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Org. Synth. 1963, 43, 27
DOI: 10.15227/orgsyn.043.0027
DIMETHYL 3-METHYLENECYCLOBUTANE-1,2-DICARBOXYLATE
[3-Methylenecyclobutane-1,2-dicarboxylic acid, dimethyl ester]
Submitted by H. B. Stevenson, H. N. Cripps, and J. K. Williams1.
Checked by R. D. Birkenmeyer, W. E. Russey, and F. Kagan2.
1. Procedure
A. 3-Methylenecyclobutane-1,2-dicarboxylic anhydride. A 2-l. stainless steel autoclave equipped with stirrer, pressure gauge, and thermocouple is charged with 500 g. (5.1 moles) of maleic anhydride, 645 ml. of benzene, and 0.25 g. of hydroquinone. The autoclave is closed, cooled to −70° with stirring, and evacuated to a pressure of about 20 mm. Allene3 (100 g., 2.5 moles) (Note 1) is sucked into the autoclave, and the mixture is heated with stirring for 8–10 hours at 200–210°. During this time, the pressure drops from 23 atm. to 15 atm. The vessel is cooled to 25°, and unreacted allene (6–13 g.) is vented into a cold trap (Note 2). The benzene solution is decanted, and about 500 ml. of acetone is added to the autoclave and stirred until the dark viscous residue goes into solution. The benzene and acetone solutions are combined, filtered, and distilled through a 19-mm. × 1.8-m. Nester spinning-band still.4 When the pot temperature reaches 170°, the pressure is reduced to 40 mm., and up to 250 g. of maleic anhydride, b.p. 110–115°/40 mm., is recovered. Finally 119 g. of crude anhydride mixture, b.p. 70–125°/3 mm. (Note 3), is collected.
The crude anhydride is carefully fractionated through a 13-mm. × 1.2-m. Nester still at a pressure of 25 mm. (Note 4) and a reflux ratio of at least 10:1. After a fore-run of maleic anhydride, b.p. 50–100°/25 mm., and a small intermediate fraction, there is obtained 75–90 g. (22–26%) of 3-methylenecyclobutane-1,2-dicarboxylic anhydride; b.p. 155–159°/25 mm.; n25D 1.4935–1.4952 (Note 5). This material is of sufficient purity for most uses, but it contains approximately 2–5% of propargylsuccinic anhydride. Redistillation through the Nester still gives 65–80 g.. (19–23%) of 3-methylenecyclobutane-1,2-dicarboxylic anhydride; b.p. 155°/25 mm.; n25D 1.4946–1.4955.
By continuing the distillation after removal of the cyclobutane anhydride, there is obtained 25–30 g. (7–9%) of propargylsuccinic anhydride; b.p. 162–168°/25 mm.; m.p. 63–68°. The melting point is raised to 69–70° by one recrystallization from 100 ml. of benzene (80% recovery of purified product).
B. Dimethyl 3-methylenecyclobutane-1,2-dicarboxylate. One liter of methanol is added cautiously with occasional shaking to 276 g. (2.00 moles) of 3-methylenecyclobutane-1,2-dicarboxylic anhydride (n25D 1.4946–1.4955; (Note 6)) and 5 g. of p-toluenesulfonic acid in a 2-l. three-necked flask fitted with a thermometer, a condenser, and a dropping funnel. Refluxing starts after about two-thirds of the methanol has been added. The remainder is added at a rate that maintains vigorous boiling. The solution is refluxed for 30–40 hours with the pot temperature increasing from 67° to 68° (Note 7). The mixture is cooled to 15°, and methanol and water are removed by distillation under reduced pressure at temperatures below 15°, using a large receiver cooled with a mixture of solid carbon dioxide and acetone. When the pressure goes below 1 mm., the temperature is increased to 50° until the distillation is completed. One liter of methanol (Note 8) is added to the residue, and the solution is heated under reflux for an additional 30–40 hours, during which time the pot temperature increases from 67° to 67.5°. The solution is cooled to 15°, 1.7 g. of finely powdered anhydrous sodium carbonate is added to neutralize the p-toluenesulfonic acid, and the methanol and water are removed as before. Crude dimethyl 3-methylenecyclobutane-1,2-dicarboxylate is distilled rapidly at 65–85°/1 mm. through a 30-cm. Vigreux column (Note 9). The ester can be purified by redistillation through a 13-mm. × 1.2-m. Nester still, with the main fraction boiling at 134–137°/25 mm.; weight 297–338 g. (81–92%); n25D 1.4624–1.4630.
2. Notes
1. Freshly distilled allene should be used. It should be free of 2-chloropropene, usually present in allene prepared by zinc dehalogenation of 2,3-dichloropropene,3 to avoid formation of chlorine-containing products that liberate hydrogen chloride on distillation.
2. The impurities present in the original allene are concentrated in the recovered material. If recovered allene is to be reused, it should be fractionated first.
3. The checkers isolated 167 g. of crude anhydride mixture boiling at 70–125°/3 mm. The large tarry residue contains allene polymers and small amounts of 1,2,3,4,5,6,7,8-octahydronaphthalene-2,3,6,7-tetracarboxylic dianhydride, which can be recovered by diluting the residue with benzene and filtering.
4. Pot temperatures above 175°, which result from use of pressures above 25 mm., cause formation of high-boiling by-products.
5. Collection of the product fraction should begin after a few milliliters of an intermediate fraction has been collected at 155°/25 mm. This material has a low index of refraction.
6. The checkers found that the use of anhydride with n25D 1.4937–1.4945 led to a product with a low index of refraction (n25D 1.4616).
7. The temperature rises because of disappearance of methanol by conversion to the methyl ester. Attainment of equilibrium is signified by the pot temperature reaching a constant temperature.
8. The second treatment with methanol increases the yield from 60% to 90%.
9. Rapid distillation from the neutralized catalyst results in much smaller loss of ester than is encountered in the more usual procedure that includes washing with water and drying.
3. Discussion
The procedure used is essentially that described by Cripps, Williams, and Sharkey.5 The anhydride has been prepared in a similar manner by Alder and Ackermann.6 No other methods have been described for the preparation of these materials.
4. Merits of the Preparation
The first step of this procedure illustrates a general reaction, the addition of allenes to alkenes to form methylenecyclobutanes. The reaction has been reviewed recently.7
Since 3-methylenecyclobutane-1,2-dicarboxylic anhydride is easily converted to 3-methyl-2-cyclobutene-1,2-dicarboxylic acid,8 it is an intermediate to a variety of cyclobutenes. The dimethyl ester of 3-methylenecyclobutane-1,2-dicarboxylic acid is also a versatile compound; on pyrolysis it gives the substituted allene, methyl butadienoate,9 and on treatment with amines it gives a cyclobutene, dimethyl 3-methyl-2-cyclobutene-1,2-dicarboxylate.8
This preparation is referenced from:

