Ethanol or ethyl alcohol is a colourless, volatile liquid, with characteristic odour. It is used as solvent for many other substances and has a variety of uses. It is present in many alcoholic beverages in varying amounts. It intoxicates and the level of its intoxication varies from individuals. It is also regarded to as psychoactive recreation drug and it is commonly abused among youth.
Ethanol is used for different purposes ranging from its industrial use in production of drugs, cleansing liquids, sterilizers, body lotion cream, alcoholic beverage drinks, solvent for paints and dyes, its use in thermometer, as a preservative for food and the likes. In Nigeria, ethanol is also used at celebrations. For instance, the traditional worshipers use this liquid in appealing to gods, it is also taken as one of the materials used in paying brides price. The artisans use this liquid to pray for their apprentice during freedom ceremony at the end of his or her apprenticeship. In Yoruba tribe, it is called “the drink for the elders”. In cold countries, this drink is used as anti-freeze agent in car radiators, and it is taking as drinks to warm body during cold. Ethanol is used as fuels in modern jet engines, either itself only, or mixed with other fuel. It is used as sedative, Ethanol is administered as an antidote to ethylene glycol poisoning. Ethanol is a very good antiseptic liquid.
Despite having psychotropic and cancerous effects, alcohol is widely available and permitted for sale in the majority of nations of the world. The sale, export/import, taxation, production, use, and possession of alcoholic beverages are all subject to legal restrictions. The most typical law forbids children from buying and using the liquid. Ethanol is source of income for some countries of the world with importation and exportation.
Chemistry of Ethanol
Ethanol has 2 carbon atoms, 6 hydrogen atoms and 1 oxygen atom. Its molecular formula is C2H5OH or C2H6O. It has single bond all through its structure with the presence of ordinary covalent bond and hydrogen bond on the O-H linkage. It has a boiling point of 78 0c, relatively higher, compare to its molecular size. This is due to the presence of hydrogen bonding in its structure.
How ethanol Intoxicates?
A healthy liver can process 8 grams of pure ethanol of alcohol per hour on average. A slower rate of metabolism is likely to be the outcome of a “abnormal” liver with disorders such hepatitis, cirrhosis, gall bladder disease, and cancer.
Alcohol dehydrogenase (ADH), which is present in numerous tissues, including the gastric mucosa, converts ethanol to acetaldehyde. Acetaldehyde dehydrogenase (ALDH), which is mostly present in liver mitochondria, converts acetaldehyde to acetate. The enzyme acetyl-CoA synthetase is utilized by muscle cells to convert acetate into acetyl-CoA, which is then utilized in the citric acid cycle.
People start to feel sleepy or lose consciousness as their alcohol intake rises because the respiratory system becomes depressed with a very large intake, and the person will stop breathing. Patients who are comatose may aspirate their vomit, which can lead to vomitus in the lungs and, if they survive, “drowning” and eventually pneumonia. Accidental damage is more likely to happen when there is CNS depression, poor motor coordination, and poor judgment. According to estimates, accidents account for around one-third of alcohol-related fatalities, and intentional injury accounts for 14% of all fatalities.
Alcohol produces major metabolic abnormalities in addition to respiratory failure and accidents brought on by its effects on the central nervous system. Alcohol inhibits gluconeogenesis, leading to hypoglycemia, which can lead to lactic acidosis, ketoacidosis, and acute renal injury, especially in youngsters. Respiratory failure exacerbates metabolic acidosis. Hypothermia may also be observed in patients.
Preparation of Ethanol
Ethanol is prepared industrially in two ways.
- From petroleum product i.e by hydration of alkene
Fermentation is the process of breaking down large organic compounds e.g sugar into simple ones by the action of organic catalyst called enzyme.
1. From starch
Carbon (IV) oxide escapes as gas. The resulting mixture is a dilute solution of ethanol and it is distilled by fractional distillation to obtain about 95% ethanol at 78oc.
Rectified or surgical spirit contains 95% ethanol and it is the purest form to which ethanol is sold.
Methylated spirit contains about 85% ethanol with pyridine and colouring matter added to discourage its being drunk. It is poisonous.
2. From palm wine
Local gin is manufactured by fermentation of palm wine. Fresh palm wine contains sugar and yeast. After standing for 3 or 4 days, the yeast fermented the sugar to ethanol.
3. Cane sugar as a source of ethanol
After crystallization of cane sugar, a syrupy liquid called molasses is left which contains 50% of sugar mainly sucrose. This is diluted until the concentrated of sugar is about 15% and yeast is then added and left to ferment for 3 to 4 days. One of the enzymes from the yeast called invertase converts sucrose into a mixture of two isomeric sugars i. e glucose and fructose.
Both the glucose and fructose can be fermented to alcohol by the enzyme called zymase.
- Wood as a source of ethanol
In countries with plenty of wood, saw dust is heated with mineral acids under pressure. This converts the cellulose in wood to glucose. After neutralizing the excess acid, the product is fermented by yeast to ethanol.
Fermentation produces many alcoholic beverages such as:
- Beer contains about 2.5 – 5% of ethanol
- Brandy: This is the name commonly given to the spirit distilled from juice of grapes such as apples, cherries, peaches. Brandy contains 50 – 60% ethanol
- Whisky: This is produced from fermentation of malted barley, maize, potato and other cereals. It contains about 50 – 60% ethanol
- Gin: It is prepared from barley, cereals, palm wine. It contains about 40% ethanol
Ethanol from petroleum product
The greater part of the world’s industrial ethanol is manufactured by this process.
Ethene is obtained from cracking
The ethene is hydrolyzed by boiling with water to form ethanol.