(v) Since the electronegativity of O is higher than thalof N, therefore, alcohols form stronger H-bonds than amines. Aniline, due to high electron density at ortho and para-positions, is ortho and para directing towards electrophilic substitution reaction. Chemistry Class 12 Important Questions are very helpful to score high marks in board exams. Acid anhydrides on reaction with primary amines give ____________. Write the structures of different isomeric amines corresponding to the molecular formula, C 4 H 11 N. (i) Write the IUPAC names of all the isomers The distinction in the three types of amines can be done by the following methods : Classify the following amines as primary, secondary and tertiary: Ans: (i) 1° (ii) -3° (iii) 1° (iv) 2° 13.2. Therefore correct order of decreasing pKb values is: 2. In the nitration of benzene using a mixture of conc. This is a very useful test for the distinction of primary, secondary and tertiary amines. Methylamine reacts with HNO 2 to form _________. Also this part will make you familiar with Diazonium salts. NCERT INTEXT QUESTIONS. Since aryl halides do not undergo nucleophilic substitution reactions easily, therefore, arylamines, i.e., aromatic, primary amines cannot be prepared by Gabriel phthalimide reaction. It involves the treatment of phthalimide with ethanolic potassium hydroxide to form potassium salt of phthalimide. •    It has tendency to explode when dry. Solution: (c) Amines on acetylation give monosubstituted product, while on alkylation gives polysubstitution product as well. (iii) Cl-(CH2)4-Cl into Hexane -1,6- diamine (b) Aromatic amines arS more stable than corresponding protonated ion; Hence, they hag very less tendency to combine with a proton to form corresponding protonated ion, and thus they are less basic. Part-I was all about the introduction to amines along with the methods of preparation of of amines, their physical properties and basicity. R—NH2—>R—NH– +H+ (ii) Reaction with nitrous acid: Ans: 13.8. In case the alkyl group is bigger than CH, Therefore, the change of nature of the alkyl group, e.g., from –CH. Here Kt is called dissociation constant for the base. Class 12 Chemistry Amines: Structure-basicity relationship of amines: Structure-basicity relationship of amines. (iii) Methylamine in water reacts with ferric chloride to precipitate hydrated ferric oxide. Secondary and tertiary amines do not show this reaction. Reaction with acid chlorides, anhydrides and esters by nucleophilic substitution reaction is known as acylation. In presence of these acids, most of aniline gets protonated to form ahilinium ion. The greater the size of the ion, lesser will be the solvation and the less stabilised is the ion. quite unstable and decompose to form a mixture of alcohols, alkenes and alkyl halides along with the evolution of N2 gas. nitrogen gas accompanied by brisk effervescence. (iv) Coupling reaction: In this reaction, arene diazonium salt reacts with aromatic amino compound (in acidic medium) or a phenol (in alkaline medium) to form brightly coloured azo compounds. Aromatic amines react with nitrous acid at low temperatures (273-278 K) to form diazonium salts, a very important class of compounds used for synthesis of a variety of aromatic compounds. (vii) Gabriel phthalimide synthesis is preferred for synthesising primary amines. (iii) ‘Hofmann’s bromamide reaction Hinsberg’s reagent (benzene suiphonyl chloride) in the presence of excess of aqueous KOH solution. (iii) Heating alkylhalide with potassium salt of phthalimide followed by hydrolysis. In other words, these are all Lewis bases. It can readily lose its electron pair and acts as a base. (i) Write the IUPAC names of all the isomers This reaction is called carbylamine reaction. The order of stability of ions are as follows: Thus, the order of basicity of aliphatic amines should be: primary > secondary > tertiary, which is opposite to the inductive effect based order. Which of the following should be most volatile? (vi) In increasing order of solubility in water: (iv) Ethanamine into methanamine (1)Substitution reactions involving replacement of diazonium group. The product of the following reaction is __________. Here you can get Class 12 Important Questions Chemistry based on NCERT Text book for Class XII. (iv) Aniline to 2,4,6-tribromofluorobenzene Note : Match the items of Column I and Column II in the following questions. 13.13. Which of the following compounds is the weakest Brönsted base? Therefore, basic strength depends only upon the +I-effect of the alkyl groups. These quick notes are prepared strictly according to the latest CBSE syllabus for Class 12th Chemistry. Generally, a mixture of primary, secondary and tertiary amine is formed. H, (ii) Acetic anyhdride/pyridine followed by conc.

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