Alcohol functional group

Presentation on alcohols

1. Carbon and its compounds Functional group-alcohols By: Yuvan Pramesh Selvarangam CASU93A01

2. Learning objectives What is alcohol? What is phenol? Classification of alcohols Physical and chemical properties of alcohols IUPAC naming of alcohols Formation of alcohol Uses of Alcohol

3. What is an alcohol? The class of compounds where alkyl chain is attached to a hydroxyl(-OH) group. General formula-C n H 2n+1 OH Represented as ROH Prefix-Hydroxy suffix- ol Common name-Alkyl radical IUPAC name-alkanols

4. What are phenols? Phenols are hydroxyl(-OH) group attached to aromatic compounds like benzene. Phenols generally exist as either liquids or solids with low melting points. Phenols are similar to alcohols but they have the ability to form strong hydrogen bonds.

5. Primary, secondary and tertiary carbon atoms

6. Classification of alcohols Based on the carbinol carbon atom, alcohols are classified as: Primary alcohols: -OH group is attached to the primary carbon atom Secondary alcohols: -OH group is attached to the secondary carbon atom Tertiary alcohols: -OH group is attached to the tertiary carbon atom

7. Classification of alcohols The examples of each of the type is given below: Primary alcohol Secondary Alcohol Tertiary alcohol

8. Classification of alcohols On the basis of number of hydroxyl groups present alcohols are classified as: Monohydroxy Alcohols Dihydroxy Alcohols Trihydroxy Alcohols Polyhydroxy Alcohols

9. Physical properties of alcohols aliphatic alcohols and lower aromatic alcohols are liquids at room temperature and have a fruity smell. Alcohol with 4-5 carbon atoms are viscous and oily and have more fruity smell highly branched alcohols and alcohols with twelve or more carbon atoms are solids.

10. Physical properties of alcohol Boiling Point: Lets take a example, ethanol( mol.wt =46) we will compare this with propane which has a similar molecular weight of 44. As we notice a large difference, we can conclude that there is a strong intermolecular Hydrogen bonding in alcohols Than a alkane with similar mol.mass , this brings a high boiling point to alcohols. Name of compound Mol.formula Mol.wt Boiling point Ethanol C 2 H 5 OH 46 A.m.u 78 °C (173 °F) propane C 3 H 8 44 A.m.u −42 °C (−44 °F)

11. Physical properties of alcohols IUPAC Name Boiling point(⁰C) Melting point(⁰C) Density (grams per millilitre) Solubility methanol 65 −97 0.79 miscible ethanol 78 −114 0.79 miscible 1-propanol 97 −126 0.80 miscible 2-propanol 82 −89 0.79 miscible 1-butanol 118 −90 0.81 9.1% 2-butanol 100 −114 0.81 7.7% 2-methyl-1-propanol 108 −108 0.80 10.0% 2-methyl-2-propanol 83 25 0.79 miscible

12. Physical properties of alcohols Acidity of alcohols: Alcohols are weak acids because when they are dissolved in water they dissociate by donating a proton to the water molecule and form a alkoxide ion.

13. Chemical properties of alcohols Combustion: Alcohols burn in air to produce CO 2 and water. They burn clean and clear, producing no soot but it becomes difficult to burn alcohols as the number of carbon atom increases. Dehydration: Alcohols produce corresponding alkenes on dehydration.

14. Chemical properties of Alcohols Oxidation: Alcohols can be oxidized to carboxylic acids. Oxidation can be done by using oxidising agents such as acidified potassium dichromate (VI), acidified potassium manganate (VII) or atmospheric oxygen. Esterification: Alcohols can react with carboxylic acids to form esters.

15. IUPAC naming of alcohols Select the longest chain of carbon atoms containing the hydroxyl group. Number the carbon so as the carbon containing hydroxyl group has the lowest possible number. Form the parent alcohol name by replacing –e of alkane name by – ol , write the number of alcohol which contains the hydroxyl group. Name other alkyl and other functional groups(if present) and deignate its position by number. -OH is named as hydroxy when it appears with a substituent of higher priority.

16. IUPAC naming of alcohols The following is the priority order of substituents Acids Esters Aldehydes Ketones Alcohols Amines Alkenes Alkynes Alkanes Ethers Halides Decreasing Priority

17. IUPAC naming of alcohols CH 2 CH CH 2 CH CH 3 OH 1 2 3 4 4 3 2 1 IUPAC NAME: 3-methyl-2-butanol 1 2 3 4 5 5 4 3 2 1 1 2 3 4 IUPAC NAME: 3-hydroxy butanoic acid IUPAC NAME: 3-methyl 2-pentanol 4 3 2 1

18. Formation of alcohols Methyl alcohol Ethyl alcohol Hydrolysis of alkyl halides Boiling methyl halides with aqueous sodium hydroxide or potassium hydroxide Boiling ethyl halides with Aqueous sodium hydroxide or Potassium hydroxide CH 3 Cl+ NaOH( aq ) CH 3 OH+NaCl C 2 H 5 Cl+NaOH C 2 H 5 OH+NaCl Industrial methods From Water Gas: Water gas when mixed with hydrogen and passed over heated catalyst like chromic oxide or zinc oxide From ethene: Ethene on reaction with conc.H 2 SO 4 at high pressure and at 80⁰C gives ethyl hydrogen sulphate which produces ethyl alcohol on boiling with alcohol. [ CO +H 2 ]+H 2 CH 3 OH H 2 C CH 2 +H 2 SO 4 CH 3 CH 2 HSO 4

19. Uses of alcohol The word alcohol in alcoholic drinks refers to ethanol. Alcohols are better solvents and hence used in cleansers and perfumes. A mixture of ethanol and methanol is used as industrial methylated spirits which is majorly used in cleansers and sanitizers. Since a wide range of compounds can be dissolved in ethyl alcohol, It is widely used as a industrial solvent. Alcohol can also be used as a fuel.

20. https://en.wikipedia.org/wiki/Hydrogen_bond https://www.britannica.com/science/phenol https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Supplemental_Modules_(Organic_Chemistry)/Alcohols/Properties_of_Alcohols/Uses_of_Alcohols https://www.britannica.com/science/alcohol/Physical-properties-of-alcohols https://sites.google.com/site/chemistryolp/properties-of-alcohols http://spmchemistry.blog.onlinetuition.com.my/2012/11/preparing-alkene.html Pearson IIT foundation class 10 IIT chemistry by OP Agarwal Sources