Polvmer Aoolications of Some Terephthalaldehyde Derivatives cioroon Y. mrinoed,' Lawrence D. Lillwitr;
Joseph P. Wuskell, and Andrew P. Dunlop
an Research Laboratories. Sanington.
The authors from left to right: Drs. Lillwitz, Dunlop, Brindel and Wuskell.
Dr. Gordon D. Brindell, a native of Long Beach, California, receiued a B.S. from UCLA a n d his Ph.D. from the University of Colorado. For the past four years he has been Manager of New Products Pioneering Research a t Quaker Oats. F'reuious to that he was engaged in chemical and polymer research for Uniroyal, Inc. for 11 years a n d petrochemical research with the Continental Oil Company for fiue years. Dr. Lawrence D. Lillwitz has been a Group Leader in New Products Pioneerine Oats - a t Quaker . for the past four years. He is a natiue of Northern Illinois, receiued his B.S. from St. Procopius College (now Illinois I'5enedictme '' ' college) in ' IYbb, -^^^ a n a his Ph.D. in Orgaiaic Chemistry from the Uniuersity of Notre Dame in 1970. n I l r m s n 7nnrIn. : n thn Dr. Joseph D W..n&all ymn .,l New Products Pioneering section, is a natiue of New York City. He receiued his B.A. from the Uniuersity of Connecticut and his Ph.D. from the University of Minnesota. He has been engaged in new product research and deuelopment a t Quaker's Bwrington Laboratories for the past fiue years. Dr. Andrew "Andy" P.Dunlop, a native of Balloch, Scotland, emigrated to the United States in 1928, attended the Uniuersity of Chicago (B.S., 1938) and has been employed in several capacities with The Quaker Oats Company since 1931, first a s a laboratory assistant in chemistry a n d currently a s Director of Chemical Research & Deuelopment. He is senior coauthor of "The Furans'' (ACS Mono2raDh No. 119). Andy was awarded the DSc. in 1973 by Coe College, Cedar Rapids, Iowa.
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Introduction In recent years, terephthalaldehyde (TPAL) has become potentially availahle by an improved procedure developed by Brill (1971). By this process it is possible to manufacture TPAL in good yield by vapor phase oxidation of p-xylene over a catalyst consisting of oxides of tungsten and molybdenum. The difunctionality of TPAL, suggesting potential value as a resin former, as well as its previous unavailability on the industrial scene led us to investigate this process further. The prior art discloses various catalyst systems used in the oxidation of alkyl benzenes (Bhattacharyya and Gulati, 1959; Bhattacharyya and Krishmamurthy, 1963); however, in all instances, they prove uneconomic since various acids and other undesirable by-products (needing separation) are obtained along with the desired aldehydes. The reactions involved in the conversion of p-xylene are shown below: it appears that tolualdehyde is not a major ii
1 oxide support. 'l'he amount of active material on the Carrier is less than 10%. The cal:alyst is prepared by inter-reacting an aqueous so:..:.+.. ^".".A":..m ""."+.>"".tote amm,,n;,.m lution -..collrp1L11116 aLIIII.YII.uI.. paLL~U~.60u.Yu~, molybdate, and aluminum oxide in amounts necessary to give the desired catalyst ratio. Over this catalyst is passed a dilute stream of p-xylene in air (-1%) a t a temperature between 475 and 575 "C, a t atmospheric pressure. The contact time in the catalyst zone is critical and seems to be optimum in the range of 0.1 to n 9 o". nn I I nilnt P I-_-, I ~ T P A T . ha- hem n h t a i n d in 40-609h r _ _ E_ " . ..". ...-. .. ... yield with Imly minor by-products: a simplitled flowsheet of the proce ss is shown in Figure 1. Prior to i ndustrialization, there remain two areas of the process whi ch need work to further improve the economics: product recovery from the dilute effluent stream and catalyst deactiv ationhegeneration. Studies relating to the deactivation of W03-Mo03 catalysts have been reported by Wheeler (1:374) and Wirtz e t al. (1975), and their findings offer valuak,le insight to guide further process development work on T I'AL. Wheeler has shown deactivation to occur hy a t least t wo mechanisms: (1)loss of MOOSthrough suhli-
.....
