CA1043042A - Aromatized polyacetylenes - Google Patents

Abstract

AROMATIZED POLYACETYLENES

Abstract of the Disclosure Polyacetylenes, either homopolymers or copolymers, are rendered more soluble and/or more thermally stable with-out destroying their film-forming properties and with minimal decrease in their high carbon content by reacting them:with one or more 2,3,4,5-tetrasubstituted cyclopenta-diones commonly called tetracyclones. These latter compounds, together with the acetylenic groups of the polymer, undergo a cyclization reaction to produce a 3,4,5,6-tetrasubstituted 1,2-phenylene moiety in the polymer backbone. Because of their high thermal stability these polymers are especially useful as binders for graphite fibers in making grap hite composites or to produce films or coatings for high temperature applications.

Description

1~4304~Z
AROMATIZED POLYACETYLENES

This invention relates to aromatized poly-acetylenes, i.e., polyacetylenes, either homopolymers or co-I ~ polymers of diethynyl co~lpounds, wherein at least 15 percent of the ethynylene groups of the polymer have been converted to 3,4,5,6-tetrasubstituted 1,2-phenylene groups by reaction with a 293,4,5-tetrasubstituted cyclopentadienone, herein-- after called by the commonly abbreviated name - a tetracyclone. More particularly, this invention reIates to polymers whose repeating units have at least one of the formulae: ;
.

(a? ~C - C-R-C -C~
~ -. _ ~ R-C -C- _ (b) - R" R"

R - ~ ~
(c) ¦R;_ ~ -R' R~ R' L R R R" R"

of which no more than 85% have formula (a)9 where each R is the residue other than the ethynylene groups of a solvent soluble acetylenic polymer whose repeating units have formula (a), each R~, independently~ is lower alkyl, lower ~k O

alkoxycarbonyl, phenyl or halophenyl and each R", independently, is phenyl or halophenyl.
Polyacetylenes are relatively new polymers having many interesting and desirable properties. They were first described by Allan S. Hay in J. Org. Chem. 25, 1275 (1960) and 27, 332~ (1962). Subsequently, a much broader class of polyacetylenes was disclosed and claimed in Hay's U.S. patents 3,300,456, 3,332~916 and 3,594,175. Using Hay's process of oxidatively coupling compo~nds having two acetylenic groups, Sladkov et al. likewise prepared polyacetylenes which they described in BU11. Acad. Sci.~ U. S . S . R. ~ Div . Chem. Sci., English Translation [7] 1220 (1963). All of these polymers and copolymers described in this prior art have, as a common property, a butadiynylene group, i.e., -C= C-C -C-, dispersed along the polymer backbone~ They also ha~e in common the fact that they are formed by oxidatively coupling of organic compounds having two ethynyl groups, i.e., -C-- CH In the , ; oxidative coupling reaction, thoroughly described by Hay in his above patents and publications, the hydrogen is removed from ~he ethynyl groups by the oxidation reaction ~o form water ~nd one of the resulting ethynylene groups o~ one molecule is joined to one of the resulting ethynylene groups of another molecule to form the butadiynylene~groups of the .
polymer molecule, It is these latter groups which cause the polymers to be vPry thermally unstable and photosensitive and .

.

~43UD4,Z RD~5683 which tend to make the polymer difficulty soluble in common solvents for polymers.
It is obvious that these polyacetylenes are entirely different in kind than polymers containing isolated i!\ ~ ethynylene groups in the polymer molecule. Typical of such polymers are the polyesters obtained by esteriication of an acetylene dicarboxylic acid and a glycol or esterification of a polycarboxylic acid with an alkynediol and polyethers obtained by the reaction of acetylenic glycols with dialkyl acetals or with alkyl halohydrins. These polymers have ethynylene, but not butadiynylene groups, along the polymer backbone. Such polymers are not included in ~he term poly-.
acetylenes.

~ Hay, in his above patents, describes uses for the polyacetylenes which make use of their thermal instability, e.g., coating a substrate with a solution of the poly-.

