Preparation And Properties Of Aldehydes and Ketones
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Transcript of Preparation And Properties Of Aldehydes and Ketones
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Preparation And Properties Of Aldehydes and Ketones
Prepared By Prerna Gupta
KV Samba
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IUPAC Nomenclature Of Aldehydes
• 1.Number the longest chain starting from carbon of aldehyde group.2. Name the compound by changing -e to -al (e.g. ethane to ethanal).
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IUPAC Nomenclature Of Ketones
1.Number the longest chain from the end nearest to the carbonyl group.2. Name the compound by changing -e to -one (e.g. ethane to ethanone).
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Preparation of Aldehydes
1. From acyl chloride (Rosenmund reduction) :
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2. From nitriles:(I) Stephen reaction :
(II) reduction of nitrile by diisobutylaluminium hydride ( AlH(i-Bu)2) and (DIBAL-H) to imine followed by hydrolysis:
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3. From aromatic hydrocarbons to aromatic aldehydes: (I) By oxidation of methylbenzene: (a) Using chromyl chloride (CrO2Cl2) (Etard reaction):
(b) Using chromic oxide (CrO3):
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(II) Chlorination followed by hydrolysis:
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(III) by Gatterman - Koch reaction:
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Preparation of Ketones
1. From acyl chlorides:
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2. From nitriles:
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3. From Friedel-Crafts acylation reaction:
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Reactions of aldehydes and ketones1. Reduction:(i) Reduction of aldehydes and ketones to primary or secondary alcohol using sodium borohydride or lithium aluminum hydride.(ii) Reduction of aldehydes or ketones to hydrocarbons using Clemmenson reduction or Wolff-Kishner reduction
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2. Oxidation:Oxidation of ketones require more stronger oxidizing agent in more vigorous conditions than aldehydes• Tollen's test (used to distinguish aldehydes from ketones,
aldehydes give positive test by producing a bright silver mirror):
• Fehling's test (used to distinguish aldehydes from ketones, aldehydes give positive test by producing a red-brown ppt. except aromatic aldehydes):
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• Oxidation of methyl ketones using haloform reaction: both aldehydes and ketones having at least one methyl group attached to the carbonyl carbon will react to give a product having one less carbon atom as shown in the reaction below:
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3. Reaction due to α-hydrogen:• Aldol condensation
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• Cross aldol condensation:
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4. Other reactions• Cannizzaro reaction:
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• Electrophilic substitution reaction:
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