Appendix Nine
Although anhydrous oxalic acid is used less frequently in (Reference 407) it is suggested in (Reference 409). The relatively low yield obtained in the example below is of pure fractionated product. Adams in his later work used relatively impure material because he found that losses during fractionation were considerable. The following procedure is from (Reference 407).
Example One: About 90 grams of the crude carbinol obtained in reaction (e) are mixed with 45 grams anhydrous oxalic acid in a flask and heated in an oil bath at 130-140 deg C. for 1.7 hours. After cooling to room temperature the product is extracted into benzene as follows. 100 ml. benzene is added and stirred, then after settling poured off and saved. Repeat with another 100 ml. benzene. The solid residue (mostly oxalic acid) is then dissolved in 250 ml. water and the solution extracted with two more 100 ml. portions of benzene after which the aqueous solution can be discarded. All the benzene extracts are combined and washed with portions of water until testing with an indicator paper shows them to be neutral. Then dry the benzene solution with anhydrous magnesium sulfate, filter, and distil off the solvent benzene at ordinary pressure. It is probably sufficient to use the crude residue without distillation for the following reduction. It can be distilled to give the product (for THC-V it is b.p. 113-153 deg. C./ 0.5-0.65mm. - mostly 123-133 deg C. Re distillation gives the pure product b.p. 114-119 deg. C./ 0.25 mm.).
Appendix Eight
Appendix Ten