Jan., 1948
PHENYL- 1,%BUTADIENE WITH
minutes with the final temperature within the flask being 165'. The crude distillate, 35'.2 g. (99%), was dissolved in ether, the ether solution washed with water and dried over anhydrous magnesium sulfate in the refrigerator. After removal of the ether the crude prodttct was distilled under reduced pressure using a 14 X 0.75 in. column packed with 0.75 in. glass helices. There was obtained 25 g. (75%) of pure product; b. p. 68' (50 mm.), n a b 1.4403. Anal. Calcd. for CsFIoNOa: N, 12.17. Found: N, 12.28. The residue in the pyrolysis was shown to be diethylamine hydrochloride by its m. p. after crystallization from ethyl alcohol (220-224') lit. 215-223') and conversion t o its benzenesulfonyl ,derivative, m. p. 59-60'. 2-Nitropropene was obtained similarly by pyrolysis a t 105-160' of the hydrochloride of N-(2-nitropropyl) piperidine under 70 mm. pressure in 50% yield. I t was identical with the 2-nitropropene prepared by other methods.* 2-Nitro-I-butene wqs obtained in 73% yield by pyrolysis of the hydrochloride of N-(S-nitrobutyl) -diethylamine a t 100-175' under 100 mm. pressure; b. p. 60.5' (50 mm.), n*% 1.4356. It was identical with an authentic sample of 2-nitro-I-butene synthesized by pyrolysis of the benzoate of 2-nitro-I -butanol .I* 2-Nitro-1-hexene was obtained in 70% yield by pyrolysis of N-(2-nitrohexyl) diethylamine at 105-165' under 50 mm. pressure; b. p. 81-82' (50 mm.), n*% 1.4462. Anal. Calcd. for C ~ H I I N O ~N, : 10.86. Found: N, 10.89. 2-Nitro-1-heptene was obtained in 70% yield by pyrolysis of N-(2-nitroheptyl) diethylamine at 110-150' under 50 mm. pressure; b. p. 93-94" (30 mm.), n"b 1.4482. Anal. Calcd. for ClHtlNO*: N, 9.76. Found: N, 9.85. $-Toluidine Derivatives of the 2-Nitro-1-alkenes.Solid derivatives of the nitro6lefins were readily obtained through reaction with p-toluidine. The general procedure used in their preparation is described. To 5 g. of the pure 2-nitro-l-alkene, cooled t o 0-5') there was added a n equivalent amount of p-toluidine. The solution became warm and deep red in color. After maintaining t h e reaction mixture at 60" for five minutes it was cooled t o room temperature and the crude product crystallized. Pure derivatives, as bright yellow solids, were obtained
-
( I C Tupp, Thesis, Cornel1 University, 1943.
[CONTRIBUTION FROM
THE
TETRAPHENYLCYCLOPENTADIENONE 149 in 80-95% yield after one recrystallization from ethyl alcohol. These compounds are listed in Table I.
TABLE I N-(%NITROALKYL)-+-TOLUIDINES Compound, p-toluidine
N-(2-Nitropropyl)N-(2-Nitrobutyl)N-(2-Nitroarnyl)N-(a-Nitrohexyl)NY(2-Nitroheptyl)-
M. p , 'C.
81,, 5 8 2 . 5 07.5-68.5 72 -72.5 68.5-09 72.5-73.5
N analyses, % ' Calcd. Found
11.42 13.45 12.60 11.86 11.19
14.38 13.37 12.88 12.18 11.51
The p-toluidine derivatives of samples of 2-nitropropehe and 2-nitro-1 -butene prepared by other methodsS were identical with those described in Table I. N-(2-Nitrobuty1)-p-toluidine(Table I ) was also prepared by an independent method. Using the procedure of Jolfnson,v I-nitropropane, formaldehyde and ptoluidine reacted to give a 26% yield of the crude p toluidine derivative, m. p. 60-66". After recrystallization from methanol its m. p., 67.5-68.5") was not depressed when mixed with the toluidine derivative prepared from 2-nitro-1-butene. 2 -Nitro-2-et h yl 1,3-bis (p-toluino) -propane, a di -sub stituted p-toluidine derivative, was prepared as a check on the mono-substituted derivative described above. To a refluxing mixture of 107 g. (1 mole) of p-toluidine, 44.5 g. (0.5 mole) of I-nitropropane, 1 g. of potassium hydroxide and 300 cc. of ethyl alcohol, 82 g. (1 mole) of 37% formalin solution was added over a period of six hours. After refluxing an additional two hours and standing at room temperature for two days the mixture was cooled in ice and filtered. There was obtained 35 g. (25%) of light tan crystals melting at 101-102° which were recrystallized from ethyl alcohol, m. p. 103-104'. Anal. Calcd. for Ct9H96NaOt: N, 12.84. Found: N, 12.73.
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-
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Summary A series of 2-nitro-1-alkenes has been readily obtained by thermal decomposition of appropriate nitro amine hydrochlorides derived from l-nitroalkanes. The 2-nitro-1-alkenes may be characterized by crystalline solid derivatives formed by their reaction with p-toluidine. ITHACA,N. Y.