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-
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__
Ind. Eng. Chem., Prod. Res. De"., Val. 15,No. 1, 1976 83
I
PURIFICACION
ful fibers and films, but has not been commercialized. The lower number of methylene groups in the repeating unit of poly(PHMBA) (compared with P E T ) should produce a stiffer chain and higher glass transition temperature. Also, it was our belief that the PHMBA polyester would less readily form cyclic oligomers and, therefore, might offer advantages over P E T films and fibers in applications where the surface cl~aracteristicsand adhesion were of critical importance. We compared two synthetic routes to PHMBA (2) from terephthalaldehyde (1). CH,OH I
I
I
I
TEREPHIIHALALEEHYDE 2-TOLLALDEHYDE
I
CHO 5 p-xylene recycle loFt.Ional1
Figure 1. TPAL process flowsheet.
carbon-rich feed stream. Reduction occurs when the lattice oxygen (which has been shown to actually be the oxidizing agent) is consumed more rapidly than it is replenished by the feed stream. Wirtz e t al., however, more recently found catalyst weight loss is caused only by sublimation of MOOS. Other work has been reported recently by Kai Yang (1974), who found that the oxygen partial pressure of the W03-Mo03 decreases linearly with time and by varying the oxygen content in the feed gas, variations in catalytic activity could be detected. Economics for the process suggest a potential selling price of 30p: per pound of TPAL from a lOMM pound plant (1972 basis) with p-xylene a t 7p: per pound. These figures predate the rapidly inflating petrochemical prices, and no effort has been made to update these figures to today's changing economy. The commercial potential of TPAL, and particularly the possibility of its utility in various condensation polymers, was the basis for our interest. The purpose of this paper is to highlight the preparation of some intermediate compounds and to indicate where TPAL may find commercial utility in the future.
p-Hydroxymethylbenzoic Acid and Polyesters Linear polyesters have become very important polymers in industry since the 1950's. Poly(ethy1ene terephthalate), P E T , has found widespread application in fibers and films. In spite of many excellent properties, the material presents surface problems in magnetic tape technology. P E T has the tendency to form cyclic, high-melting, crystalline, insoluble oligomers which cannot be separated from the bulk of the polymer according to Cobbs (1973). The majority of the high-melting oligomer fraction has been found to be the dimer. The dimer is always present a t an equilibrium concentration in the range of 1-2%. The dimer has the tendency to migrate to the surface of the polyester where it limits surface quality, particularly in regard to disorientation of magnetic bits. A similar migration of dimer may be responsible for some adhesion problems in polyester cords used to reinforce tires. Although adhesives may be able to cover the surface-deposited dimer on the fibrils initially, a continued migration of dimer would tend to disrupt the initially successful adhesion. As the dimer comes to the P E T surface, it may tend to release and displace adhesive bonding above it. The linear polyester derived from p-hydroxymethylbenzoic acid (PHMBA) is reported by IC1 (1948) to form use84
F""
Ind. Eng. Chem., Prod. Res. Dev., Vol. 15, No. 1, 1976
dHO 1 VH,OH
TH,OH
dOOH
~ H ~ O H COOH
2
3
TOOH
4
First, we considered the one-step Cannizzaro reaction, albeit recognizing the simultaneous formation of benzenedimethanol (3) and terephthalic acid (4) as major byproducts which would limit the yield of 2 to possibly no more than 50% and quite probably complicate its purification to the degree required for polymerization to high molecular weight. The reaction was attempted, however, and reasonably pure 2 was obtained after recrystallization from hot water. The second and preferred laboratory route to 2 involved selective reduction of one aldehyde function of terephthalaldehyde followed by oxidation of the resulting hydroxyaldehyde to 2. Higher yields of 2 were obtained and purification was easier. The selective reduction of 1 was repeatedly achieved in yields of 85-90%. Only small amounts of over- and under-reduced material were present in the reduction mixture. Direct oxidation of the crude 5 with alkaline hydrogen peroxide gave the acid 2 which was readily purified by recrystallization from hot water. Although IC1 (1948) used both the hydroxy acid 2 and the methyl ester (6) to make the polyester, we worked with the ester in the belief that polymerization would proceed more smoothly and to higher molecular weight this way. CH,OH
COOCH, 6
Purification of the methyl ester by distillation afforded further opportunity to separate impurities. Crude 6 was obtained in 97% yield from 2 in excess methanol with sulfuric acid as catalyst, the reaction being driven to completion by scavenging water with 2,2-dimethoxypropane. The crude ester analyzed 97%. pure by gas chromatography and was further purified by distillation and recrystallization to a purity of 98.5% (minimum) prior to polymerization. The melt polymerization of 6 was carried out on a small scale using an antimony trioxide, calcium acetate catalyst.
