Prakhar Gupta has 4+ years of experience in Content Marketing Field. 

Content Marketing Specialist

Today we will talking about Nomenclature of organic compounds and Reaction Intermediates.

<h2 id="content-id-1965-0">Nomenclature of organic compounds</h2>

Trivial System:

It is the oldest system in which names are derived from source or some property. These are mainly derived from Latin or Greek names. e.g. acetic acid (acetum = vinegar), oxalic acid (oxalis), malic acid (pyrus malus), citric acid (citrum), formic acid (obtained from red ant (formicus)].

IUPAC System:

The IUPAC (International Union of Pure and Applied Chemistry) system, given in 1957, is superior and widely used. IUPAC amends these rules from time to time. Here, we are following the 1993 recommendations of IUPAC nomenclature. Following rules are used to write the IUPAC name of an organic compound.

Rule 1 (Longest chain rule): The chain containing the principal functional group, secondary functional group and multiple bonds as many as possible is the longest possible chain. In the absence of functional group, secondary group and multiple bonds, the chain containing the maximum number of C-atoms will be the longest possible chain.

<img loading="lazy" alt="Longest chain Diagram Representation" src="https://study.kdcampus.live/admin/assets/uploads/ckeditor/Longest chain Diagram Representation.webp" style="height:67px; width:250px">

For example, choose the word root from the table given below for the longest possible chain.

<table cellspacing="0" class="Table" style="border-collapse:collapse; border:none; margin-left:16px">
	<tbody>
		<tr>
			<td>
			2
			</td>
			<td>
			Word root
			</td>
			<td>
			Chain Length
			</td>
			<td>
			Word root
			</td>
		</tr>
		<tr>
			<td>
			C1
			</td>
			<td>
			Meth-
			</td>
			<td>
			C7
			</td>
			<td>
			Hept
			</td>
		</tr>
		<tr>
			<td>
			C2
			</td>
			<td>
			Eth-
			</td>
			<td>
			C8
			</td>
			<td>
			Oct
			</td>
		</tr>
		<tr>
			<td>
			C3
			</td>
			<td>
			Prop-
			</td>
			<td>
			C9
			</td>
			<td>
			Non
			</td>
		</tr>
		<tr>
			<td>
			C4
			</td>
			<td>
			But-
			</td>
			<td>
			C10
			</td>
			<td>
			Dec
			</td>
		</tr>
		<tr>
			<td>
			C5
			</td>
			<td>
			Pent-
			</td>
			<td>
			C11
			</td>
			<td>
			Undec
			</td>
		</tr>
		<tr>
			<td>
			C6
			</td>
			<td>
			Hex-
			</td>
			<td>
			C12
			</td>
			<td>
			Dodec
			</td>
		</tr>
	</tbody>
</table>

Rule 2 (Lowest number rule): Numbering is done in such a way so that:

<ol>
	<li>Branching if present gets the lowest number.</li>
	<li>The sum of numbers of the side chain is lowest.</li>
	<li>The principal functional group gets the lowest number.</li>
</ol>

Select the principal functional group from the preference series:

Functional groups other than the principal functional group are called substituents.

Rule 3 (Naming the prefixes and suffix): Prefix represents the substituent and suffix is used for the principal functional group. Primary prefixes are cyclo, bicyclo, di, tri, tetra, tries, tetrakis etc. Primary suffixes are ene, ane, or yne used for double, single and triple bonds respectively.

Some few examples of prefixes:

<table cellspacing="0" class="Table" style="border-collapse:collapse; border:none; margin-left:15px">
	<tbody>
		<tr>
			<td>
			Substituent
			</td>
			<td>
			Prefix
			</td>
			<td>
			Substituent
			</td>
			<td>
			Prefix
			</td>
		</tr>
		<tr>
			<td>
			-F
			</td>
			<td>
			Fluoro
			</td>
			<td>
			-N=N-
			</td>
			<td>
			Diazo
			</td>
		</tr>
		<tr>
			<td>
			-Cl
			</td>
			<td>
			Chloro
			</td>
			<td>
			-N=O
			</td>
			<td>
			nitroso
			</td>
		</tr>
		<tr>
			<td>
			-Br
			</td>
			<td>
			Bromo
			</td>
			<td>
			-NO2
			</td>
			<td>
			nitro
			</td>
		</tr>
	</tbody>
</table>

Hence, according to the rules, given above, the IUPAC name of a compound can be written as

Prefixes + root word + suffixes primary prefix + secondary prefix root word primary suffix secondary suffix

Example: C2H5OH stands for ethanol.

Attacking Reagents:

These are of three types:

<ol>
	<li>Electrophiles or Electrophilic Reagents: These are electron deficient species i.e. they behave as Lewis acids. The following species behave as electrophiles: 

	<ol>
		<li>All non-metal cations and metal cations which have vacant d-orbitals. e.g. Cl+ , NO+ 2 , CH3CO+ etc.</li>
		<li>Lewis acids (incomplete octet), e.g. BF3 , ZnCl2 (anhydrous), FeCl3 (anhydrous), AlCl3 (anhydrous), CH2 etc.</li>
		<li>Non-metal (acidic) oxides e.g. CO2 , SO2 etc.</li>
	</ol>
	</li>
	<li>Nucleophiles or Nucleophilic Reagents: These are electron rich species i.e. behave as Lewis bases. These attack at electron-deficient areas. The following species behave as nucleophiles:
	<ol>
		<li>All anions e.g. Cl- , NH2 - , OH- etc.</li>
		<li>Lewis bases</li>
		<li>Benzene, alkenes etc.</li>
	</ol>
	</li>
</ol>

Nucleophilicity order is H- > CH-3 > NH-2 > OR- > OH-

In the case of the same nucleophilic site, nucleophilicity parallels basicity i.e. as the basicity increases, nucleophilicity also increases.

