July 5, 1952
3343
SELF-CONDENSATION PRODUCT OF 1-PHENYL-2-PYRAZOLINE
TABLE I ACETATEESTERS %" 10
Eater NO.* Calcd. Found
B.p.
Yield, Formula
OC.
Mm.
nuD
CHaCHpCHzOAc 96-99 ... 1.3810 550 516 CiHoOAc 33 108-123 ... .... ... ... CHs(CH*)&H( CH~)CH*OAC 11 157-1 59 ... 1 ,4060 389 365 CsHpCHiOAc 7 45-50 5 1 ,4300 395 406 C&Hio( CO*H)(CH?OAc)' 29 150-158 1-2 1 .4688 280 274 CaHiiOAc 37 60-63 1-2 1.4180 326 283 CgHigOAc 70 55-60 2 1.4225 301 295 CioHir(CHz0Ac)z 19 155-165 2-3 1.4878 401 375 Ci3HnOAcd 46 88-90 1-2 1.4350 232 225 CisHwOAc' 59 88-95 1-2 1.4360 232 232 1 1.4469 188 183 CiiHs60A~ 54 123-130 * The ester, acid or hydroxyl number is the number of milligrams 4 Yield based on amount of unsaturated material used. Calcuof potassium hydroxide equivalent to the amount of functional group undergoing reaction in one gram of sample. Acetate ester from Sharples triiosbutylene. e Acetate ester from Shell tetrapropylated acid number: 280; found.272. lene. acid in the presence of one or two grams of cobalt acetate with a 1:1 gas mixture of carbon monoxide and hydrogen at 225-275" and 700 atm. pressure for one hour in a stainless steel shaker tube (325-cc. capacity). The shaker tube was cooled to room temperature and the pressure released. The resulting liquid products were worked up by distillation. In the case of ethylene and propylene, the propyl acetate and butyl acetates were isolated by steam distillation followed by drying and distillation. Cobalt laurate in the hydroformylation reactions gave comparable results to cobalt acetate. Recycling of the foreshot material (bailing in the range of the olefin) from the hydroformylation of liquid olefins produced substantially no additional acetate esters, indicating that the foreshot material was essentially the saturated hydrocarbon. The yields and properties of the acetate esters are listed in Table I. Alcohols.-The alcohols were obtained in quantitative yields by methanolysis of the corresponding acetate esters in the presence of traces of sodium methoxide. The properties of the alcohols are given in Table 11.
[CONTRIBUTION FROM
THE S O Y E S
TABLEI1
ALCOHOLS B.P. Formula
OC.
Mm.
n%
OH No. Calcd. Found
GH,OH" 107-114 . . , 1.3935 .., ... C8Hi70Hb 177-181 . . . 1.4281 . . . ... C I ~ H ~ ~ O H95-100 2-3 1.4450 281 277 Ci3H270H 110-117 2-3 1.4460 281 278 Ci,HasOH 140-145 4-5 1.4571 219 216 "Analysis of the butanols by the mass spectrograph showed the following composition in mole %: 24.1 n-butyl alcohol, 71.6 isobutyl alcohol, 1.8 n-butyl formate, 2.5 nbutyl acetate. "he mass spectrograms of an authentic sample of 2-ethylhexanol and the C ~ H I ~ Ofraction H were made and found to be quite similar. However, differences were sufficient to indicate that more than one compound was present in one or both of the samples. WILMINGTON, DEL.
CHEMICAL LABORATORY, UNIVERSITY
OF
ILLINOIS]
The Structure of the Self-Condensation Produet of l-Phenyl-2-pyrazoline BY H. R. SNYDER, FRANK VERBANAC AND D. BRUCE BRIGHT' RECEIVED DECEMBER 17, 1951 The product obtained from the self.condensation sf l-phenyl-2-pyrazoline is shown to be l,l'-diphenyl-3,3'-bi-2-pyrazoline (11). The structure is proved by characterization of oxidation products and by infrared studies. Oxidation of the substance (V), identified by independent synthesis. l,l'-Diphenyl-3,4'-bipyrazole(IV) has yields l,lf-dipheny1-3,3'-bipyrazole also been prepared. The reaction of 3-methyl-l-phenylpyrazolewith n-butyllithium produces the 5-lithium derivative.
