to give a light gray polymer and that for Experiment 14 from
DMF, THF, and finally from water to give a white nylon-9 with the highest molecular weight achieved under the conditions used. The nylons of Experiments 15 and 16 have the highest molecular weights obtained in this investigation. Both were dark gray, illustrating that this discoloration has no other effect on polymerization. Nylon-9 Properties. Some properties of nylon-9 fiber were compared with those of other nylons in exploratory studies with some of t h e first nylon-9 samples prepared. Monofilaments were prepared by melt spiiiiiing with a laboratory model monofilameiit extruder. Fibers %ere also prepared in the same way from samples of commercial nylons6, 4 6 , -8, -11, and -12. Table IV compares some properties of these filaments. Tenacities of nylon-9 are up to 8.2 grams per denier a t the break denier (the denier a t the instant of fiber rupture) and up to 14.5 grams per denier for a hand-drawn threedenier filament as compared with maxima of 7.0-7.8 for nylons-11 and -12 and 8.4-10.5 for commercial fiber-forming nylons. The high tenacity of this sample could indicate that high-tenacity fibers are easier to obtain from nylon-9 (and other odd-numbered nylons) than from other nylons. N o r e thorough evaluation of nylon-9 is now being carried out a t the Southern Research Institute, Birmingham, Ala., and will be reported later. Nylon-9 could be precipitated from trifluoroethaiiol solution in water to give a fibrous polymer. Granulation of nylon-9 by heating in ethanol under autogenous pressure (Joshi, 1966) caused coiisiderable degradation. The molecular weight of the granulated polymer was approximately half the value observed before granulation. Acknowledgment
We thank B. R. Heaton, K. A. Jones, C. E. AIcGrew, and RI. A. Spencer for microanalyses; R. L. Reichert for pressure
Evans for atomic absorption analyses ; D T h and glc analyses and laboratory .Idlof and J. K. Roseman for laboratory Bates, University of Arizona, for advice; and the companies listed in Table IV for nylon samples.
reactions; C. D. W. E. Keff for assistance; R. 0. assistance; R. B. literature Cited
Anders, D. E., Pryde, E. H., Cowan, J. C., J . A?ner. Oil Chem. SOC., 42, 236 (196th). Anders, D . E., Pryde, E. H., Cowan, J. C., ibid., 824 (1965b). Awl, R. A , , Pryde, E. H., Weisleder, D., Rohwedder, W. K., Cowan, J . C., ibid., 48, 232 (1971). Emerson. W.S.. in “Ornanic Reactions.’’ T’ol IV. Wilev. “ , Sew York. h.Y.. 1948. D 1?4. Horn, C. F., Freure, B. T., Vineyard, H., Decker, H. J., J . A p p l . Polym. Sci., 7, 887 (1963). Joshi, R. Al., i b t d . , 10, 1806 (1966). Kohlhase, W. L., Neff, W. E., Awl, R. A., Pryde, E. H., unpublished data, 1970. Little, John C. (to Dow Chemical Co.), US.Patent 3,354,203 iNov. 21. 1967): Chcm. A b s t r . . 68. 87589~11968). Ohama. Jl.’.0zaG.a. T.. J . Polum. ~‘$5.. A-2. 4. Sl7 11966) Otsuki,’H.,’Funahashi,’H., Aduan. Ch’em. Ser:, 21, 205 (1958). Pryde, E. H., Cowari, J. C., Chem. X k t . Prepr., ACS, 8 (2), 130 (1967). Pryde, E. H., Anders, D. E., Cowan, J. C., J . Amer. O i l Chem. SOC.,46, 67 (1969). Prvde. E. H.. Anderq. D . E.. Teeter. H . RI.. Cowan. J. C.. ibid.. 38, i 7 5 (1661). ’ Pryde, E. H., Anders, D. E., Teeter, H. ll., Cowan, J. C., J . Org. Chem., 25, 618 (1960). Sorenson, W.R., Campbell, T. W.,“Preparative Methods of Polymer Chemistry,” Interscience, New York, N.Y., 1961, p 69. Stalling, D. L., Gehrke, C. W., Separ. S c i . , 2 , 101 (1967). Throckmorton, P. E., Hansen, L. I., Christenson, R . C., Pryde, E. H., J . Amrr. Oil Chem. S O C . , 45, 59 (1968). RIXEIVED for revielv May 10, 1971 ACCLPTED August 12, 1971 - I
I
~
Presented a t the Division of Organic Coatings and Plastics Chemistry, 154th Meeting, ACS, Chicago, Ill., September 1967. The Northern Laboratory is part of the Northern Marketing and Nutrition Research Division, Agricultural Research Seivice, U.S.Department of Agriculture. Mention of firm names or commercial products does not constitute an endorsement by the U.S. Department of Agriculture.
Composition of Oxonated Rosin Wilmer A. Rohde’ and Glen W. Hedrick iyaoal Stores Laboratory, Southern Marketing and il‘zitrition Research Division, Agricultural Research Service, USD.4 , Olustee, Fla. 32072
T o expand the commercial utilization of gum rosin, research
is being conducted in this laboratory to make polyfunctional derivatives of the r e m acids. The polyhydroxymethyl compounds have shown adaptability for use in urethane polymers. I n recent work derivatives of rosin products as extenders produced rigid foams of enhanced properties a t lower costs (Darr and Backu., 1967). The oxo process appeared feasible and economical for converting the diolefinic resin acids in rosin to the saturated hydroxymethylated compounds. Levering and Glasebrook (1958) reported that with use of the preformed cata1y.t dicobalt octacarbonyl and 50y0 by weight of a hydrocarbon solvent, the resin acids underwent oxonation to an apparent 89.5% yield of added hydroxy1
To whom correspondence should be addressed.
