A
1-l., three-necked flask is fitted with an
acetone-dry ice condenser, a
glass stirrer, and a
glass stopper (Note
1).
Potassium amide is prepared in
400 ml. of liquid ammonia with
8.0 g. (0.20 g.-atom) of potassium metal (Note
2). The
glass stopper is replaced with an addition funnel containing
32.1 g. (0.300 mole) (Note 3) of 2,6-lutidine dissolved in
ca. 20 ml. of anhydrous diethyl ether. The
lutidine solution is added. to the amide solution, and the funnel is rinsed with a little
ether, which is also added. The resulting orange
potassiolutidine solution is stirred for 30 minutes, then cooled in an
acetone–dry-ice bath (Note
3). As rapidly as possible,
11.8 g. (0.100 mole) of freshly distilled diethyl carbonate is added, the cooling bath is removed, and the solution changes to a green color. After 5 minutes the reaction mixture is neutralized by the addition of
10.7 g. (0.200 mole) of ammonium chloride. The green color is discharged; the final mixture is gray. The condenser is removed, and the
ammonia is allowed to evaporate (Note
4). The residue is stirred with
500 ml. of ether, filtered, and extracted with an additional
100 ml. of ether. The combined ethereal extracts are concentrated with a
rotary evaporator, and the residual oil is distilled using a modified
Claisen flask.
2,6-Lutidine (22 g.,
69%) is collected at
46–56° (10 mm.), and
10.7–13.4 g. (
59–75%) of the ester is collected at
87° (0.7 mm.) as a bright yellow liquid,
n25D 1.4995,
d204 1.0608 (Note
5).