Medical Chemistry: Alcohols and Phenols (1ST stage 2024) - PDF

Medical Chemistry Alcohols and Phenols Dr/ Wael Sobhy Darwish 1ST stage&2024 Some Important function groups 2 Identify and name of the functional groups present in the following compounds. Name the functional groups present in the following compounds...

Medical Chemistry Alcohols and Phenols Dr/ Wael Sobhy Darwish 1ST stage&2024 Some Important function groups 2 Identify and name of the functional groups present in the following compounds. Name the functional groups present in the following compounds 3  Alcohols General Formula:- CnH(2n+2)O Functional group :- Hydroxyl ( OH) group bonded to a saturated carbon atom. Many alcohols are commonly encountered in everyday life. Ethanol is used in beverage, 2- propanol is used as bactericidal agent. In the laboratory and in industry, all these compounds are used as solvent and reagents. Alcohols can be classified as 1, 2, or 3 depending on the type of carbon atom to which the -OH is attached.  Nomenclature of alcohols 1.Select the longest continuous carbon chain. 2.Change the name of the alkane by dropping the final –e and adding the suffix -ol. 3.Number the longest continuous carbon chain so as to give the carbon atom bearing the hydroxyl group the lower number 4.Indicate the position of the hydroxyl group by using this number as a locant 5.indicate the positions of other substituents (as prefixes) by using the numbers corresponding to their positions along the carbon chain as locants. Examples :- Summary of reactions of Alcohols  Ethers Ethers compounds containing C-O-C unit undergo relatively few chemical reactions. This lack of reactivity makes them valuable as solvents for fats, oils, resins and organic preparations (e.g. Grignard reagents). Ethyl ether was once used as anesthetic Dimethyl ether  Preparation of ethers By Intermolecular Dehydration of Alcohols:  Physical properties of ethers Methyl ether is a gas, and the other higher homologes are liquids. The boiling points are much lower than those of isomeric alcohols, since the hydrogen bonding that holds alcohol molecules strongly together is not possible for ethers, as they contain hydrogen bonded only to carbon. Ethers, however, are able to form hydrogen bonds with compounds such as water and, therefore, have solubilities in water that are nearly similar to those of alcohols of the same molecular weight and that are very different from those of hydrocarbons.  Phenols They are a chemical compounds consisting of a hydroxyl group (-OH) bonded directly to an aromatic hydrocarbon group. The chemical formula of phenol is C6H5OH. Characteristics of Phenol  They have low molecular weight.  They are extremely diverse in chemical structure.  Some are soluble in organic solvents and some are soluble in water while others are insoluble.  They are polar because of the hydroxyl group.  Their polar side and hydrogen bonding allow them to dissolve in water. Classification of Phenol Phenols are mainly divided into four groups – 1. Simple phenols 2. Phenolic carboxylic acids (or phenolic acids) 3. Phenyl propane derivatives (or propenyl phenol) 4. Flavan derivatives  Uses of phenols  Used in plastic synthesis or related materials.  Used in drugs (aspirin) but also many herbicides pharmaceutical drugs.  They are used as an oral anesthetic or analgesic.  They are also used in the preparation of cosmetics including sunscreens, hairdyes and skin lightening preparations.  Aldehydes & Ketones Aldehydes and ketones are widely distributed in the animal and plant worlds. Many carbonyl compounds contribute to the flavors and aromas of many foods and assist in the biological functions of a number of enzymes. Industry makes considerable use of aldehydes and ketones. Thus, ketones are not sensitive to atmospheric oxygen, and therefore can be used as excellent solvents e.g. acetone. Formaldehyde is the most important aldehyde in industry and in aqueous solution (formalin), has applications as a disinfectant and a fungicide  Aldehydes & Ketones Def :- They are organic compounds which incorporate a carbonyl functional group, C=O Formula :- Nomenclatur e 1. Identify and name the parent. substituents. 3.Assign a locant to each substituent. 4.Assemble the substituents alphabetically. - Aldehydes are named by replacing the final -e of the name of the correspondin alkane with -al. Ketones are named by replacing the final -e of the name of the corresponding alkane with -one. Many aldehydes also have common names are derived from the common names of the corresponding carboxylic acids by changing “ic” ending to “aldehyde”.  Physical properties Aldehydes and ketones have higher boiling points than hydrocarbons because they are more polar. They have lower boiling points than alcohols, because, unlike alcohols, two carbonyl groups cannot form hydrogen bonds to one another. Aldehydes and ketones can form hydrogen bonds with the protons of water and are thus more soluble hydrocarbons, but less soluble than alcohols. Carbonyl compounds with more than six carbons are rather insoluble in water.  Preparation of Aldehydes and Ketones 1. Hydrolysis of geminal dihalides 2. Reduction of Acyl Chlorides 3. Decarboxylation of calcium salt of di-acids 4. From nitrile 5. Oxidation od alcohols 6. Ozonolysis of alkenes 7. Hydration of alkynes 1. Hydrolysis of geminal dihalides 17 Question :- Convert toluene to benzaldehyde Answer :- 2. Reduction of Acyl Chlorides 3. Decarboxylation of calcium salt of acids 4. From nitrile i-Aldehydes i-Ketones 19 5. Oxidation od alcohols 6. Ozonolysis of alkenes 7. Hydration of alkynes