methyl groups. Because of the complex mixtures of compounds in rosin, the evaluation of Levering and Glasebrook was based on mass analysis-i.e., hydroxy1 and ester values of the gross product. Since rosin conbains generally 15-207’, of material unreact’ive to osonation-e.g., dehydro- and tetrahydroabiet’ic acids (Joye and Lawrence, 1967)--and this yield was higher than theoretical on the basis of monoaddition to the conjugated diene systems in abietic-type acids, they speculated t,hat the high value iTas due to diaddition with the pimarictype acids. Their oxonation of pure pimaric acid indicated that about 25y0 was converted to a dihyclroxy compound. This early work, however, did not reveal the act,ual product composition of oxonated rosin. -1copper chromite and lithium aluminum hydride reduction in this laboratory (Parkin et al., 1966) showed that coniiderable unosonated resin acids were Ind. Eng. Chem. Prod. Res. Develop., Vol. 10, No. 4, 1971
441
present in oxonated rosin. Levering and Glasebrook also reported t h a t carboxylation and esterification occurred during the oxonation; however, their data (Saponification No. 172 for both the wood rosin and its oxonation product) did not agree with this contention. The primary objectives in this work were to determine the composition of oxonated rosin-Le. , its product distributionto devise a feasible separation of these oxo products, and to improve processing conditions. Column chromatography and liquid-liquid countercurrent partitioning combined with gas-liquid partition chromatography (glpc) and chemical analyses proved adequate for the products encountered. Experimental
Melting points and boiling points recorded are uncorrected. Infrared spectra were determined on a Perkin-Elmer Model 21 spectrophotometer. Glpc was done with a Hewlett-Packard 700 series chromatograph, by use of a flame ionization detector with a 6-ft X I/B-in. w-98 high-efficiency packed column. Synthesis gas refers to a 1: 1 mixture of CO and Hz. Oxonation of Gum Rosin. A stainless steel pressure reaction vessel (1.8-liter cap.) was charged with 400 grams of WW gum rosin [N.E. 343, OHE 2100 (0.8% OH)], 300 grams of isooctane, and 30 grams of Coco3. The vessel was charged to 3300 psig a t 27°C with a 1 : 1 mixture of HZand CO, and heating and rocking were begun. After 2.5 hr the temperature and pressure had risen to 197°C and 5050 psig; after a n additional 30 min the pressure had dropped to 3200 psig at 210°C. The temperature was maintained at 200 f 10°C, and after 15 h r the pressure had dropped to 2200 psig, a t which time the heater was turned off. After cooling to 15OoC, the contents of the vessel were vented into a flask, taken up in ether (3 liters) , and washed several times with a 1: 1 mixture of 6N hydrochloric acid and a saturated ammonium chloride solution to remove the cobalt color, then with water, and finally with salt solution to remove the mineral acid. After being dried over Na2SOd, the solvent was stripped in a rotary evaporator. The oxonation product was a hard brittle resin (N.E., 462; OHE, 537). Saponification of Oxonated Rosin. A solution of 200 grams of oxonated gum rosin (N.E., 462; OHE, 537) in 1500 ml of ethylene glycol and 40 grams of NaOH was refluxed for 6 hr. The cooled solution was diluted with 1500 ml of water and extracted with 3 x 500-ml portions of a 1 : l hexaneether mixture. The combined hexane-ether extract solution was washed with 3 x 200 ml of water (the wash water was returned to the glycol saponification solution) , dried, and evaporated to yield 9.5 grams of neutral material as a n oil. The alkaline saponification solution was then acidified with 6 N HC1 acid and extracted with 4 x 700 ml of ether. The combined ethereal extract was washed free of mineral acid with water, dried, and the solvent removed on a rotary evaporator to a syrup (209 grams); a dried sample had N.E. of 350 and O H E (methyl ester) of 413 (4.14% OH). The syrup was dissolved in 1500 ml of 95% aqueous methanol (previously equilibrated with 95% hexane) and extracted with six 500-ml portions of hexane equilibrated with 95% aqueous methanol. Glpc of the first hexane extract indicated approximately a 90: 10 mixture of unoxonated to monoxonated resin acids. The last extract (sixth), which held only a slight amount of material compared with the first extract, was about 1: 1 mixture of these same components. The combined hexane extract, 59 grams, contained about 80% unoxonated material. T h e methanol raffinate contained 127 grams of solid resin 448
Ind. Eng. Chern. Prod. Res. Develop., Vol. 10, No. 4, 1971
[OHE, 302 (5.63% OH); N.E., 3601. Glpc of the acetoxy esters showed peaks for acetates of monohydroxy and dihydroxy compounds with a minor amount of unoxonated resin acids present. Preparation of Methyl Esters of Rosin Acids. A 450gram (1.31 moles) charge of gum rosin (A.N., 163; N.E., 343) was placed in a resin flask equipped with a paddle stirrer, reflux condenser, and Dean-Stark trap. T o this were added 1300 ml of dioxane, 100 ml of hexane, and a solution of sodium hydroxide (60 grams, 1.5 moles) in 40 ml of water (Parkin and Hedrick, 1965). The slurry was vigorously stirred and heated to reflux; the water azeotrope was collected and drawn off the Dean-Stark trap until water ceased to be evolved. The dried solvent-salt mixture was cooled and transferred to a rocking stainless steel autoclave, sealed, and charged with 120 grams (2.37 moles) of methyl chloride. The mixture was rocked a t 160°C for 6 hr. After cooling, the dioxane solution of ester was filtered to remove the NaCI, and the dioxane was removed by distillation under reduced pressure. The acid number of the crude product from several runs ranged from 1.1-1.7. The crude product derived from 2600 grams (7.54 moles) of gum rosin was distilled under reduced pressure: 1996 grams of distillate were collected over the bp range of 165-75"C/.07 m m H g (pot temp., 185"C), and a n additional 175 grams were collected up to 185"C/.07 m m (pot temp., 21OoC), for a totaI of 2171 grams (80.6%) of distilled methyl resinate ( A N . , 