Q.Write the IUPAC name of CH3OCH2CH2Cl.
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🔒 Start your 14-day free trial to unlock the full solution →Concept understanding — Classification of Haloalkanes and Haloarenes
Classification of Haloalkanes and Haloarenes
Organic halogen compounds are classified by the hybridisation and environment of the carbon bearing the halogen:
- Alkyl halides (haloalkanes) — X on an sp3 carbon; further divided as primary, secondary or tertiary by the number of carbons attached to the C–X carbon (e.g. chlorocyclohexane is a secondary halide).
- Allylic halides — X on an sp3 carbon adjacent to a C=C double bond.
- Benzylic halides — X on an sp3 carbon attached directly to an aromatic ring (e.g. 1-bromo-1-phenylethane).
- Vinylic halides — X on an sp2 carbon of a C=C double bond.
- Aryl halides (haloarenes) — X directly on an sp2 carbon of the aromatic ring (e.g. 3-bromotoluene). …
Naming this compound requires treating its ether oxygen as a substituent prefix rather than as the parent suffix, then numbering the two-carbon chain to give the lowest possible locants to both substituents. …
CH3OCH2CH2Cl is named 1-chloro-2-methoxyethane.
The compound CH3–O–CH2–CH2–Cl has a two-carbon chain (ethane) bearing two substituents: a chloro group and a methoxy (–OCH3, an ether-oxygen substituent, since the lower-priority ether function is named as an alkoxy substituent prefix rather than the parent suffix here).
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- CBSE 2026Set ANNUAL1 markQ.The chemical formula of allyl bromide is ______ (fill in the blank).
›Reveal solutionSolution
Allyl bromide is the bromide of the allyl group (CH2=CH-CH2-), so its formula is CH2=CH-CH2Br.
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- CBSE 2025Set ANNUAL1 markMCQQ.The hybridised state of carbon atom attached to halogen atom in benzylic halide is -(a) sp(b) sp2(c) sp3(d) sp3d
›Reveal solutionSolution
A benzylic halide has the general structure Ar-CH2-X (or a substituted variant); the halogen-bearing carbon makes 4 single (sigma) bonds, so it is sp3 hybridised.
In a benzylic halide such as benzyl chloride, C6H5-CH2-Cl, the carbon attached to the halogen atom is bonded to:
- the aromatic ring carbon (single/sigma bond) 2 & 3. two hydrogen atoms
- the halogen atom …
- CBSE 2025Set ANNUAL1 markMCQQ.The compound CH3CH2C(CH3)2CH2Cl is a ........................ .(a) primary alkyl halide(b) primary allyl halide(c) secondary alkyl halide(d) secondary benzyl halide
›Reveal solutionSolution
The class of a haloalkane (1°, 2°, 3°) is decided by how many carbons are attached to the carbon bearing the halogen — not by how substituted that neighbouring carbon is.
In CH3–CH2–C(CH3)2–CH2–Cl, the carbon bearing chlorine is the terminal –CH2Cl carbon. Look only at this carbon: it is bonded to Cl, two H atoms, and just ONE other carbon (the quaternary-like C(CH3)2 carbon). Since exactly one ca …
- CBSE 2024Set 56/2/11 markMCQQ.Which of the following contains sp2 hybridised carbon bonded to X ? (A) CH2=CH−CH2−X (B) C6H5−CH2−X (C) CH2=CH−X (D) CH3−CH2−X
›Reveal solutionSolution
The question asks which molecule has an sp2 hybridised carbon directly bonded to the leaving group X. Only option (C) CH2=CH−X has the X attached to a vinylic carbon (which is sp2 hybridised). The correct answer is (C).
Concept and Intuition
The key idea here is hybridisation of the carbon atom that is directly attached to the group X. X could be any halogen or substituent — the question is about the carbon’s orbital geometry, not about X itself.
Hybridisation is determined by the number of sigma bonds and lone pairs around a carbon.
- A carbon with four sigma bonds (like in an alkane) is sp3 hybridised.
- A carbon with three sigma bonds and one pi bond (like in an alkene or aromatic ring) is sp2 hybridised.
- A carbon with two sigma bonds and two pi bonds (like in an alkyne) is sp hybridised.
So we need to check, in each option, the carbon that holds X: is it making a double bond (or part of an aromatic ring) or only single bonds?
Let’s go through each option one by one.
Step-by-step analysis
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Option (A): CH2=CH−CH2−X
Draw the structure:
CH2=CH−CH2−X
The carbon bonded to X is the last carbon — it is CH2−X. This carbon has four single bonds (to two H atoms, to the adjacent carbon, and to X). No double bond. So it is sp3 hybridised.
Not the answer.
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Option (B): C6H5−CH2−X
This is benzyl halide (or benzyl derivative). The carbon attached to X is the CH2 group directly attached to the benzene ring. That carbon is bonded to: the ring carbon, two H atoms, and X — again four sigma bonds, no pi bond. So it is sp3 hybridised.
Watch outA common mistake is to think that because the benzene ring has sp2 carbons, the side-chain carbon is also sp2. It is not — the CH2 group is saturated. Only the ring carbons are sp2.
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Option (C): CH2=CH−X …
- CBSE 2024Set ANNUAL1 markMCQQ.Tertiary alkyl halide among the following is(a) 2-chlorobutane(b) secondary butyl chloride(c) isobutyl chloride(d) 3-chloro-3-methyl pentane
›Reveal solutionSolution
An alkyl halide is classified as primary, secondary, or tertiary by how many carbon groups are attached to the carbon bearing the halogen.
Checking each:
- 2-chlorobutane, CH3-CHCl-CH2-CH3: the C-Cl carbon is attached to 2 other carbons -> secondary halide.
- Secondary butyl chloride: by name, this is a secondary halide (same as 2-chlorobutane).
- Isobutyl chloride, (CH3)2CH-CH2-Cl: the C-Cl carbon (a CH2) is attached to only 1 other carbon -> primary halide. …
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