Terephthalaldehyde (TPAL) has recently become potentially available in good yields (40-60 % ) by the vapor phase oxidation of pxylene. The difunctionality of TPAL enables it and its derivatives to be used as monomers in several classes of polymers. This paper highlights the synthetic routes that lead to several TPAL derivatives and also discusses the polymers derived from these difunctional derivatives. The derivatives described and the corresponding polymers discussed are as follows: phydroxymethylbenzoic acid, polyesters; pxylylenediamine and pbis(Baminoethy1) benzene, polyamides, polyurethanes, epoxies; a,a'dihydroxy-pphenylenediacetic acid, polyamides; benzenedimethanol, polyethers and polyesters.
FREQUENCY ICMII 4000
3600
3200
2600
2400
2000
1600
100
*
90
-
60
B
60
E E
_
I-
1400
1600
1200
1000
600
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I t
70
50
5
40
2
30
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0
,
,
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,
,A 3 0
25
35
40
6
5
9
8
7
1 0 11 121314 16
I M crons!
Figure 4. Ir spectrum of poly(PHMBA), inherent viscosity 0.35. FREQUENCY lCM'l 4000 3600
3200
2800
2400
2000
I800
1600
FREOUENCY ICM1l 1400
1200
1000
600
600
4000
3600
3200 2800
2400
2000
1600
1600
1400
1200
1000
600
600
100
90
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80
70 60
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f
2 +
40
30 20 10
I
0 25
30
36
40
6
5
6
7
9
10 11 121314 16
LMicrons!
Figure 3. Ir spectrum of methyl p-hydroxymethylbenzoate.
r
Figure 5. Ir spectrum of P E T sublimate.
01
The procedure was patterned after that described by Sorensen and Campbell (1968) to prepare PET. Using a total polymerization time of 40 h and final heating to 260 "C a t 0.2 mm Hg, a polymer with inherent viscosity of 0.35 (phenolhetrachloroethane, 60/40) was produced. This polymer was fiber-forming and could be pressed from the melt into clear films. Examination for oligomers was carried out by subjecting about 18 g of this polymer to a sublimation procedure a t 260 "C and 0.2 mm Hg. In 20 h, 40 mg of noncrystalline but wax-like material was separated. It softened a t 45-50 O C and finally melted a t 140-155°C. The infrared spectrum of the sublimate, Figure 2, showed hydroxyl absorption and more closely resembled the spectrum of 2, Figure 3, than that of the polymer, Figure 4. By way of comparison, a 10-g sample of commercial P E T film was heated in the absence of air above its melting point. A white crystalline solid rapidly sublimed in the cooler regions of the vessel. In 6 h, 40 mg of sublimate was obtained which melted at around 300 "C. The infrared spectrum of this material, Figure 5, showed no hydroxyl absorption and the typical terephthalate split carbonyl. Based on the above observations, we concluded that the volatile fraction from poly(PHMBA) was a mixture of linear, low molecular weight fragments and perhaps some unreacted monomer. The melting behav-
I . . . . . . . . . . . . . . . . . . . . .
0
100
, I
1
,
,
,
200 300 TEMPERATURE l a c )
,
,
,
,
,
I
,
, #,
I
, ,
400
L
600
Figure 6. DTA of poly(PHMBA) in nitrogen. ior confirmed that it was not the same type of crystalline solid that inhabits PET. A brief TGA and DTA examination confirmed our belief that the PHMBA polyester would have good thermal characteristics. TGA'S of poly(PHMBA) and a commercial P E T film showed essentially identical thermal stability for the two polyesters up to 380 "C. At that point, rapid decomposition took place in both polymers. Some interesting differences are evident in the DTA thermograms for poly(PHMBA), Figure 6, and commercial P E T film, Figure 7. The PET sample showed a crystalline melting point of 260 Ind. Eng. Chem., Prod. Res. Dev., Vol. 15, No. 1, 1976
85
Table I. Polyamides of PBAEB with a,w-Alkanedioic Acids, HOOC(CH,)nCOOH (Saotome and Komoto, 1966) Polymer
f
n
7
6 9 10 11
4
0
200
100
300
400
5(
TEMPERATURE I'CI
Figure 7. DTA of PET (Mylar film) in nitrogen.
