April, 1943
NORMAL ADDITION OF HYDROGEN BROMIDE TO SOMEACIDSIN HEXANE
683
ing the excess acetic anhydride was recrystallized from ethyl acetateligroin and formed colorless needles, m. p-
34.07. Calcd. for CBHIOO~: -0CH8, 31.31. Found: -OCHa, 32.62. 106-107.5 (B) With Potarsium Permanganate.-Powdered potasAnal. Calcd. for CS,H~*OIO:C, 61.27; H, 4.72; eium permanganate was added slowly to a hot solution of 0.60 g. of leptosidin trimethyl ether in 60 ml. of acetone -OCHa, 6.58. Found: C, 61.21; H, 5.00; -0CH8, until the purple color remained for five minutes. The 6.45, Methylation of the Flavanone. The Methyl Ether, W. solution was cooled and the solid collected by filtration. -Methylation of 0.30g. of the flavanone (111), dissolved in The solid was extracted with several small portions of hot methanol, with a fourfold excess of diazomethane in ether water. Acidification of the aqueous solution so obtained solution, afforded 0.195 g. of a compound as faintly yellow yielded a white solid. A small additional amount was crystals, m. p. 139-140 ' after three recrystallizations from obtained by working up the acetone solution. After three recrystallizations from hot water the product (85 mg.) no dilute alcohol. longer gave a ferric chloride color and melted at 178Anal. Calcd. for C10H2006: C, 66.26; H, 5.86; 179.5'. An authentic sample of veratric acid melted a t -0CH8, 36.00. Found: C, 66.27; H, 5.95; -0CH8, 179-180' and a mixture of this and the oxidation product 35.81. melted at 178.5-179.5'. Oxidation of Leptosidin Trimethyl Ether. (A) With Anal. Calcd. for C~HIOO,: C, 59.33;H, 5.53. Found: Hydrogen Peroxide.-A solution of 0.50 g. of leptosidin C,59.12; H, 5.69. trimethyl ether (VIII) in 50 ml. of acetone, 0.5 ml. of Summary 50% aqueous potassium hydroxide and 7 ml. of 30% 1. From the ray flowers of Coreopsis prandihydrogen peroxide was rduxed for two hours. After the addition of 2 ml. of saturated sodium bisulfite solution the flora have been isolated luteolin (as the acetate) acetone was removed under reduced pressure, 20 ml. of 1 % and three new substances: a glucoside, leptosin, hydrochloric acid was added and the solution was extracted its aglucon, leptosidin, and a flavanone. with ether. The ether solution was extracted with three 2. Tentative structures have been assigned small portions of sodium bicarbonate solution and upon acidification of the bicarbonate extract a white precipitate to leptosin, leptosidin and the flavanone, on the formed (0.150g.). This melted from 140" to 155" and basis of (a) their compositions and those of their repeated recrystallization did not raise or sharpen the methyl ethers and acetates, (b) their distinctive melting point appreciably. The substance gave a purple color reactions and (c) biogenetic evidence from color with ferric chloride. Its methoxyl content was intermediate between that of veratric acid and a dimeth- previous studies of flower pigments of related members of the Compositae. oxysalicylic acid. Anal. Calcd. for CoHl004 (veratric acid): --OCHa, h S ANGELES,CALIFORNIA RECEIVED DECEMBER 23,1942
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[cONTRIBUTION FROM T B E CONVERSE LABORATORY, HARVARD UNIVERSITY ]
Normal Addition of Hydrogen Bromide to 3-Butenoic, 4-Pentenoic and 5-Hexenoic Acids in Hexane' BY ARTHUR MICHAEL AND HOWARD S. MASON~J
Evidence exists that non-polar solvents can induce abnormal addition of hydrogen bromide to terminally unsaturated aliphatic acids, but the independence of the character of this phenomenon has been controversial since the development of an understanding of the role of peroxides and oxygen in such reversals. The object of this investigation was to resolve this controversy4r5by deter-
mining whether or not the direction of addition of hydrogen bromide to such acids can be influenced by hexane under rigidly anti-oxidant conditions. It has now been found that under these conditions 3-butenoic, 4-pentenoic, and 5-hexenoic acids in hexane solution add hydrogen bromide preponderantly normally (Table I).
(1) This paper was originally presented before the Organic Division at the Buffalo meeting of the American Chemical Society, September, 1942. (2) Although this research was carried out under the direction of the late Professor Arthur Michael, the statements contained in this report, and the responsibility for them, are those of the junior author. (3) Now at the National Institute of Health, Bethesda, Maryland. (4) Gaubert, Linstead and Rydon, J . Cham. Soc., 1974 (1937). "The persistent anomaly is the formation of the terminal bromoacids in hexane or petroleum solution in the presence of hydrogen
and anti-oxidant, which we have now observed in the case of five 1, acids of the general formula CHs=CH[C&InCOd3 (wkere I) 2, 3, 4, and 6) but which is not shown by undecenoic acid (I) 8). or by allylacetic acid in the experiments of Kharasch and McNab." (5) Kharasch and McNab, Clem. and Ind., 54, 989 (1938). "The addition of hydrogen bromide to allyl acetic acid with. , solvents [hexane] has now been repeated in thia Laboratory It is evident that these data are in complete agreement with our previous statements that peroxides and not the solvents control the direction of addition."
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ARTHURM I C H A ~AND L HOWARD S. MASON
684
hDDIT1ON OF
TABLE I HYDROGEN BROMIDE TO OLEFINIC ACIDSI N HEXANE SOLUTION M o k cat.) Moles add
Technique 3-Butenoic acid
Molesd of HBr
1 1
0.0051 ,0051
0.01
I 1 I
,0051
Kharasch Kharasch Kharasch Kharasch Kharasch
Mole9 of acid
Solvent,
1 2 3 1 5
0.008 ,008 .016 to16
ti
.rm
7 8
,024 ,024 ,024 ,024 ,024 ,024
Expt.