Treatment of l-phenyl-2-pyrazoline with hydrogenchloride yields a self-condensation product which was referred to as bis-N-phenyl-Aa-pyrazofine by Curtius and Wirsing.2 In the present work the reaction was accomplished with boron trifluoride and boron trifluoride etherate as well as with dry hydrogen chloride. The product, a yellow solid which exhibits blue fluoresence in ether solution, was reported2 to have a melting point of 221Qand an empirical formula of C1d&N4. However, the product obtained in this Laboratory melted a t 235237' (cor.), and the empirical formula ClgHlaN4 was required by the analyses and the molecular weight determinations. Thus, the substance is (1) Atomic Energy Commission Fellow, 1951-1952. (2) T h Curtius and F. Wirsing. J . prekr Chcm., 12)
W,531 (lSQ4)
not a simple dimer but rather the product of an oxidative coupling. The infrared absorption spectrum of the selfcondensation product is characterized by the presence of strong bands a t 1596 and 1499 crn.-l, the absorption being much more intense than that ordinarily attributed to a phenyl group. Similar bands were observed in the spectra of l-phenyl-2pyrazoline, 1,5cdipheeyl-2-pyrazoline and 1,5-diphenyl-3-p-tolyl-2-pyrazoline.The great similarity of the absorption bands indicates that the structural feature common to these known pyrazolines, i.6, the l-phenyl-2-pyrazoline system, is also presegt in the self-condensation product. The spectrum of the unknawn substance gave no indication of the presence of an -N-H group. Because
H. R. SNYDER, F. VERBANAC AND D. B. BRIGHT
3244
Vol. 74
of the fluorescence of the substance, no detailed study of the ultraviolet absorption was undertaken. The self-condensation product could not be acetylated by acetic anhydride in pyridine; this test confirms the absence of -N-H groups. No pure product could be isolated after reduction with sodium and n-amyl alcohol or with zinc and acetic or hydrochloric acid, or after hydrogenation in the presence of Raney nickel catalyst. Oxidation with potassium permanganate in pyridine yielded 1-phenylpyrazole-3-carboxylicacid along with a dehydrogenated compound, Ci8H14N4, evidently a bipyrazole. When this product was reduced with sodium and ethyl alcohol, the yellow color and the fluorescence characteristic of the original substance were again observed. The isolation of the compound C18H14N4and the 3-carboxylic acid, together with the infrared studies, clearly indicates that the substance is a bi-2-pyrazoline and that the 3-position of one of the pyrazoline units must be a point of union. The possible structures are I, I1 and 111.