RECEIVED JULY 28, 1947
MORLEY CHEMICAL LABORATORY O F WESTERN RESERVE UNIVERSITY]
Reactions with Tetraphenylcyclopentadienone. 11. Condensation with 1-Phenyl1,3-butadiene BY OLIVERGRUMMITT AND ERNEST I. BECKER*
2,3,4,5-Tetraphenylcyclopentadienone (tetracyclone) is of interest in diene chemistry through its addition reactions with a,&unsaturated carbonyl compounds3 and with conjugated di(1) Presented before the Division of Organic Chemistry at the Atluntic City meeting of the American Chemical Society, April 15,
1947. (2) Sherwin-Williums Research Fellow in Organic Chemistry; 1946. Prtaent uddreso: Polytechnic Institute of Brooklyn, Brooklyn, New York. (8) For example, with muleic anhydride: cf. Dilthey. Schommu, and Troakm, k., 66B, 1627 (1933),and Allen and Shepa, Can. J .
hsroreh. 11, 171 (1984).
enes.'.' In the case of butadiene the adduct con. tains two tetracyclone groups as the result of 1,2 and 3,4 addition a t the 2,5 positions of the tetracyclone ring. With cyclopentadiene only one tetracyclone reacts, the addition occurring a t the 2,3 double bond and at the 2,5 positions of tetracyclone.' These addition reactions are usually considered (4) Dilthey, Schommer, Hoschen and Dierichs, Bn.,008, 1159 (19315). (5) Grummitt. Kloppu und Blenkhorn. TEISJOUD.NAL, 64, 601 (1942).
150
OLIVERGRUMMITT AND ERNEST I. BECKER
to be Diels-Alder reactions.' Although tetracyclone has an a,b-unsaturated carbonyl group, and therefore might behave as a dienophile, it characteristically reacts as a conjugated diene. In the presence of tetracyclone a conjugated diene behaves as a dienophile. Irl terms of the structures associated with typical Diels-Alder reactions, tetracyclone and the diene show reversed functions. A survey of the addition reactions of l-phenyl1S-butadiene has shown that most reagents preferentially add 3,4 instead of 1,2 or 1,4.7 Furthermore, unsymmetrical reagents which add 3,4 usually obey Markownikoff's rule. Since styrene also shows normal addition in most cases, this behavior of phenylbutadiene is in accord with the principle of vinylogy.8 As a continuation of the study of the mode of addition of both tetracyclone and phenylbutadiene, an investigation of the reaction of these compounds is reported here. Although l-phenyl-1,3-butadiene has been made by several different reaction^,^ the synthesis of this hydrocarbon in good yields proved to be quite difficult. The reaction of cinnamaldehyde and methylmagnesium bromide to give methylstyrylcarbinol followed by dehydration of this carbinol was tried first.g Although the carbinol can be made in 80-90% yields, dehydration of it gave poor yields because of rapid polymerization of the hydrocarbon during dehydration. The relatively high boiling point of phenylbutadiene aggravates this problem, because it cannot be quickly removed from the reaction mixture, as is possible for lower boiling hydrocarbons. von der HeidelO modified this synthesis by hydrolyzing the intermediate Grignard addition compound in acid solution so that phenylbutadiene was formed without isolation of the methylstyrylcarbinol. This reaction also gave low yields until the conditions of hydrolysis were thoroughly explored. By hydrolysis in 30% sulfuric acid solution under carefully controlled conditions of time and temperature, it is now possible to prepare l-phenyl-1,3-butadiene consistently in 7040% yields. In the absence of an inhibitor phenylbutadiene polymerizes more rapidly than 1,3-butadiene. l1 To facilitate work with this compound several inhibitors were tested a t a concentration of 1% and a t a temperature of 100'. The experiments summarized in Table I were run by noting the time required for samples to flow vertically in 7-mm. reaction tubes. The interval of time elapsed for the flow time to exceed one second was arbitrarily taken as the inhibition period. (6) For a review of the chemistry of tetracyclone and related compounds see (a) Norton, Chem. Rev.,81, 398 (19429,and (b) Allen, ibid., 87, 209 (1945). (7) Becker, Ph.D. thesis, Western Reserve University, 1946. (8) Fuson, Chem. Ra.,16, 1 (1935). (9) Klagei, BIT., 81, 2649 (1902); Strauss, ibid., CP, 2882 (1909). (10) von der Eeide, ibid., W , 2101 (1004). (11) Whitby and Gallay, Can. J . Research, 1, 220 (1952).
Vol. 70
TABLE I POLYMERIZATION INHIBITORS FOR DIENE"
Inhibitor
Inhibition period, hr.
Blank Picric acid m-Dinitrobenzene Phenyl-@-naphthylamine Diphenylamine Triphenylamine p-Phenylenedismine Hydroquinone &Butylcatechol Benzoquinone Chloranil
