NOAH J. HALBROOK and RAY V. LAWRENCE Naval Stores Station, Southern Utilization Research Branch, U. S. Department of Agriculture, Olustee, Fla.
Fumaric Modified Rosin
IT
HAS BEEN noted that on prolonged heating, a tricarboxylic acid, made commercially from the reaction of fumaric acid and rosin, is converted to a maleic anhydride-rosin addition product. Thus, the two products have been described as identical (70). The maleic-rosin reaction has been studied ( 4 4 , but little information is available on the fumaricrosin reaction.
Experimental Influence of temperature was determined, using 100 parts of WW gum rosin, having an acid number of 164 and a softening point of '75' C., with 10 parts of fumaric acid at 25' C., a t intervals between 175' and 275' C. For each run, about 1 mole of rosin was placed in a 500-ml. three-necked flask provided with a stirrer, thermometer, nitrogen inlet, water condenser, and water trap. The rosin was heated to the desired temperature in an inert atmosphere before the fumaric acid was added. Then samples were removed a t 30-minute intervals for determining water-soluble acid, acid number, acid anhydride, saponification number, softening point, and color grade. Unreacted fumaric acid was determined by dissolving a sample in benzene, extracting with water, and titrating the aqueous solution with standard alkali. Saponification number (3) and color grade (7) were determined by methods of the ASTM. Extent of anhydride formation was measured by determining the acid number of the sample in two solvents-ethyl alcohol and an 80% aqueous acetone
solution using thymolphthalein as indicator. Maleopimaric acid titrates as a tricarboxylic acid in aqueous acetone. When boiled for hour under reflux in an ethyl alcohol solution, maleopimaric acid is converted to the monoethyl ester and titrates as a dicarboxylic acid. Difference between the acid number in these solvents indicates the progress of F anhydride formation, Because the adducts tended to shatter-especially those containing more than 15 p.h.r. of fumaric acid (parts per 100 parts of rosin)-obtaining satisfactory ring and ball (3) softening points using ASTM methods was difficult. Therefore, a Fisher-Johns melting point apparatus was used-the rosin was crushed to a fine powder and a thin layer
Table I.
placed between two microscope slide covers. With the temperature rising steadily a t 2' C. per minute, a lapse of 4 ' C. occurred between formation of small droplets and the point a t which the entire sample started to run together. The softening point was taken a t the halfway point. After a little experience with the technique, reproducible results were obtained. These softening points were from 7' to 17" C. lower than the ring and ball method, but this difference gradually decreased as the ratio of fumaric acid in the product increased. Discussion Under the conditions used, fumaric acid reacted a t 200' C. almost completely
Reaction of Rosin with Fumaric Acid at 200" C.
Fumaric, G./ Reaction Acid Numbers 100 G. Rosin Time. Hr. Alcohol Acetone Water sol. 3
5 10
1 3 1 3 1 3 1 3 1 3 1 3
183 183 194 189 234 23 1 258 250 287 276 308 292 336 3 13 352 326 380 352
WW Gum Rosin 184 2.5 183 2.0 194 3.8 197 2.1 234 6.0 232 5.0 260 7.5 259 7.1 292 17.3 288 5.9 314 30.2 306 8.5 342 69.7 329 21.2 359 97.0 344 42.0 387 168.0 368 65.0
1 3
289 280
295 292
1 3 1 3 3
267 261 294 287 336 325
270 269 297 293 343 336
1 3 1 3 1 3
261 254 288 277 345 340
'/2 3 1/2 3 1 11/2
15 20 25 30
35 40
Sapon.
No.
196 195 207 204 247 245 276 272 304 301 33 1 324 349 344 392 381 399 391
N Gum Rosin 20
25.2 10.5
305 300
Soft Pt., O
C."
91 94 99 99 116 116 124 127 138 142 140 151 142 153 152O
15lC 15OC 15OC
... 138
Color Gradeb
N M N
M M M M M WG N WG N WG N WG N M H
...
