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Published byClaud Lucas Modified over 9 years ago
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Alcohols and Phenols and how to identify them
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2 Classification Primary: carbon with –OH is bonded to one other carbon Secondary: carbon with –OH is bonded to two other carbons Tertiary: carbon with –OH is bonded to three other carbons Aromatic (phenol): -OH is bonded to a benzene ring
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3 Classify these:
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4 IUPAC Nomenclature Find the longest carbon chain containing the carbon with the -OH group Drop the -e from the alkane name, add –ol Number the chain, starting from the end closest to the -OH group Number and name all substituents. =>
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Chapter 105 Name these: 2-methyl-1-propanol 2-methyl-2-propanol 2-butanol 3-bromo-3-methylcyclohexanol =>
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6 Naming Phenols -OH group is assumed to be on carbon 1 For common names of disubstituted phenols, use ortho- for 1,2; meta- for 1,3; and para- for 1,4 Methyl phenols are cresols. 3-chlorophenol meta-chlorophenol 4-methylphenol para-cresol
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7 Physical Properties Unusually high boiling points due to hydrogen bonding between molecules Small alcohols are miscible in water, but solubility decreases as the size of the alkyl group increases.
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Acidity of Phenol In water, phenol acts as a weak acid phenol phenoxide ion
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Oxidation of Alcohols: Do I have a tertiary alcohol? For Primary alcohols that dehydrogenate from the aldehyde to the carboxylic acid tertiary alcohols do not dehydrogenate (oxidize) Secondary alcohols only oxidize to the ketone 9 If chromic acid is used for H 2 CrO 4 =[O] then the product includes Cr 3+ which is green + Cr 3+
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Oxidation with Chromate Negative test tertiary alcohol Positive test primary or secondary alcohol
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Test of a Phenol: FeCl 3 test You can test for a phenol with ferric chloride (FeCl 3 ) Phenol + Fe 3+ [Fe 3+.phenol complex] colorless yellow purple
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Experiment You will test the following ethanol 2-propanol 2-methyl-2-propanol Cyclohexanol Phenol Unknown
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Experiment Odor Solubility in water Acidity Reaction with Chromic Acid Ferric Chloride Test Use test results to identify your unknown
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