8 public questions tagged with this topic.
A benzylic alcohol has the -OH group on a carbon directly attached to a benzene ring. C₆H₅CH₂OH (benzyl alcohol) fits this definition.
Ref: NCERT Class 12 Chemistry > Chapter 7: Alcohols, Phenols and Ethers > Topic: Chemical Reactions of Phenols and Ethers and Uses
An allylic alcohol has the -OH group on a carbon adjacent to a double bond. CH₂=CH-CH₂OH (allyl alcohol) fits this definition.
Ref: NCERT Class 12 Chemistry > Chapter 7: Alcohols, Phenols and Ethers > Topic: Chemical Reactions of Alcohols - Dehydration Oxidation Esterification
A tertiary halide has the halogen on a carbon bonded to three other carbons. CH₃CH₂C(CH₃)2Cl (2-chloro-2-methylbutane) is tertiary.
Ref: NCERT Class 12 Chemistry > Chapter 6: Haloalkanes and Haloarenes > Topic: Polyhalogen Compounds - Chloroform Iodoform DDT Freons
A vicinal dihalide has halogens on adjacent carbons. CH₃CHBrCH₂Br (1,2-dibromopropane) is a vicinal dihalide.
Ref: NCERT Class 12 Chemistry > Chapter 6: Haloalkanes and Haloarenes > Topic: Polyhalogen Compounds - Chloroform Iodoform DDT Freons
CH₃CH₂CH₂CHO (butanal, aldehyde) fits C₄H₈O, has a carbonyl, and no halogens, consistent with a negative Lassaigne’s test.
Ref: NCERT Class 11 Chemistry > Chapter 8: Organic Chemistry - Some Basic Principles and Techniques > Topic: Fundamental Concepts - Reaction Mechanism - Fission and Reaction Intermediates
Degree of unsaturation = (2C + 2 - H)/2 = (12 - 8)/2 = 2. CH₃CH₂C≡CCH₃ has one triple bond (2 units), fitting C₅H₈.
Ref: NCERT Class 11 Chemistry > Chapter 8: Organic Chemistry - Some Basic Principles and Techniques > Topic: Electronic Effects - Inductive Mesomeric Hyperconjugation and Resonance
In infrared spectroscopy, region from 4000 to 1000 cm-1, especially 4000-1500 cm-1, is designated functional group region because fundamental stretches of diagnostic bonds absorb with minimal coupling. Strong absorptions for X-H stretches including O-H, N-H, C-H near 3700-2800, triple bonds near 2260-2100, double bonds C=O, C=C near 1850-1550 cm-1 appear here, enabling quick classification of alcohols, amines, alkynes and carbonyls in biomolecules. Below 1000 cm-1 vibrations overlap producing fingerprint pattern reflecting molecular skeleton, better suited for identity confirmation than functional assignment, distinguishing primary chemistry from overall fingerprint.
Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.
Functional group identification relies on high-wavenumber region from 4000 to 1000 cm-1, where characteristic stretching vibrations remain relatively isolated from coupling. O-H stretching near 3600, N-H near 3300, C-H near 2900-3100, triple bonds near 2100-2260, carbonyl C=O near 1700 cm-1 appear prominently here. This window allows rapid recognition of alcohols, amines, alkanes, alkynes and carbonyls in proteins, lipids and nucleic acids. Below 1000 cm-1 skeletal vibrations overlap extensively, creating fingerprint pattern useful for confirmation rather than initial functional assignment, distinguishing primary chemistry from overall architecture.
Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.
