Medicneet Logo
NEET 2019 · ChemistryPrevious Year Question

The correct order of the basic strength of methyl-substituted amines in aqueous solution is:

Answer: (A) . \textbf{Answer:} (a) \textbf{Solution:} In aqueous solution the basicity of amines is governed by three competing factors: the effect (methyl groups donate electron density to N), steric hindrance (bulky groups hinder protonation), and solvation/H-bonding stabilisation of the conjugate cation (more N-H bonds give more H-bonding stabilisation).

  1. A.✓
  2. B.
  3. C.
  4. D.

Correct Answer

(A)

Solution & Explanation

\textbf{Answer:} (a) \textbf{Solution:} In aqueous solution the basicity of amines is governed by three competing factors: the effect (methyl groups donate electron density to N), steric hindrance (bulky groups hinder protonation), and solvation/H-bonding stabilisation of the conjugate cation (more N-H bonds give more H-bonding stabilisation). The net result for methylamines in water is . Trimethylamine is least basic because steric crowding and poor solvation outweigh the inductive effect.

🎯
43,000+ questions in हिंदी & English · one-tap toggle
Practice NEET 2019 Chemistry — free, with instant solutions
43,000+ NEET questions solved step-by-step, chapter-wise, in the MedicNEET app.
📚Practice all NEET Chemistry PYQs chapter-wise →💡Don't get it? Learn the General Principles Of Organic Chemistry concepts →
← Chemistry Q16Chemistry Q18 →

More NEET PYQ solutions

ChemIdentify the suitable reagent for the following conversion: C6H5COOCH3 -> C6H5CHO (methyl benzoate to benzaldehyde)ChemThe correct order of decreasing acidity of the following aliphatic acids isChemThe major product of the following reaction is: 4-oxo-4-phenylbutanenitrile C6H5-CO-CH2-CH2-CN is treated with (i) CH3MgBr (excess) and then (ii) H3O+.ChemOut of the following complex compounds, which compound will have the minimum conductance in solution?ChemWhich of the following are paramagnetic? A. [NiCl4]^2- B. Ni(CO)4 C. [Ni(CN)4]^2- D. [Ni(H2O)6]^2+ E. Ni(PPh3)4ChemThe correct order of the wavelength of light absorbed by the following complexes is: A. [Co(NH3)6]^3+ B. [Co(CN)6]^3- C. [Cu(H2O)4]^2+ D. [Ti(H2O)6]^3+ChemThe correct order of decreasing basic strength of the given amines is: (N-ethylethanamine = (C2H5)2NH; ethanamine = C2H5NH2; N-methylaniline = C6H5NH(CH3); benzenamine/aniline = C6H5NH2)ChemPredict the major product P in the following sequence of reactions. The starting material is 1-methylcyclopent-1-ene: (i) HBr, benzoyl peroxide; (ii) KCN; (iii) Na(Hg)/C2H5OH P (major). The structures of the options (A)-(D) are shown in the image below:
More: All NEET 2019 Chemistry PYQs · NEET Chemistry PYQs · All NEET PYQs · Previous year papers