3. Ambiphiles: These species behave like both electrophiles as well as nucleophiles. Organic compounds containing a multiple bond between carbon and a more electronegative atom can act as ambiphiles.

<h2 id="content-id-1965-1">Reactions intermediates</h2>

These are formed as an intermediate during the course of a reaction. These are short lived and highly reactive. Free radicals, carbocations, carbanions, carbenes and nitrenes are important reactions intermediates.

<ol>
	<li>Free Radicals: These are the product of homolysis and contain an odd electron. These are highly reactive planar species with sp2 - hybridisation. Their order of stability is 2. 
	<img loading="lazy" alt="Free radicals Diagram Representation" src="https://study.kdcampus.live/admin/assets/uploads/ckeditor/Free radicals Diagram Representation.webp" style="height:47px; width:250px"></li>
	<li>Carbocations: These are the product of heterolysis and contain a carbon bearing positive charge. These are electron-deficient species. Carbocations contain six electrons in the valence shell. These are also planar chemical species, i.e. sp2 -hybridized with an empty p-orbital. The stability order of carbocations is: 
	<img loading="lazy" alt="Carbocations Diagram Representation" src="https://study.kdcampus.live/admin/assets/uploads/ckeditor/Carbocations Diagram Representation.webp" style="height:44px; width:238px"></li>
	<li>Carbanions: These are also the product of heterolysis and contain a carbon bearing negative charge and 8 electrons in its valence shell. These have a pyramidal shape with sp3 -hybridised carbon (having one lone pair) The order of stability of carbanions is  
	<img loading="lazy" alt="Carboanions Diagram Representation" src="https://study.kdcampus.live/admin/assets/uploads/ckeditor/Carboanions Diagram Representation.webp" style="height:42px; width:265px"></li>
	<li>Carbenes: These are divalent carbon species having two non-bonding electrons along with two bond pairs. These are obtained by photolysis or pyrolysis, e.g.  
	<img loading="lazy" alt="Carbenes Diagram Representation" src="https://study.kdcampus.live/admin/assets/uploads/ckeditor/Carbenes Diagram Representation.webp" style="height:52px; width:181px">
	<ol>
		<li>Singlet carbene: In it, the C-atom is sp2 -hybridized. The unhybridized orbitals contain no electrons and a hybridised orbital contains two electrons: 
		<img loading="lazy" alt="Singlet Carbenes Diagram Representation" src="https://study.kdcampus.live/admin/assets/uploads/ckeditor/Singlet Carbenes Diagram Representation.webp" style="height:122px; width:128px"> 
		Singlet carbene has a bent structure and is less stable than triplet carbene. The order of stability of singlet carbenes is 
		<img loading="lazy" alt="Singlet Carbenes Order Diagram Representation" src="https://study.kdcampus.live/admin/assets/uploads/ckeditor/Singlet Carbenes Order Diagram Representation.webp" style="height:44px; width:261px"></li>
		<li>Triplet carbene: In it, the central C-atom is sp-hybridised. The unhybridised orbitals contain 1 electron each Triplet carbene has linear geometry. 
		<img loading="lazy" alt="Triplet Carbenes Diagram Representation" src="https://study.kdcampus.live/admin/assets/uploads/ckeditor/Triplet Carbenes Diagram Representation.webp" style="height:123px; width:154px"></li>
	</ol>
	</li>
	<li>These being electron deficient behave as Lewis acids. These are of two types:</li>
	<li>Nitrene: These are neutral monovalent nitrogen species in which the N atom has two unshared pairs of electrons with a monovalent atom or group attached. These are obtained by thermolysis of asides and are as reactive as carbenes. These are of two types : singlet nitrene and triplet nitrene. </li>
</ol>

In next blog we extend our discussion further deep and study about Electromeric and Resonance Effect etc.

Since 1995, Neetu Mam is Providing Free Content for English to the Students

Best Publisher for English Content

Learn the&nbsp;key concepts&nbsp;of&nbsp;Nomenclature of organic compounds&nbsp;

Learn the key concepts of Science topic -  Nomenclature of organic compounds

Latest Notifications

Exam Eligibility

Exam Dates

Exam Pattern

Syllabus

Admit Card

Exam Cutoff

Answer Key

Exam Results

Daily Current Affairs

Current Affairs Quiz

Daily Editorial

Daily Vocabulary

Study Plan

Important Days

Question Paper

Previous Year PDF

English Language

Logical Reasoning

Quantitative Aptitude

General Knowledge

General Awareness

General Science

Today in History

Know Your State

Full Form

Know Your Country

Government Schemes

Know Your City

Know Your Leader

Books and Authors

question answer

Quiz

Courses

Classes

Learn the key concepts of Science topic - Human Digestive system

No title

General Science Most Asked Questions in SSC CGL Till Date

Click to study the Complete Theory of Nomenclature of organic compounds and practice a lot of questions difficulty wise on this chemistry topic that can be asked in your competitive exam.

Learn the key concepts of Science topic - Nomenclature of organic compounds

Nomenclature of organic compounds FAQs

Nomenclature of organic compounds Comments:

Nomenclature of organic compounds RELATED ARTICLES