0.6; S.E., 357). There was a pot residue of 384 grams (14.3%) of a dark friable resin (AN., 11; S.E., 374). Oxonation of Rosin Methyl Esters. A charge of 420 grams (1.185 moles) of the distilled methyl resinate [S.E., 357; Ah'.,0.6; OH Xo. 16 (0.5070 OH), derived via sodium salt/CHaC1 method], 300 grams of isooctane, and 20 grams of C o c o 3 were placed in a 1.8-liter stainless steel reaction vessel. Synthesis gas (1 : 1) was pumped into the vessel to a pressure of 4000 psig a t 90°C with rocking. After 35 min the temperature and pressure had risen to 150°C and 4500 psig, a t which time uptake of gas was observed. During another 30 rnin the pressure dropped to 4000 psig a t 2OOOC and to 2500 psig after a n additional 20 min a t 200°C. Synthesis gas was added (5000 psig, 2OO0C), and the temperature maintained with agitation for another 4 hr during which time the pressure had levelled off a t 3700 psig. The product was vented from the reaction vessel under pressure while hot (125°C) through a valve into an Erlenmeyer flask and taken up in 2 liters of ether. The cobalt was removed by stirring the ether solution with a mixture of 6N HCl (250 ml) and a saturated NH&l solution (250 ml) with a large size magnetic stirring bar and by carefully warming the mixture in a water bath. Within 30 min the ether layer was colorless, and free cobalt was attached to the magnetic stirring bar. The ether layer was separated, washed with water and salt water until acid-free, dried over sodium sulfate, filtered, and the solvent stripped on a rotary evaporator. The product, 458 grams, was a water white, viscous resin (OHE, 385; 4.42% hydroxyl or 26.2 grams, 1.19 equiv OH added). The glpc (240°C) had peaks a t 1.5 rnin (unoxonated esters) ; 2.75, 3.75, 5.75 min (monoxonated esters); and 7.75, 9.0, 11.5 min (dioxonated esters). A work-up of a similar oxonation run was done with benzene as a solvent. At room temperature the decomposition of catalyst was slow, but upon heating the magnetically-stirred mixture, decomposition of cobalt catalyst was rapid. The free cobalt precipitated and collected on the stirring bar, leaving a colorless benzene solution of the oxonation product. The hydroxyl equivalent of several oxonation runs varied
~~
The oxonation of distilled methyl esters of gum rosin yielded oxonation products relatively free of neutral and complex impurities compared to those prepared from commercial gum rosin. The methyl esters were prepared in high yield from sodium resinate and methyl chloride. The oxonated methyl resinate averaged 0.88 equivalent of added hydroxyl per equivalent of methyl resinate. The composition of the oxonated methyl resinate was 21.9 mol % dihydroxymethyl-, 43.3 mole 70monohydroxymethyl-, and 34.8 mol % unoxonated-hydrogenated esters. The partition coefficients of these products between hexane and aqueous methanol were determined. Partitioning of the oxonated methyl resinate between this solvent system gave a satisfactory separation of the dioxonated, monoxonated, and unoxonated esters. The BaCuCrOs-catalyzed hydrogenolysis of the esters yielded the respective dihydroxy and trihydroxy compounds which were incorporated in a formulation for casting polyurethane films.
from 385-430; the higher hydroxyl value was found when the temperature exceeded 210°C. Separation of Oxonated Methyl Resinate Products
Column Chromatography. A 50-gram sample of oxonated methyl resinate (oxonated for 3 hr; OHE, 440; S.E., 387) was dissolved in 200 ml of hexane and adsorbed on a 7.5-cm column holding 600 grams of Alcoa F-20 alumina. The eluant was collected in 250-ml fractions, and solvent stripped on a rotary evaporator under aspirator pressure. The unoxonated methyl esters, 15.1 grams, were eluted with 3750 ml of 5Y0 ether-hexane; an additional 0.4 gram, mixed with a few percent of monohydroxy esters, was collected as the solvent system was changed up to 35% ether-hexane. Elution with 5 X 250 ml of 35% ether-hexane provided a 2.3-gram fraction comprised of 85% of the monohydroxy esters and 15% of the unoxonated material. A 20.6-gram fraction of monohydroxy esters [OHE, 360 (calcd, 350)] was next collected from 11 X 250 ml of 40% ether-hexane. Further elutions with etherhexane to 4 X 250 ml of ether yielded only traces of material. The dihydroxy esters were then stripped from the column with 2 liters of 10% methanol-ether [11.8 grams; OHE, 183.3 (theor., 190)]. Based on the total material recovered (50.2 grams), the composition of oxonated methyl resinate calculated to be 34.5 mol 70unoxonated (15.9 grams), 44.1 mol % monohydroxy (22.5 grams), and 21.4 mol % dihydroxy esters (11.8 grams). Countercurrent Distribution. Hexane was equilibrated with 90% methanol a t room temperature. A 5-gram sample of the oxonated rosin methyl esters that had been oxonated for 6 hr a t 200°C (OHE, 385) was dissolved in 50 ml of the methanol phase, and 10 ml of this were placed in each of tubes 0-4 of a 100-tube Craig apparatus. Lower phase solution (10 ml) was placed in the remaining tubes to the transfer level. Hexane (10 ml) was added to the first tube of the train, and the solutions were equilibrated for 1.5 min, allowed to settle for 1 min, and upper phase was transferred. This process was repeated for 100 transfers of 10-ml portions of hexane. The upper phase solutions were collected individually a t the end of the train after another 100 transfers. Each lower layer tube (0-100) was collected in individual tubes, solvent stripped, and residue weighed for each collection. The residues were examined by glpc for presence of dihydroxymethyl, monohydroxymethyl, and hydrogenated unoxonated esters. HEXASE LAYERS.Tubes 1-10 contained 1.503 grams of unoxonated, hydrogenated methyl resinate, and tubes 11-20 an additional 0.111 gram contaminated with traces of the monohydroxymethyl material. Tubes 21-30 held only 0.040 gram of material ranging from 50% unoxonated (tube 21) to nearly all monohydroxymethyl material (tube 30). The total unoxonated material identified, 1.614 grams (32.2 wt %), thus comprised 34.8 mol % of the oxonated methyl resinate.
