Solution- Pharmacy's video: 29 Alcohols Method of Preparation Physical Properties Organic Chemistry 01 B Pharm 2nd Sem

Download the "Solution Pharmacy" Mobile App to Get All Uploaded Notes, Model Question Papers, Answer Papers, Online Tests and other GPAT Materials - https://play.google.com/store/apps/details?id=co.bolton.nqilv Alcohols are a class of organic compounds characterized by the presence of one or more hydroxyl (-OH) groups attached to a carbon atom. When one or more hydroxyl groups (-OH) are directly attached to the hydrocarbon chain then the compound formed is known as alcohol. Some examples of alcohol are phenol, methanol and ethanol. Properties of Alcohols Physical Properties of Alcohols 1. The physical properties of alcohol can be explained by the following points – 2. Alcohols are colourless. 3. They generally give a sweet smell except for glycerol and a few lower alcohols. 4. They are flammable and produce a blue flame. 5. They don’t produce any smoke while burning. 6. They are generally liquid at room temperature. Although glycerol is a viscous liquid. Boiling Point of Alcohol - They generally have higher boiling points if we compare them with other hydrocarbons. For example, ethanol shows a boiling point of 78.29℃ while hexane shows a boiling point of 69℃. This is because of the presence of intermolecular hydrogen bonding between hydroxyl groups of alcohols. The boiling point of alcohol increases with an increasing number of carbon atoms in organic alcoholic compounds. Preparation of Alcohols 1) Hydrolysis of Alkyl Halides This is a nucleophilic substitution reaction. The method is not a very effective one. This is because it has as olefins as by-products. 2) Oxymercuration and Demercuration of Alkanes Alkenes react with mercuric acetate in presence of H2O and tetrahydrofuran to give alkyl mercury compounds. This is one of the most common types of methods to prepare alcohols. 3) Preparation of Alcohols from Grignard Reagent We can obtain the three types of monohydric alcohols (primary, secondary and tertiary alcohols) by using Grignard reagents and carbonyl compounds. The addition of RMgX on carbonyl compounds, along with hydrolysis gives us alcohols. The Grignard reagent is basically an organometallic compound. When we allow a solution of an alkyl halide in dry ethyl ether, (C2H5)O to stand overturnings of metallic magnesium, we witness a vigorous reaction. We can see that the solution turns cloud and begins to boil. The magnesium metal gradually disappears. The resulting solution is the Grignard reagent. Grignard Synthesis of Alcohols What class of alcohol we obtain from a Grignard synthesis depends upon the type of carbonyl compound that we use in the reaction: formaldehyde, HCHO, yields primary alcohols. On the other hand, aldehydes yield secondary alcohols while ketones, R2CO, yield tertiary alcohols. 4) Reduction of Carbonyl Compounds We can also get alcohols by the reduction of aldehydes and ketones. We can reduce aldehydes to primary alcohols and ketones to secondary alcohols. This process can take place by the catalytic hydrogenation or by the use of chemical reducing agents like lithium aluminium hydride, LiAlH4. Such reduction techniques find an important place in the preparation of certain alcohols that are less available than the corresponding carbonyl compounds. What we must note here is that Sodium borohydride, NaBH4, does not reduce carbon-carbon double bonds, not even those conjugated with carbonyl groups. 5) Reduction of Acids to Alcohols Lithium aluminium hydride, LiAlH4, is one of the few reagents that can reduce an acid to an alcohol. By Fermentation Fermentation is the slow decomposition of complex organic compounds into simpler organic compounds by the activity of enzymes. Enzymes are complex, nitrogenous (proteins), non-living macromolecules of high molecular weight. We usually get these enzymes from living organisms. This process is usually followed by the evolution of gases like CO2 & CH4. They release a lot of energy and are exothermic in nature. The alcoholic fermentation involves the conversion of sugar into ethyl alcohol by yeast. Get in touch with the solution by just clicking the following links- Facebook Group- https://www.facebook.com/groups/solutionpharamcy Mobile App - https://play.google.com/store/apps/details?id=co.bolton.nqilv New Channel (Pharmacy Dictionary) https://www.youtube.com/channel/UCt6OXVV_2oxf5DD0Mad6e9A E-Mail for official and other work - solutionpharmacy@gmail.com