Some Commercially Important Alcohols And Phenols
Some Commercially Important Alcohols And Phenols
(i) Methanol: Methanol is also called wood spirit since originally it was obtained by destructive distillation of wood. Now a days it is prepared by catalytic hydrogenation of water gas.
Uses: It is largely used as:
(a)ਊ solvent for paints, varnishes and celluloids.
(b)ਏor manufacturing of formaldehyde.
(c)ਏor denaturing ethyl alcohol, i.e. to make it unfit for drinking purpose. Denatured alcohols is called methylated spirit.
(d) in manufacture of perfumes and drugs.
Ethanol: Ethanol is mainly prepared by hydration of ethene formation of carbohydrates gives only 95% alcohol the rest being water. This is called rectified spirit.
Uses: It is largely used as an
(a)ਊntiseptic.
(b) solvent for paints, lacquers, varnishes, dyes, cosmetics, perfumes, tinctures, cough syrups etc.
(c)ਊs an important starting material for manufacture of ether, chloroform, Iodoform etc.
(d)ਊs an important beverages.
(e)ਊs power alcohol a mixture of 20% absolute alcohol and 80% petrol (gasoline) with benzene or tetralin as a co-solvent.
(f) ਊs an antifreeze in automobile radiators.
Absolute alcohol: Absolute alcohol is 100% ethanol prepared from rectified spirit 95.5% alcohol as follows:
In laboratory absolute alcohol is prepared by keeping the rectified spirit in contact with calculated amount of quick lime for few hours and then refluxing and distilling it.
Phenol or Carbolic Acid
Uses
(i) As an antiseptic and disinfectant in soaps and lotions.
(ii) In manufacture of drugs like, aspirin, salol, salicylic acid, phenacetin.
(iii) In the manufacture of bakelite.
(iv) In the manufacture of picric acid, phenolphthalein, azo dyes.
(v)ਊs a preservative for ink.
Ethylene Glycol: Ethane 1, 2 diol
Preparation: Lab preparation by hydroxylation.
Manufacture
Physical properties:
It is highly viscous because of the presence of two OH bond it undergoes extensive intermolecular H-bonding. Same reason owes to high solubility in water and high boiling point.
Chemical properties
Reaction with sodium
(vi)
Oxidation: Ethyelene glycol upon oxidation gives different products with different oxidising agents. For example.
(a)
(b) With periodic acid HIO4 or lead tetra acetate.
Dehydration
Uses
(a) As a solvent.
(b) ਊntifreeze in the radiators of cars and aeroplanes.
(c) In manufacture of terylene and other polyester.
Glycerol (Propane 1, 2, 3 triol)
One of the most important trihydric alcohol.
Preparation:
(i) y Saponification of oils and fats.
(ii)ਏrom Propylene
$\begin{align} & C{{H}_{3}}-CH=C{{H}_{2}}\xrightarrow[-HCl]{C{{l}_{2}},\,\,773K}\underset{Allyl\,\,chloride}{\mathop{Cl-C{{H}_{2}}-CH=C{{H}_{2}}}}\,\xrightarrow[423K,\,\,12\,\,atm]{aq.N{{a}_{2}}C{{O}_{3}}}\underset{Allyl\,\,alcohol}{\mathop{HO-C{{H}_{2}}-CH=C{{H}_{2}}}}\, \\ & \,\,\xrightarrow[\left( trans\,\,C{{l}_{2}}+{{H}_{2}}O \right)]{HOCl\left( C{{l}^{+}}O{{H}^{-}} \right)}\underset{\left( glycerol\,\,\beta -monochlorohydrin \right)}{\mathop{HOC{{H}_{2}}-CHOH-C{{H}_{2}}Cl\xrightarrow[-NaCl]{aq.\,\,NaOH}\underset{glycerol}{\mathop{C{{H}_{2}}OH-CHOH-C{{H}_{2}}OH}}\,}}\, \\ \end{align}$
(iii) Synthesis from its elements
\begin{align}#xA0amp 2C+{{H}_{2}}\xrightarrow[Berthelets\,\,synthesis]{Electric\,\,ore}CH\equiv CH\xrightarrow[196\,\,K]{Na\,\,in\,\,liq.\,\,N{{H}_{3}}}N{{a}^{+}}{{C}^{-}}\equiv CH\xrightarrow[-NaI]{C{{H}_{3}}I} \\#xA0amp \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\underset{Propyne}{\mathop{\,{{H}_{3}}C-C\equiv CH}}\,\xrightarrow[Lindlaraposs\,\,catalyst]{{{H}_{2}}/Pd+BaS{{O}_{4}}}\underset{Propylene}{\mathop{C{{H}_{3}}-CH=C{{H}_{2}}}}\, \\ \end{align}
Physical Properties
Highly viscous due to three OH group due to which it undergoes extensive intermolecular
H-bonding.
Chemical Properties
(i) It undergoes reaction of both secondary and primary alcoholic group.
(ii)
To replace the third hydroxyl group in either of two dichlorohydrins, PCl5 or PCl3 is fused.
3. Reaction with concentrated nitric acid:
A mixture of glyceryl trinitrate and glyceryl dinitrate absorbed on Kieselguhr is called dynamite.
4. Reaction with KHSO4 – Dehydration.
5. Oxidation.
(i) With dil. HNO3, a mixture of glyceric acid and tartronic acid is produced.
(ii) With conc. HNO3, mainly glyceric acid is obtained.
(iii) With bismuth nitrate, only mesoxalic acid is formed.
(iv) Mild oxidising agents like bromine water, sodium hypobromite (Br2/NaOH) and Fenton’s reagent (H2O2 + FeSO4) give a mixture of glyceraldehyde and dihydroxyacetone. The mixture is called glycerose.
(v) With periodic (HIO4) acid.
(vi) With acidified potassium permanganate.
6. Reaction with phosphorous halides.
7. Reaction with monocarboxylic acids. Glycerol reacts with monocarboxylic acids to form mono-, di- and tri- ester depending upon the amount of the acid used and the temperature of the reaction. An excess of the acid and high temperature favour the formation of tri-esters. For example, with acetic acid, glycerol monoacetate, diacetate and triacetate may be formed.
8. Acetylation. When treated with acetyl chloride, glycerol forms glycerol triacetate.
9. Reaction with oxalic acid
Uses: Glycerol is used:
1. In the preparation of nitroglycerine used in making dynamite. Nitroglycerine is also used for treatment of angina pectoris.
2. ਊs an antifreeze in automobile radiators.
3. In medicines like cough syrups lotions etc.
4. In the production of glyptal or alkyl resin (a cross – linked polyester obtained by the condensation polymerization of glycerol and phthalic acid) which is used in the manufacture of paints and lacquers.
5. In making non-drying printing inks, stamp colours, shoes polishes etc.
6. In the manufacture of high class toilet soaps and cosmetics since it does not allow them to dry due to its hydroscopic nature.
7. ਊs a preservative for fruits and other eatables.
8. ਊs a sweetening agent in beverages and confectionary.
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