"C and a stronger fusion endotherm than the lower melting (240 "C) and less crystalline poly(PHMBA). The latter displays a glass transition a t about 90 "C followed by an exothermic crystallization a t about 160 "C. This suggests the sample of poly(PHMBA) had little or no crystallinity to begin with. The ability to crystallize the polymer by annealing encourages us to believe that orientation and resulting good film and fiber properties should be achievable. The glass transition temperature on the P E T sample was 78 "C, in good agreement with the 80 "C reported by Beaman (1952). From the above considerations we believe that poly(PHMBA) deserves further examination as an oligomerfree polyester which may exhibit superior surface characteristics. Thermal data confirm basic structural considerations. Diamines. In light of the many applications for diamines such as polyamides, intermediates to diisocyanates for polyurethanes and epoxy curatives to name just a few, we examined routes to diamines. From terephthalaldehyde we obtained p-xylylenediamine, p-XDA (7), and the homologous p-bis(2-aminoethy1)benzenePBAEB (8). CH,CHJH, I
I
CH2NH, 7
I
CH,CH,NH, 8
Previous investigation has shown that both offer interesting possibilities in polyamides for fiber use. Saotome and Komoto (1966) have reported that polyamides from 7 show a T, 35-65 "C higher than polyamides from the same diacid with linear diamines. Polyamides from 8 show a T, 35-55 "C higher than comparable ones from linear diamines. In this connection, it is of interest that a 70130 m, p-mixture of xylylene diamines has been commercialized by Showa Denko Co. under the trade name Sho-Amine-X. Polyamides from the mixed xylylene diamines have been reported by Oga (1966) to have several good properties. I t is noteworthy that the mixed poly(xyly1eneadipamide) fiber has a higher Young's modulus than conventional nylons while retaining the other good properties. The combination of properties has apparently opened the door for consideration of these fibers in staple as well as continuous filament applications. Inasmuch as homopolymers generally have better mechanical properties than copolymers, we 86
Ind. Eng. Chem., Prod.
Res. Dev.. Vol. 15,No. 1, 1976
Polymer code
TP, C
PBAEB-9 PBAEB-10 PBAEB-11 PBAEB-12 PBAEB-13 HMDA-6 (nylon 6,6)
290 300 275 280 262 262
anticipate that the homopolymers from p-XDA should have still better properties. p-XDA should also find utilization as an epoxy curing agent. The high reactivity of the xylylene diamine derivatives offers the possibility for curing a t room temperature. Improvement in the heat distortion temperature compared with conventional polyalkyleneamines should be particularly noteworthy with the pure p-XDA as curative. PBAEB shows much promise as an intermediate for polyamide fibers. The aromatic polyamides with even carbon methylene chains between a phenylene and the amide group generally have higher melting points than the corresponding ones with odd methylene chain units as was pointed out by Saotome and Komoto (1966). The polyamides of 8 with the 9-12 carbon atom dicarboxylic acids all have melting points above nylon 6,6. This is shown in Table I. Our pathway to 7 was through 1,4-benzenedimethanol, 9, followed by ammonolysis over Raney nickel. CHO CH,OH CH,NH,, I I I
CHO 1
CHLOH
CHJVH?