The remaining upper layer tubes 31-100 contained 0.222 gram of the monohydroxymethylated isomers. METHANOL LAYERS.Tubes 0-10 (1.013 grams) and 11-17 (0.192 gram) contained the dihydroxymethyl esters (OHE, 198); glpc (acetates) showed peaks a t t = 7.8, 9, and 11.5 min (24OoC, see above) only. This 1.205 grams, 24.0 w t % of the sample, represents a 21.9 mol 70yield of dioxonated methyl resinate. Tubes 18-21 held only 4 mg of material, a mixture of monoand dihydroxymethyl esters. The isomeric monohydroxymethyl esters were recovered from tubes 22-90 for a total of 2.191 grams of monoxonated material, 43.8 wt Yo and 43.3 mol % of the sample of oxonated methyl resinate. Solvent Extraction of Oxonated Methyl Resinate Products. T o provide working samples of the mono- and dihydroxy esters in large amounts of material for polymer evaluations, the following procedure was generally followed : A 500-gram portion of oxonated methyl resinate was dissolved in 5 liters of 95% methanol (previously equilibrated with hexane). This solution was extracted with 6 x 1-liter portions of hexane. The combined hexane extracts (A) were cross-extracted with 2 x 500 ml of 90% methanol (glpc showed preferential extraction of the hydroxy material) and washed once with water (750 ml). The wash water and 90% methanol cross-extractions were then added to the primary 95% methanol solution to provide an 80% methanol solution. This was then extracted with 3 x 1500 ml of hexane. Extracts were combined and washed with water to provide hexane extract (B) ; the methanol raffinate provided Fraction C. The composition of the above fractions was determined by glpc examination and OH values and are close approximations : Fraction
Wt, g
OHE
A
200 103 205
1476 433 246
B C
Composition, % Unoxonated Mono-OH
76 19
24 81 35
Di-OH
65
Distillation of Fraction A through a 6-in. vacuum jacketed Vigreaux column provided a clean separation of the unoxonated esters from the oxonated material. From one distillation of 119 grams of Fraction A material, 78.4 grama of the saturated methyl esters were collected over the range of 138245OC/.O2 mm Hg (pot temp, 175°C). The monohydroxy ester distilled a t 162-7loC/.02 mm (pot temp, 220°C). However, pot residues of 15-18% consisting of polyesters formed by transesterification were generally found, particularly, in attempts to separate the monohydroxy from the dihydroxy esters. Oxonation of Methyl Pimarate. Pimaric acid (50 grams) was esterified with diazomethane and oxonated (200" C, 5000 Ind. Eng. Chem. Prod. Res. Develop., Vol. 10, No.
4, 1971 449
psig, 1: 1 hydrogen-carbon monoxide) for 6 h r as described for other oxonations. The product (59.6 grams; OHE, 397) showed little difference in composition from the oxonated methyl resinate by glpc analysis. The resin was partitioned between 95% methanol-hexane t o remove the unoxonated material (hexane phase). The methanol raffinate was again partitioned between 80% methanol-hexane; the dihydroxy material was recovered from the methanol raffinate. Analysis of the fractions (glpc and hydroxy equivalent values) showed that oxonation had yielded 15 grams (28.1 mol %) of unoxonated material, 28.3 grams (48.5 mol %) of the monohydroxymethyl, and 15 grams (23.3 mol %) of the dihydroxymethyl pimarate. Oxonation of 12-Hydroxymethylabietic Acid (12HMAA). Fifty grams of 12-HMAA (N.E., 333) were esterified with diazomethane and loaded into the autoclave with 2.5 grams of C o c o 3and 150 ml of isooctane. The system was charged to 3800 psig a t 55OC with synthesis gas with rocking, and the temperature raised to 208°C (5750 psig). The temperature was maintained a t 200 i 10°C for 5.5 hr, by which time the pressure dropped to 5300 psig at 196°C. The near colorless product was recovered in the usual procedure [59 grams; OHE, 440 (3.86% OH)]. The glpc of the crude product showed that considerable methyl tetrahydroabietate was present, and the tracing was almost identical with that for oxonated methyl resinate. Partitioning of the crude material between hexane-95% methanol and hexane-80yo methanol, as previously described, again provided a separation of the products. The hexane extract (A) of 95% MeOH yielded 18.6 grams (OHE, 1203) calculated to be 71% (13.2 grams) methyl tetrahydroabietate, 27.3 mol %. The 80% methanol raffinate (C) contained 23.5 grams of oxonated products (OHE, 267). The glpc showed this was a mixture of mono- and dihydroxymethyl esters. From the hydroxyl value, it was calculated to be 5201, dihydroxymethyl esters (12.2 grams), 21.3 mol % of the oxonated material. The hexane extract of the 80% methanol (B) contained 4.3 grams of material (OHE, 445); the glpc showed a strong major peak for the monohydroxymethyl, but different from the starting material, with a minor amount of methyl abietanate present. Hydrogenolysis of Methyl Tetrahydroabietate. Methyl tetrahydroresinate (50 grams) recovered from the separations of oxonated methyl resinate (glpc had one principal peak; no hydroxyl was apparent in