolyzing the bisimide with a base to produce the corresponding tetra acid salt, acidifying the salt to produce the corresponding tetra acid, dehydrating said tetra acid to produce the corresponding diahydride.

8. A method in accordance with claims 1, 2 or 3 including the steps of hydrolyzing the bisimide with a base to produce the corresponding tetra acid salt, acidifying the salt to produce the corresponding tetra acid, dehydrating said tetra acid to produce the corresponding diahydride.

9. A method in accordance with claim 4 or 5 including the steps of hydrolyzing the bisimide with a base to produce the corresponding tetra acid salt, acidifying the salt to produce the corresponding tetra acid, dehydrating said tetra acid to produce the corresponding diahydride.

10. Bisimides included by the following formula where R is a divalent aromatic radical having from 6-30 carbon atoms, and where R1 is a monovalent organo radical selected from the class consisting of C(1-8) alkyl radicals and organic radicals having from 6-20 caxbon atoms, selected fxom the class consisting of aromatic hydrocarbon radicals and halogenated derivatives thereof.

11. An isomeric 3 bisimide in accordance with claim 10 where R is 1,4-benzene and R1 is n-butyl.

12. An isomeric 3 bisimide in accordance with claim 10 where R is 1,3 benzene and R1 is phenyl.

13. An isomeric 3 bisimide in accordance with claim 10 where R is 4,4'-biphenyl and R1 is phenyl.

14. An isomeric 4 bisimide in accordance with claim 10 where R is 4,4'-biphenyl and R1 is phenyl.

15. An isomeric 3 bisimide in accordance with claim 10 where R is 4,4'-diphenylether and R1 is phenyl.

16. An isomeric 4 bisimide in accordance with claim 10 where R is 4,4'-diphenylether and R1 is phenyl.

17. An isomexic 3 bisimide in accordance with claim 10 where R is 4,4'-diphenylsulfide and R1 is phenyl.

18. An isomeric 4 bisimide in accoxdance with claim 10 where R is 4,4'-diphenylæulfide and R1 is phenyl.

19. An isomeric 3 bisimide in accordance with claim 10 where R is 2,2-bis(4-phenyl)propane and R1 is n-butyl.

20. An isomeric 4 bisimide in accordance with claim 10 where R is 2,2-bis(4-phenyl)propane and R1 is n-butyl.

21. An isomeric 3 bisimide in accordance with claim 10 where R is 4,4'-benzophenone and R1 is phenyl.

22. An isomeric 3 bisimide in accordance with claim 10 where R is 2,2-bis(4-phenyl)propane and R1 is methyl.

23. An isomeric 4 bisimide in accordance with claim 10 where R is 2,2 bis(4-phenyl)propane and R1 is methyl.