Alcohols, Phenols and Ethers 3 Flashcards
what is the common name of methanol? what is obsolete method of preparation
Methanol, CH3OH, also known as ‘wood spirit’, was produced by
destructive distillation of wood.
Methanol is a colourless liquid and boils at 337 K.
commercial method of preparation of methanol
Today, most of the methanol is
produced by catalytic hydrogenation of carbon monoxide at high
pressure and temperature and in the presence of ZnO – Cr2O3
catalyst.
CO + 2H2 —-ZnO-Cr2O3/200-300atm/573-673K–> CH3OH
if your forget the atmospheric conditions just write high temp, pressure in exam
describe the physical effects of methanol
It is highly
poisonous in nature. Ingestion of even small quantities of methanol
can cause blindness and large quantities causes even death. Methanol
is used as a solvent in paints, varnishes and chiefly for making
formaldehyde.
why is methanol so harmful
Biological oxidation of methanol and ethanol in the body produces the corresponding
aldehyde followed by the acid. At times the alcoholics, by mistake, drink ethanol,
mixed with methanol also called denatured alcohol. In the body, methanol is oxidised
first to methanal and then to methanoic acid, which may cause blindness and
death.
how to treat methanol poisoned patients
A methanol poisoned patient is treated by giving intravenous infusions of
diluted ethanol. The enzyme responsible for oxidation of aldehyde (HCHO) to acid
is swamped allowing time for kidneys to excrete methanol.
what is the oldest method of preparation of ethanol
Ethanol, C2H5OH, is obtained commercially by fermentation, the
oldest method is from sugars. The sugar in molasses, sugarcane
or fruits such as grapes is converted to glucose and fructose, (both
of which have the formula C6H12O6
), in the presence of an enzyme,
invertase. Glucose and fructose undergo fermentation in the
presence of another enzyme, zymase, which is found in yeast.
C12H22O11 —-invertase—> c2h12o6 glucose + c6h12o6 fructose
Glucose —–zymase—-> 2ethanol + 2co2
must balance eqn
explain how fermentation is done
In wine making, grapes are the source of sugars and yeast. As
grapes ripen, the quantity of sugar increases and yeast grows on the
outer skin. When grapes are crushed, sugar and the enzyme come in
contact and fermentation starts. Fermentation takes place in
anaerobic conditions i.e. in absence of air. Carbon dioxide is released
during fermentation.
The action of zymase is inhibited once the percentage of alcohol
formed exceeds 14 percent.
why is fermentation done in anaerobic conditions
If air gets into fermentation mixture, the
oxygen of air oxidises ethanol to ethanoic acid which in turn destroys
the taste of alcoholic drinks.
uses of ehtanol
Ethanol is a colourless liquid with boiling point 351 K. It is used
as a solvent in paint industry and in the preparation of a number of
carbon compounds.
what is denaturation of alcohol
The commercial alcohol is made unfit for drinking
by mixing in it some copper sulphate (to give it a colour) and pyridine
(a foul smelling liquid). It is known as denaturation of alcohol.
