Org. Synth. 1950, 30, 75
DOI: 10.15227/orgsyn.030.0075
trans-1-PHENYL-1,3-BUTADIENE
[1,3-Butadiene, 1-phenyl-, trans-]
Submitted by Oliver Grummitt and Ernest I. Becker
1.
Checked by Charles C. Price and T. L. Patton.
1. Procedure
In a 1-l. three-necked flask equipped with a mercury-sealed stirrer, a reflux condenser protected with a calcium chloride drying tube, a separatory funnel, a nitrogen inlet tube, and a thermometer is placed 0.515 mole of methylmagnesium bromide in 250–350 ml. of ether (a 1.5–2.0N solution). The mixture is cooled to a temperature below 10° by means of an ice-water bath, the stirrer is started, and a solution of 66.1 g. (0.50 mole) of cinnamaldehyde (Note 1) in 60 ml. of absolute ether is added, the rate of addition being controlled so that the temperature is kept below 10°. Throughout the addition, which takes about 1 hour, a slow stream of dry nitrogen is passed through the flask (Note 2).
The flask is detached from the condenser and stirrer, and its contents are transferred to a
500-ml. separatory funnel. The apparatus is then reassembled, without the nitrogen inlet tube or the drying tube, and
175 ml. of 30% sulfuric acid (by weight) is placed in the flask. Without cooling, but with efficient stirring with a
Hershberg Nichrome wire stirrer at 1500–1700 r.p.m.
(Note 3),
2 the ethereal solution of the
cinnamaldehyde-methylmagnesium bromide adduct is added rapidly to the acid. The time for this addition (5–7 minutes) is limited by the efficiency of the condenser. Heat then is applied to maintain gentle reflux until the
total time elapsed from the initiation of hydrolysis is 20 minutes. The contents of the flask are
immediately transferred to a
1-l. separatory funnel, the lower aqueous layer is discarded, and the
ether layer is washed successively with 50 ml. of water, a mixture of
50 ml. of 5% aqueous sodium hydroxide and
50 ml. of saturated ammonium chloride solution, and 50 ml. of water. Before each of the washings the air in the separatory funnel is displaced with
nitrogen. When the second wash solution is added, 0.3 g. of
phenyl-β-naphthylamine is dissolved in the
ether layer. The washed solution is dried with
20 g. of anhydrous sodium sulfate for 30 minutes and then with
15 g. of anhydrous potassium carbonate for 12 hours.
The ethereal solution is filtered and concentrated by distillation from a
steam bath to a residual volume of 80–100 ml. Some water separates at this time, and the mixture is cooled and then dried with about
15 g. of anhydrous potassium carbonate. The concentrated solution is filtered into a
125-ml. modified Claisen flask3 and distilled under reduced pressure in a
nitrogen atmosphere into a
receiver containing 0.3 g. of
phenyl-β-naphthylamine. In this manner
52–54 g. (
80–83%) of crude
trans-1-phenyl-1,3-butadiene is obtained, b.p.
81–85°/10–11 mm.;
n25D 1.606–1.608, which may contain some
methylstyrylcarbinol and water. This material is dried with
5 g. of anhydrous potassium carbonate, filtered, and distilled as before. The yield of
trans-1-phenyl-1,3-butadiene is
47–49 g. (
72–75%), b.p.
78–81°/8 mm.;
n25D 1.607–1.608. This product is satisfactory for most purposes
(Note 4) and
(Note 5).
2. Notes
1.
Cinnamaldehyde obtained from the Eastman Kodak Company was purified by washing a solution in an equal volume of
ether with aqueous
sodium carbonate and then with water, dried, and distilled under
nitrogen; b.p.
101–102°/2–3 mm.;
n20D 1.6195.
2.
The procedure may be altered at this point so that
trans-methylstyrylcarbinol is obtained. It is necessary, however, to observe the precaution that all apparatus coming in contact with the
trans-methylstyrylcarbinol be free from traces of acid.
The solution is stirred for 30 minutes after the addition is complete. Then 125 ml. of a saturated solution of ammonium chloride (about 28%), which has been neutralized to litmus with concentrated ammonium hydroxide, is added dropwise, the temperature being held at 5–10°. This addition takes from 1 to 1.5 hours. After decanting the ether layer, breaking up the precipitate and extracting it with two 60-ml. portions of absolute ether, and adding the extracts to the main solution, the solution is distilled from a steam bath until the residual volume is about 100 ml. The solution is transferred to a Claisen flask, and the residual ether is removed by evacuation with a water pump. After the discard of a small fore-run, the product is collected at 93–94°/1.5 mm.; yield, 65–67 g. (88–90%).
Upon cooling at 0–10° the trans-methylstyrylcarbinol forms a mass of white crystals melting at 30–34°. These may be purified by crystallization from petroleum ether (b.p. 30–35°) -methylene chloride (6:1). For each 30 g. of the carbinol, 350 ml. of the solvent mixture is used. The solution is cooled to −75° to −80° in Dry Ice and kept at that temperature for about 3 hours. The solution is filtered quickly by suction through a chilled funnel, washed with the cold solvent mixture, and dried in a vacuum desiccator. The yield of pure trans-methylstyrylcarbinol is 28.5 g., m.p. 33.5–34.5°; n35D 1.5598; d354 0.9995.