9 7 Benzenedimethanol is an aromatic diol which we may incidentally note is potentially useful in a wide range of applications. More will be said about it later. Several methods of preparation of benzenedimethanol have been described. The method employed by Quelet (1933) involved hydrolysis of the corresponding dihalide. The chloride or bromide can be used along with sodium carbonate and water. A number of hydrogenation catalysts were found to exhibit good activity in the smooth and rapid reduction of 1 t o 9 with hydrogen in a liquid phase reduction. Conversion of 9 to 7 was also accomplished smoothly using the catalyzed ammoniation of alcohols originally studied by Winans and Adkins (1932). Raney nickel and nickel on kieselguhr were both active in producing ammonolysis, but the former gave a cleaner reaction product. A third route to 7 involved the sequential treatment of 1 with methyl amine followed by ammonia and hydrogen in the presence of a nickel catalyst. The reductive ammoniation of carbonyl compounds with ammonia and hydrogen in the presence of a catalyst is a general method well known for the preparation of primary, secondary, and tertiary amines (Emerson 1948). However, when 1 was treated with ammonia and hydrogen, no p-XDA was obtained. Instead there occurred a rapid formation of insoluble hydrobenzamide condensation products. T o circumvent the formation of the hydroterephthalamide, the soluble diimine was formed first using methyl amine. Subsequent treatment with excess ammonia in the presence of a Raney nickel catalyst followed by addition of hydrogen in the presence of
the same catalyst produced the desired replacement of the alkyl imine structure with ammonia and gave 7. The yield was over 80%. The methyl amine liberated may be recycled in the process. Several routes to PBAEB were explored (Scheme I). The synthesis of 8 from 1 led through some interesting chemistry of the bis(cyanohydrin), 10. Terephthalaldehyde, 1, was treated with liquid HCN in the presence of catalyst to give 10 in quantitative yield. The method used was that of Journeay (1956) which involved a carboxylic acid/carboxylic salt buffer. Until this was done, the HCN addition invariably led to polybenzoin formation. The most successful route to diamine 8 from an economic standpoint was the direct one-step hydrogenolysis of the benzylic hydroxyl accompanied by nitrile reduction, 10 --c 11. Neutralization with a base to liberate 8 was a simple procedure. The literature only records such reactions on monocyanohydrins. Hartung (1928) converted mandelonitrile to 0-phenethylamine in 52% yield using Pd/C in the presence of HCl. The acetoxy derivative gave a higher yield under the same conditions. More recently Kindler and Schrader (1949) studied the effect of strong acid on mandelonitrile esters under hydrogenation conditions with Pd/C. In the absence of acid, phenylacetonitrile was obtained. With acid, @-phenethylaminewas formed. In our study under similar conditions, the hydrogenolysis could not be accomplished as long as HCl was present. However, when HC1 was replaced with HzS04, the reaction went smoothly to give the p-bis(2-aminoethy1)benzeneacid sulfate salt 11. The latter was liberated with caustic to give the desired 8. Other routes to 8, although somewhat more involved, proved workable. The diacetoxy derivative 12 and bis(cyanohydrin) 10 were the main intermediates. Reducing 12 with PdIC in methanol with sulfuric acid present gave the diamine salt 11. Reduction was a t a faster rate than reduction of 10. This agreed with the result of Hartung (1928), namely that acetate is hydrogenolyzed more readily than hydroxyl. Catalyst activity decreased less in 12 -+ 11 than 10 11. When sulfuric acid was left out of the reaction, the PdIC, methanol system reduced the diacetate to the dinitrile 13 which, of course, could be reduced directly to 8 as reported much earlier by Ruggh et al. (1935). The reduction of the diacetate 12 with Pd black in acetic anhydride constituted another route to 8 through the diacetamide 14 in good yield. The product, 14, was hydrolyzed to diamine 8 using standard conditions. Thus, whether one goes directly by one-step hydrogenolysis and nitrile reduction or through the diacetate routes, the bis(cyanohydrin) 10 inserts the two needed carbons to form PBAEB and acts as a convenient, high yield intermediate from terephthalaldehyde. a&-Dihydroxy-p-phenylenediacetic Acid and Polyamides. Another potential utilization of the bis(cyanohydrin) was explored hy hydrolyzing it to a,a'-dihydroxy-pphenylenediacetic acid (15). The hydrolysis went smoothly
