p-PROPIOLACTONE WITH PHENOLS, THIOPHENOLS AND THEIR SALTS
Feb., 1949
[CONTRIBUTIONFROM
p-Propiolactone. VI. BY T. L. GRESHAM, J. E.
THE
B. F. GOODRICH RESEARCH CENTER]
Reactions with Phenols, Thiophenols and their Salts1
JANSEN,
F. W. SHAVER, R. A. BANKERT, W. L. BEEARSAND MARIEG. PRENDERGAST
8-Propiolactone (I) and phenol react slowly a t room temperature to give p-phenoxypropionic acid (11) and a small amount of a polymer of I. At higher temperatures (above 150') the polymerization2 becomes the major reaction. Except for the rate these results are similar to those obCHzCHz
1
I
0-c==o
66 1
+ CeHaOH +Cd%OCH2CHnCOOH
crylates and phenyl p- (p-hydroxypropionoxy)-propionates. The amount of self-alcoholysis tended to increase with increasing acid strength of the phenol. The lactone and sodium phenoxide in water solution gave rise to sodium P-phenoxypropionate (V) in low yield. Hydrolysis to sodium hydracrylate (VI) accounts for most of I and variations in time, temperature, concentration and excess sodium phenoxide had only minor effects on the yields of V. I n these reactions cleavage of the lactone ring occurred a t the alkyl-oxygen link as in the salt reaction^.^ Using the optimum conditions found for the reaction of I with sodium phenoxide, large variations in the yields of 0-phenoxypropionates were observed with nuclear substituted phenols. The
I I1 served in the reaction between alcohols3 and I. The polymers were separated from the phenoxy acids by alkaline saponification but i t was necessary to avoid an excess of alkali; otherwise the phenoxy acids were cleaved to phenol and hydracrylic acid. Nuclear substituents had marked effects on the yields of 0-phenoxypropionic acids CHzCHz (Table 11). These products result from ring open1 1 + CeHsOKa --+ CsHjOCH~CH~COONa ing of I at the alkyl-oxygen link. 0-c=o In the presence of catalytic amounts of sulfuric v acid a striking change in the reaction of I with CHzCHz phenol occurs. Phenyl hydracrylate (111) is 1 I NaOH +HOCHzCH2COONa 0-c=o formed rapidly in high yield. This product must VI arise from ring opening of I a t the acyl-oxygen linkage and i t is somewhat surprising that none of effects of substituents (Table 11) differ from those I1 is formed. This appears to be in direct con- reported for Similar reactions of phenoxides with alkyl halides6 and ethylene oxide. CHzCHn Hf 0-Propiolactone reacts much more rapidly with I I C6HrOH + HOCH&H&OOC&s 0-c=o thiophenol than i t does with phenol and the 111 yield of P-thiophenoxypropionic acid is higher. Hf With aqueous sodium thiophenoxide the yield of 2HOCHzCHzCOOCeHa + HOCH2CH~COOCH~CHzCOOCd3~C&sOH sodium P-thiophenoxypropionate is nearly quantitative. IV Experimental trast to the acid catalyzed reactions of I with alcoMaterials.-The phenols were Eastman Kodak Comhol~ since ~ the hydracrylate does not result from pany chemicals or equivalent grade. They were redistilled the polymers of I and phenol. The polymerization before use. The P-propiolactone was similar t o that deof I occurs to only a small extent. scribed in the first paper' of this series. Reaction of 6-Propiolactone with Phenol. A. NonThe primary product (111) undergoes a selfP-Phenoxypropionic Acid. (11) .-A solution alcoholysis to give phenyl p-(0-hydroxypropion- oCatalyzed. f one mole (72 9.) of j3-propiolactone and three moles oxy)-propionate (IV). This reaction continues a t (282 g.) of phenol was kept a t 100" for six hours with the expense of I11 beyond the few minutes required stirring. The unreacted lactone and most of the excess for complete reaction of I with phenol and i t is pheriol was distilled a t 20 mtn. until the flask temperature 140'. An ether solution of the distillation residue possible to minimize it only to a small extent by was was extracted with three 300-nil. portions of saturated increasing the excess of phenol or by reducing the sodium bicarbonate solution. Evaporation of the exacid catalyst concentration. The reaction also oc- tracted ether solution left a small residue of phenol. The curs to a similar extent with I11 and sulfuric acid combined sodium bicarbonate extract was boiled to hydrolyze the polymer until the volume was 500 ml. On in phenol solution. cooling and acidifying with concentrated hydrochloric Nuclear substituents have little or no effect on acid, pure j3-phenoxypropionic acid was deposited. After the yields of phenyl hydracrylates (Table I) as standing overnight, the precipitate was filtered with sucjudged by the combined yields of phenyl hydra- tion, washed with water and dried a t room temperature.
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(1) Presented in part at the 113th meeting of the American Chemi-
cal Society, Chicago, Illinois, April 22, 1948. (2) Gresham, Jansen and Shaver THIS JOURNAL, 70, 998 (1948). ( 3 ~Gresham Janwn, Shaver, Gregory and Beears, rbid., 70, 1004 (1848).
The colorless product melted a t 94-95'; yield 24.8 g., 14.8%; (18hr.reaction time; yield42.5g., 24%). _____~ (4) Greahmi, J a n r e n , Shaver dud Gregory, i b i d . , 70, 99U (1948). ( 5 ) Boyd and hlarle, J. Chem. So
