2. What are Aldehydes ??
Aldehydes are the first oxidation products of primary alcohols. The
functional group in aldehydes is formyl or aldehyde group { -CHO }.
The aldehyde group is always present at the terminal carbon of the
atom.
3. What is Formaldehyde ?
Formaldehyde is the simplest aldehyde made
with carbon , hydrogen and oxygen with
formula CH2O.
Other names formalin, methanol , formol.
Formaldehyde is a reactive molecule and
first in the series of aliphatic aldehydes.
4. History and Occurrence of Formaldehyde
Formaldehyde was reported in 1859 by the Russian chemist
Alexandra Mikhailovich Butlerov and conclusively identified in 1869
by German chemist Hofmann .
Formaldehyde has become a major industrial product. Hoffmann
passed a mixture of Methanol and air over a heated platinum spiral
and then identified formaldehyde as the product .
Formaldehyde can be in nature , as one of the component of the
atmosphere and in the instellar space. The formaldehyde in the
atmosphere is formed by the reaction of oxgen and methane.
Human produce about 1.5 ounces (42.52 grams) of formaldehyde a
day as a normal part of our metabolism. Inhaled Formaldehyde is
rapidly metabolized and ultimatedly converted to carbon dioxide and
exhaled.It doesn’t accumulate in our body.
5. PREPARATION OF FORMALDEHYDE
Formaldehyde is produced industrially by the catalytic oxidation of
methanol. The most common catalyst are silver metal or a mixture
of iron and molybdenum / vanadium oxides. In the commonly used
formox process , methanol and oxygen react at 250 - 4000C in the
presence of iron oxide in combination with molybdenum or
vanadium to produce formaldehyde according to chemical equation :
2CH3OH + O2 → 2CH2O + 2H2O
The silver catalyst operates at a high temperature, about 6500C.Two
chemical reactions on it simultaneously produce formaldehyde which
is shown above and the dehydrogenation reaction :
CH3OH → CH2O + H2O
6. Physical and Chemical Properties
Appearance Flammable, colorless gas at room
temperature
Odor Pungent, suffocating
Molecular weight 30.031 g/mol
Molecular formula CH2O
Density 815 kg/m³
Melting point 181 k
Soluble in Water , acetone
Boiling point 254 k
8. Uses of Formaldehyde
1] Preservative in medical laboratories.
2] Embalming agent in mortuaries
3] Manufacture of urea , phenol, and melamine resins and for a variety of
special industrial chemicals.
4] Adhesives in the manufacture of particle board , fiberboard, and
plywood , and for molding, paper treating and coating , textile treating ,
surface coating and foams for insulation .
5] Formaldehyde is also used as a treatment for athlete's foot, in cough
drops , skin disinfectants, mouthwashes , spermatic creams, as a
disinfectants for vasectomies and root canals.
