2026 JOURNAL OF POLYMER SCIENCE: PART A-1, VOL. 4 (1966)

Vinyl Esters of Rosin Rosin waa first vinylated by Reppe.1 The ester gave, by free-rsdical initiation, low

molecular weight polymers which were resins of little value. This might be expected aa a result of the presence of the conjugated diene system in the resin acids present in conven- tional rosin. Roppz describes some copolymers of vinyl acetate and vinyl stearate with vinyl esters of hydrogenated and dehydrogenated rosins. These apparently gave more satisfactory polymers than obtainable from rosin. Montgomery et al.* described the preparation of a perhydrogenated rosin which is for all practical purposes completely hydrogenated. Rosins having a high degree of unsaturation are available commercially and are prepared by direct catalytic hydrogenation of rosin or by disproportionation re- sulting from heating rosin to 150°C. with hydrogenation catalysts.

A comparison of the compositions of the three types of rosin are given in Table I.

TABLE I Composition of Hydrogenated and Disproportionated Rosinse

Resin acid compositions, %

Two double Single double No double Dehydro- bondsb bonds bonds genated

Perhydrogenated Nil 1-2 88 1 Disproportionated 3 26 5-7 57 Hydrogenated 1-3 69 2-6 11

a Data obtained from supplier, Hercules Powder Company, Wilmington, Delaware. b Nonconjugated.

Vinyl esters were made from the three types of rosin and a comparison of their behavior toward polymerization under similar conditions was made (Table II).4 The perhydro- genated rosin gave better conversions to polymers than did the hydrogenated and dispre portionated materials.

TABLE I1 Vinyl Esters of the Three Rosins and Monomer Conversions

Con- ver-

sions, Rosin Hydro- Refrae %

neutral Yield, Boiling point, genation tive poly- Type equivalent" % "C./mm. Hg equivalent index naDO merb

Prehydrogenated 346.8 79.2 168-172/0.5 342.4 1.5088 83 Hydrogenated 342 79.0 172-180/0.8 337.8 1.5196 11 Disproportionated 360 76.0 170-186/0.4 354.2 1.5289 20

* Contains nonacidic materials. b Data of Liepins and Marvel.'

Pure resin acid value is 302.

The method used for vinylation was that of Adelmans and others6 and involved ester interchange with vinyl acetate with a mercuric catalyst.

Experimental

A typical vinyhtion consisted of dissolving the rosin (370 g., 1.06 mole), in 1760 ml. (19 mole) vinyl acetate and adding a t room temperature 0.32 g. copper resinate, 6.40 g. mer- curic acetate and 1.60 g. concentrated sulfuric acid. When about 1 moleequivalent of

NOTES 2027

acetic acid had been liberated the reaction was considered complete and the batch wm worked up by distilling excw vinyl acetate in vacua. The residue was washed with dilute aqueous mineral acid, dilute alkali then distilled in uaew, bulb-to-bulb and fractionated. Yield and other data are tabulated in Table 11.

Mention of commercial products by name is for purposes of identification only and does not constitute their endorsement by the Department over others which might be appli- cable.

References

1. C. E. Shildknecht, Vinyl and Related Polymers, Wiley, New York, 1952, Chap.

2. W. S. Ropp, U. S. Pats. 2,727,871 and 2,727,872 (Dec. 20, 1955). 3. J. B. Montgomery, A. N. Hoffmann, A. L. Glasebrook, and J. I. Thigpen, Ind. Eng.

4. R. Liepins and C. S. Marvel, J. Polymer Sci. A-I, 4,2035 (1966). 5. R. L. Adelman, J. Org. Chem., 14, 1057 (1949). 6. J. C. Robinson, Jr. and W. S. Ropp, U. S. Pat. 2,614,887 (Oct. 1952); J. C. Robin-

son, Jr., U. s. Pats. 2,615,011 and 2,615,012 (Oct. 1952).

5, p. 385.

Chem., 50,313 (1958).

J. B. LEWIS G. W. HEDRICK

Naval Stores Laboratory Southern Utilization Research and Development Division Agricultural Research Service, USDA Olustee, Florida

Received March 31, 1966