Org. Synth. 1958, 38, 22
DOI: 10.15227/orgsyn.038.0022
[Malonic acid, methylene-, diethyl ester]
Submitted by Wayne Feely and V. Boekelheide1.
Checked by Max Tishler, Barbara P. Birt, and Arthur A. Patchett.
1. Procedure
A solution of 108 g. (0.5 mole) of diethyl ethoxymethylenemalonate (Note 1) in 100 ml. of commercial absolute alcohol is placed in an apparatus for high-pressure hydrogenation together with 10 g. of Raney nickel catalyst (Note 2). The pressure in the bomb is raised to 1000–1500 lb. with hydrogen, and the temperature is adjusted to 45° (Note 3). The bomb is shaken, and the reaction is allowed to proceed for 12–20 hours, during which time 0.5 mole of hydrogen is absorbed.
The apparatus is allowed to cool to room temperature, the pressure is released, and the catalyst is removed by filtration. Concentration of the filtrate under reduced pressure at room temperature yields a colorless oil (Note 4).
The residual oil is transferred to a distillation flask (Note 5), and the flask is carefully warmed with a small flame (Note 6). After a fore-run of ethanol is collected, the variable transformer controlling the heating tape is set at a voltage to give an internal temperature in the distilling head of 80–100° before distillation. The flask is then heated to effect slow distillation at atmospheric pressure. About 10–13 g. of fore-run is collected before the temperature of the distillate vapor reaches 200°. The main fraction (68–71 g., 79–82%) is collected between 200° and 216° as a colorless oil. For most purposes, the fore-run is sufficiently pure that it can be combined with the main fraction to give an over-all yield of 78–81 g. (91–94%) (Note 7). Diethyl methylenemalonate polymerizes on standing to a white solid, from which the monomer can be recovered by slow distillation. The diethyl methylenemalonate should be distilled just prior to use (Note 8).
2. Notes
1. Diethyl ethoxymethylenemalonate can be prepared by the method of Parham and Reed.2 The submitters used diethyl ethoxymethylenemalonate obtained commercially from Kay-Fries Chemicals Inc., 180 Madison Avenue, New York 16, New York.
2. Raney nickel catalyst can be prepared by the method of Mozingo.3 The submitters used Raney nickel catalyst obtained commercially from the Gilman Paint and Varnish Company, Chattanooga, Tennessee.
3. At higher temperatures (about 70°) the diethyl ethoxymethylmalonate formed tends to eliminate ethanol, forming diethyl methylenemalonate which is hydrogenated to diethyl methylmalonate.
4. This oil, n20D 1.4254, is presumably diethyl ethoxymethylmalonate, as evidenced by its infrared and ultraviolet absorption spectra. It is relatively stable and can be stored at room temperature without change. If the concentration of the filtrate under vacuum is carried out by heating on a steam bath instead of by keeping it at room temperature, the diethyl ethoxymethylmalonate undergoes elimination of ethanol to some extent, giving diethyl methylenemalonate directly. The yield of diethyl methylenemalonate obtained eventually is not altered by this procedure.
5. The distillation apparatus is shown in Fig. 7. The upper part of the flask and the short column are wrapped in electrical heater tape, which is operated during distillation of the product.
Fig. 7.
Fig. 7.
6. The elimination of ethanol is slightly exothermic. It is advisable to heat the flask cautiously with a small flame until the reaction starts and then to remove the flame until the reaction subsides.
7. The fore-run has a refractive index (usually about n22D 1.4154) lower than that of the main fraction (about n22D 1.4250). The combined fractions show refractive indices in the range n22D 1.4210–1.4259.
8. When the solid polymer from the above preparation was slowly distilled to recover diethyl methylenemalonate, there was obtained 57 g. of colorless oil, b.p. 210–216° /730 mm., n20D 1.4220.
3. Discussion
Diethyl methylenemalonate was prepared first by Perkin4 from formaldehyde and malonic ester, and more recently a study has been made of the effect of various catalysts on this system.5 An alternative procedure involving the reaction of methylene chloride or iodide with sodiomalonic ester has been developed by Tanatar.6 Diethyl methylenemalonate also is formed when hexaethyl pentane-1,1,3,3,5,5-hexacarboxylate is treated with methylene iodide and sodium ethoxide,7 or when methyl chloromethyl ether is caused to react with sodiomalonic ester.8 Diethyl methylenemalonate has been obtained from paraformaldehyde9 and vapor and liquid reactions of formaldehyde with diethyl malonate in the presence of various catalysts.10

References and Notes
  1. University of Rochester, Rochester, New York.
  2. Org. Syntheses Coll. Vol. 3, 395 (1955).
  3. Org. Syntheses Coll. Vol. 3, 181 (1955).
  4. Perkin, Ber., 19, 1053 (1886).
  5. Takagi and Asahara, J. Chem. Soc. Japan, Ind. Chem. Sect., 56, 901 (1953) [C. A., 49, 6836 (1955)].
  6. Tanatar, Ann., 273, 48 (1893).
  7. Bottomley and Perkin, J. Chem. Soc., 77, 294 (1900).
  8. Vasiliu and Barbulescu, Analele univ. C. I. Parhon Bucuresti, Ser. stiint. nat., No. 16, 99 (1957) [C. A., 53, 1238 (1959)].
  9. Sakurai, Midorikawa, and Aoyama, J. Sci. Research Inst. (Tokyo), 52, 112 (1958).
  10. Bachman and Tanner, J. Org. Chem., 4, 493 (1939).

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

methylene chloride or iodide

ethanol (64-17-5)

hydrogen (1333-74-0)

formaldehyde (50-00-0)

Raney nickel (7440-02-0)

sodium ethoxide (141-52-6)

diethyl malonate (105-53-3)

Methylene iodide (75-11-6)

methyl chloromethyl ether (107-30-2)

diethyl methylmalonate (609-08-5)

diethyl ethoxymethylenemalonate (87-13-8)

Diethyl methylenemalonate,
Malonic acid, methylene-, diethyl ester (3377-20-6)

diethyl ethoxymethylmalonate

hexaethyl pentane-1,1,3,3,5,5-hexacarboxylate

paraformaldehyde (30525-89-4)