acetylene and thereafter thermally decomposing the coating under controlled conditions to obtain a resistor of the desired electrical properties. In his U.S. patent 39594,175, he describes a means of increasing the sol~bility in common solvents by either making the polyacetylenes from dipropargyl ethers of dihydric phenols or copolymerizillg ~he diethynyl compounds with the dipropargyl ethers. In the same patent he also describes the very interesting application for the polyacetylenes which make use of their photosensitive 1043~4Z ~
properties.
CoM~ Krutchen, in hls Canadian application, Serial No.l26,040, iled October 26, 1971, describes means for converting the polyacetylenes into fibers which are there-after, because of their thermal instability, readily converted into carbon or graphite fibers. Because of the extremely high carbon content and because the thermal decomposition can be carried out in a controlled fashion, the polyacetylenes are readily converted into carbon and graphite fibers ln a higher yield and by a more rapid process than can the usual organic polymers previously used for making carbon and graphite fibers. In my Canadian- application, Serial No.
; 1330623, filed February 1, 1972, I disclose a particular terpolymer suitable for making the carbon and graphite fibers.
As this prior art shows, thQre are many uses and interesting applications for the polyacetylenes. However, because of the extremely high carbon content, it would be especially desir-able if polymers could also be prepared having this same high carbon content but not possessing the thermal instability.
It has been known for a long time that tetracyclones would react with simple compounds containing one or two ethynylene groups. Dilthey et al., ChemO ~er. 689 1159 (1935), describes the reaction of tetraphenylcyclone with diphenylbutadiyne to give 2,3,4,5,6-pentaphenyltolane~ i.e., the tetracyclone reacted with one but not both of the 1043Q4~ RD 5683 ethynylene moieties of the butadiynylene group. Ried et al., Chem. Ber. 93, 1769 (1960) likewise reacted tetracyclon s with diphenylbutadiyne and obtained correspondin~ tolanes.
However, the same tetracyclones when reacted with compounds containing two ethynylene groups separated by an intervening carbon chain3 for example, an aromatic compound having two ethynyl groups on different carbon atoms of the aromatic ring could both be reacted with the tetracyclone. This was also reported in a review article on the chemistry of cyclopenta-dienones by Ogliaruso et al., Chem. Rev. 65, 261 (1965) on page 337. However, in a later paper with Becker? J. Org.
Chem. 309 3354 (1965) 7 Ogliaruso reported that when heated in a sealed tube to 325, two moles of tetraphenyl-cyclone could be reacted with one mole of diphenylbutadiyne to produce the corresponding octaphenylquaterphenyl.
Ogliaruso et al~ in J. Org. Chem. 28, 2725 (1963) had prepared bistetracyclones and reacted them with two moles of a compound containing one ethynylene group. Ried et al.
in an extension of their work mentioned above, reported the fi~rst preparation of a-polymer by reacting a bistetracyclone with a diethynyl benzene in Naturwiss. 53, 30~ (1966).
Stille and coworkers likewise reported the making of polymers from bistetracyclones and diethynyl compounds in J. Polym.
Sci. A-l, 5, 2721 (1967) and extended this work to include the polymers from bis-2-pyrones and diethynyl compounds in -1043~2 RD-5683 Macromol. 2, 85 (1969). A review of the work on the cyclization of unsaturated compounds is found in a review article on polyphenyls and polyphenylenes by ~peight et al.
in Rev. Macromol. Chem. 6, 295 (1971) beginning on page 354.
Although these polymers had the desired very high carbon content, solubility in ordinary solvents and thermal stability, they suffer from the fact that the required bis-tetracyclones or bispyrones are extremely expensive since they cannot be prepared from readily available materials Al~hough many materials are known to readily react with the ethynylene groups, I have unexpectedly found that the tetra-cyclones form a unique class of compounds that can be reacted with the polyacetylenes to produce thermally stabla, solvent soluble polymers. Although the other materials will .
react with the polymers, only crosslinked materials are obtained. This is true even for pyrones ~inich is surprising in view of the fact that bispyrones could be used to make polymers from diethynyl comp~unds. Materials which I have tried to react with polyacetylenes include: anthracene, phenanthrene, 2,4-diphenyl furan, l,~-diphenylbutadiene, 1,6-diphenylbutatriene, hexachlorocyclopen~adiene, coumarin, a-carboethoxypyrone, ~-carboethoxy ~-phenylpyrone, 2-pentyl-3,4-dLphenylcyclopentadiene dimer~ 2-meth~ 3,4-diphenyl-cyclopentadiene dimer. It will be noted that even ~icyclones could Rot be used in place of the tetracyclones, even though ; -6-: .