H
N Wood Rosind 15 20 30
1
19.3 8.0 54.0 9.2 69.7 27.5
272 270 304 300 346 342
WW Tall Oil Rosine 15 20
30
Comparison of softening points for a fumaric acid modified rosin A. Ball and ring method; B. Fisher-Johns method
Ball and ring method.
266 262 295 290 349 343
29.2 12.0 43.0 12.2 75.0 26.0
274 269 302 297 378 369
120 123 120 134 e . .
14lG
...
118
... ... 14lC 132c
Wood rosin and tall oil rosin products were darker than those Estimated from Fisher-Johns melting point. d Acid number 167; softening point 77.5' C. 6 Acid number 162; softening point 79.5' C. I,
of the gum rosin products.
VOL. 50, NO. 3
MARCH 1958
321
in less than an hour without a detectable amount of anhydride formation. The longer reaction time required at 175' C. caused formation of an appreciable amount of anhydride which increased with higher temperatures (225' C. and above). This formation of anhydride apparently resulted from conversion of the rosin-fumaric acid addition product to the rosin-maleic anhydride addition product, rather than by conversion of fumaric acid into maleic anhydride before it reacted with the rosin. This was shown by the fact that at 250' C., 89% of the fumaric acid had reacted with the rosin in 5 minutes without appreciable anhydride formation. Continued heating a t 250' C. for 1 hour resulted in formation of anhydride equivalent to 28.2% of the fumaric acid added. This conversion was increased to 56.6% in a sample heated for 1 hour at 275' C. Optical rotation and infrared spectra of the fumaric modified rosins also indicated that the original adduct was converted into the maleic modified product. At temperatures of 225" C. and above, anhydride production was caused partly by formation of polymeric anhydrides. Both abietic acid (9) and rosin ( I I) are reported to show appreciable amounts of intermolecular anhydride formation when heated alone a t 225' C. or higher. A series of products was prepared at 200' C. with fumaric acid varied from 3 to 40 p.h.r. for W W gum rosin. Comparative runs were also made with N gum rosin, N wood rosin, and W W tall oil rosin a t concentrations selected to show greatest differences in the final reaction products. The reaction rates of fumaric acid with the rosins used, are approximately equal as shown by water-soluble acids present. Examination of the end products for the 30 p.h.r. of fumaric acid show that a t the end of three hours, 26.3 parts had reacted with the N wood rosin, 26.5 parts with the W W tall oil rosin, and 27.2 parts with the W W gum rosin (Table I). For products formed with the WW gum rosin (Table I), the water-soluble acid content increased sharply when the fumaric acid to rosin ratio exceeded 30
p.h.r. Water-soluble acids collected from adducts prepared with less than 30 parts, indicate that this water-soluble acid was not fumaric acid. With more than 30 p.h.r. free fumaric acid was present in the water extract. The softening points and water-soluble acid content of the reaction products indicated that little fumaric acid in excess of 30 p.h.r. reacted. The softening points of the fumaric modified rosins rose gradually as fumaric acid was increased to 30 p.h.r. Above 30 p.h.r., softening points of the reaction products decreased slightly. Products formed with N wood rosin (Table I), and with W W tall oil rosin, were similar and had considerably lower melting points than the corresponding product obtained from gum rosin. Also, they were darker in color. All color grades were determined on products obtained from small (300-gram) runs, but large scale runs should yield products showing improved color grades. When fumaric acid content exceeded maximum reaction ratios, the reaction products were one or two grades darker. For comparison, a few samples of maleic modified rosin were prepared a t 200" C. with the same gum rosin used for the fumaric acid modification. The maximum softening point for maleic anhydride modified rosin was 125' C. This was obtained with 25.4 p.h.r. of maleic anhydride; on a molar basis this compares with 30 p.h.r. of fumaric acid, the product of which had a softening point of 153' C. Finally, a sample prepared with 15 p.h.r. of fumaric acid gave a softening point of 127' C. (Tables I and 11). T o determine if characteristics of fumaric modified rosin are imparted to its derivatives, glycerol esters were prepared from 10 p.h.r. fumaric modified rosin and 10 p.h.r. maleic modified rosin (Table 111). The fumaric modified rosin esterified more rapidly and gave an ester with a higher softening point and a lower acid number than did the corresponding maleic modified rosin. These differences indicate that the esters of the fumaric modification have retained the trans endo configuration of the ad-
Reaction of Gum Rosin with Maleic Anhydride at 200" C. Acid Numbers Maleic Anhyd., Reaction Water Saponifi- Soft. Pt., Color G./100 G. Rosin Time, Hr. Acetone sol. cation No. O C.a Grade 215 207 3.2 94 N 5 I/a 205 1.7 213 3 95 N 3.0 258 102 N 10 '/a 242 3 241 1.6 254 104 K 322 113 M 4.0 20 '/a 312 3 312 4.0 321 117 M 370 117 M 358 19.8 25.4b 1/2 30
'/a
3
355 354 366 356
16.2 5.6 35.0 10.8
369 365 377 373
Ball and ring method. * Equivalent to 30 parts of fumaric acid on a molar basis. a
~
322
INDUSTRIAL AND ENGINEERING CHEMISTRY
119 125 106 125
..
