To 1 gramm-equivalent (g-eq) of dimethylaminoethanethiol in 150 ml of ether,
a suspension of g-eq of 50% sodium hydride in 50-ml of anhydrous ether was
added. After boiling for 1 hour, the reaction mixture was cooled to 0°C,
whereupon g-eq of 9,9-dimethylacridan-10-carboxylic acid chloride (prepared
from 9,9-dimethylacridan and phosghene - cf. Swiss Specification No.
426,821) were added and the mixture was heated for a further 6 hours to
boiling temperature. After cooling to ambient temperature, the precipitated
sodium chloride was filtered in a Buchner funnel fitted with a filter cell. The
corresponding 9,9-dimethylacridan-10-carboxylic aciddimethylaminoethanethiol
ester was immediately precipitated out of filtrate as
base, which melted at 110.5°-111°C. Ethanesulphonic acid salt melted at
147°-150°C.
