Edexcel International A Level (IAL) Chemistry (YCH11) - Unit 4 - 15.13 Nomenclature (acyl chlorides, esters)-Study Notes - New Syllabus
Edexcel International A Level (IAL) Chemistry (YCH11) -Unit 4 – 15.13 Nomenclature (acyl chlorides, esters)- Study Notes- New syllabus
Edexcel International A Level (IAL) Chemistry (YCH11) -Unit 4 – 15.13 Nomenclature (acyl chlorides, esters)- Study Notes -International A Level (IAL) Chemistry (YCH11) – per latest Syllabus.
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Edexcel International A Level (IAL) Chemistry (YCH11) -Concise Summary Notes- All Topics
15.13 Nomenclature and Formulae of Acyl Chlorides and Esters
Acyl Chlorides
Acyl chlorides are derivatives of carboxylic acids in which the \( \mathrm{-OH} \) group of the carboxyl group is replaced by chlorine.
Functional Group
\( \mathrm{-COCl} \)
General Formula
\( \mathrm{RCOCl} \)
Naming Acyl Chlorides
- Derived from the corresponding carboxylic acid name.
- Replace:
-oic acid
with:
-oyl chloride
Examples
- \( \mathrm{HCOCl} \) → methanoyl chloride
- \( \mathrm{CH_3COCl} \) → ethanoyl chloride
- \( \mathrm{CH_3CH_2COCl} \) → propanoyl chloride
Structural Formulae of Acyl Chlorides
Examples
- Ethanoyl chloride:
\( \mathrm{CH_3COCl} \)
- Propanoyl chloride:
\( \mathrm{CH_3CH_2COCl} \)
Displayed Formulae
- Show:
- Carbonyl double bond \( \mathrm{C=O} \)
- Bond to chlorine
- All atoms and bonds
Skeletal Formulae
- Carbon chain shown as zig-zag lines.
- Functional group \( \mathrm{-COCl} \) shown clearly.
Esters
Esters are compounds formed from reactions between carboxylic acids and alcohols.
Functional Group
\( \mathrm{-COO-} \)
General Formula
\( \mathrm{RCOOR’} \)
Naming Esters
Ester names have two parts:
- Alkyl group from the alcohol
- Carboxylate part from the acid
Naming Rule
- Acid ending -oic acid changes to:
-oate
Examples
- \( \mathrm{CH_3COOCH_3} \) → methyl ethanoate
- \( \mathrm{CH_3COOCH_2CH_3} \) → ethyl ethanoate
- \( \mathrm{CH_3CH_2COOCH_3} \) → methyl propanoate
How to Name an Ester
Example:
\( \mathrm{CH_3COOCH_2CH_3} \)
- Alcohol part = ethyl
- Acid part = ethanoate
Name = ethyl ethanoate
Structural Formulae of Esters
Examples
- Methyl ethanoate:
\( \mathrm{CH_3COOCH_3} \)
- Ethyl ethanoate:
\( \mathrm{CH_3COOCH_2CH_3} \)
Displayed Formulae
- Show:
- Carbonyl group
- Single-bond oxygen linking two carbon groups
- All atoms and bonds
Skeletal Formulae
- Carbon skeleton shown as lines.
- Ester functional group shown explicitly.
Key Naming Points
- Acyl chlorides use suffix -oyl chloride.
- Esters use suffix -oate.
- Ester names begin with alkyl group from alcohol.
- Functional groups must be shown clearly in all formulae.
Key Features
- Acyl chlorides contain \( \mathrm{-COCl} \).
- Esters contain \( \mathrm{-COO-} \).
- Acyl chlorides named using -oyl chloride.
- Esters named using alkyl + -oate.
- Structural, displayed and skeletal formulae must be recognised and drawn.
Example 1:
Name the compound \( \mathrm{CH_3CH_2COCl} \).
▶️ Answer/Explanation
The compound contains three carbon atoms and the \( \mathrm{-COCl} \) group.
Parent acid is propanoic acid.
Suffix changes to -oyl chloride.
Name:
\( \mathrm{propanoyl\ chloride} \)
Example 2:
Name the ester \( \mathrm{CH_3CH_2COOCH_3} \).
▶️ Answer/Explanation
The alkyl group attached to oxygen is methyl.
The acid-derived part contains three carbons → propanoate.
Name:
\( \mathrm{methyl\ propanoate} \)