EXERCISE 7:

EXERCISE 7:Organic Derivatives of Water

oxygen containing compounds in addition to carbon and hydrogen

arise from the replacement of one or both of the hydrogen atoms of water by an organic group Organic Derivatives of Water

Alcoholone hydrogen atom is replaced by an alkyl group

Functional group is a hydroxyl group

can be classified as a primary, secondary or tertiary depending on the number of carbon substituents bonded to the hydroxyl bearing carbonOrganic Derivatives of Water

Phenolone hydrogen atom is replaced by an aryl group

hydroxyl group is directly bonded to an aromatic systemOrganic Derivatives of Water

Etherboth hydrogen atoms are replaced by an alkyl or aryl groups

relative inert molecules since the C-O-C bond is quite stable and can be cleaved only under drastic conditionsOrganic Derivatives of Water

SampleH2ONaOHH2SO41-butanol--+2-butanol+/--+tert-butanol+-+phenol-++diethyl ether--+

SOLUBILITY TESTS

Solubility in waterimmiscibility of 1-butanol, phenol and diethyl ether in water is explained by the size of the hydrophobic portions of the molecules as compared to their hydrophilic partssize of the hydrophobic parts in each molecule is so great compared to the hydrophilic portion, rendering each molecule as water-insoluble.SOLUBILITY TESTS

Solubility in waterEffect of branchingas degree of branching increases, the molecule becomes more spherical in shape. The increase in spherical shape reduces the surface area of each molecule which reduces the intermolecular forces of the alcohol molecules. This makes it easier for water to solvate the molecules. SOLUBILITY TESTS

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Solubility in NaOHboth alcohols and phenols under certain conditions can act as Lewis acids due to the proton present in the moleculethe solubility test in NaOH clearly shows that phenols are stronger Lewis acids than alcoholsthe difference in acidities can be explained by the relative stabilities of the conjugate basesSOLUBILITY TESTS

Solubility in NaOHThe negative charge on the O atom of the butoxide is intensified by the electron releasing alkyl group and is therefore destabilizedMost alkoxides are strong bases and will easily attract protons to form back the alcoholsFor phenol, it forms upon losing a proton the resonance-stabilized phenoxide ionBecause of the resonance forms of the phenoxide, phenol has a greater tendency to lose a proton to form the more stable phenoxide ion. Phenol is thus a stronger acid than butanolSOLUBILITY TESTS

Solubility in H2SO4Most organic derivatives of water are soluble in sulfuric acid

Used to indicate the presence of oxygen atoms in a moleculeSOLUBILITY TESTS

Reagent: hot acidic KMnO4Positive result: loss of purple color and formation of brown precipitateused to detect presence of primary and secondary alcohols and phenolsPotassium Permanganate Test

SampleResultSample Result1-butanol+tert-butanol-2-butanol+phenol+diethyl ether-

Potassium Permanganate Test

Potassium Permanganate Test

KMnO4MnO2(s)MnO2(s)

Potassium Permanganate Test

KMnO4MnO2(s)

KMnO4MnO2(s)

Reagent: HCl-ZnCl2Positive result: appearance of cloudiness due to alkyl chloride formedused to detect presence of secondary and tertiary alcohols

Lucas Test

Lucas Test

HCl/ZnCl2H2O

HCl/ZnCl2H2O

Reagent: FeCl3Positive result: formation of a colored (usually red or purple) complexdetect presence of phenolsFerric Chloride Test

SampleResult1-butanol-phenol+

Ferric Chloride Test

FeCl3Fe3+33Cl-3H+

Reagent: I2/KIPositive result: formation of yellow precipitatedetect presence of methyl alcoholsIodoform Test

SampleResult1-butanol-2-butanol+

Iodoform Test

I2/OH-

Reagent: Ag(NH3)2+Positive result: formation of silver mirrordetect presence of phenols

Tollens Test

SampleResult1-butanol-2-butanol-phenol+

Tollens Test

Ag(NH3)2+Ag0

SampleHot acidic KMnO4Lucas TestFeCl3 testTollens TestPrimary ROH+---Secondary ROH++--Tertiary ROH-+--Ar-OH+NA++R-O-R-NA--

Generalization