{"id":4475,"date":"2025-06-01T15:04:19","date_gmt":"2025-06-01T15:04:19","guid":{"rendered":"https:\/\/diznr.com\/?p=4475"},"modified":"2025-06-01T15:04:19","modified_gmt":"2025-06-01T15:04:19","slug":"iupac-nomenclature-rules-for-selection-of-parent-chain-in-easy-way-part-03","status":"publish","type":"post","link":"https:\/\/www.reilsolar.com\/pdf\/iupac-nomenclature-rules-for-selection-of-parent-chain-in-easy-way-part-03\/","title":{"rendered":"IUPAC Nomenclature – Rules for Selection of Parent Chain In easy way Part 03."},"content":{"rendered":"

IUPAC Nomenclature – Rules for Selection of Parent Chain In easy way Part 03.<\/p>\n

[fvplayer id=”788″]<\/p>\n

IUPAC Nomenclature \u2013 Rules for Selection of Parent Chain (Easy Way) | Part 03<\/strong><\/h3>\n

When naming organic compounds using IUPAC (International Union of Pure and Applied Chemistry) rules<\/strong>, selecting the longest parent chain<\/strong> is the most crucial step. Here\u2019s how you can do it easily:<\/p>\n

\u00a0Rule 1: Select the Longest Continuous Chain<\/strong><\/h3>\n

\u00a0The parent chain<\/strong> is the longest continuous carbon chain<\/strong> present in the compound.<\/p>\n

Example:<\/strong>
CH\u2083\u2013CH\u2082\u2013CH\u2082\u2013CH\u2083<\/strong> (Butane)
CH\u2083\u2013CH\u2013CH\u2082\u2013CH\u2083<\/strong>
\u2003\u2003\u2003|
\u2003\u2003CH\u2083<\/strong>
Here, the longest chain has 4 carbon atoms<\/strong>, so the parent name is butane<\/strong>.<\/p>\n

\u00a0Rule 2: Consider the Chain with Maximum Substituents<\/strong><\/h3>\n

\u00a0If two chains of equal length exist, choose the one with more branches (substituents).<\/strong><\/p>\n

Example:<\/strong>
CH\u2083\u2013CH\u2082\u2013CH\u2013CH\u2083<\/strong>
\u2003\u2003\u2003|
\u2003\u2003CH\u2083<\/strong>
(Choose the chain with the methyl (-CH\u2083) group<\/strong>)<\/p>\n

\u00a0Rule 3: Consider Functional Groups<\/strong><\/h3>\n

\u00a0If a functional group<\/strong> (like \u2013OH, \u2013COOH, =O, \u2013NH\u2082) is present, choose the longest chain that includes the functional group<\/strong>.<\/p>\n

Example:<\/strong>
CH\u2083\u2013CH\u2013CH\u2082\u2013COOH<\/strong>
\u2003\u2003\u2003|
\u2003\u2003CH\u2083<\/strong>
(The chain must include -COOH<\/strong> (carboxyl group), so the parent chain is butanoic acid<\/strong>).<\/p>\n

\u00a0Rule 4: Priority Order for Functional Groups<\/strong><\/h3>\n

\u00a0If multiple functional groups<\/strong> are present, follow this priority order for selecting the chain:
-COOH (Carboxylic acid) > -SO\u2083H (Sulfonic acid) > -COO- (Ester) > -CHO (Aldehyde) > -C=O (Ketone) > -OH (Alcohol) > -NH\u2082 (Amine) > Alkene > Alkyne > Alkane<\/strong><\/p>\n

Example:<\/strong>
CH\u2083\u2013CH\u2082\u2013CH\u2013OH<\/strong>
\u2003\u2003\u2003|
\u2003\u2003CH\u2083<\/strong>
(Here, the chain must include -OH<\/strong>, so it is butanol<\/strong>).<\/p>\n

\u00a0Rule 5: Choose the Chain with Maximum Double or Triple Bonds<\/strong><\/h3>\n

\u00a0If alkenes (-C=C-) or alkynes (-C\u2261C-)<\/strong> are present, the parent chain must include the longest sequence of multiple bonds<\/strong>.<\/p>\n

Example:<\/strong>
CH\u2083\u2013CH=CH\u2013CH\u2083<\/strong> (But-2-ene)
(Chain must include the double bond<\/strong>)<\/p>\n

\u00a0Summary: Easy Way to Select the Parent Chain<\/strong><\/h3>\n

Longest chain<\/strong> is the parent chain.
More branches (substituents)?<\/strong> Choose that chain.
Functional groups?<\/strong> Always include them.
Double\/triple bonds?<\/strong> Always include them.
If tie?<\/strong> Follow functional group priority.<\/p>\n

\u00a0Do you want practice questions or more examples?<\/strong><\/p>\n

IUPAC Nomenclature – Rules for Selection of Parent Chain In easy way Part 03.<\/a><\/h3>\n

