Alcohols and Their Classification

ALCOHOLS ALCOHOLS What are Alcohols? What are Alcohols? The term alcohol is applied to all organic compounds whose molecules contain hydroxyl group, OH, attached to a saturated carbon atom. The general formula is R-OH, R- Alkyl group - OH - the functional group of alcohol

CLASSIFICATION OF ALCOHOL a. Aliphatic alcohol: OH group is linked to an aliphatic carbon chain i) Monohydric alcohol : Primary alcohol Secondary Alcohol Alcohol CH3-OH Methanol Tertiary ii) Dihydric alcohol iii) Trihydric alcohol

iv) Polyhydric alcohol Polyhydric alcohol eg eg: : b) b) Aromatic Alcohol Aromatic Alcohol - -OH group is linked to side chain of an aromatic hydrocarbons. OH group is linked to side chain of an aromatic hydrocarbons.

NOMENCLATURE OF ALCOHOL Alcohol Alcohol Common Name Common Name Carbinol Carbinol Name Name IUPAC Name IUPAC Name R-OH Alkyl alcohol Carbinol Alkanol CH3-OH Methyl alcohol Carbinol Methanol CH3-CH2-CH2-OH n-Propyl alcohol Ethyl carbinol 1-Propanol Isopropyl alcohol Dimethyl carbinol 2-Propanol Isobutyl alcohol Isopropyl carbinol 2-Methyl-1-Propanol sec-butyl alcohol Ethyl methyl carbinol 2-Butanol tert- Butylalcohol Trimethyl carbinol 2-Methyl-propan-2-ol

GENERAL METHODS OF PREPARATION 1. 1. Oxymercuration Oxymercuration demercuration demercuration ( (Markownokoff s Markownokoff s products) products) 2. Hydroboration 2. Hydroboration oxidation ( oxidation (Antimarkownokoff s Antimarkownokoff s products) products) 3. Grignard synthesis (Reaction of 3. Grignard synthesis (Reaction of RMgX Epoxides) Epoxides) RMgX with Carbonyl comp & with Carbonyl comp & 4. Hydrolysis of alkyl halide 4. Hydrolysis of alkyl halide 5. 5. Aldol Aldol condensation condensation 6. Reduction of carbonyl compounds 6. Reduction of carbonyl compounds 7. Reduction of acids and ester 7. Reduction of acids and ester 8. Hydroxylation of alkene 8. Hydroxylation of alkene 9. Hydration of alkene 9. Hydration of alkene 10. Hydrolysis of alkene 10. Hydrolysis of alkene

Grignard Synthesis of alcohols Formaldehyde primary alcohol Acetaldehyde Secondary alcohol Acetone Tertiary alcohol Epoxide Primary alcohol General Reaction: Reaction with Formaldehyde:

Reaction with Acetaldehyde Reaction with Acetone Reaction with Epoxide

Hydrolysis of Alkyl halide Hydrolysis of Alkyl halide Hydrolysis of alkyl halide is an example of Nucleophilic Substitution reaction. Unimolecular Nucleophilic substitution reaction SN1eg: primary alkyl halides Bimolecular Nucleophilic substitution reaction SN2 eg: tert: alkyl halides While secondary alkyl halide can undergoes either SN1 or SN2

Reduction of Carbonyl Compounds to alcohol Aldehyde 10 alcohol Ketone - 20 Alcohol Reagents: 1. Catalytic hydrogenation 2. Chemical reducing agents like lithium aluminium hydride Exercise: 2-Butenal 2-butanone Propanadehyde Acetophenone

Reduction of acids and esters to alcohol Reduction of Carboxylic acids Reduction of Carboxylic acids Carboxylic acid on reduction gives corresponding alcohol. LiALH4 - one of few reagents. Excercise Excercise: : Propionic acid, Propionic acid, - - methyl butyric acid methyl butyric acid Reduction of Esters Reduction of Esters Esters on reduction gives mixture of alcohols. Excercise Excercise: : Ethyl acetate Ethyl acetate Propyl butyrate Propyl butyrate

Hydrolysis of ester to alcohol Reaction is carried out in presence of dilute solution of an alkali or a mineral acid, the organic esters are hydrolyzed to form the parent carboxylic acid and alcohol. Exercise: Exercise: Propyl acetate, Methyl Propyl acetate, Methyl formate formate

ALDOL CONDENSATION ALDOL CONDENSATION Under the influence of dilute acid or base, two molecules of aldehyde or ketones, having alpha hydrogen atom may combine to form Beta-hydroxy aldehyde or Beta hydroxy ketone. The reaction is called as Aldol condensation.

