Rapid preparation of gaseous methanediol (CH 2 (OH) 2 ).

The simplest geminal diol CH 2 (OH) 2 serves as an important precursor to form atmospheric formic acid. CH 2 (OH) 2 vapour can be generated by the evaporation of an aqueous formaldehyde solution, prepared by dissolving paraformaldehyde under reflux. Its rovibrational feature at 980-1100 cm -1 is consistent with the simulation and free of the intense interferences of H 2 O and CH 2 O.