109~3~L2 in ~oth cases the dimer depolymerizes during heating to the monomer.
Since the cyclization reaction by which my polymers axe formed involves only one or both ethynylene moieties of the butadiynylene groups, I can use any of the solvent-soluble acetylenic polymers of the prior art.
Thus, for example, any of the acetylenic polymers disclosed in the above-mentloned literature and patent references will be found to be generally suitable for conversion to the corresponding aromatized polymer by reaction with tetracyclone. For example, Hay in his U.S. patent 3,300,456, discloses polyacetylenes corresponding to the formula, H~ C- C-R-C--C ~ H
wherein n is an integer representing a number of repeating units joined together to form a polymer molecule and is at least two but usually represents a value of at least 10 and is more probably at least 50 and the hydrogen atoms are on the terminal ethynylene groups of the polymer molecule, and R is a divalent organic ; radical which can be an aliphatic or aromatic radical wherein ~ne or more of the hydrogens of the aliphatic or aromatic nucleus has been substituted by, for example, O O O O
~, ~1 ,1 11 .
example, halogen, -OH, -OR, ~O-C-R, -C-OR, -C-R, -C-NEI2, O O
Il ~I
-C-NHR, -C-NR2, -CN~ -SH, -SR, -SSH, -SSR, -SOR, -N02, -S02R, -NH2, -NE~R, -NR2, etc. In all of the above ~or~lulas, R may ;;

be a monovalent organic radical such as defined above. From a practical standpoint of being readily available at a reasonable C08t, the polymers are general'y polymers of diethynylalkanes or diethynylarenes~ preferably diethynyl-benzenes, diethynylbiphenyls, bis(ethynylphenyl)ether, etc.
Hay, in his patent 3,3329916, discloses heteroatom containing acetylenic polymers having the formula, H f ~ H
- C-RI-C- C t M-C -C-R'~C _C ~ J

. . m where M is a polyvalent radical selected from the group con-sisting o~ -Hg-, ~,TlR-, ~Si(R)2, -Ge(R)2, -Sn(R)2, -Pb(R)2, -PR, -~sR, -SbR, -BiR, -S~9 -Se-, -Te-, -Ni(AsR3)2,

2 , (S R3)2~ Pd~AsR3)2s -Pd(PR3)29 -Pd(SbR3) ~Pt(AsR3~2, -Pt(PR3)2 and -Pt(SbR3)2, where R is a monovalent hydrocarbon radical, R' is a divalent hydrocarbon radical, : 15 and n is a positive integer and is at leas one and m is a positive integer and is at least two. Here again, from a practical s~andpoint, R' is generally alkylene, preferably lower alkylene or arylene, preferably phenylene.
The polyacetylenes disclosed by Hay in his patent

3,594,175 have one of the formulas (a) H~ c~t~cH2o~ t-ocH2~ c 3c~ H
; m m n -~o~

where m is one of the integers O and l; n is an integer and is at least 10 and R is selected from the group consisting of arylene, including lower alkyl substi~uted arylene, halo-arylene~ including lower alkyl substituted haloarylene, and, 5 in addition, when m is 0, alkylene and when m is 1, -Ri-X-R'~
where R~ is selected from the group consisting of phenylene, halophenylene and lower alkyl substituted phenylene and X is selected from the group consisting of -O-, O R"
,.
-S- and -C-O R"

where R" is selected from the group consisting of hydrogen and lower alkyl, (b) H-t-C --C~CH2~-R -OCH2-C -C-]- --H

where n has the value defined above and Ra is one of the formulae, _Rb_c_Rb_ and .
RC ~, ' C-O
: ~ Rd ` 1043042 RD-5683 where Rb is arylene, R is arenyl, also called artriyl and R
is alkyl and aryl, (c) copolymers having at least 10 repeating units having both formulas (a~ and (b~; and (d) copolymers having at least 10 repeating units having : both formulas, -O-CH2--C--~-- and C----C~Rg~ C~
where Rf is as defined above for R when m is 1 and Rg is alkylene or p-arylene.
51adkov et al. described polyacetylenes made from dipropargyl ethers of dihydric phenols as well as poly- .
acetylenes prepared from dipropargyl esters of dicarboxylic acids and dipropargyl acetals of aldehydes such as, for example, benzaldehydesO Other suitable polyacetylenes are those found in the scientific journals wherein other investigators have prepared a wide variety nf polyacetylenes based on the teachings of Hay. All such po~yacetylenes can be used as starting material for preparing my polymers. In addition, Hay in UDS. patent 39519,611 describes modified polyacetylenes obtained by reacting a polyacetylene with N
arylsydnones to introduce pyrazole units in ~he polymer backboneO Such modified polymers still con~aining some un-reacted butadiynylene groups likewise can be used as the polyacetylene for making my polymersO

Of all of the above polyacetylenes, the most readi-ly available are those from diethynylhydrocarbons and di-propargyl ethers of dihydric phenols. In order to have the highest carbon content, the polymers shou d be made from di-ethynyl arenes, the most readily available ones being - diethynylbenzenes. To increase ~he solubility of the poly mers of the latter in solvents, the isomers can be copolymeriz~d together or still further increased by co-polymerizing with the dipropargyl ethers. A particularly good one whlch is effective in low concentrations is the dipropargyl ether of 4,4'-isopropylidened~phenol (Bisphenol A), also called 4,4'-isopropylidenebis(propargyloxybenzene).