Mechanism of Aldol Condensation

Applications of Aldol Condensation 1. Preparation of Saturated alcohol 1. Preparation of Saturated alcohol

Reactions of Alcohols 1. Reaction with hydrogen halide: Formation of alkyl halide 2. Reaction with PCl3/PCl5/SOCl2: Formation of alkyl halide 3. Dehydration of alcohol: Formation of alkene 4. Reaction as an acids: Reaction with active metal 5. Ester formation: a) Reaction with acid chloride and 6. Oxidation of alcohol: Formation of aldehyde, ketone and acid 7. Catalytic dehydrogenation: Formation of aldehyde, ketone b)Reaction with carboxylic acid and alkene 8. Reaction with acetylene : Formation of acetal

1. Reaction with hydrogen halide: Formation of alkyl halide Lucas Test Differentiate Pri, sec and tert alcohols Order or reactivity of Order or reactivity of alcohol: alcohol: 3 30 0>2 >20 0>1 >10 0 Order or reactivity of Order or reactivity of HX: HX: HI HI > > HBr HBr > > HCl HCl Alkyl halide form is insoluble and shows turbidity. Alkyl halide form is insoluble and shows turbidity. 3 30 0 alcohol: Cloudiness immediately alcohol: Cloudiness immediately 2 20 0 alcohol: Cloudiness alcohol: Cloudiness within 5 minutes 1 10 0 alcohol: alcohol: No cloudiness at room temp. and gives cloud only on heating No cloudiness at room temp. and gives cloud only on heating within 5 minutes

2. Reaction with PCl3/PCl5/SOCl2: Formation of alkyl halide

3 3. Dehydration of alcohol Dehydration of alcohol Refer Alkene Chapter for full detail Refer Alkene Chapter for full detail 4 4. Reaction as an acids Reaction with active metal

5. Ester formation: Two methods a) Reaction with acid chloride and b)Reaction with carboxylic acid

6. Oxidation of alcohol: Formation of aldehyde, ketone & carboxylic acid Used to differentiate pri, sec and tert alcohol Loss of one or more -H atom Oxidising agents: KMnO4, Chromic acid, CrO3 in glacial acetic acid CrO3 in pyridine

7. Catalytic dehydrogenation: Formation of aldehyde, ketone and alkene Used for Used for differentiating differentiating pri pri, sec and , sec and tert tert alcohol alcohol

8. Reaction with acetylene: Formation of acetal

Differentiate Between Primary Secondary & tertiary Alcohol Victor Meyer test Victor Meyer test 1. Oxidation test: Also known as Dichromate test 2. Catalytic dehydrogenation 3. Lucas test: Reaction with Hydrogen halide 4. Victor Meyer test

Structure and uses Structure and uses of of Ethyl alcohol, chlorobutanol, cetosteryl alcohol, benzyl alcohol, glycerol, propylene glycol CH3-CH2-OH, CN: Ethyl alcohol, IUPAC: Ethanol Ethyl alcohol Ethyl alcohol It is the exhilarating principle of all wines and is also named as Spirit of Win Technicaly it is known as Grain alcohol, since it is often manufactured from starchy grains. Ethyl alcohol is used : (1) as a fuel for lamps and stoves. For the sake of convenience in transportation, it is converted into solid state (Solid alcohol) dispersion in saturated calcium acetate and a little stearic acid (2) as a substitute of petrol in internal combustion engines (3) as a solvent for drugs, tinctures, oils, perfumes, inks, dyes, varnishes (4) as a beverage (5) as a preservative for biological specimens (6) as an antifreeze for automobile radiators (7) as a low freezing ( fp -11.7 ) and mobile fluid in scientific apparatus such as thermometers and spirit level (8) as a raw material for large number of organic compounds including ethylene, ether, acetic acid, iodoform, chloroform, chloral etc. (9) for manufacture of terylene and polythene. (Solid alcohol) by

Structure and uses Structure and uses of of Glycerol Glycerol is the simplest trihydric alcohol (triol). The name glycerol or glycerine was originally derived from the word glyceros, meaning sweet. It is a trihydroxy derivative of propane. It occurs in almost all natural animal fats and vegetable oils as the glyceryl esters of higher organic acids. Uses: Glycerol is used (I) as a sweetening agent in beverages and confectionary (ii) in the preparation of high class toilet soaps and cosmetics; (iii) in preserving tobacco from drying out (iv) as antifreeze in automobile radiators (v) for lubricating fine machinery such as watches and clocks; (vi) as a preservative for fruits & other eatables which require to be kept moist (vii) in making printing inks and inks for stamp pads (viii) in the preparation of nitroglycerine (ix) as a starting material for several allyl and propyl derivatives, and (x) for the manufacture of glyptal plastics used for artificial fibers.