K
K G
Conclusions An addition product, prepared by allowing rosin to react with fumaric acid, differed from that of a maleic anhydride rosin in physical properties such as acid number and melting point. The product can impart these differences to its gIycerol esters. The fumaric modification converts to the maleic modification on continued heating; therefore, a series of products may be obtained with characteristics intermediate between the two modifications. The reaction rates of tall oil and wood rosin were slightly less than for gum rosin. Literature Cited Am. SOC. Testing Materials, Philadelphia, Pa., ASTM Standards 1955, D 509-55, Pt. 4., p. 686, 1956. Zbid.,D 509-53, p. 692. Ibid., E 28-51 T i p . 1281. Castle, R., Paint Oil CYColour J. 120, 854, 860 11951). Ellis, Carltdn, U.'S. Patent 2,063,542 (Dec. -~ 8. 1936). Hovey, A. G., Hodgins, T. S., IND. ENG.CHEM.32, 2,72-9 (1940). Hundret, M. B., Am. Paint J . 36, No. 38,78, 80, 82,84,86, 88 (1952). Krumbhaar. William, "Coatings and Ink Resins," pp. 11'6-18, Reghold. New York. 1947. ( 9 ) LaLande, W. A., IND.ENG. CHFM. 26, 678-81 (1934). (IO) Mannheim, Hans, Krizikalla, Wolff, Werner, U. S. Patent 2,039,243, . . . (April 28, 1936). (11) Stinson, J. S., Lawrence, R. V., IND. ENG.CHEM.46, 784-7 (1954). \-
- 2
- - I -
RECEIVED for review Feb. 9, 1957 ACCEPTED June 10, 1957 Division of Paint, Plastics, and Printing Ink Chemistry, 131st Meeting ACS, Miami, Fla., April 9, 1957. I t is not the policy of the Department of Agriculture to recommend products of one company over those of another engaged in the same business.
Table 111. Glycerol Esters of Maleic and Fumaric Modified Rosins" Maleic Fumaric Acid, -4nhydride,
Table II.
1 3
duct, and did not revert to the cis endo configuration of the maleic anhydride adduct. Once the fumaric modified rosin had been partially esterified, no conversion to the anhydride was observed. O n a mole for mole or a gram for gram basis, fumaric acid appeared to give a greater modification in the rosin than did the maleic anhvdride.
10 P.H.R. Soft. pt.,
Total Time, Temp., Acid Hr. O C. No. 0 237O 1 200 165 2 225 122 3 250 78 4 275 43 5d 275 34 6 275 21.5
...
0
O
C.*
... ...
...
118 129 131 134
10 P.H.R.
Acid No. 243O 190 159 101 55 43 28.7
Soft. O C.
pt.,
... ... . I .
105 118 124 123 Stoichiometric amount of glycerol added at beginning of
run. 6 Ball and ring method. c Calculated. cess glycerol added after 5th hour.
10% ex-
