Org. Synth. 1948, 28, 31
DOI: 10.15227/orgsyn.028.0031
m-CHLOROSTYRENE
[Styrene, m-chloro-]
Submitted by C. G. Overberger and J. H. Saunders.
Checked by Arthur C. Cope and Theodore T. Foster.
1. Procedure
A
500-ml. three-necked round-bottomed flask is attached to a
250-ml. dropping funnel and a total-condensation variable take-off
fractionating column with a 20 by 1.2 cm. section packed with glass helices (Note 1). The fractionating column is fitted to a
500-ml. receiving flask. In the reaction flask are placed
12.5 g. of powdered fused potassium acid sulfate and
0.05 g. of p-tert-butylcatechol. The flask is immersed in an
oil bath maintained at 220–230°, and
145 g. (0.925 mole) of m-chlorophenylmethylcarbinol (p. 200) and
0.05 g. of p-tert-butylcatechol (Note 2) are placed in the dropping funnel. The system is evacuated to a pressure of 125 mm., maintained by a manostat, and the
m-chlorophenylmethylcarbinol is added dropwise at a rate (15–20 drops per minute) which maintains a vapor temperature at 110–120° at the top of the column. The
m-chlorostyrene and water formed are collected in a
receiver. When the addition is completed (5.5–8.5 hours) the pressure is held constant until distillation stops, and it is then reduced to 20 mm. until no more liquid distils.
The distillate is rinsed into a separatory funnel with 25 ml. of ether, and the organic layer is separated and dried over 10 g. of anhydrous magnesium sulfate. The drying agent is separated and rinsed with 25 ml. of ether, and 0.1 g. of p-tert-butylcatechol is added to the solution. The ether is removed, and the product is distilled under reduced pressure. m-Chlorostyrene is obtained in a yield of 102–106 g. (80–82.5%), boiling at 55–57°/3 mm.; nD20 1.5625 (Note 3) and (Note 4). A small amount (3–8 g.) of m-chlorophenylmethylcarbinol can be recovered as a higher-boiling fraction.
2. Notes
1.
Effective separation of
m-chlorostyrene from
m-chlorophenylmethylcarbinol is possible with the short column specified. If a fractionating column is not used, lower conversions result and the crude product contains
m-chlorophenylmethylcarbinol, which can be separated by fractional distillation and used in a subsequent preparation.
2.
The submitters state that
hydroquinone is not a satisfactory polymerization inhibitor for use in this preparation but that
picric acid is very effective (less than 0.01 g. is required).
3.
The submitters have used a similar procedure to prepare the following substituted styrenes from arylmethylcarbinols. The reactions were conducted more rapidly (addition rate about 2 drops per second), and no fractionating column was used in the initial distillation. A lower pressure (100 mm.) was used in dehydration of the dichlorophenylmethylcarbinols. The yields cited are based on the weights of arylmethylcarbinols which reacted; varying amounts of the carbinols were recovered in the distillation of the products.
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Boiling Point
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% Yield
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o-Chlorostyrene
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67–69°/3–3.5 mm.
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64–66.5
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p-Chlorostyrene
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65°/4 mm.
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57
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o-Bromostyrene
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64–65°/3 mm.
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64.5
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m-Bromostyrene
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74–75°/3 mm.
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56
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p-Bromostyrene
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87–88°/12 mm.
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50
|
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m-Fluorostyrene
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30–32°/2 mm.
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45
|
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2,3-Dichlorostyrene
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92–94°/4–5 mm.
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44
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2,4-Dichlorostyrene
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81°/6 mm.
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33
|
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3,4-Dichlorostyrene
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95°/5 mm.
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63.5
|
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2,6-Dichlorostyrene
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64–65°/3 mm.
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31.5
|
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3,5-Dichlorostyrene
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59°/1 mm.
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43.5
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The dehydration procedure of this preparation is stated to be unsatisfactory for substituted phenylmethylcarbinols which have a strongly electronegative group, such as the nitro or trifluoromethyl group, in the meta position.
4.
Some color due to small amounts of
iodine may be present in substituted styrenes prepared by this procedure from arylmethylcarbinols synthesized from the corresponding aldehyde and
methylmagnesium iodide. If present,
iodine may be removed by shaking the crude product with
1 g. of powdered zinc and 25 ml. of water.
3. Discussion
m-Chlorostyrene has been prepared by dehydration of
m-chlorophenylmethylcarbinol by modifications of this procedure,
1,2,3 and by the vapor-phase dehydration in the presence of
alumina at reduced pressure.
4
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
alumina
potassium acid sulfate
ether (60-29-7)
hydroquinone (123-31-9)
iodine (7553-56-2)
zinc (7440-66-6)
picric acid (88-89-1)
methylmagnesium iodide (917-64-6)
magnesium sulfate (7487-88-9)
2,3-Dichlorostyrene
2,4-Dichlorostyrene
3,4-Dichlorostyrene (2039-83-0)
2,6-Dichlorostyrene (28469-92-3)
3,5-Dichlorostyrene
p-tert-butylcatechol (98-29-3)
o-Bromostyrene (2039-88-5)
m-Chlorophenylmethylcarbinol (5182-44-5)
m-Chlorostyrene,
Styrene, m-chloro- (2039-85-2)
o-Chlorostyrene (2039-87-4)
p-Chlorostyrene (1073-67-2)
m-Bromostyrene (2039-86-3)
p-Bromostyrene (2039-82-9)
m-Fluorostyrene (350-51-6)
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