16
The objective of this investigation was preparation of a hydrophilic nylon. The limited moisture regain of nylon has been a negative feature of this fiber for a long time. Polyamide textiles that accept more moisture should be more comfortable to the wearer. The added moisture would aid discharge of static electricity, thereby reducing the static cling problem. In adhesive areas, hydroxylic groups could be potential covalent bonding sites for improved adhesion and permanence. They could conceivably m-odify the polymer surface energy to improve adhesion to other substrates such as metals. Therefore, a more hydrophilic monoper and polymer is an attractive prospect. To test this possibility, we melt-polymerized nylon 6,6 salt with HMDAIl5 salt in the ratio 80:20. Polymerization was carried out first in a sealed tube a t 210 O C . On completion of this reaction, the tube was opened and evacuated and heated a t 265 "C for 1 h. The pressure was reduced to 0.5 mm Hg and heating was continued for another hour at this pressure. The fraction of the polymeric mass that was highest in molecular weight was dissolved in hot 98% formic acid. This polymer, (mp 235-240 O C dec) which was shown by NMR to contain aromatic groups and could be drawn into fibers, showed much different behavior toward water than was noted with nylon 6,6. When water was added in small increments to the formic acid solution, a flocculent precipate resulted which appeared to be plasticized. A similar experiment with nylon 6,6 in formic acid gave only solid chunks of polymer that appeared to be unaffected by the added water. A more rigorous test of moisture characteristics such as moisture-retain must await the preparation of suitable fibers. NMR analysis showed about 10 wt % incorporation of an aromat-
Scheme I 1
1-
-+
HFHCOOH 10
3%
@ I
HOCHCOOH 15
and in good yield. The hydroxy acid was utilized as a monomer in copolyamide preparation along with adipic acid and HMDA. The resulting copolymer had the structure 16 and mln 9.
-
HTHCN
A& -FHCN
H&HCN
A~-~HCN
10
12
~H,CH,NH,OHSO,~ 11
14
13
CH2CH2NH2
I
~H~CH,NH~ 8 Ind. Eng. Chem., Prod. Res. Dev., Vol. 15, No. 1, 1976
87
Table 11. Comparison of Polyurethane-Ureas
Chain extender
Tensile strength," psi
Elong., %
300% Mod, psi
100% Mod, psi
Split tearb
NCOi 2"
MEK resistancec
p-XDA (99.9%) 7930 520 1200 2960 54 1.00 Yes Sho-Amine-X 7250 470 1040 2890 56 1.00 no ASTM D1708-59T. b ASTM D1938-62T. C Visual examination after dropping MEK on coated fabric laminates. ic residue in the dicarboxylic segment of the polymer. In several polymerization attempts, we learned the importance of close temperature control to avoid cross-linking through ether formation. If temperatures and times were extended much beyond those stated above, gelation occurred, making it for all practical purposes an infusible mass. With control, however, the hydroxy acid 15 presages an interesting potential in fiber and plastic applications. Diisocyanates and Polyurethanes. At the present time, polyurethane coatings, fibers, and films made with aromatic diisocyanates suffer discoloration and loss in physical properties on outdoor exposure. In a study on thermoplastic polyurethane made from diphenylmethanep,p'-diisocyanate, adipic acid, and 1,4-butanediol, Schollenberger et al. (1958) attributed the degradation to the combined action of air and sunlight acting on the carbamate ester groups to form quinone-imides. p-Xylylene diisocyanate, p-XDI, obtained by phosgenation of 7 should show good utility in nondiscoloring polyurethane applications. The color stability stems from the placement of the methylene group between the urethane group and the aromatic ring. Schollenberger and Stewart (1972) have confirmed this point and added that xylylene diisocyanates have higher reactivity than straight aliphatic diisocyanates such as hexamethylene diisocyanate, HMDI. The benzene ring lowers the volatility of p-XDI, such that it is a solid a t room temperature, mp 45 OC as reported by Siefken (1949). The danger of toxicity by inhalation