:
For many applications, I prefer to use as my starting poly-acetylene, the copolymer obtained by oxidatively coupling a mixture of m-dLethynylbenzene, p-diethynylbenzene and 4,4'-isopropylidenebis (propargyloxybenzene), specially those having, on a weight basis, 1-25% p-diethynylbenzene, 60-99a/o m-diethynylbenzene and 0-35% 4,4'-isopropylidenebis(propargyl-oxybenzene), i e., R in the formulae of the repeatin~ units of the polymer are 1-2S% p-phenylene, 60-99% m-phenylene and CH
0 35% -CH2 0 ~ ~ O-CH2-Alt~ough I can use any of the tetracyclones, the , most readily available tetracyclones are those having the formula 3 ~4~42 RD-5683 o "
"C~
Il "
- R"-C - ~-R"

where each R', independently, :is lower alkyl, lower alkoxy-carbonyl, phenyl or halophenyl and each R", independently, is phenyl or halophenyl. Typical of the substituents which R' can be, are methyl, ethyl, propyl, isopropyl, the various butyl isomers, i.e., n-butyl, isobutyl, cyclobutyl, t-butyl, the varioas pentyl isomers, the various hexyl isomers, the various heptyl isomers, the various octyl isomers, etc., the 0.
lower alkoxycarbonyl, i.e.; R'OC-, where R' is~lower alkyl, ~10 examples of which are given above, or phenyl or halophenyl, i.e., phenyl in which from 1 to 5~ preferably 1 to 2 of the hydrogen atoms have been replaced by halogen, preferably chlorine. R" is phenyl or halophenyl, examples of which have been given above.
~15 Those tetracyclones where each R' independently is lower alkoxycar~onyl are new chemical co~poundsO ~hey are readily prepared by first reacting benzil or the appropriate halobenzil with the appropriate lower dialkyl ester o~ 3-oxoglutaric acid, sometimes called acetone dicarboxylic acid, in the pre~ence of a dilute alkali metal hydroxide solution -in an alkanol~ generally methanol, to pro~duce a par~ially dehydrated intermediate which is then dehydrated to the ' -. , tetracyclone. The reaction proceeds readily at room temperature where it is generally run, but may be hastened by heating if desired. The progress of the reaction is easily followed by monitoring the disappearance of the benzil from the reaction medium. The partially dehydrated intermediate is ~urther dehydrated with an anhydride, for example, acetic anhydride in the presence o a small amount of sulfuric acidO These reactions are shown in the following equations where each Ra independently is lower alkyl and each Rb individually is phenyl or halophenylS

O O O 0 0 alkali metal R O-C-cH2-c-cH2-c-~Ra + Rb b ~ H20 lower dialkylbenzil or 3-oxoglutaratehalobenzil O
O " O
" jC ~ " __ dehvdratine R -O-C-C CH~C-ORa agent b- C~, Rb OH

4-hydroxy-2,5-bis(lower alkoxycarbonyl)-3,4-di(phenyl or - halophenyl)-2-cyclopentene o O " O
.t ~C~ "
-- R O-C-C C-C-OR
a " " a - Rb~C ~ Rb 2,5-bis(lower alkoxycarbonyl)-3,4-di-(phenyl or halophenyl)-cyclopentadienone These te~racyclones react with ~)ne of the ethynylene moieties of the butadiynylene groups found in the poly--~ -13-~ ! ' :~ ~

104304z RD-5683 acetylenes according to the following scheme:
O

Rl-C~ `C-R
,. ,.
~ ~ -C--C-C--C- ~ R2-C---C-R - - >

-C =C-C_C- .~
1 C ~ ~C-Rl ~ CO

The reaction is carried out at elevated temperatures under an ~5 inert atmosphere using a solvent in which the polyacetylene is soluble or at least becomes somewhat soluble at temperatures in the range of 50 to 130C. in the presence of a free-radical scavenger, e.g., a phenol such as a 2,4,6-trisubsti-tuted phenol. ~Haloarenes and haloarene ethers especially chloroarenes~and chloroarene ethers or mixtures thereof, for example,-chlorobenzenes, chlorobiphenyls, chlorodiphenyl : ethers, etc., are excellent solvents for carrying out this reaction. The reactîon is carried out, generally using the ~ lowest temperature at which the reaction proceeds at a reasonable rate which is easily monitored by noting the evolution of carbon monoxide~
In the presence of sufficient tetracyclone, reaction ~- between one ethynylene moiety of the butadiyny~ne group and the tetracyclone proceeds readily to com~letion ~or every butadiynylene group o~ the polymer and the polymer repeating , .
. . ~ . . ~
.~ -14- ~

