Alcohols Chemistry Notes: Properties, Reactions, and Uses PDF

Alcohols (R-OH) In an alcohol, a hydroxyl group (-OH) replaces a hydrogen atom in an alkane.The ending (-e) is changed to (-ol). CH2=CH-CH2-CH2-OH 3-Buten-1-ol  Naming Alcohols IUPAC name: We replace the -e in alkane name with...

Alcohols (R-OH) In an alcohol, a hydroxyl group (-OH) replaces a hydrogen atom in an alkane.The ending (-e) is changed to (-ol). CH2=CH-CH2-CH2-OH 3-Buten-1-ol  Naming Alcohols IUPAC name: We replace the -e in alkane name with -ol. Common name: As simple alcohols using the name of the alkyl group followed by “alcohol”. CH4 methane CH3─OH methanol (methyl alcohol) CH3─CH3 ethane CH3─CH2─OH ethanol (ethyl alcohol)  Naming Alcohols 3 2 1 CH3─CH2─CH2─OH 1-propanol OH │ CH3─CH─CH3 2-propanol (isopropanol) 3 2 1 CH3 OH │ │ CH3─CH─CH2─CH2─CH─CH3 5-methyl-2-hexanol 6 5 4 3 2 1  CH3 │ CH3-C-OH │ CH3 2-methyl-2-propanol Tert-butanol  Physical Properties of Alcohols 1. Alcohols are polar molecules (because of O-H and C-O). C-O: (3.5 – 2.5 = 1.0) O-H : (3.5 – 2.1 = 1.4) 2. Hydrogen bonding between alcohol molecules. 3. Have higher boiling points than Alkanes, Alkenes, and Alkynes. 4- More soluble in water (Molecular weight ↑ : solubility ↓). 5- The carbon side of alcohols are non polar polar while –OH side is polar. nonpolar OH Some important alcohols and it is uses; 1-Methanol (CH3OH) The simplest alcohol is found in many solvents and paint removers. It is sometimes called wood alcohol because methanol is produced when wood is heated to high temperatures in the absence of air. Methanol is prepared commercially by reacting carbon monoxide with hydrogen gas at high temperatures and pressures. 200-300C / 200Atm CO + 2H2 CH3-OH ZnO/Cr2O3 Catalyst Methanol is a poisonous liquid, if ingested, methanol is oxidized to formaldehyde, which cause headaches, blindness, and death, because react rapidly with proteins of cells and cause denaturizing. O Liver enzyme ║ CH3OH H-C-H Methanol Formaldehyde 2-Ethanol CH3CH2OH In the hospital the word alcohol means ethanol, one important property of ethanol is ability to denature proteins by forming hydrogen bonds. Because of this property, ethanol (70%) is widely used as an antiseptic.  Ethanol is widely found in most homes as a solvent for pharmaceuticals (Tinctures iodine in alcohol), colognes, perfumes, mouth washes, and hair sprays. ‘Gasohol’ is a mixture of ethanol and gasoline used as a fuel.  Ethanol, is used as a beverage, most of alcoholic beverages, are made by fermentation of starch or sugars. Hydrolysis Zymase Complex sugars C6H12O6 2CH3CH2OH +2CO2 Ethanol is toxic, extensive ingestion over along period of time leads to; 1- Deterioration of the liver, a condition is known cirrhosis. 2- Loss of memory. 3- Strong physiological addiction. 3- 2-propanol (isopropanol) CH3-CHOH-CH3 Used as an astringent antiseptic, because it evaporates rapidly and cools the skin, reducing the size of blood vessels near the surface Used to clean of the skin, before an injection or taking a blood sample. It is also used to sterilize equipment because it destroys bacteria by coagulating protein. 4-Ethelene glycol (ethanediol) (dihydroxy alcohol) HO-CH2-CH2-OH Is used as antifreeze in heating and cooling systems, it is also a solvent for paints, inks, and plastics, and is used in the preparation of fibers such as Dacron.  If ingested, it is extremely toxic. In the body, it is oxidized to oxalic acid, which forms insoluble salts in the kidneys that cause renal damage, convulsions, and death. Because it sweet taste is attractive to pets and children, ethylene glycol solutions must be carefully stored. [O] HO-CH2-CH2-OH HOOC-COOH Fomepizole [4-methylpyrazole] Fomepizole, also known as 4-methylpyrazole Is a medication used to treat methanol and ethylene glycol poisoning. It may be used alone or together with hemodialysis. It is given by injection into a vein. Common side effects include headache, nausea, sleepiness, and unsteadiness. Fomepizole works by blocking the enzyme that converts methanol and formaldehyde to their toxic breakdown products. 5-(Glycerol, Glycerin, 1, 2, 3-propanetriol) [tri hydroxyl alcohol] Is a constituent of fats, it is produced from hydrolysis of all fats. Lipase TG + 3H2O Glycerol + fatty acids It is used in production of the nitroglycerin (Glyceryl tri nitrate). H2SO4 Glycerol + 3HNO3 Nitroglycerin + 3H2O Nitroglycerin It is used to relive angina pectoris (pain in the chest), it has an effect of relaxing cardiac muscle and smooth muscle in the smaller vessel it was provide in small tablet of (0.3-0.6 mg) under the tongue, or applied to the skin as cream. Reactions of alcohols; 1-Dehydration H2SO4/180 CH3-CH2-OH CH2=CH2 +H2O 2-Ester formation ACID R-OH +R`-COOH R`COOR + H2O 3-Oxidation Primary alcohols are oxidized to aldehydes; [O] [O] RCH2-OH RCHO RCOOH Secondary alcohols are oxidized to ketones; [O] RCH-OH RCOR` │ R` Oxidation of alcohols in living systems The oxidation of alcohols is an important reaction in living systems, enzymes called dehydrogenases catalyze these reactions. Example is the oxidation of malate to oxalo acetate Malate dehydogenase Malate +NAD Oxalo acetate +NADH +H