SS3 First Term Chemistry Lesson Note – Alkanoates

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WEEK 2

TOPIC: ALKANOATES:

1. Sources, nomenclature.
2. Preparation and structure.
3. Physical and chemical properties and uses.

PERIOD  1: SOURCES, NOMENCLATURE

Alkanoates are found widely in nature. Short carbon chain simple alkanoates exist as liquids and have a characteristic pleasant smell. They occur in essential oils, many fruits and flowers and sometimes called fruit essence because of the pleasant odours. The general molecular formula is C_nH_2n+1COOC_nH_2n+1. The structural formula is:

The names end in-ate

EVALUATION:

1. State four sources of alkanoate
2. Give the IUPAC names of the following:

1. CH₃CH₂CH₂CH₂CH₂COOC₃H₇
2. HCOOC₂H₅

3. Draw the structures of the following”

• Ethyl butanoate, propyl ethanoate, propyl propanoate.

PERIOD 2: PREPARATION OF ALKANOATE

Alkanoates are prepared by esterification reaction between alkanoic acid and alkanols in the presence of concentrated tetraoxosulphate (vi) acid.

RCOOH + R¹OH  → RCOOR¹ + H₂O

In this reaction the alkyl group of alkanol replaces the acidic hydrogen of the alkanoic acid

Ethanoic acid reacts with ethanol to give ethyl ethanoate.

CH₃COOH + CH₃CH₂OH   → CH₃COOCH₂CH₃ + H₂O

Ethyl propanoate is prepared by the reaction between ethanol and propanoic acid.

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