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Carbon and its Compounds - Nomenclature of carbon compounds

Grade 10CBSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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The IUPAC name of a carbon compound consists of three parts: Prefix + Word Root + Suffix.

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The Word Root depends on the number of carbon atoms in the longest continuous chain: C1C_1: Meth-, C2C_2: Eth-, C3C_3: Prop-, C4C_4: But-, C5C_5: Pent-, C6C_6: Hex-.

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Primary Suffix identifies the saturation: −ane-ane for single bonds (C−CC-C), −ene-ene for double bonds (C=CC=C), and −yne-yne for triple bonds (C≡CC\equiv C).

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Functional groups are atoms or groups of atoms that define the chemical properties: Halogens (Prefix: chloro-, bromo-), Alcohols (Suffix: −ol-ol), Aldehydes (Suffix: −al-al), Ketones (Suffix: −one-one), and Carboxylic acids (Suffix: −oic acid-oic\ acid).

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Rule for naming: If the suffix of the functional group begins with a vowel (a,e,i,o,ua, e, i, o, u), the final 'e' of the primary suffix (−ane,−ene,−yne-ane, -ene, -yne) is removed. Example: Ethane+−ol=EthanolEthane + -ol = Ethanol.

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Numbering: The carbon chain is numbered from the end that gives the functional group the lowest possible locant number.

📐Formulae

CnH2n+2 (General formula for Alkanes)C_nH_{2n+2} \text{ (General formula for Alkanes)}

CnH2n (General formula for Alkenes)C_nH_{2n} \text{ (General formula for Alkenes)}

CnH2n−2 (General formula for Alkynes)C_nH_{2n-2} \text{ (General formula for Alkynes)}

R−OH (Alcohol functional group)R-OH \text{ (Alcohol functional group)}

R−CHO (Aldehyde functional group)R-CHO \text{ (Aldehyde functional group)}

R−CO−R′ (Ketone functional group)R-CO-R' \text{ (Ketone functional group)}

R−COOH (Carboxylic acid functional group)R-COOH \text{ (Carboxylic acid functional group)}

💡Examples

Problem 1:

Give the IUPAC name for CH3−CH2−CH2−OHCH_3-CH_2-CH_2-OH.

Solution:

Propan-1-ol (or Propanol)

Explanation:

The longest chain has 3 carbon atoms (Word root: Prop). All bonds are single (Primary suffix: -ane). The functional group is an alcohol (Secondary suffix: -ol). Since -ol starts with a vowel, we drop 'e' from propane. Numbering starts from the right to give −OH-OH the number 1.

Problem 2:

Name the compound: CH3−CO−CH2−CH3CH_3-CO-CH_2-CH_3.

Solution:

Butan-2-one

Explanation:

The chain has 4 carbons (Word root: But). Single bonds between carbons (Primary suffix: -ane). The functional group is a ketone (>C=O>C=O, Secondary suffix: -one). Numbering from the left gives the ketone carbon the number 2.

Problem 3:

What is the IUPAC name of CH3−CH2−COOHCH_3-CH_2-COOH?

Solution:

Propanoic acid

Explanation:

There are 3 carbon atoms including the one in the carboxylic group (Word root: Prop). It is saturated (-ane). The functional group is −COOH-COOH (Suffix: -oic acid). Removing 'e' from propane gives Propanoic acid.

Problem 4:

Name the compound CH3−CH=CH2CH_3-CH=CH_2.

Solution:

Prop-1-ene (or Propene)

Explanation:

The chain has 3 carbons (Word root: Prop). There is a double bond present (Primary suffix: -ene). The position of the double bond is at carbon 1.