formaldehyde - Sciencemadness Dot Org

MONOMELIC FORMALDEHYDE 25
gen which is maintained throughout the run. The temperature of the oil
bath is raised gradually until practically all the polymer has vaporized.
Formation of polymer on the walls of the tubes leading from the vaporizer
to the condensing tubes should be kept to a minimum by heating the
RUBBER CONNECTION 6 MM, 0.0 lb MM. O.0
PHOSPHORUS
PENTOXIDE:
TUBE
'NITROGEN
INLET-
-p
RUBBER
-CONNECTION
SAFETY
VALVt
VAPORIZING
APPARATUS
CONDENSING
APPARATUS
12 MM. 0.0
FIRST
CONDENSING
TUBC
yx i^i
DEWAft TUBE
WITH FREEZING
MIXTURE
CALCIUM CHLORIDE
TUBE
NOTE = ALL GROUND CLASS
CONNECTIONS AftE INTER­
CHANGEABLE - *HE "t
Fnr*£X 0LA5S
Fig. Sa. Apparatus for preparing liquid formaldehyde. Preparation of crude
liquid. (From Walker, J. P., Jt Am. Chem. Sac, 55, 2S25 (1935).)
'PHOSPHORUS
•PENTOXIDE
TUBE
NITROGEN
•INLET
RUBBER
CONNECTION
RUBBER CONNECTION
SAFETY
VALVE
DEWAR TUBE WITH
FREEZING MIXTURE
Fig. 8b. Apparatus for preparing liquid formaldehyde.
Walker, J. F., J. Am. Chem. Soc., 56, 2325 (1935).)
DEWAP TUBE WITH
FREEZING MIXTURE
CALCSUM CHLORIDE
TUBE
Purification step. (From
exposed portion of these tubes. This is best accomplished by winding the
tubes with resistance wire and heating with electricity. The crude liquid,
which is opalescent with precipitated polymer, is then purified by distillation
in a slow current of nitrogen (lower figure). Dry formaldehyde gas