Short Summary of IUPAC Nomenclature of Organic …<\/a><\/h3>\n

Brief Guide to the Nomenclature of Organic Chemistry<\/a><\/h3>\n

Some Basic Principles and Techniques: IUPAC …<\/a><\/h3>\n

Organic Compounds: Alkanes and Cycloalkanes<\/a><\/h3>\n

IUPAC nomenclature of organic chemistry<\/a><\/h3>\n

Nomenclature of Organic Compounds<\/a><\/h3>\n

Sure! Here’s an easy-to-understand guide<\/strong> to IUPAC Nomenclature \u2013 Rules for Selection of Parent Chain<\/strong> (Part-03), simplified for beginners, especially students of Class 11, NEET, JEE, or B.Sc.<\/strong> level.<\/p>\n

\n

\ud83e\uddea IUPAC Nomenclature \u2013 Part 03<\/strong><\/h1>\n

\ud83d\udd0d Rules for Selection of Parent Chain<\/strong><\/h2>\n

(In the easiest possible way)<\/em><\/p>\n

\n

\ud83d\udcd8 What is a Parent Chain?<\/strong><\/h2>\n

Parent Chain<\/strong> = The longest continuous chain of carbon atoms that contains the principal functional group<\/strong>, multiple bonds<\/strong>, and maximum substituents<\/strong>.<\/p>\n

\n

\u2705 Basic Rules to Select the Parent Chain (in order of priority):<\/strong><\/h2>\n
\n

\ud83d\udd39 Rule 1: Longest Chain Rule<\/strong><\/h3>\n

Choose the longest continuous chain of carbon atoms<\/strong>.<\/p>\n

Example:
\nIn CH\u2083\u2013CH\u2082\u2013CH\u2082\u2013CH\u2083
\n\u2192 Longest chain = 4 carbon atoms \u2192 Butane<\/strong><\/p><\/blockquote>\n

\n

\ud83d\udd39 Rule 2: Highest Priority Functional Group First<\/strong><\/h3>\n

If there\u2019s a functional group (like \u2013OH, \u2013COOH, \u2013CHO, \u2013NH\u2082), the parent chain must include<\/strong> it, even if it\u2019s not the longest chain.<\/p>\n

Example:
\nCH\u2083\u2013CH(OH)\u2013CH\u2082\u2013CH\u2082\u2013CH\u2083
\n\u2192 Include \u2013OH group \u2192 Parent chain = 5 carbons
\n\u2192 Compound = Pentanol<\/strong><\/p><\/blockquote>\n

\n

\ud83d\udd39 Rule 3: Maximum Number of Multiple Bonds<\/strong><\/h3>\n

If there\u2019s a double (=)<\/strong> or triple (\u2261)<\/strong> bond, the parent chain should include the maximum number of multiple bonds<\/strong>.<\/p>\n

Example:
\nCH\u2082=CH\u2013CH\u2082\u2013C\u2261CH
\n\u2192 Include both = and \u2261 \u2192 Parent chain = 5 carbons
\n\u2192 Name = Penta-1-en-4-yne<\/strong><\/p><\/blockquote>\n

\n

\ud83d\udd39 Rule 4: Maximum Substituents<\/strong><\/h3>\n

If there are two or more chains of equal length, choose the one with more substituents<\/strong>.<\/p>\n

Example:
\nTwo chains of 6 carbons \u2013 one has 2 methyl groups, one has 1
\n\u2192 Choose the one with 2 methyls<\/strong> (more substituents)<\/p><\/blockquote>\n

\n

\ud83d\udd39 Rule 5: Lowest Locant Rule<\/strong><\/h3>\n

Number the chain so that the functional group<\/strong>, multiple bonds<\/strong>, or substituents<\/strong> get the lowest possible number<\/strong>.<\/p>\n

Example:
\nCH\u2083\u2013CH\u2082\u2013CH=CH\u2013CH\u2083
\n\u2192 Number from left: But-2-ene<\/strong>, not But-3-ene<\/p><\/blockquote>\n

\n

\ud83e\udde0 Trick to Remember Order of Priority:<\/strong><\/h2>\n

\u27a4 Functional group > Double bond\/Triple bond > Substituents<\/h3>\n

When selecting or numbering, this is the priority order<\/strong>.<\/p>\n

\n

\ud83d\udcca Example Summary:<\/strong><\/h2>\n\n\n\n\n\n\n\n
Molecule<\/th>\nCorrect Parent Chain<\/th>\nReason<\/th>\n<\/tr>\n<\/thead>\n
CH\u2083\u2013CH(OH)\u2013CH\u2082\u2013CH\u2083<\/td>\n4 carbon chain<\/td>\nIncludes \u2013OH (functional group)<\/td>\n<\/tr>\n
CH\u2261C\u2013CH=CH\u2082<\/td>\n4 carbon chain<\/td>\nIncludes both \u2261 and =<\/td>\n<\/tr>\n
CH\u2083\u2013CH\u2082\u2013C(CH\u2083)\u2082\u2013CH\u2082\u2013CH\u2083<\/td>\n5 carbon chain<\/td>\nHas 2 methyl substituents<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
\n

\ud83e\uddea Coming Up in Part 04:<\/h2>\n