the infrared spectra), 100 ml of methanol, and 5 grams of copper chromite catalyst powder (Girdler G-13) were charged into a 1.8-liter stainless steel autoclave, which was flushed and then charged with hydrogen to 3000 psig a t 83°C. The autoclave was rocked and heated to 275OC (5300 psig), and samples were removed a t 1-hr intervals for analyses by glpc and infrared spectra. After 1 hr, as evidenced b y infrared and glpc, hydrogenation was approximately 50% complete. After 2 h r there was little carbonyl absorption in the infrared spectrum, and a strong abietanol peak with a shoulder for unreacted ester showed in the glpc. After 3 hr the hydrogenation was complete. A second 50-gram sample was hydrogenated a t 25OOC for 5 hr (OHE, 319; calcd, 292 for pure abietanol). The glpc and infrared spectra were identical with the run at 275OC. Hydrogenolysis of Monohydroxymethyl Esters. A 215gram sample rich in the monohydroxymethyl esters (OH, 430; distilled from a hexane extract of oxonated methyl resinate), p-dioxane (200 ml), and 21 grams of Girdler G-13 copper chromite catalyst were placed in a 1.8-liter stainless steel autoclave. The system was flushed with and then charged with hydrogen to 2500 psig a t 47°C. The autoclave was 450
Ind. Eng. Chem. Prod. Res. Develop., Vol. 10,
No. 4, 1971
rocked and heated to 285°C and 5000 psig. This temperature was maintained for 4 hr, a t which time the heater was turned off, but rocking continued overnight (18 hr). The contents were charcoaled, filtered through Celite, and brought to dryness; infrared spectrum of the residue (210 grams; OHE, 381; S.E., 346) had strong carbonyl absorption. The recovered material was thoroughly redried in vacuo and again subjected to hydrogenation with 25 grams of G-13 catalyst a t 275 =t10°C for 5 hr. The recovered colorless product had O H E of 331 (5.14% OH) and S.E. of 498. Hydrogenolysis of Oxonated Rosin Esters-BariumPromoted Copper Chromite. A 320-gram charge of oxonated rosin esters [OHE, 425 (hexane extract of 85% methanol solution of oxonated rosin esters) ] was placed in the autoclave with 200 ml of dry dioxane and 35 grams of barium-promoted copper chromite catalyst (Girdler G-22). The system was flushed with and charged with hydrogen to 2500 psig a t 53°C. Shaking was begun and the temperature was raised to 260°C (4095 psig), a t which point uptake of hydrogen was evident as the pressure dropped to 3750 psig in 1-hr time. Hydrogen was added to 400 psig, and the temperature raised and maintained a t 265OC for 3 hrs, at which time the pressure had dropped to 3660 psig. The heater was then turned off, and rocking continued until the autoclave was cool. The reaction mixture was transferred to an Erlenmeyer flask with acetone, treated with charcoal, and filtered while hot through a CeIite bed. The solvent was removed in vacuo from the colorless filtrate. The product (OHE, 190) had a weak carbonyl band in the infrared spectrum. The glpc of the acetates had a minor peak for tetrahydroresinyl acetate and a major peak for the diacetoxy compounds. Crystallization of the diol started in the acetone/dioxane filtrate after a few minutes cooling. After setting overnight, 78.5 grams of crystalline diol (OHE, 164) were filtered from the solution. A glpc of the solids (diacetate) showed a sharp single peak (t = 3.8 min, T = 225°C) and a slight peak for the presence of some monohydroxy impurity (t = 1.4 min). Stripping of the solvent from the mother liquor left 195 grams of water white, hard resin for which glpc indicated about 90% diol. Saponification of this resin in ethylene glycol (see above) yielded 20 grams (6.27,) of resin acids (X.E., 315); the carbinol fraction had O H E of 164 (calcd, 161 for diol). Hydrogenolysis of Dihydroxy Esters. n'hen material rich in the dihydroxy isomers of oxonated rosin esters was hydrogenated under the same conditions successfully used for the monohydroxy esters, the uptake of hydrogen was slow and hydrogenolysis incomplete when 10 wt yo of catalyst (G-22) was used. The methanol raffinate Fraction C (OHE, 249) of oxonated methyl resinate (250 grams), 25 grams of Girdler G-22 catalyst, and 200 ml of dry p-dioxane were placed in the stainless steel autoclave. The system was flushed with and charged with hydrogen to 2500 psig a t 50°C. The bomb was rocked and heated to 265°C (4150 psig) for 8 hr. Rocking continued during cooling overnight (14 hr). Work-up provided a resinous product with an O H E of 207. The recovered product (210 grams) mas then rehydrogenated under identical conditions except that 35 grams (15%) of G-22 catalyst was used for 4 h r a t 265OC. The recovered product had an O H E of 148 (S.E., 3830). Crystalline triol (50 grams) precipitated from a chloroform solution of the poly01 mixture. The mother liquor residue (151.5 grams) was saponified and separated to yield 16.8 grams of oxonated rosin acids ( S . E . , 335); the neutral carbinol fraction had a n OHE of 137. The glpc (acetates) showed a mixture of diols and triols.