CeI-15
t‘.5Hb
661 refluxed for 1.5 hours. The addition of water t o the cooled reaction mixture caused the precipitation of 3.1 g. of a light green substance, m.p. 120-125'. Treatment with Darco and crystallization from a water-alcohol mixture gave 2.4 g. of white crystals, m.p. 123.5-126'. Three recrystallizations raised the melting point to 128-129'. Anal. Calcd. for ClpHleK40: C, 72.13; H, 5.06; S, 17.71. Found: C, 71.89;H. 5.09; S . 17.83. 1,l '-Diphenyl-5-methyl~3,4"-bipyrazole (XII).-The method of Stoermer and Martinsen" was followed with some modifications. A mixture of 1.6 g. of XI, 2.0 g. of freshly distilled phosphorus tribromide, and 0.25 g. of red phosphorus was heated in a sealed tube a t 240-255' for 9.5 hours. The contents of the tube was treated with alcohol and Darco. Two crystallizations after filtration yielded 0.6 g. (40%) of white needles, m.p. 96-9Sq. A sample prepared for analysis melted at 97.5-98'. Anal. Calcd. for CIgH~&: C, 75.98: H, 5.37; S , 18.65. Found: C,75.74; H, 5.36; S , 18.61. 1,l '-Diphenyl-3,4'-bipyrazole-5-carboxylicAcid (XIII) .To a mixture of 0.6 g. of X I I , 10 g. of potassium permanganate and 15 ml. of pyridine was added sufficient water to effect solution. The mixture was heated for 3.5 hours. The manganese dioxide was filtered and washed with three portions of hot 3: 1 pyridine-water solution. The combined filtrates were diluted with 50 ml. of 3% sodium hydroxide, washed with chloroform, concentrated, treated with Darco, filtered and acidified t o congo red paper with concentrated hydrochloric acid t o yield 0.13 g. of a light tan solid, m.p. 206-207' (dec.). Two crystallizations from methanol resulted in the formation of white needles, m.p. 24-225" (dec.). Anal. Calcd. for C l ~ H t r O ~ N ~ C,: 69.09; H , 4.27; X, 16.96. Found: C,69.21; H,4.21, 4.26; 9, 16.82. From the chloroform extracts 0.4 g. of XI1 was recovered. 1,l'-Diphenyl-3,4'-bipprazole (IV).-In a small Pyrex test-tube was placed 0.13 g. of XIII. The test-tube was heated in a Wood's metal-bath a t 210-230' for 20 minutes. The black reaction mixture was treated with 5 ml. of hot alcohol and Darco. When cooled 35 mg. of solid was obtained. Recrystallization from a water-alcohol mixture yielded white crystals, m.p. 125.5-126.5'. Anal. Calcd. for ClIH~4S4: C, 75.50; H.4.93. Found: C, 75.35; H, 5.06. Reaction of 3-Methyl-I-phenylpyrazole with n-Butyllithium.-A solution of 5.0 g. of 3-methyl-1-phenylpyrazolel2 in 20 ml. of anhydrous ether was added dropwise to 0.04 mole of freshly prepared butyllithium in 65 ml. of ether. The mixture was stirred for two hours after the addition and then poured into a slurry of solid carbon dioxide in ether. The carbon dioxide was allowed to evaporate, and 50 ml. of water was cautiously added. The water layer was separated, concentrated and acidified with concentrated hydrochloric acid. A white material precipitated after chilling,oand it was recrystallized from hot water; m . p . 178.q'!--179.a . Anal. Calcd. for C ~ I H I ~ N ~ OC,? : 6.5.33: H, 4.98; S , 13.86. Found: C, 65.18; H, 5.13; N,13.91. The amide was prepared and recrystallized from methanol: m.p. 177-178'. The melting point of 3-methyl-I-phenyl,
I
-
i l l ) R , Stoermer and 0.Martinsen. A x n . . 352, 322 i l 9 0 7 ) 1121 I.. Knorr ibid. a38, 137 ( 1 8 8 7 )
Vnl, 71
