The Condensation of 2-Butanone with Normal Aliphatic Aldehydes¹

Abstract

In a previous paper2 it was shown that when 2-butanone reacts with n-butyraldehyde the condensation takes place through the methylene group of the ketone. This is also the case in its reaction with formaldehyde3 and a~etaldehyde.~ On the other hand Thoms and Kahre6 have shown that the reaction between 2-butanone and isobutyraldehyde yields 2methyl-3-heptene-5-one1 (CH&CHCH=CHCOCzH6. In view of this difference in behavior it seemed desirable to investigate the reaction between 2-butanone and other aldehydes.It was found that the condensation of 2-butanone with propionaldehyde, n-valeraldehyde and n-heptaldehyde takes place through the methylene group of the ketone. From these results and those previously obtained in the cases of formaldehyde, acetaldehyde and n-butyraldehyde, it appears that the normal aliphatic aldehydes in general react in this manner with 2-butanone. As Thoms and K a h e have shown that the branched-chain isobutyraldehyde brings about a different reaction, an investigation of the reaction between 2-butanone and other branched-chain aldehydes is now under way.The constitution of the condensation product was determined in each case by dehydration of the aldol to the unsaturated ketone and reduction of this to the corresponding saturated alcohol. In the case of propionaldehyde this saturated alcohol was iound to be identical with the 3-methyl-2hexanol described by Bjelouss6 and on oxidation yielded a ketone identical with the 3-methyl-2-hexabone obtained by the hydrolysis of ethyl methyln-propyl-acetoacetate. The striictures of the alcohols obtained from nvaleraldehyde and n-heptaldehyde were determined by oxidation and identification of the resulting acids as n-valeric and enanthic acids, respectively. The condensation, dehydration, reduction to the saturated alcohol, and oxidation of this to the saturated ketone were carried out as described in the previous paper.2In Table I are listed the new compounds prepared. Identification of the Acids Obtained by Oxidizing 3-Methyl-2-octanol and 3-Methyl-2-decanol.-The alcohols were oxidized by boiling with a (1) This paper is based in part upon lheses presented by Hazel C. Murray and Maynard M.Baldwin in partial fulfilment of the requirements for the Master's degree.

New Oxidation of β-Hydroxy α-Methyl Ketones: A Convenient Synthesis of 3-Methylalkane-2,4-diones

“…Bp 70-76 °C/2 Torr (lit. 11 98 °C/16 Torr). 1 H NMR (syn/anti mixture) 0.93 (t, J ) 6.9 Hz), 1.16 (t, J ) 7.9 Hz), 1.27-1.52 (m), 2.22 (s), 2.23 (s), 2.48-2.66 (m), 2.80 (br s), 3.70 (br s), 3.94 (br s); 13 C NMR (syn/anti mixture) 9.62 (CH 3 ), 13.66 (CH 3 ), 13.88 (CH 3 ), 22.34 (CH 2 ), 22.51 (CH 2 ), 22.52 (CH 2 ), 27.54 (CH 2 ), 28.09 (CH 2 ), 29.02 (CH 3 ), 29.66 (CH 3 ), 33.69 (CH 2 ), 34.12 (CH 2 ), 50.93 (CH), 52.16 (CH), 70.92 (CH), 73.29 (CH), 213.69 (C), 213.87 (C); IR (neat) 3458, 2958, 2872, 1708, 1460 cm -1 ; EI-MS (m/e, relative intensity) 157 (M + + 1, 1), 140 (11), 125 (6), 111 (6), 101 (49), 83 (8), 72 (91), 57 (38), 43 (100).…”

“…Bp 98-103 °C/3 Torr (lit. 11 147 °C/23 Torr). 1 H NMR (syn/anti mixture) 0.89 (t, J ) 6.8 Hz), 1.06 (t, J ) 7.4 Hz), 1.14 (t, J ) 7.3 Hz),…”