is greatly lessened relative to HMDI. This combination of properties suggests very attractive product possibilities. In this regard, m,pXDI of Takeda Chemical Co. is offered commercially for making nonyellowing polyurethanes. The diisocyanate from phosgenation of 8 should lead to very color-stable polyurethanes just as the aliphatic diisocyanates are known to do. The structure suggests a material which will perform in a manner analogous to HMDI, but with greatly reduced volatility. The boiling point reported by Siefken (1949) for the diisocyanate from 8 is 142-145 OC a t 0.1-0.2 mm Hg. As polyurethane chain extenders, the high reactivity of 7 and 8 allows them to be used only with aliphatic diisocyanate prepolymers or those that are somehow terminated in aliphatic NCO groups. In the laboratory, we compared p-XDA and Sho-Amine-X as chain extenders for a Polymeg 1000 (Quaker Oats Co.)-Hylene W (H12-MD1, E. I. DuPont Co.) prepolymer. We found that the resulting polyurethane-urea films had about the same split tear and tensile strength. However, the p-XDA-extended product had higher modulus and elongation. An additional advantage apparent in the p-XDA-cured films and which should have importance in the fabric coating industry is the resistance
88
Ind. Eng. Chem., Prod. Res. Dev., Vol. 15, No. 1, 1976
to MEK. A comparison of the p - and m,p-XDA amines is shown in Table 11. Benzenedimethanol. 1,4-Benzenedimethanol which we utilized as an intermediate to p-XDA above is an aromatic glycol containing two reactive primary hydroxyl groups. As such it should provide a convenient route to many useful esters, ethers, and urethanes. Rhoad and Flory (1950) prepared polyethers of the glycol by acid-catalyzed condensation. Such benzylic polyethers are expected to be sensitive to cleavage under acidic but not basic conditions. In recent years, this originally negative feature has taken on new importance. Many investigators are now interested in polymeric products that can be easily degraded for disposal or recovery of ingredients a t the end of the service life. Further research will be necessary to see whether this feature is useful. Fully aromatic polyesters have been prepared by Nishimura (1967) by transesterification with dimethyl terephthalate. Such polyesters appear to be attractive alternatives for the poly( 1,4-butylene terephthalate) materials that are taking on much economic importance. Many other polymers and intermediates are possible. I t is not the purpose of this paper to review the literature in depth. However, we believe that benzenedimethanol is worthy of examination in the light of today's changing needs.
Literature Cited Beaman, R. G.. J. Polym. Sci., 9, 470 (1952). Bhattacharyya, S. K., Gulati, I. B., lnd. Eng. Cbem., 50, 1719-1726 (1959). Bhattacharyya, S. K., Krishnamurthy, R., J. Appl. Cbem., Dec 13, 1963. Briii. W. F.. U.S. Patent 3 597 485 (1971). Cobbs, W ' H , The Quaker Oats Co , Bairington, ill , personal communication, 1973 Emerson, W. S., "Organic Reactions", Vol. IV, pp 174-208. Wilev. New York, N.Y., 1948. Hartung. W. H.. J. Am. Cbem. Soc., 50, 3370 (1926). ICI, British Patent 604 985 (1948). Journeay, G. E., U.S. Patent 2 748 154 (1956). Kindler, K., Schrader, K., Ann. Cbem., 564, 49 (1949). Nishimura. A. A,. Polvmer. 6. 446-448 11967). Oga, TI. hydroc&i Process, 45, 1741176 (1966). Quelet. R., Bull. Soc. Cbim., 53, 222-234 (1933). Rhoad, M. J.. Flory, P. J., J. Am. Chem. Soc., 72, 2216-2219 (1950). Ruaah, P., Bussemaker, B. B., Muller, W.. Staub, A,, Helv. Cbim. Acta, 1388-1395 (1935). Saotome, K., Komoto, H., J. Polym. Sci., Part A-1, 4, 1463-1473 (1966). Schollenberger. C. S., Scott, H.. Moore, G. R., Rubber World, 549-555 11958). Schollenberger, C. S..Stewart, F. D., J. Elastoplasfics, 4, 294-331 (1972). Siefken, W., Ann. Cbem., 562, 75-136 (1949). Sorensen. W. R., Campbell, T. W., "Preparative Methods of Polymer Chemistry," 2nd ed, pp 130-132, Wiley, New York, N.Y., 1968. Wheeler, J. S..M.S. Thesis, University of Illinois, 1974. Winans, C. F., Adkins, H.. J. Am. Cbem. Soc., 54, 306 (1932). Wirtz, G. P., Wheeler, J. S., Sis, L. B., J. Catal., 38, 196-205 (1975). Yang. K., M.S. Thesis, University of Illinois. 1974.
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\
- - - I
Received for review August 18, 1975 Accepted November 24, 1975