CC.
,016
VOl. 65
,0051 ,0051
.01
.02 .02 .02
Yield,
Composition.
1 day 1 day 1 day 14 days 14 days
100 100 100 100 100
100 P-Br" 100 P-Br 91 P-Br 89 p-Br 88 8-Br
1 day 10 days 10 days 12 days 12 days 1 day 1 day
85 94 96 94 95 96 98
94 y-Brf 97 y-Br 96 y-Br 90 y-Br 89 y-Br Y 5 y-Br 97 y-Br
Time
%
%
LPentenoic acid
9 10 11
12
1 1 1 1 1 1
.0059
1
.0059
Kharasch Kharasch Kharasch Kharasch Kharasch Linstead Lins tead
,0059
,0059 .0059 ,0059 ,0059
.03 .03 .03 .03 .03 ..
..
5-Hexenoic acid
13 ,030 3 ,0069 Kharasch . o0lC 14 ,030 3 Michael Michael 15 . a30 3 none a Accurate t o 0.02 g . Diphenylamine. Benzoyl peroxide original reference). Accurate to *l%.
'
Experimental6 Preparation of the O f s h i c Acids and their Hydrobromides.3-Butenoic acid was synthesized from its nitrile. The nitrile was prepared aceording to thedirections of BreckpotTand hydrolyzed to the acid by the method of Linstead.* The once-distilled product was refractionated in a high efficiency Fenske type column under a diminished presJure of nitrogen. The portion boiling at 81.5' at 23 mm. (manostat used), n% 1.4222, was used for the addition studies. @-Bromobutyricacid was prepared by bubbling hydrogen bromide through molten crotonic acid until the theoretical weight increase was obtained. The product was allowed to stand in a vacuum desiccator over potassium hydroxide pellets for two days, and was then fractionated, boiling principally at 130' (25 mm.); crystallized from petroleiim ether, the solid melted at 17". Boorman, Linstead and Rydon9 report 17-17.5'. y-Bromobutyric acid was prepared from 3-butenoic acid by hydrogen bromide addition to a solution of the olefinic acid in purified hexane in the presence of benzoyl peroxide. The reaction product was crystallized three times from petroleum ether, when it melted at 32-33'. The literature also reports a melting point of 32-33' for this c o m p ~ u n d . ~ y-Pentenoic acid and its hydrobromides were prepared by methods already described by Linstead, el only one variation was carried out, as noted below. The 4-pentenoic acid boiled at 67" (2 mm.), #*OD 1.4281; the earlier investigatorsreported b. p. 90" (16 mm.), n 1.4283.1° The yield of y-valerolactone, a n intennediiste in the synthesis of 4-bromopentanoic acid, prepared by Wohl~
1
.
~
(6) All meltiag points and boiling points reported were obtained by total immersion methods.
(7) Breckpot, Bull. SOL. chim. b d g . , Sa, 465 (1930). (8) Linatead, Noble and Boorman, J . Chdm. Soc., 667 (1938) (9) Boorman, L i n s t d and Rydon. {bid., 668 (1938) IUI
Zln,tr*d .*Ed R,.dur,
ibiri
Mi 19351
9
.06 2 days 1 day .06 .06 1 day Accurate to about 0.1 g.
98 e-Rr' 75 a-Br 94 a-Br 99 ' Correction applied (set 99 99
gemuth's method,11 was 46%. The following procedure was found to be a n improvement: 35 g. (0.30 mole) of levulinic acid (Eastman Kodak technical grade) and 13 g. (0.33 mole) of sodium hydroxide were dissolved in 48 cc. of water and the volume reduced to 60 cc. by evaporation. To the resulting solution was added 1 g. of Raney nickel and the mixture subjected to hydrogenation a t 2000 lb. pressure and 135". The product was acidified with 40 cc. of coned. hydrochloric acid and extracted with ether. Twenty-two and a half grams of y-valerolactone, b. p 67' (2 mm.), was obtained: yield, 75%. y-Bromovaleric acid prepared from this lactone melted at 21' afler three recrystallizations from petroleum ether. The literatureg reports 21-22.5'. S-Bromovaleric acid melted at 39.5-40', comparing favorably with the reported value of 3940°.9 5-Hexenoic acid was prepared by a series of reaction5 previously employed by Linstead and RydonI2: 3-nbutenol-1 was synthesized from allyl bromide, trioxymethylene and magnesium; this was converted to its bromide with phosphorus tribromide in pyridine and the bromide malonated. The ester was then hydrolyzed and decarboxylated. It was found possible to increase the yield of the first step of this series from the original 42 to 72% by employing Gilman's directions for the preparation of allylmagnesium bromidel8 and Ziegler's method for the formaldehyde-Grignard reacti0n.1~ The h a 1 product, purified through its sodium salt in the usual manner and fractionated by vacuum distillation, boiled a t 107' (17 mm.), #*OD 1.4343. These constants are identical with those of the purest previously prepared sample.18 6-Bromovaleric acid was also prepared by a synthesis already describedle; it boiled at 114-115' ( 2 mm.). eRromocapric acid was prepared by the addition of
~
~
;
Wohlgemuth, Ann. chtm., 1, 298 (1914). $12) LinsLend and Rydon, J . Chem SOL.,1095 ( 1 Y W 13) c31lman BUZZ soc r h l m , 48, 1322 (1928) a 1i 71cgl