~ ' ~

l043~æ

unit are those having formula ~b). Since it is the conjugated triple bonds of the butadiynylene groups which render ~he polymers thermally unstable~ the thermostability increases as the degree of this reaction increasesO Like-wise, the solubility of the polymer, especially noticeable ifi~ is initially only very slightly solubl3 increases as the degree of reaction increases. The temperature necessary to cause this reaction is lowest for 2,5-dialkyl-3,4-diaryl-cyclones, generally in the range of 130-150C. and is highest, generally in the range of 225-240C. for the 2,3,4,5-tetra-arylcyclones with the 2,5-di(lower alkoxycarbonyl)-3,4-, diarylcyclones requiring intermediate temperatures, generally in the range of 18Q-200C. The best temperature to use for cyclizing any particular polyacetylene with any particular tetracyclone i5 readily determined by rapi~ly heating the reaction mixture and using that temperature at which a controlled rate of evolution of the carbon monoxide is obtained.
The second ethynylene moiety of the original buta-diynylene groups of the polymer can also be reacted with the same or different tetracyclone by heating under the same general conditions above but to a higher temperature than that required for the first reaction for that particular ; tetracyclone. The reaction does not proceed ~o completion ;~ 25 apparen~ly because of the steric effects of the neighboring -15- ~

10~3042 RD-5683 adducts. Highest yields in the second reaction are obtained when a tetraarylcyclone is used in which case about 60% of the remaining ethynylene groups (80% of the total) can be reacted wlth the tetraarylcyclones. Where both ethynylene moieties of the butadiynylene group are reacted, the repeat-ing unit of the polymer has formula (c).
It is obvious that one t~tracyclone can be used for the first reaction and a second tetracyclone used for the second reaction~ In this case, since the tetraarylcyclones give the highest yield in the second reaction~ if one wanted .
to use a 2,5-dialkyl-394-diarylcyclone or a 255 di(alkoxy-- .
carbonyl)-3,4~diarylcyclone in conjunc~ion with a tetraaryl-cyclone, the latter, preferably would be used for the second reaction. Although solubility and polymer stability are not generally increased with the degree of this seeond reaction, oxidative stability at elevated temperatures below the thermal decom~osition point are improvedO
Solutions of the polymers obtained by either re-action are readily cast into films. These solutions also can be used to coat fibers, cloths, papers or mats of carbon or - other high impregnate carbon in order to permit the coated ; article~to be molded under heat and pressure into composites or laminates~
.:
In order that those skilled in the art may better ~- 25 understand my invention, the following examples are given by -16_ :

1~43042 RD-5683 way of illustration and not by way of limi~ation. In all the examples parts are by weight and temperatures are in degrees cen~igrade unless otherwise stated. Where eIemental analyses are given, the determined values are followed by the theoretical values in parentheses, In Examples 5 and 6, the tetracyclone exists as the dimer at room temperature, but readily dissociates during heating to the reaction temperature.

A mixture of 0.5 g. of a polyacetylene made by oxidatively coupling a mixture of 90% m-diethynylbenzene and 10% ~-diethynylbenzene, 0.02 g. of 2,6-dioctadecyl-4-methyl-phenol, 5 g~ of 2,3,4,5 tetraphenylcyclopentadiene and 5 ml.
of a mixture of chlorinated biphenyls having 32% chlorine was heated to~300 under a nitrogen atmosphere for 6 hours in a liqoid metal bath. At the end of this time, an ~- addi.tional 5 ml. of the chlorinated biphenyl mixture was added to cool the reaction mixture quickly to about 200 ~ and to aid in the removal of the solution from reaction - vessel. The solution was added dropwise to 250 ml of methanol wLth stirring. After washing with additional ~` methanol to remove unreacted tetracyclone and drying, the -~ polymer weighed 2.83 g. The infrared and nmr spectra were .
consistent with a polymer structure some of~whose repeating units contained 1 cyclized structure and the other units ~.
contained 2 such structures. Based on the yield of polymer, each one of the butadiynylene groups of the polymer has , .