pyrazole-5-carboxamide is 181 . 4 The monocarboxylic acid was oxidized by potassium permanganate in the usual manner, and an acid was obtained, m.p. 237-258' (dec.). The melting point of authentic l-phenylpyrazole-3,5-dicarboxylic acid i s 260°.4 A mixed melting point determination showed no depression. The diamides of the dibasic acids were prepared. The melting point of the authentic diamide was 192-194' (lit.4190'). The melting point of the diamide derived from the acid obtained from the n-butyllithium reaction was 190-192'; mixed m.p. 190-193'. Dieth 1 l-Phenyl-5-methylpyrazole-3-carboxylmalonate (XIV) .-$ o a mixture of 2.7 g. of magnesium, 5 ml. of absolute alcohol and 0.5 ml. of carbon tetrachloride, heated a few minutes on the steam-bath, was added 50 ml. of dry ether with stirring. A mixture of 16 g. of diethyl malonate, 6.7 ml. of absolute alcohol and 25 ml. of dry ether was added 4owly a t reflux temperature. When the mixture had refluxed for three hours, a solution of 22.0 g. of VI1 in 300 ml. of ether was slowly added over a period of 15 minutes. The white precipitate that formed was decomposed with 3.50 ml of i0yo sulfuric acid. The aqueous layer was extracted with two 150-m1. portions of ether. The combined ether solutions were dried over magnesium sulfate and evaporated to dryness, yielding 28.3 g. (82%) of crude XIV. The 2,1dinitrophenylhydrazone of XII' served to characterize it The derivative was recrystallized four times from a 95% ethanol-ethyl acetate mixture and once from t-butyl a h hol; m.p. 209' (dec.). Anal. Calcd. for C?dH2408S~: C, 54.96; H, 4.61; S 16.03. Found: C, 55.26; H, 4.92; S,16.17. 1-Phenyl-3-(1-phenyl-5-methyl-3-pyrazolyl)-5-pyrazolone
(XV).-.4 solution of 4.0 g. of crude XI\' and 1.25 g. of phenylhydrazine in 25 ml. of glacial acetic acid was refluxed for 1.5 hours. To the mixture was added 68 ml. of 25% dfuric acid, arid refluxing was continued for five hours. The addition of water caused 2.5 g. of yellow material to precipitate, m.p. 160-175". Treatment with Darco and two crystallization? from 95% alcohol yielded white crystals, m.p. 187-188.5'. .-lnnl. Calcd. for C19HleOS4: C, 72.13; H, 5.06; S , 17.71 Found: C,72.18; H,5.13; S,17.73. 1,l '-Diphenyl-5-methyl-5'-bromo-3,3'-bipyrazole (XVI).This reaction was carried out by the procedure described for the preparation of XII, except that the sealed tube wac heated a t 225240" for 12 hours. This resulted in the formation of n white crystalline material, m.p. 162-164', in 33% yield. After two recrystallizations from 95% alcohol the melting point was 166-167' .Inal. Calcd. for CIYHIeSIBr: C, 60.19; H, 3.99; S. 14.77 Found: C, 60, 17; H, 4.15; S,14.76. 1 , l'-Diphenyl-5-methyl-3,3'-bipyrazole (XVII).-A miuture of 1.3 g. of XYI (m p 162-164'), about 4 g. of Raney nickel catalyst and 40 ml. of a 10% solution of potassium hydroxide in alcohol was refluxed for 30 minutes. Filtration and concentration gave 0.8 g. (78%) of a white crystalline material, m p. 163-163'. A small portion was purified by two recrvstallizations from a water-alcohol mixture; m . p 162-163 '. Anal. Calcd. for C I ~ H I ~ N C,~75.98; : H, 5.37; X, 18.65. Found: C , 76.08; H, 5.26; N,18.63. 1,1'-Diphenyl-3,3'-bipyrazole-5-carboxylic Acid.-This reaction was run as described above (XIII). One recrystallization from methanol produced white crystals, m.p. 22.5226" (dec.). Anal. Calcd. for CNHI~N~O.: C , 69.09; H, 4.27. Found: c, 68.73; 13, 4.50. 1, I '-DiphenyL3,3'-bipyrazole (VI.-Employment of the procedure used for IV yielded 25 mg. of nearly colorless crystals, m.p. 182-184', from 96 mg. of l,l'-diphenyI3,3'bipyrazole-5-carboxylic acid. The infrared spectrum of the product is identical with that of the C14HlaN4 oxidation product of the bis-compound; mixed m . p . 183-181'. Anal. Calcd. for C18H14S4:C , 75.50; H, 4.93: S. 19.*57. Found: C , 75.73: N,5.13; S , 19.41. ITRBANA,I~.r.rxors