A 200-gram portion of solvent-extracted oxonated methyl resinate Fraction C (OHE, 246), 30 grams of Gridler G-22 catalyst, and 200 ml of dry p-dioxane were placed in t'he stainless steel autoclave. The system was flushed with and charged with hydrogen to 4000 psig a t 245OC. The bomb was maintained a t 265 i: 5 ° C for 5 hr; the pressure had levelled off a t 3850 p i g after 3 hr. The bomb was kept rocking overnight while cooling. Work-up yielded 186 grams of the water white product (OHE, 146). Saponification and separation yielded 22.4 grams of acids (S.E., 335; the neutral fraction had a n O H E of 142; ca. 50% triol). Distillation of Polyols from Oxonated Methyl Rosin. d 189-gram lot of oxonated met,hyl resinate was reduced with 24 grams of L-IH in et'lier in the usual manner. Work-up furnished 173.6 grams of water white solids with an O H E of 177.5; infrared spectra did not show any absorption for carbonyl. This inixture of polyols was then distilled at' reduced pressure (0.2 mm Hg) in a simple bulb-to-bulb distillatioii. Four distillate fractions were collected and analyzed: Pot, Fraction
'C
Head, O C
195 153-161 203 163 223 174-184 4 245 196-231 P o t residue 1 2 3
Wt, g
OHE
39.7 24.1 55.5 29.9 11.5
255 213 164 146 206
Mono- Di-OH Tri-OH, OH, % % %
72 40
4
28 60 85 66
11 34
The content of tetrahydroabietaiiol aiid the mono- and dihydroxy oxo productswere calculated froin the hydroxyl values and glpc tracings. ,1sample of bhe pot residue was acetylated for glpc analysis which shoived only a minor peak, iiidicatiiig that' this was likely polymeric material formed duriiig the oxoiiat'ioii reaction or distillation of the polyols. The pot residue was examined by column chromatography on *\koa F-20 alumina. Elution with 150 nil of 1: 1 CHCI,: hexane furnished 5 grams of material (OHE, 271) that' did not show any peaks in a glpc a t 240OC. Elution with 900 ml of 1 : 1 CHC13:hexane furnished 2 grams (OHE, 224) whose glpc of the acetylated mat,erial showed only a minor deflection in the region of the triacetoxy derivatives. Chloroform (400 nil) eluted 0.8 gram (OHE, 189); glpc s h o w d two minor peaks in triacetoxy region. Final elution with 300 nil of ether provided 2.7 grams (OHE, 158); glpc showed oiilj- a large peak for the triacetate compound. Partition Coefficients of Oxo Products. Four-gram samples of methyl tetrahydroabietate ( K O )methyl , nioiiohydroxymethylabietate ( K 1 ) , and methyl dihydroxyinethylabietate (K2) were each dissolved in 40 in1 of 95% methanol and equilibrated against' 40 ml of hexane for 5 miii in separatory funnels. The solveiits lvere previously equilibrated before introduction of sample. Results are expressed as K = E / R where E is hexane-extract,ed material, aiid R is grams of raffiiiate in aqueous methanol. Discussion
The previous iiivest'igators stated that tlie preferred coiiditions for oxonation of rosin required the use of the preformed cobalt carbonyl cat,alyst, 50% solvent, aiid a 2 to 1 mixture of hydrogen-carbon nioiioxide a t 200°C. Under these condition? yields of up to 89.5% were described, whereas when cobalt acetate was used as the catalyst, the oxonation yields dropped to 42'%. Work iii this laboratory on the oxonation procedure has shown that yields of 85-9070 were obtained n-ith gum rosin by use of cobalt carbonate a s catalyst (5 n-t % of rosin) in t'he presence of solvent (isooctane, 25% solution) aiid a 1: 1 ratio of hydrogen-carbon moiioside. That the catalytic co-
balt carbonyl rras formed in situ during the heat-up of the reaction mixture was evidenced by the observation that a take-up of gas and a n exothermic reaction would begin a t 140-l5OoC, quickly carrying the temperature up to 200°C with a decrease in pressure. h reaction time of 4-5 hr a t 200°C was sufficient for production of the carbinols. Longer reaction periods gave a slight increase in hydroxyl content, but these longer periods, as with temperatures much above 20OoC, led to coiiaiderable polyesterification of the hydroxy acids. In the work-up of the oxonation reaction, the complete removal of cobalt from the product is quite essential if the product is t o be used for polymers, especially polj-urethanes. In small batchwise preparations one procedure followed was t o empty the reaction vessel, while under pressure, through a valve into a flask while it was still hot (125-150°C). This effected a partial thermal decobaltiiig by decomposition of the dicobalt octacarbonyl. The product was then taken up in ether and washed with a bolution of ammonium chloride and hydrochloric acid until the ether solution \vas free of tlie cobalt blue-pink color. .In analysis of a pot residue from a distillation of osoiiated rosin esters indicated that t,he oxonated rosin had contained 1.4 ppni of cobalt. An improved decobalting was effected by taking up the dark brown reaction product iii beiizene, adding a 1:1 solution of saturated ammoilium chloride aiid dilut,e hydrochloric acid (ea. volume), and stirring the heated mixture vigorously with a large magnetic stirring bar. The free cobalt was attracted t o t,he t,eflon-coated magnet, and usually within 30 mill of heating aiid stirring, the benzene layer would be free of color. The beiizeiie solution, after separation from tlie blue aqueous layer, was then washed free of mineral acid with salt solution. The recovered oxoiiated rosin, a colorless resin, gave a negative test for cobalt ion. A typical oxonation of gum rosin (see Experimental) provided a light yellow, brittle resiii with a neutral equivalent of 462 aiid a hydroxy equivalent (methyl ester) of 537. Saponification of this product t o remove polyesters, along with extraction of neutrals from the alkaline solution, furnished a product with a neutral equivalent of 350 and a hydroxyl equivalent of 413 (4.1% hydroxyl). ;inalyses showed the composition of ail oxoiiated gum rosin mixture was about 57, iieutrals, 30-337, unoxonated (tetrahydro aiid dehydro) resin acids, 3 8 4 0 % Iiionohydroxymethyl acids, 14-20% dihydrosymethy1 acids, aiid 10-13% polymeric material. dttenipts t o separate tlie oxoiiated products of rosin per se t o effect an accurate assessment of the uiioxonated, mono-, and dioxoiiated material iii the product, as with the osoiiated nietliyl ester;;, n-ere oiily fairly successful because of tlie complex mixture of neutral and polynieric niaterials present in gum rosin. Coluiiiii chromatography or liquid-liquid partitioiiiiig of the crude product' always gave fiactioiis contaminated with these undesirable materials. Fractional distillatioii of the methyl esters iinder high vacuum left considerable pot residues owing to polyesterification. Distillation of the polyols derived froin lithium aluiiiiiiuni hydride reduction of the csters also left pot residues of polymeric niaterial as atte;ted t o by lack of response in glpc analysis. The niethyl esters of rosin acids (methyl resinate) were easily made iii liigli yield by reacting a slu sodium salts with methyl chloride (Parkin and Hedrick, 1965). The glpc pattern of the methyl esters prepared in tliis fashion was identical with the product derived when diazoniethaiie ~ v used a ~ a.: tlie esterifying reagent. Osoiiatioii of the distilled methyl esters of rosin provided a colorless resiii with hydroxyl equivalent values corresponding Ind. Eng. Chem. Prod. Res. Develop., Vol. 10, No. 4, 1971
451
0
4
6
, 610
e
450
W
m
3 I-
390
a
W
n t
r 2
330
W
2 10
Y
t
PI0
I60
so
I
30
0
TUBE NO.
