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Org. Synth. 1952, 32, 90
DOI: 10.15227/orgsyn.032.0090
NEOPHYL CHLORIDE
[Benzene, (2-chloro-1,1-dimethylethyl)-]
Submitted by W. T. Smith, Jr. and J. T. Sellas1.
Checked by N. J. Leonard and R. O. Kerr.
1. Procedure
In a 2-l. three-necked flask equipped with a mechanical stirrer, thermometer, and dropping funnel are placed 500 g. (570 ml., 6.4 moles) of benzene (Note 1) and 34.6 g. (18.8 ml.) of concentrated sulfuric acid (sp. gr. 1.84). The resultant mixture is brought to 20°. To this is added dropwise 201 g. (219 ml., 2.22 moles) of methallyl chloride (Note 2) over a period of 12 hours, during which time vigorous stirring is maintained and the temperature is kept at 20° with the aid of a water bath. The mixture, which becomes an amber color, is stirred for an additional 12 hours.
The reaction mixture is then transferred to a 1-l. separatory funnel, and the sulfuric acid layer is removed. The remaining benzene solution is then washed with four 200-ml. portions of distilled water (Note 3). In this step the amber color disappears and the liquid becomes colorless. The benzene solution is dried with anhydrous sodium sulfate and transferred to a 1-l. distilling flask. The benzene is removed by distillation under a pressure of about 45 mm. The liquid residue is poured into a 500-ml. flask and distilled through a 40-cm. Vigreux column under reduced pressure. The yield of neophyl chloride boiling at 97–98° /10 mm. is 262–275 g. (70–73%) (Note 4) and (Note 5); nD20 1.5250.
2. Notes
1. The benzene is purified by washing with three 80-ml. portions of concentrated sulfuric acid and then drying with anhydrous sodium sulfate. It is used directly after removal of the sodium sulfate by filtration.
2. The methallyl chloride used was a redistilled commercial sample and had the following properties: b.p. 71–72° /760 mm., nD20 1.4274, d420 0.918.
3. To ensure good results it is necessary to remove all of the sulfuric acid by washing the mixture thoroughly with water. The final washing should be neutral to litmus.
4. If the residue in the distilling flask is dissolved in ether, treated with activated carbon, and evaporated to dryness, the solid so obtained can be recrystallized from about 25 ml. of 95% ethanol to give 10 g. (2.7%) of p-di(chloro-tert-butyl)benzene; m.p. 54.5–55.0°.
5. In a run in which the temperature was kept at 10–15° during the addition of methallyl chloride, the methallyl chloride was added over a period of 1 hour. Stirring was continued for 1 hour, and the reaction mixture was worked up as described above to give a 53% yield.
3. Discussion
(Chloro-tert-butyl)benzene has been prepared by the direct chlorination of tert-butylbenzene in the presence of strong light;2 by chlorination of tert-butylbenzene with sulfuryl chloride in the presence of benzoyl peroxide;3 by the action of thionyl chloride on the corresponding alcohol;4 and by the hydrogen fluoride-catalyzed alkylation of benzene with methallyl chloride.5 The sulfuric acid-catalyzed alkylation described here is based on the procedure of Whitmore, Weisgerber, and Shabica.6 A variation using a shorter reaction time has also been described.7

References and Notes
  1. State University of Iowa, Iowa City, Iowa.
  2. Truce, McBee, and Alfieri, J. Am. Chem. Soc., 71, 752 (1949).
  3. Kharasch and Brown, J. Am. Chem. Soc., 61, 2147 (1939).
  4. Haller and Ramart, Compt. rend., 174, 1211 (1922).
  5. Calcott, Tinker, and Weinmayr, J. Am. Chem. Soc., 61, 1010 (1939).
  6. Whitmore, Weisgerber, and Shabica, J. Am. Chem. Soc., 65, 1469 (1943).
  7. Schmerling and Ipatieff, J. Am. Chem. Soc., 67, 1862 (1945).

Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)

ethanol (64-17-5)

sulfuric acid (7664-93-9)

Benzene (71-43-2)

ether (60-29-7)

thionyl chloride (7719-09-7)

sodium sulfate (7757-82-6)

carbon (7782-42-5)

sulfuryl chloride (7791-25-5)

benzoyl peroxide (94-36-0)

methallyl chloride (563-47-3)

Neophyl chloride,
Benzene, (2-chloro-1,1-dimethylethyl)-,
(Chloro-tert-butyl)benzene (515-40-2)

tert-butylbenzene (98-06-6)

p-di(chloro-tert-butyl)benzene