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Org. Synth. 1955, 35, 87
DOI: 10.15227/orgsyn.035.0087
β-METHYL-δ-VALEROLACTONE
[Valeric acid, 5-hydroxy-3-methyl-, δ-lactone]
Submitted by Raymond I. Longley, Jr. and William S. Emerson1.
Checked by T. L. Cairns and W. W. Gilbert.
1. Procedure
A 1-l. three-necked flask fitted with an efficient stirrer, a thermometer, and a reflux condenser attached to a device for measuring gas evolution (Note 1) is charged with 197 g. (1.67 moles) of 3-methyl-1,5-pentanediol (p. 660) and 10 g. of copper chromite (Note 2). The mixture is heated rapidly to 200° (Note 3) with good stirring and is held at 195–205° for 1.5–3.0 hours, during which time 3.1 cu. ft. of hydrogen is evolved (Note 4). The product is distilled directly from the flask with stirring through a 2 by 120 cm. Vigreux column (Note 5). The yield of β-methyl-δ-valerolactone is 172–180 g. (90–95%), b.p. 110–111°/15 mm., n25D 1.4495.
2. Notes
1. A standard wet test meter may be used.
2. Copper chromite is prepared according to Organic Syntheses2 and washed with sodium bicarbonate solution. The glycol is slurried with sodium bicarbonate and filtered before use.
3. At this point gas evolution becomes so rapid that the temperature tends to drop slightly.
4. If gas evolution subsides more catalyst may be added.
5. The column is substituted for the reflux condenser in the same set-up. Stirring during distillation prevents serious bumping.
3. Discussion
β-Methyl-δ-valerolactone has been prepared by heating 3-methyl-1,5-pentanediol with copper chromite in the liquid phase,3 by passing the vapors of 3-methyl-1,5-pentanediol over copper on pumice,3 by heating 2-methoxy-4-methyl-3,4-dihydro-2H-pyran with water and copper chromite,3 by treating 3-methylglutaraldehyde with aqueous alkali,3 and by reducing β-methylglutaric anhydride with sodium and ethanol.4 The present method was first developed by Kyrides and Zienty.5

References and Notes
  1. Monsanto Chemical Company, Dayton 7, Ohio.
  2. Org. Syntheses Coll. Vol. 2, 142 (1943).
  3. Longley, Emerson, and Shafer, J. Am. Chem. Soc., 74, 2012 (1952); Emerson, Longley, and Shafer (to Monsanto Chemical Co.), U. S. pat. 2,680,118 [C. A., 49, 6315 (1955)].
  4. Sircar, J. Chem. Soc., 1928, 898.
  5. Kyrides and Zienty, J. Am. Chem. Soc., 68, 1385 (1946).

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

ethanol (64-17-5)

hydrogen (1333-74-0)

sodium bicarbonate (144-55-8)

copper (7440-50-8)

sodium (13966-32-0)

COPPER CHROMITE

2-methoxy-4-methyl-3,4-dihydro-2H-pyran (53608-95-0)

β-Methylglutaric anhydride (4166-53-4)

3-Methyl-1,5-pentanediol (4457-71-0)

3-methylglutaraldehyde (6280-15-5)

β-Methyl-δ-valerolactone,
Valeric acid, 5-hydroxy-3-methyl-, δ-lactone (1121-84-2)