Ketene Di 2-methoxyethyl acetal

KETENE DI(2-METHOXYETHYL) ACETAL [Ketene bis(2-methoxyethyl) acetal] 

Submitted by William C Kdr U.a and John E. Hyre 1 Checked by Earl M. Lest and Peter Yates 

The ethereal filtrate and washings are distilled under reduced pressure (Note 9) with the use of a 6-in. Vigreux column, and pure ketene di(2-methoxyethyl) acetal (Note 10) is obtained b.p. 81-84° (2.0 mm.), m25d 1.4411, yield 98-132 g. (56-75%). The infrared spectrum of the product shows a very strong C=C absorption band at 1640 cm.-1. 

A dry ice type of condenser has been found to be the most satisfactory because of the low boiling point (32°) of the vinylidene chloride. An efficient water-cooled condenser is satisfactory, however. 

An addition funnel is fitted in this port after the sodium addition is complete. 

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Sodium 2-methoxyethoxide, reaction -with vinylidene chloride to yield ketene di(2-methoxyethyl) acetal,... 

Ketene di(2-methoxyethyl) acetal has been obtained by the present method with the use of diethylene glycol dimethyl ether as solvent.3 Other methods for the preparation of ketene acetals include the dehydrohalogenation of a halo acetal with potassium t-butoxide 4 and the reaction of an a-bromo orthoester with metallic sodium.6... 

Small pieces of Na added under Ng at 130-150 during 2 hrs. to a stirred mixture of 2-methoxyethanol and xylene, heating discontinued after all the Na has reacted, vinylidene chloride added dropwise with stirring at 140-175° during 20 min., and stirring continued 10 min. ketene di-(2-methoxyethyl) acetal. Y 56-75%. W. G. Kuryla and J. E. Hyre, Org. Synth. 47, 78 (1967). 

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