1043(~42 RD-5683 reacted with the tetracyclone to form at least one 3,4,5,6-tetraphenyl-1~2-phenylene ring of which 52% had formed 2 such ringsO This polymer therefore contained repeating units, 38% having formula (b) and 62% having formula (c), where R is m-phenylene or ~-phenylene and each R' an~ Rl' is phenyl~

When the above reaction was repeated but using a temperature of 225, the yield was l.9 grams showing that all of the butadiynylene groups had reacted with the tetracyclone but that only one of the ethnylene moieties bf the buta-diynylene group had been cyclized~ The presence of the remaining ethynylene group was established by measuring the 13C nmr spectrum.

:

When Example 1 was repsated but the heating was initiated at ~10 and over a period of 40 minutes raised to 292 and maintained a temperature of 292-298 for 80 minutes, the product contained 81% (b~ units and l~V/o (c) units as defined in Escample 1.
The polymers described above are soluble at 25 in common organlc solvents as benzene, chlorinated aromatic liquids, chloroform and tetrachloroethane. Clear, coherent films can be cast from the solutions. MelCing point ranges on a hot-stage microscope vary with extent of reaction: for -18- , . .

lb 4 3~L2 RD-5683 100~/o (b) units, 338-350; for 81% (b) units - 19% (c) units, 352-375C.; for 38% (b) units - 62% (c~ units: 360-375C.
When polymers with only (b) units were heated in air at 10C./minO weight losses did not occur until approximately 430, in a nitrogen atmosphere the sample began~to lose weight at 460C.

When Example 1 was repeated but using a polyacetylene obtained by oxidatively coupling a mixture of 82% m-diethynyl-benzene, 8% ~-diethynylbenzene and 10% 4,4'-isopropylidene bis(proFargyloxybenzene) 9 the dipropargyl ether of 4,4'-isopropylidenediphenolO In one case~ a high molecular weight polymer was used and in another case a polymer in which suffi-cient phenylacetylene was used as a chain stopper to obtain - 15 a low molecular weight polymer having an average degree of polymerization of 10. In these reactions, 5 ml. of benzene was used in place of ~he chlorinated biphenyl as solvent which, although i~ evaporated during the heating of the reaction mixture9 did~provide an initial liquid phase for the reaction mixture which was maintained even after the evaporation of the benzene. No chlorinated biphenyl was add~d after the reaction period, so that on cooling a solid ma~ss resulted.
This was worke;d up with acetone but due to the extreme solubility of the resulting polymers, especially that from .

` -19-: ~43~42 RD-5683 the low molecular weight initial polymer, even in methanol, it was impossible to recover all of the resulting polymer.
Based on the amount of recovered polymer, at least 44% of the repeating units of the resulting polymer of the initially low molecular weight polymer had been converted to (b) units and in the case of the higher molecular weight product, 49% of the repeating units.

EXA~LE 5 .... _ .
A mixture of 2.48 g. of the polyacetylene of Example l, 5.72 g. of 2~5-dimethyl-3J4-diphenylcyclopenta dienone, 0,05 g. of 236-dioctadecyl-4-methylphenol and 40 ml of chlorobenzene were heated at 130, the reflux temperature of the reaction mixture, for a period of two hours under a nitrogen atmosphere~ The reaction mixture was added drop-wise to 450 mL. of acetone, the precipitate separated by filtration, washed and dried to yield 6.72 grams of product.
~ Based on this yield, one of the ethynylene moieties of each ; butadiynylene group of the initial polymer had been converted to 3,6~dimethyl-4,5-diphenyl-192-phenylene groups, i,e., all of the repeating units of the ~olymer corresponds to formula (b) where each R' is methyl, each R" is phenyl and R is m-phenylene or ~phen~lene.

A mixture of 0.25 g. of the polyacetylene of -20~

~ - RD-5683 Example 1, 1.69 g. of ~ me~ yl-3,4-diphenylcyclopenla-dienone9 0,01 gu of 2,6-dioctadecyl-4-methylphenol and 2.5 ml. of a chlorinated biphenyl having a chlorine content of 32% was heated at 225 under nitrogen atmosphere for one hour.
An additional 5 ml. of the chlorinated biphenyl was added and the reaction mixture precipitated by adding to 500 ml. of acetone. After filtering and drying the precipitate, a yield of 0.85 g. of polymer was obtained. Based on this yield, each repeating unit of the polymer had at least one 1,2-phenylene group on the backbone and of these 30% had ~wo such unitsg i~e., 70% of the repeatlng units had-formula (b) and , 30~/O had formula (c) where each R' is methyl and each Rl' is phenyl and each R is m-phenylene or ~phenylene.

