- Fermentation is usually carried out by adding yeast to a mixture of sugars and
water.
- Yeast contains enzymes that promote a long series of reactions that ultimately
convert a simple sugar (C 6 H 12 O 6 ) to ethanol and carbon dioxide.
C 6 H 12 O 6 yeast 2 CH 3 CH 2 OH + 2 CO 2
2) Enzymes of the yeast are deactivated at higher ethanol concentrations ⇒
fermentation alone does not produce beverages with an ethanol content greater
than 12-15%.
3) To produce beverages of higher alcohol content (brandy, whiskey, and vodka)
the aqueous solution must be distilled.
4) The “proof” of an alcoholic beverage is simply twice the percentage of ethanol
(by volume) ⇒ 100% proof whiskey is 50% ethanol.
5) The flavors of the various distilled liquors result from other organic compounds
that distill with the alcohol and water.
- An azeotrope of 95% ethanol and 5% water boils at a lower temperature (78.15°C)
than either pure ethanol (bp 78.3°C) or pure water (bp 100°C).
- Azeotrope can also have boiling points that are higher than that of either of the
pure components.
- Benzene forms an azeotrope with ethanol and water that is 7.5% water which
boils at 64.9°C ⇒ allows removal of the water from 95% ethanol.
- Pure ethanol is called absolute alcohol.
- Most ethanol for industrial purposes is produced by the acid-catalyzed hydration
of ethene.
CH 2 =CH 2 + H 2 O Acid CH 3 CH 2 OH
- Ethanol is a hypnotic (sleep producer).
- Ethanol depresses activity in the upper brain even though it gives the illusion of
being a stimulant.
