NOTES
Feb., 1944 But even this material soon turned pink when expwed to a=. However, after several recrystsllmtions of the vacuumdistilled product from 70% alcohol the pyrrole was obtained in a form which remained colorless; m. p. 128-129O.5 (5) The melting point has been reported to be 129” (ref. 4).
COLLEGE OF PHARMACY UNIVERSITY OF MICHIGAN ANN ARBOR, MICHIGAN RECEIVED &3PTEMBER 30,1943
Reactions of &Butyl Cinnamate and &Butyl Benzoate with Phenylmagnesium Bromide’ BY FREDFROSTICK, ERWINBAUMGARTEN AND CHARLES R. HAWSER
305
in 160 ml. of eth?), contaiqed in a reaction h k equipped with a U-tube Lmmefsed m a dry ice-bath, was added during one-halfhour 0.3 mole of t-butyl benzoate’ in 100 ml. of ether. After standing overnight the reaction mixture was duxed for five hours. The liquid condensed in the U-tubedid not absorb an appreciable amount of bromine in carbon tetrachloride solution, indicating that no signidcant amount of isobutene was farmed. After daxnnposition of the n&ctloIl mixture with ammonium &laride, the ether solution was Wen with bicarbollpte (fromwhich was isolated a 10% yield of benzoic acid), dried and the solvent distilled. The residue was subjected to steam distillation until oily material (containing diphenyl but apparently no tbutylbenzene) ceased to pass over, and then re-crystaUized from alcohol, yielding triphenykarbinol (41%), m. p. 169-162”. In a similsr experiment, carried out with &butylbenzoate and methylmagnesium iodide, no isobutene appeared to be formed.
Kohler and Heritage’ showed that methyl (6) Nodm and Rigby. THIS JOURMAL, 64, 2097 (1932). cinnamate undergoes both 1,2- and 1,4ddition with phenylmagnesium bromide yielding a mix- DEPARTMENTOF CHEMISTRY 6.1943 ture of products. We have found that t-butyl D r w r U ~ ~ v ~ ~ s m RECEIVED DECEMBER cinnamate (in which the carbonyl group is rela- DURBAY.NORTHCAROLINA tively hindered) undergoes apparently only 1,4addition yielding t-butyl @,@-diphenylpropionate. Nature of Carotenes in Alfalfa -6MgBr BY A. R. KEXKERERAND G. S. Fruw G”CH=CHCOOC(CHs), (OH~)SCHCHICOOC(C&)~ According to Beadle and Zscheile,’ spinach and To a stirred solution of phenylmagnesium bromide, pre- some other plants contain appreciable amounts pared from 6.6 g. (0.23 mole) of magnesium and 46.1 g. of “neo-@-carotene,”stereoisomer of 8-carotene, (0.23 mole) of bromobenzene in 100 ml. of dry ether, was which can be produced by heating @-carotenein added during twenty minutes 23.5 g. (0.116 mole) of t petroleum ether. This pigment is the same as butyl cinnamate.’ The reaction mixture d u x e d gently and a precipitate formed. After duxing for three hours, that termed pseudo-a-carotene by Gillam and El and neo-p-carotene B, by Polg6r and Zechthe muture was poured into an icecold saturated ammonium chloride solution. The ether layer was shaken with meister.8 Kemmerer and Fraps,‘ by chromacold 10% sulfuric acid, and then with cold 6% po-um hydroxide solution. After drying with anhydrous wxhum tographic analysis with calcium hydroxide, found, sulfate followed by “Drierite,” the solvent was distilled, besides @-caroteneand this “neo-@-carotene”in finally using the water aspirator. The solid residue plants, another pigment which they termed “caro(29.6p) was recrystallized from petroleum ether (b. p. tenoid X.” “Carotenoid X” did not possess 30-60 ), yielding. 16 g. (44%) of essent+lly pure.t-buty1 vitamin A potency, while “neo-@-carotene”had &&diphenylpropionate. Four recrystalhattons w e da one-half the potency of &carotene. PolgC and product meltiug at 65.5-55.6”. by various treatments of @-carotene, Anal.‘ Calcd. for CI&~&: C, 80.86; H, 7.86. Found: Zechmei~ter,~ secured about twelve neo-@-carotenes including C. 80.93;H,7.60. The product was further identified by hydrolysis in the neo-@carotenesB and U. Since the identificapresence of concentrated hydrochloric acid to fl,@-diphe-nyl- tion of the carotenes in plants is of both practical propionic acid, which, after recrystallizationfrom acetone- and scientiiic importance,both the “neo-0-carowater mixture, melted at 152-154’ (reported, 166O)f tene” and “carotenoid X”in alfalfa were studied. Analogous to methyl or ethyl benzoate, &butyl Neo-B-carotene B was prepared by d d n g a solution benzoate has been found to undergo the “normal” of 20 mg. of crystalline carotene in 100 ml. of hexane for carbonyl addition reaction with phenylmagnesium one hour.‘ The solution was chromatographed on calcium bromide, yielding triphenylcarbinol. Some ben- hydroxide and the neo-&carotene B was separated and Then it was purified by another chromatozoic acid (which might have resulted from hydroly- extracted. graphic treatment. This pigment is just below the fl-carosis of the ester) was also isolated. Neither iso- tene band in the chromatogram. Neo-&carotene U was butene nor t-butylbenzene was found; these prod- prepared by dissolving about 10 mg. of crystalline car* tene in petroleum naphtha (Skellysolve P). adding a small ucts would have resulted had the elimination or crystal of iodine, and allowing the solution to stand an substitution reaction occurred. hour.’ The neo-&carotene U was separated and purified To a stirred solution of phenylmagnesium bromide (prepared from 0.5 mole each of magnesium and bromobeazene
(1) This work was muppfnted by a grant from the Duke UniverCounal. aity R-ch (2) Kohlu and Heritage, A m C h . J., 88, 21 (IW5); see atro Allen and Blatt in ‘‘Organic Chemhry,” Gilman, Editar-in-Chid, John Wiley and So=, Inc., New York, N. Y.,1843, p. 681. (8) Abramovitch, Shivers, Hudson and H a w , TEIS JOURNAL,
(1943).
06, 986 (4) Analysis by T. S. Ma. Univemity of Chicago, Chicago,IUioOir (6) Baun~,Am. Chem. J . , 88, 84 (1905).
by absorption on calcium hydroxide. The neo-&carotene U is just above the ,%arotene in the chromatogram. “Carotenoid X” and “neo-~carotene”were prepared from alfalfa leaf meal by extraction with alcholic potassium hydroxide and petroleum naphtha (Skdyso!ve,F) and chromatographic ScpSration on calcium hydroxide.
(1) B. W. &uikandP. P.Zchdle,J. Bid. C h . ,144,21(1842). (9 h E. Gilhm a d M.9. El RW,Biocksn. J., 80, 1735 (1986). (8) A. Pol& and L. ZLehrndSter, TEIS JOURNAL. 64,1856 (1942). (4) h R. Kemmaer and G. S. Fram I d . En#. C h . , Anal. Ed., 11,714 (1948).