- 15 Using a polymer similar to that prepared in Example ; 5 but having only 0.8 of its repeating units cyclized to units corresponding to formula (b) where each R' is methyl and each R" is phenyl and R is m-phenylene or ~-phenylene, further cyclization was carried out as follows: A mixture of 0.71 g. of this polymer, 1,54 g. of 2,3,4,5-tetraphenylcyclo-pentadienohe~ 0.02 g. of 2,6-octadecyl-4-methylphenot and 5 ml. of a chlorinated biphenyl having a chlorine content of 32% was heated under nitrogen at 300 for 30 minutes. Upon cooling, a precipitate started to form and acetone was added to complete the precipitation. The polymer was filtered off~

? 21 ~ 04304Z RD-5683 dried and redissolved in 15 ml. of chlorobenzene and again precipitated by pouring into acetone. After filtering, wash-- ing and drying, a yield of 0.9 g. of product was obtained.
The nmr spectrum of this polymer indicated that 60% of the remainLng ethynylene moieties had been cyclized to 1,2-phenylene gro~ps, i.e., 60% of the repeating units of the polymer had formula (b) and 40% of the repeating units had formula (c) where each R' is methyl or phenyl, each R" is phenyl and each R is m-phenylene or p-phenylene ., This example is a typical preparation to be used in .
preparing 2,5-bis(lower-alkoxycarbonyl)-3~4-diarylcyclopenta-dienones. A solution of 34.8 g. of dimethyI 3-oxoglutarate, 21.0 g. of benzil in a 0.5% potassium hydroxide solution in 250 ml. of methanol was allowed to stànd under a nitrogen atmosphere with stirrlng at room temperature After one hour, the solution had become clear. After 20 hours, a precipitate had formed in the reaction mixture and a sample o~ the liquid phase showed that no benzil was present. The reaction mixture was poured into 500 ml. of water to precipitate all the product. After filtration9 washing and drying, there was obtained 28.82 g. of 4-hydroxy-2,5-bis(methoxycarbonyl)-3,4-diphenyl-2-cyclopentenone. After recrystallization from 200 mlO of benzerle, elemental analysis showed: C, 69.5 (68.9);

:

.

.

.

H, 4.9 (4.92). The compound was further identified by its nmr spectrum.
The above intermediate was further dehydrated to the desired tetracyclone by dissolving 22.01 g. of the above intermediate in 40 g. of acetic anhydride to which 3 drops of concentrated sulfuric acid were added. The reaction mixture was heated to obtain a homogeneous solution and allowed to stir 1/2 hour after removal of thP source of heat. The reaction mixture wa~ poured to 450 ml. of water, causing the desired 295-bis(methoxycarbonyl)-3,4-diphenylcyclopentadienone to precipitate as crystals which after filtering, washing and - drying in a vacuum at 50, weighed 20.57 g. After recrystallization from acetic acid~ the product had a melting point of 162-164C, The product was identified by its nmr , ~ 15 and infrared spectra.
, Elemental analysis is shown: C, 72.2 (72041); H, 4.7 (4.6). Mass spectrum showed the parent peak, m/e 348.

EXAMPLE 9 ~ ~
A mixture of 0~62 g~ of the polyacetylene of Example l, 2.68 g. of the tetracyclone of Example 8, 0.02 g. of 2,6-octadecyl-4-methylphenol and 10 ml~ of o-dichlorobenzene was heated at 180, the reflux temperature o the re~ction mixture, under a nitrogen atmosphere for 2 hours. After cooling, the reaction mixture was added dropwise to a 50-50 ~3~42 RD-5683 methanol acetone mixture and the precipita~e washed with additional acetone and methanol. After drying there was ob-tained 1.85 g~ of polymer. Based on this yield, 80~/o of~the butadiynylene groups of the original polymer had been

5 converted to repeating units having the formula (b), the balance being formula (a) where each R' is methoxycarbonyl, each R" i5 phenyl and each R is m-phenylene or p-phenyleneO