3.
The stirring must be vigorous in order to mix the
ether and aqueous layers. This is absolutely essential for the production of reasonable yields. Slower stirring necessitates a longer time for the hydrolysis with consequent longer contact time between the
1-phenyl-1,3-butadiene and the
sulfuric acid, which results in extensive polymerization of the product and corresponding decrease in yield.
4.
Pure
trans-1-phenyl-1,3-butadiene was obtained by distillation of the twice-distilled product under
nitrogen through a
12-plate column of the total reflux-variable takeoff type
2 after adding 0.5% of phenyl-β-naphthylamine. The packed section of the column was an 18-in. section of Pyrex tubing (10 mm. o.d.) filled with 4-mm. single-turn glass helices. Insulation was provided by means of a vacuum jacket, and heat losses were compensated by resistance wire wound on the jacket.
About 50% of the sample taken was collected, b.p. 86°/11 mm.; n25D 1.6086–1.6090; d254 0.9235–0.9239.
5.
Present evidence indicates that
1-phenyl-1,3-butadiene4 prepared by this method is the
trans isomer.
5
3. Discussion
1-Phenyl-1,3-butadiene has been prepared by the decarboxylation of
allocinnamylideneacetic acid6 and of
cinnamylidenemalonic acid;
7 the dehydration of
methylstyrylcarbinol from the Grignard addition of methylmagnesium halide to
cinnamaldehyde;
8 the rearrangement and dehydration of the alcohol intermediate formed by the Grignard addition of phenylmagnesium bromide to
crotonaldehyde;
9 the formation of
methylstyrylcarbinol, its conversion to
methylstyrylcarbinyl chloride, and dehydrohalogenation;
10 a modified Wurtz reaction in which
benzyl chloride is coupled with
allyl chloride by means of
sodium in liquid ammonia;
11 the condensation of
styrene and
acetaldehyde and dehydration of the intermediate in the presence of
sulfuric acid in
acetic acid;
12 and by the dehydrochlorination of
4-chloro-1-phenyl-2-butene (prepared by the condensation of
butadiene with
benzenediazonium chloride).
13 Reference
12 describes the preparation of
1-phenyl-1,3-butadiene by pyrolysis of
1-phenyl-1,3-butyleneglycol diacetate and
2,6-dimethyl-4-phenyl-1,3-dioxane. The present method is a modification of the procedure of von der Heide.
8
trans-Methylstyrylcarbinol has been prepared by several methods: the hydrolysis of the addition product formed from methylmagnesium halide and
cinnamaldehyde in a variety of ways;
10,14 hydrolysis of the addition compound formed from
styrylmagnesium bromide and
acetaldehyde;
4 hydrolysis and hydrogenation of the product formed in the Grignard reaction of
phenylethynylmagnesium bromide and
acetaldehyde;
15 the addition of
hypobromous acid to
1-phenyl-1,3-butadiene followed by reduction with
sodium amalgam in acetic acid;
16 the allylic rearrangement of
1-phenyl-1-acetoxy-3-butene to
1-phenyl-3-acetoxy-1-butene followed by saponification;
17 and the reduction of
benzalacetone by means of
aluminum isopropoxide.
18 The method employed here is essentially that of Kenyon, Partridge, and Phillips.
14
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
petroleum ether
phenyl-β-naphthylamine
cinnamaldehyde-methylmagnesium bromide
allocinnamylideneacetic acid
acetaldehyde (75-07-0)
potassium carbonate (584-08-7)
sulfuric acid (7664-93-9)
acetic acid (64-19-7)
ammonia (7664-41-7)
ether (60-29-7)
ammonium chloride (12125-02-9)
sodium hydroxide (1310-73-2)
sodium carbonate (497-19-8)
sodium sulfate (7757-82-6)
nitrogen (7727-37-9)
allyl chloride (107-05-1)
benzenediazonium chloride
Benzalacetone (122-57-6)
sodium (13966-32-0)
aluminum isopropoxide
benzyl chloride (100-44-7)
hypobromous acid (13517-11-8)
ammonium hydroxide (1336-21-6)
cinnamaldehyde
methylene chloride (75-09-2)
styrene (100-42-5)
butadiene (106-99-0)
styrylmagnesium bromide
methylmagnesium bromide (75-16-1)
crotonaldehyde (123-73-9)
methylstyrylcarbinol
1-phenyl-1,3-butadiene (31915-94-3)
cinnamylidenemalonic acid (4472-92-8)
methylstyrylcarbinyl chloride
4-chloro-1-phenyl-2-butene
1-phenyl-1,3-butyleneglycol diacetate
2,6-dimethyl-4-phenyl-1,3-dioxane
phenylethynylmagnesium bromide
1-phenyl-1-acetoxy-3-butene
1-phenyl-3-acetoxy-1-butene
trans-1-Phenyl-1,3-butadiene,
1,3-Butadiene, 1-phenyl-, trans- (16939-57-4)
trans-Methylstyrylcarbinol (17488-65-2)
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