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Org. Synth. 1925, 5, 37
DOI: 10.15227/orgsyn.005.0037
CYCLOPENTANONE
Submitted by J. F. Thorpe and G. A. R. Kon.
Checked by Roger Adams and C. R. Noller.
1. Procedure
In a 1-l. distilling flask (Note 1), fitted with a thermometer reaching within 5 mm. of the bottom, is placed an intimate mixture of 200 g. (1.34 moles) of powdered adipic acid (Note 2) and 10 g. of finely ground crystallized barium hydroxide. The mixture is gradually heated in a fusible alloy bath (Note 3) to 285–295° (Note 4) during about one and one-half hours, and maintained at that temperature until only a small amount of dry residue remains in the flask. This requires about two hours longer. The cyclopentanone distils slowly, accompanied by small quantities of adipic acid.
The ketone is separated from the water in the distillate, either by salting out with calcium chloride or by extracting with a little ether (Note 5). It is washed with a little aqueous alkali and then with water, dried over calcium chloride, and distilled through a good fractionating column (Note 6). The fraction boiling at 128–131° is cyclopentanone. The yield is 86–92 g. (75–80 per cent of the theoretical amount).
2. Notes
1. If larger runs are made, a three-necked flask provided with a mechanical stirrer should be used for the reaction.
2. The unrecrystallized adipic acid, prepared as described on p. 18, may be used.
3. An air bath may be used, but the metal bath insures better temperature control.
4. If the temperature goes above 300°, the adipic acid begins to distil quite rapidly. It is best to hold the temperature as near 290° as is possible.
5. It is reported that potassium carbonate is more satisfactory than calcium chloride for salting out the product from the distillate; traces of adipic acid are removed, and the loss which attends washing with alkali is avoided.1
6. Cyclopentanone is quite volatile with ether vapor, and careful fractionation is necessary when ether is used for the separation of the ketone from the water.
3. Discussion
Cyclopentanone can be prepared from adipic acid by distilling the calcium salt,2 heating alone3 or with acetic anhydride,4 or in the presence of various catalysts such as barium hydroxide,5 barium oxide,6 thorium oxide,7 manganous oxide,7 uranium nitrate,5 ferrous sulfate5 and others.8 A yield of 94 per cent has been reported using barium carbonate as a catalyst.9

References and Notes
  1. Wagner, J. Chem. Education 10, 115 (1933).
  2. Hentzchel and Wislicenus, Ann. 275, 312 (1893); Holleman, Van Der Laan, and Slijer, Rec. trav. chim. 24, 23 (1905).
  3. Aschan, Ber. 45, 1605 (1912).
  4. Blanc, Compt. rend. 144, 1357 (1907); Godchot and Taboury, Ann. chim. phys. (8) 26, 43 (1912).
  5. Friedr. Bayer and Co., Ger. pat. 256,622 [Frdl. 11, 49 (1912–14)]; Harries and Wagner, Ann. 410, 36 (1915).
  6. Vavon and Apchie, Bull. soc. chim. (4) 43, 667 (1928).
  7. Sabatier and Maihle, Compt. rend. 158, 987 (1914).
  8. Chavanne and Simon, ibid. 168, 1326 (1919).
  9. Boedtker, J. pharm. Chim. 15, 225 (1932).

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

calcium salt

calcium chloride (10043-52-4)

potassium carbonate (584-08-7)

ether (60-29-7)

acetic anhydride (108-24-7)

Adipic acid (124-04-9)

barium oxide

ferrous sulfate (13463-43-9)

thorium oxide

Cyclopentanone (120-92-3)

barium hydroxide (17194-00-2)

uranium nitrate

barium carbonate (513-77-9)