formaldehyde - Sciencemadness Dot Org

REACTIONS WITH INORGANIC AGENTS 135
compatible with most organic solvents. It reacts with alcohols, producing
formals.
Addition of small percentages of hydrochloric acid to concentrated
formaldehyde solutions results in the precipitation of polyoxymethylenes.
When commercial formaldehyde solution containing methanol is reacted
with hydrogen chloride, monochloromethyl ether is obtained:
CH3OH + CH2Q(aq) -f HC1 ~> C1CH20CH3 -f H20
The symmetrical dibromo- and diodo-methyl ethers were prepared by
Tischenko 106 by reacting polyoxymethylene with hydrogen bromide and
iodide respectively. Symmetrical dibromomethyl ether, (CH2Br)20? is
reported to boil at 148.5~151.5°C; the diiodoether, (CH2I)20, at 218-219°C.
According to Henry 49 , the dibromoether solidifies at — 34°C and boils at
15«55°C.
Phosphorus Halides- Methylene halides are obtained when paraformaldehyde
and polyoxymethylenes are treated with phosphorus halides.
Phosphorus pentachloride and phosphorus pentabromide give methylene
chloride and bromide respectively 50 . Phosphorus tri-iodide gives methylene
iodide 16 . Phosphorus trichloride and polyoxymethylene react in
the presence of zinc chloride to give sym-dichloromethyl ether and symdichloromethylal
24 . In the absence of this catalyst methylolphosphinic
acid, HOCHa • PO3H2, is obtained on hydrolyzing the reaction product 85 ,
Phosphorus, bromine, water, and paraformaldehyde react to give a 60
per cent yield of sym-dibromomethyl ether 107 :
lOBr + 2P + 3HaO + 10CHsO(p) -+ 2H3PO* -f 5(CH2Br)20
Halogens. In direct sunlight, paraformaldehyde reacts with chlorine
in the cold, forming phosgene, carbon monoxide, and hydrogen chloride.
In the absence of sunlight, the sole products are carbon monoxide and hydrogen
chloride and gentle warming is required to initiate the reaction 13 .
2C12 + CH2OCp) -> C0C12 + 2HCI
CI* + CH20(p) -> CO -f 2HC1
Bromine reacts with aqueous formaldehyde to give carbon dioxide and
formic acid 1 . The mechanism of this reaction has been studied by Scheffer
and Tan Went 97 .
Iodine is stated not to act upon paraformaldehyde even in the presence
of sunlight at ordinary temperatures- However, on heating in a sealed
tube at 120-125°C for 7 to 8 hours, reaction takes place with formation of
methyl iodide, acetaldehyde, diiodomethyl ether (ICHaOCHJ), carbon
monoxide, and hydrogen iodide 136 . In the presence of alkali, solutions of
iodine in potassium iodide oxidize formaldehyde quantitatively to formic
acid.