LOWER PHASE
UPPER PHASE.
Figure 1 . Distribution pattern of oxonated methyl resinate System:
90% methanol-hexane;
t o the addition of up to 91 mol % of hydroxyl groups. This product mixture of methyl esters appeared quite free of highmolecular-weight polyesters and lent itself readily t o separation by column chromatography or liquid-liquid partitioning. A sample of oxonated methyl resinate was chromatographed on a n alumina column and provided a good analysis of its composition, which was 34.5 mol % ’ of unoxonated saturated esters, 44.7 mol yo of monohydroxy, and 21.4 mol % of dihydroxy esters. The glpc of the eluted materials had peaks with the same retention times as the original product mixture, indicating that no change had occurred on the alumina column. Although the glpc analysis of the individual eluates showed that some separation of the isomeric hydroxy esters was being affected, no effort was expended during this research t o isolate or characterize the compounds. With essentially pure unoxonated, monohydroxy, and dihydroxy esters recovered from the chromatographic separations, the partition coefficients for these materials (Table I) were determined for the hexane-aqueous methanol system for subsequent separation by solvent partitioning. A sample of oxonated methyl resinate was partitioned between hexane-90yo methanol in a 100-tube Craig apparatus (10-ml volume of each phase). The unoxonated material was
Table 1. Partition Coefficients of Oxonated M e t h y l Esters Solvent
452
Hexane-95% MeOH
KQ
9
K1 K2
0.45 0.03
Hexane-90% MeOH
36 0.9 0.03
Hexane-E5% MeOH
2.33 0.03
Ind. Eng. Chem. Prod. Res. Develop., Vol. 10, No. 4, 1971
100 post tubes
concentrated and recovered from the first 20 tubes of the hexane phase (Figure 1). The monohydroxy and dihydroxy compounds were both retained in the 90% methanol phase but were well separated with the dihydroxy esters staying in tubes 0-15. The monohydroxy esters as evidenced by the curve were well spread out through tubes 20-90. The glpc analysis of the material in these tubes showed in some tubes remarkably good isomer purity as evidenced by single peaks with only a minor shoulder. The weights of the collected material gave values of 34.8, 43.3, and 21.9 mol % of the unoxonated, monohydroxy, and dihydroxy esters. This is in good agreement for the composition as determined by column chromatography with a sample of material from another oxonation run. While attempts to separate these principal oxonation products on a relatively large scale in the laboratory by partitioning in separatory funnels (up t o 10 stages) did not give the complete separation of the mono- and dihydroxy esters as with the Craig apparatus, material consisting of u p to 9&95% of the desired mono- or dihydroxy components could be obtained. By use of the separatory funnel technique in the laboratory, it was best t o remove the unoxonated material by first partitioning between 95 or 90% methanol-hexane, followed by dilution of the methanol phase t o 85%, and then extraction of the monohydroxy compounds into a fresh hexane phase. Previous work has shown that the 1Zhydroxymethyl resin acids and esters were easily reduced t o the polyols by use of powdered copper chromite catalyst (Parkin et al., 1966). I n this instance, however, repeated attempts t o hydrogenolyze the monohydroxy ester material with copper chromite repeatedly led to recovery of most of hhe starting ester. Experiments conducted with samples of recovered methyl tetra-
Table II. Hydroxyl-Terminated Poly(ethy1ene Adipate) Glycols Containing Oxonated Diols and Triols N.E., adipic acid ester
OHE Diol
Found
Calcd
CziH380z 162.96 161.15 CziH380z 162.96 161.15 Triol CzzH410a 122.9 117.44 a Calcd from OHE found. b 1% ethylene glycol could account for transesterification. d Calcd from OHE value found; 122.9.
OHE, ethylene adipate glycol
Found
Calcd
295 289.6
.290.9 290.9.
Found
Calcd
330.0 301.9b
333.2 333.2
262.8. 250 9d 255.5 294.9d this low value. The high value could result from a minor amount of
Table 111. Polyurethane Films from Ethylene Adipate Glycols of Diols and Triols Concn ofb in Bu(OH)z film, % equivC
Poly (ethylene adipate) equivd
Av OHE glycol mix
TDI equive
Tensile strength, psi
100
200
Modulus, psi,
% 300
Elongation,
%f
Brittle point, O CQ
Item
OHE
Equiva
1 2
333 302'
2.84 2.84
15.15 15.6
5.04 5.04
1.0 1.0
249 239
9.32 9.32
5620 5538
285 332
394 516
662 948
553 521
-7
3
302' 255;
1.62 1.21
15.6
2.41
1.0
312
6.56
5576
244
351
576
497
-23
4
302h 255i
1.62 1.21
13.7
5.18
1.0
233
9.00
5646
303
519
1195
462
5
302' 255;
1.62 1.21
13.8
5.05
1.0
233
8.87
4295
226
330
600
487
-17
62 343 2 75 15.0 4.85 1.0 252 9.03 6067 447 749 1548 450 -12 a Abietanylethylene adipate. Abietanyl moiety. 1,4-Butanediol. Poly(ethy1ene adipate) glycol; OHE, 1000. e Toluene diisocyanate ratio to glycol, equiv 1.05: 1 for items 1, 2, 3, 4, 7 ; 1.02: 1 for item 5 ; and 1.0:1 for item 6. 1 From bench marks. Brittle point ASTM D-746. Diol. Triol. 3 Taken from item 3, Table 111, Lewis and Hedrick (1970).