~ .
A mixture of 2 . 22 gO of a polyacetylene made by oxidatively-c~upling m-diethynylbenzene, 6.96 g. of the cyclone of ExampIe 8, 0.1 g. of 2,6-octadecyl-4-methylphenol and 60 mlO of a chlorinated biphenyl having 32% chlorine was hea~ed under a ni~rogen atmosphere at 185 for 2 hours. The reaction mix~ure was poured into a mixture of 700 ml. of methanol and 700 ml. of ac~tone~ The product was filtered, washed and dried - yield 4. 0 g. Based on this yield, 90% of ~he initial butadiynylene groups had ~een cyclized so that 90~tO of the repeating units had formula (b), the balance being formula (a) where eàch R' is methoxycarbonyl, each R" is phenyl and each R~is m-phenylene.
All of the polymers from the above examples are readily soluble to at least 10% at room temperature in such commonly available solvents as ^hloroform~ tetrachloroethane, benzene, chlarobenzene and nitrobenzene and can be cast into clear flexible films. These films are thermally stable with ~24-~43~æ RD-5683 the thermostability increasing in the order from those whose R' groups are methoxycarbonyl to t:hose whose R' groups are methyl to those whose Rl groups are phenyl. Incipient de-composition does not begin in nitrogen or air below 360 for ; 5 any of the polymers and goes as high as 46~ in nitrogen.
When heated in nitrogen at 900, weight loss increa~es in the order of those polymers where the R' groups are methyl (27%) to those where the R' groups are phenyl (31%) to those where the R' groups are methoxycarbonyl (34%)~ In the case where the R' groups are phenyl, io e.~ both R' and R" groups are phenyl, the weight loss is in close agreement for that which would be.expected if all of the phenyl groups in the 3 and 6 positions were cleaved from the 1~2-phenylene rings.

`
Solutions of the polymers in addition to being able to be cast into films readily coat the surface of carbon fibers and:~can be used to impregnate the tows of such fibers to produce.prepregs which can be aligned and molded to pro-doce high performance composites. Best physical properties are obtained from those cycllzed polymers where both the R' and R'i groups are-phenylO
. Those cyclized polymers where the R' groups are methoxycarbonyl can be hydrolyzed so that the alkoxycarbonyl groups are converted to carboxyl groups to produce polymers having ion exchange properties~ If desired, the ester groups can be converted to amide groups.

: : .

10 4 3~ ~ 2 RD-568 In addition to increasing the thermostability and solubility, the polymers of this invention likewise have softening points which increase with the degree of reaction.
Although the examples have illustrated how to attain a high degree of cyclization, a lower degree of cyclization is at-tained either by using 3 shorter reaction time or a deficlency of the tetracycloneO However, ~hen the latter technique is used, the reaction rate is slower and gelation due to thermal instability of the polymer ean occur, especial-ly if the tetraarylcyclones are used which require generallyhigher reaction temperatures than the other tetracyclones.
In those cases where I have attained a low degree of cycli-zation, a noticeable improvement in stability and solubility is attained when as low as 15% of the butadiynylene groups have been cyclized to contain at least one cyclic structure~
i.e., no more than 85% of the repeating units have formula (a).
Although the above examples have illustrated many modifications of my invention, obviously, other modi~ications and variations of the present invention are possible in light of the above teachings. Tt is, therefore, to be understood that changes may be made in the particular embodiments of the invention described which are within the full intended scope of the invention as defined by the appended claims.

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Claims (11)

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

1. Polymers whose repeating units have at least one of the formulae:

' (a) ' (b) ' CC) of which no more than 85% have formula (a) and the ratio of (b) to (c) units is not less than about 2 : 3, where each R
is the residue other than the acetylenic groups of a solvent-soluble acetylenic polymer whose repeating units have formula (a), each R', independently, is lower alkyl, lower alkoxycarbonyl, phenyl or halophenyl and each R", independently, is phenyl or halophenyl.

2. The polymers of claim 1, wherein the repeating units are free of those having formula (a).

3. The polymers of claim 1, all of whose repeating units have formula (b).

4. The polymers of claim 1, wherein each R', individually, is phenyl or lower alkyl and each R" is phenyl.

5. The polymers of claim 4, wherein each R` and each R" are phenyl.

6. The polymers of claim 1, where n R is m-phenylene, p-phenylene or .

7. The polymers of claim 1, wherein, of the total R groups, 1-25% are p-phenylene, 60-99% are m-phenylene and

8. The polymers of claim 7, wherein each R' is lower alkoxycarbonyl and each R" is phenyl.

9. The polymers of claim 7, wherein each R' is lower alkyl and each R" is phenyl.

10. The polymers of claim 7, wherein each R' and each R" are phenyl.

11. A process of stabilizing an acetylenic polymer containing a plurality of butadiynylene groups which comprises reacting said polymer in solution in a suitable solvent therefor with a tetracyclone so as to convert at least about 15% ethynylene moieties of said butadiynylene groups into aromatic groups.