References and Notes
  1. Contribution No. 567 from the Central Research Department, Experimental Station, E. I. du Pont de Nemours and Co., Wilmington, Delaware.
  2. The Upjohn Company, Kalamazoo, Michigan.
  3. H. N. Cripps and E. F. Kiefer, this volume, p. 22.
  4. R. G. Nester, Anal. Chem., 28, 278 (1956).
  5. H. N. Cripps, J. K. Williams, and W. H. Sharkey, J. Am. Chem. Soc., 81, 2723 (1959).
  6. K. Alder and O. Ackermann, Ber., 90, 1697 (1957).
  7. J. D. Roberts and C. M. Sharts, Org. Reactions, 12, 1 (1962).
  8. H. N. Cripps, J. K. Williams, V. Tullio, and W. H. Sharkey, J. Am. Chem. Soc., 81, 4904 (1959).
  9. J. J. Drysdale, H. B. Stevenson, and W. H. Sharkey, J. Am. Chem. Soc., 81, 4908 (1959); H. B. Stevenson and W. H. Sharkey, this volume, p. 734.

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

cyclobutene, dimethyl 3-methyl-2-cyclobutene-1,2-dicarboxylate

hydrogen chloride (7647-01-0)

Benzene (71-43-2)

methanol (67-56-1)

hydroquinone (123-31-9)

sodium carbonate (497-19-8)

carbon dioxide (124-38-9)

acetone (67-64-1)

2,3-dichloropropene (78-88-6)

Allene (463-49-0)

maleic anhydride (108-31-6)

2-chloropropene (557-98-2)

Dimethyl 3-methylenecyclobutane-1,2-dicarboxylate,
3-Methylenecyclobutane-1,2-dicarboxylic acid, dimethyl ester,
dimethyl ester of 3-methylenecyclobutane-1,2-dicarboxylic acid (53684-52-9)

3-Methylenecyclobutane-1,2-dicarboxylic anhydride

propargylsuccinic anhydride

1,2,3,4,5,6,7,8-octahydronaphthalene-2,3,6,7-tetracarboxylic dianhydride

3-methyl-2-cyclobutene-1,2-dicarboxylic acid

Methyl butadienoate (18913-35-4)

p-toluenesulfonic acid (104-15-4)