hydroresinate, where the course of reduction could be followed by infrared, showed t h a t hydrogenolysis of the ester group proceeded rapidly; after 3 hr a t 275OC there was 110 detectable carbonyl absorption in the infrared. However, the oxoiiated esters failed t o give any appreciable reduct'ion under ident'ical conditions. When a barium-promoted copper chromite catalyst \vas used in the amount of 10 wt %, hydrogenolysis of the ester proceeded quite rapidly at 26OOC (4100 psig) and after 3 hr, the reduction as determined b y ir spectroscopy mas complete. Upon dilution of the filtered dioxane reduction mixture with acetone, crystalline diol would precipitate from the solution. Whe11 hydrogenolysis of the dihydroxymethyl esters was attempt'ed a s with the monohydroxy esters, the reduction was again slow and incomplete. By increasing t'he amount of catalyst t o 15% (w,/w), hydrogenolysis proceeded as well a s with the monohydroxy ester. Crystalline triol could be precipitated from a chloroform solution of the hydrogenolysis product. Unreduced ester left in the filtrates (ea. 5%) was best removed from t'he polyols by a saponification in ethylene glycol, followed b y dilution with water and extraction of t'he carbinols with ether or methylene chloride. The unreduced resin acids were then recovered from the aqueous glycol solution. The mixture of carbinols obtained was friable colorless resins. Inasmuch as conjugated dienes generally yield only t'he monoaddition product (Hat'ch, 1957), the 22 mol % of dihydroxyniethyl product found here mas unexpected and requires some comment. If the unconjugated pimaric-type acids, which coiist'itute about 26% of the resin acids present in commercial gum rosin, undergo dioxonation, they would then account for the percentage found. Levering and Glasebrook
(1958) oxonat'ed pimaric acid and reported that apparently only one-fourth was converted to a dihydroxy compound. Accordingly, we ran a n oxonation of methyl pimarate under the conditions used for met'hyl resinate. The reaction product analysis was almost identical with that for methyl resinate: 28.1 and 48.5 molyO of unoxonated and monoxonated methyl pimarate, respectively, and only 23.3 mol % of methyl dihydroxymethyl pimarate. This would account for only a 6-7% dihydroxy content in oxoiiated methyl resinate. Our results led t o the conclusion that the abietic-type acids undergo diaddition and monoaddition t o the same extent a s the pimaric-type acids. In support of this, when pure methyl 12-hydroxymethylabietate was oxonated, the product (OHE, 440) contained 26.3 mol yomethyl abietaiioate (hydrogenolysis of 12-methyl01 group) and again a 21.3 mol % yield of the dihydroxyniethyl esters. Lewis and Hedrick (1970) described t'he use of hydroxymethylated derivatives of resin acids in polyurethane films. One of the composit'ions used for the glycol mixture was a blend of 1,4-butanediol, poly(ethy1eiie adipate) glycol (OHE, 1000), and a hydroxyl-terminated ethylene glycol ester of the dimonoadipic acid ester of 12-hydroxymethylabietanol (OHE, 343). Good polyurethane elastomeric films were reported for products contaiiiiiig about 15% of the 12hydroxymethylabietane moiety. I t was of interest t o compare films made with the diols and triols derived from oxonated rosin to t'hose made with 12-hydroxymethylabieta~iol.Adipic acid esters mere prepared from each of the glycols and reacted with ethylene glycol t o obtain the hydroxyl-terminated diols and triols. The results of these syntheses are included in Table 11. The rosin-derived adipate glycols were used in polymers Ind. Eng. Chem. Prod. Res. Develop., Vol. 10, No. 4, 1971
453
following as closely as possible the procedure used t o make the polymers listed in the article b y Lewis and Hedrick (1970). The composition and results of the new polymers are given in Table 111. The data for the last item in the table are included for comparison and mere taken from the cited reference. The first two polymers and results were made from the two diols in Table 11,and items 3-5 mere made from a synthetic mixture of the adipate glycols prepared from a 2: 1 molar ratio of the diol and triol. The combination would represent a poly01 composition similar to the diol-triol mixture found in oxonated rosin. The results indicate that for polyurethane films as described, the diol and mixture of diol and triol compare favorably with the stereochemically pure 12-hydroxymethylabietanol reported in the earlier work. Obviously, the crosslinking resulting from incorporating the triol had little effect on the properties of formulations described. Conclusions
The oxonation of gum rosin with Coco3 as catalyst produces a mixture of products consisting of the saturated monohydroxy-, dihydroxy-addition products, and unoxonated material in a ratio of approximately 44, 21, and 35 mol yo, respectively. Countercurrent partitioning of this mixture between aqueous methanol and hexane gave a satisfactory separation of these oxo products. The preferred procedure was
454
Ind. Eng. Chem. Prod. Res. Develop., Vol. 10, No.
4, 1971
oxonation of the distilled methyl esters of gum rosin, thus excluding the polymeric and other nonvolatiles present in rosin from the oxo products. iifter separation of the oxonated products, the diols and triols were obtained by catalytic hydrogenolysis of the ester group. The oxonation of rosin is a convenient method t o increase the functionality of the diterpene acids in rosin. As the products contain no unsaturation, they should be considered premium products for use in adhesives, printing inks, and plastics. References
Darr, W. C., Backus, J. K., Ind. Eng. Chem. Prod. Res. Develop.,
6, 167-73 (1967). Hatch, L. F., “Higher Oxo Alcohols,” Wiley, New York, N.Y., 1957, p 11. Joye, N. AI., Jr., Lawrence, R. V., J . Chem. Eng. Datu, 12,279-81 (1967). Levering, D. R. (to Hercules Powder Co.), U.S. Patent 2,906,745 (Sept. 1959). Levering, D. R., Glasebrook, A. L., Ind. Eng. Chem., 50, 317-20 /, lrOn:u Quj , .
Lewis, J. B., Hedrick, G. W., Ind. Eng. Chem. Prod. Res. Deoelop., 9, 304-10 (1970). Parkin, B. A , , Jr., Hedrick, G. W., J . Org. Chem., 30, 2356 (1965).
Parkin, B. A,, Jr., Summers, H. B., Jr., Settine, R. L., Hedrick, G. W., Ind. .Fng. Chem. Prod. Res. Develop., 5 , 257-62 (1966). RECEIVED for review May 26, 1971 ACCEPTEDAugust 30, 1971