Structure and uses Structure and uses of Benzyl alcohol of Benzyl alcohol It is the simplest member of the class and is isomeric with cresols. It occurs is Peru and Tolu balsams as free alcohol and as esters (acetate and benzoate) oil of Jasmine and other essential oil. 1. Benzyl alcohol and its esters are largely used in the perfumery industry. 2. Being a local anaesthetic and antiseptic, it is used in making ointments for relieving itching. 3. Benzyl benzoate Is a remedy for asthma asthma and and whooping cough. whooping cough.

Structure and uses Structure and uses of of Cetostearyl Cetostearyl alcohol alcohol Cetostearyl alcohol, cetearyl alcohol or cetylstearyl alcohol is a mixture of fatty alcohols consisting predominantly of cetyl and stearyl alcohol and is classified as a fatty alcohol. It is used as 1. an emulsion stabilizer 2. an opacifying agent, 3. foam boosting surfactant 4. an aqueous and non-aqueous viscosity- increasing agent. 5. It imparts an emollient feel to the skin and can be used in water-in-oil emulsions, oil- in-water and anhydrous formulations. 6. It is commonly used in hair conditioners and other hair products. CH CH3 3- -( (CH CH2 2) )n n- -CH CH2 2- -OH OH n n Variable, 14 Variable, 14- -16 16 Cetostearyl Cetostearyl alcohol alcohol emulsions

Structure and uses of Propylene Glycol Structure and uses of Propylene Glycol 1. 1. Propylene Propylene glycol glycol is is used used as as a a humectant humectant 2. 2. preservative preservative in in food food and and for for tobacco tobacco products products 3. 3. It It is is also also one one of of the the major major ingredients ingredients (< (<1 1 92 92% %), ), along along with with glycerol, glycerol, of of the the e e- - liquid liquid and and cartridges cartridges used used in in electronic electronic cigarettes cigarettes where where it it is is aerosolized aerosolized in in the the atomizer atomizer 4. 4. Propylene Propylene glycol glycol is is also also used used in in various various edible edible items items such such as as coffee coffee- -based based drinks, drinks, liquid liquid sweeteners, sweeteners, ice ice cream, cream, whipped whipped dairy dairy products products and and soda soda. . 5. 5. Vaporizers Vaporizers used used for for delivery delivery of of pharmaceuticals pharmaceuticals or or personal personal- -care care products products often often include include propylene propylene glycol glycol among among the the ingredients ingredients. . 6. 6. used used as as chemical chemical feedstock feedstock for for the the production production of of unsaturated unsaturated polyester polyester resins resins

7 7. . It It reacts reacts with used used to to produce Used Used including including for for diazepam diazepam and Certain Certain formulations formulations of of artificial glycol glycol as as an an ingredient ingredient It It is is able able to to lower lower the icing fluid fluid. . 11 11. . Propylene Propylene glycol glycol is is frequently low low toxicity, toxicity, environmentally environmentally friendly 12 12. . It It is is also also used used to to winterize 13 13. . Propylene Propylene glycol glycol is is used for for hyperketonaemia hyperketonaemia in in ruminants 14 14. . Propylene Propylene glycol glycol is is partially can can be be used used as bloodstream bloodstream and with propylene propylene oxide produce polyurethanes polyurethanes. . as as a a oral, oral, and lorazepam lorazepam which oxide to to give give oligomers oligomers and and polymers polymers that that are are 8 8. . solvent solvent in in topical topical insoluble in in water tears, such such as many many formulations formulations, , water. . as Systane Systane, , use pharmaceuticals, pharmaceuticals, such such injectable injectable and and are insoluble as as which are artificial tears, 9 9. . use proplyene proplyene 10 10. . icing the freezing freezing point point of of water, water, and and so so it it is is used used as as aircraft aircraft de de- - frequently used friendly automotive automotive antifreeze winterize the the plumbing plumbing systems used in in veterinary ruminants. . partially metabolized metabolized in in the as an an energy energy source source. . The and used used by by the the liver liver used as as a a substitute substitute for antifreeze. . systems in in vacant veterinary medicine medicine as for ethylene ethylene glycol glycol in in vacant structures structures. . as an an oral oral treatment treatment the rumen rumen remainder remainder is is absorbed for gluconeogenesis gluconeogenesis. . to to propionate propionate absorbed into which which into the The the for

Structure and uses of Structure and uses of Chlorobutanol Chlorobutanol Chlorobutanol (trichloro-2-methyl-2-propanol) 1. It is used as a preservative, sedative, hypnotic and weak local anesthetic. 2. similar in nature to chloral hydrate. It has antibacterial and antifungal properties. 3. Chlorobutanol is typically used at a concentration of 0.5% where it lends long term stability to multi-ingredient formulations. 4. However, it retains antimicrobial activity at 0.05% in water in injection, eye drop ointment and cosmetics.