ALCOHOLS
ALCOHOLS, ETHERS, AND PHENOLS
Juris Marie G. Garcia
Institute of Chemistry, University of the Philippines, Diliman, Quezon City
Date Performed: February 27, 2015
Date Submitted: March 06, 2015
Answers to Questions:
1.) Balanced equations:
A. Lucas Test
Test Sample
Equation
Ethyl Alcohol
C2H5OH + HCl + ZnCl2 C2H5Cl + H2O
Isopropyl Alcohol
(CH3) 2CHOH + HCl (CH3) 2CHCl + ZnC2 + H2O
Tert-butyl Alcohol
(CH3) 3COH + HCl + ZnCl2 (CH3) 3CCl + ZnCl2 +H2O
Benzyl Alcohol
C6H5CH2OH + HCl + ZnCl2 C6H5CH2Cl +ZnCl2 +H2O
B. Oxidation of Alcohols
Test Sample
Equation
Ethyl Alcohol
C2H5OH + KMnO4 CH3COOH + H2O + MnO2 +K+
Isopropyl Alcohol
2(CH3)2CHOH + KMnO4 2(CH3) 2CO + 2H2O + MnO2 + K+
Tert-butyl Alcohol
No reaction
Benzyl Alcohol
C6H5CH2OH + KMnO4 C6H5COOH + H2O +MnO2 + K+
Diethyl Ether
C4H10O + KMnO4 C4H8O2 + H2O + MnO2 + K+
C. Reaction of Phenols
Test Sample
Equation
Phenol
C6H5OH + 3Br2 C6H5OHBr3 + 3HBr
C6H5OH + KMnO4 C6H4O2 + MnO2 + H2O + K+
FeCl3 + 6C6H5OH [Fe(OC6H5) 6] 3- + 3H+ + 3Cl- p-Nitrophenol 3C6H5NO3 + FeCl3 Fe(C6H4NO3) 3 + 3HCl
Picric Acid
---
p-Bromophenol
3BrC6H5OH + FeCl3 Fe(BrC6H4O) 3 + 3HCl β-Naphthol 3C10H7OH + FeCl3 Fe(C10H7O)3 + 3HCl
2.) Explain why Lucas test is applicable only to alcohols containing 5 or less carbons
The Lucas reagent is an aqueous solution of strong acid (HCl) and zinc chloride. The alcohol starting material must be sufficiently soluble in aqueous environments for the reaction to take place. Having more than 5 carbons would decrease the compound’s solubility. Only water-soluble alcohols with low molecular weight can be dissolved by the reagent. 3.) Explain why tertiary alcohols and ethers cannot undergo oxidation upon reaction with potassium permanganate.
Tertiary alcohols does not get oxidized by mild oxidizing agents either in aqueous, alkaline or under neutral conditions. They undergo oxidation under acidic condition. Same is true with ethers. Both can only be oxidized under extreme
Juris Marie G. Garcia
Institute of Chemistry, University of the Philippines, Diliman, Quezon City
Date Performed: February 27, 2015
Date Submitted: March 06, 2015
Answers to Questions:
1.) Balanced equations:
A. Lucas Test
Test Sample
Equation
Ethyl Alcohol
C2H5OH + HCl + ZnCl2 C2H5Cl + H2O
Isopropyl Alcohol
(CH3) 2CHOH + HCl (CH3) 2CHCl + ZnC2 + H2O
Tert-butyl Alcohol
(CH3) 3COH + HCl + ZnCl2 (CH3) 3CCl + ZnCl2 +H2O
Benzyl Alcohol
C6H5CH2OH + HCl + ZnCl2 C6H5CH2Cl +ZnCl2 +H2O
B. Oxidation of Alcohols
Test Sample
Equation
Ethyl Alcohol
C2H5OH + KMnO4 CH3COOH + H2O + MnO2 +K+
Isopropyl Alcohol
2(CH3)2CHOH + KMnO4 2(CH3) 2CO + 2H2O + MnO2 + K+
Tert-butyl Alcohol
No reaction
Benzyl Alcohol
C6H5CH2OH + KMnO4 C6H5COOH + H2O +MnO2 + K+
Diethyl Ether
C4H10O + KMnO4 C4H8O2 + H2O + MnO2 + K+
C. Reaction of Phenols
Test Sample
Equation
Phenol
C6H5OH + 3Br2 C6H5OHBr3 + 3HBr
C6H5OH + KMnO4 C6H4O2 + MnO2 + H2O + K+
FeCl3 + 6C6H5OH [Fe(OC6H5) 6] 3- + 3H+ + 3Cl- p-Nitrophenol 3C6H5NO3 + FeCl3 Fe(C6H4NO3) 3 + 3HCl
Picric Acid
---
p-Bromophenol
3BrC6H5OH + FeCl3 Fe(BrC6H4O) 3 + 3HCl β-Naphthol 3C10H7OH + FeCl3 Fe(C10H7O)3 + 3HCl
2.) Explain why Lucas test is applicable only to alcohols containing 5 or less carbons
The Lucas reagent is an aqueous solution of strong acid (HCl) and zinc chloride. The alcohol starting material must be sufficiently soluble in aqueous environments for the reaction to take place. Having more than 5 carbons would decrease the compound’s solubility. Only water-soluble alcohols with low molecular weight can be dissolved by the reagent. 3.) Explain why tertiary alcohols and ethers cannot undergo oxidation upon reaction with potassium permanganate.
Tertiary alcohols does not get oxidized by mild oxidizing agents either in aqueous, alkaline or under neutral conditions. They undergo oxidation under acidic condition. Same is true with ethers. Both can only be oxidized under extreme