Nitrogen Compounds | Prep and Chemical Reactions of Amines | A level H2 Chem | Making Sense Chem скачать в хорошем качестве

Nitrogen Compounds | Prep and Chemical Reactions of Amines | A level H2 Chem | Making Sense Chem

A LEVEL CHEMISTRY!! music by: Zight - Paradise - https://thmatc.co/?l=3B73F710 In today's video, we will be re-looking at the most important concepts in the chapter Amines! 0:00 Introduction 1:18 What are amines 1:34 Reduction of nitrobenzene to form phenylamine 5:14 Basicity of Amines 9:29 Nucleophilicity of Amines 11:37 Reactions of Amines What is an amine? -NH2 group directly bonded to C Aliphatic amine: the C is saturated (sp3); Phenylamine: the C is part of a benzene ring Reduction of nitrobenzene to form phenylamine Reduction of nitrobenzene Reagents and Conditions: Sn, and excess conc. HCl, heat Followed by NaOH(a.q.), r.t.p Consider the half eqn: 6 e- + 6 H+ + RNO2 = RNH2 + 2H2O Sn is NOT a catalyst but the reducing agent (since it gets oxidised to Sn2+ to release electrons for reduction) Excess conc. HCl is the source of protons used to form -NH2 Since phenylamine (Ar-NH2) is basic, it reacts with the excess H+ to form the conjugate acid (Ar-NH3+). NaOH(aq) added to the conjugate in an acid-base reaction to generate Ar-NH2 from Ar-NH3+ Ar-NH2 is then distilled out of the mixture (since it has a lower bp than Ar-NH3+) Basicity of amines: 1) Bronsted base (in aqueous medium) lone pair on N accepts H+ from water 2) Lewis base (in gaseous phase) lone pair on N atom is available for donation to an electrophile (not H+) 3) Relative Basicity higher the availability of the lone pair = stronger the base Gaseous phase: (1° amine less basic than 2° amine less basic than 3° amine) since more electron-donating alkyl groups increases the e- density about N atom, making lone pair more available = more basic Aqueous medium: R- NH2 more basic than NH3 more basic than phenylamine R- NH2 more basic than NH3 because electron-donating R group increases e- density on N atom, making lone pair more available NH3 more basic than phenylamine since the lone pair of N in phenylamine can delocalise into the benzene ring, making the lone pair of N less available Delocalisation can occur only if the p-orbitals are parallel and adjacent Nucleophilicity of amines: Amines are nucleophilic due to the lone pair on N atom more available lone pair = stronger nucleophile R- NH2 more basic than NH3 more basic than phenylamine R- NH2 more basic than NH3 since electron-donating R group increase e- density on N atom, making lone pair more available NH3 more basic than phenylamine since the lone pair of N can delocalise into the benzene ring, making the lone pair of N less available 3o amines are less nucleophilic than expected due to steric hindrance of extra alkyl groups on the lone pair on N. TLDR: 3° amines can be more/less nucleophilic than 1°/2° amines! LOOK AT DATA TO VERIFY! Reactions of amines: Nucleophilic acyl substitution to form amides: Reagents: R’COCl (acyl chlorides) Conditions: r.t.p To quickly determine products, circle away one H and one Cl to form an amide and HCl Mechanism: nucleophile (lone pair of N in amine) attacks electrophile (C in COCl) kicking out Cl as a leaving group! Halogenation of phenylamine (electrophilic substitution): Reagents: X2 (aq) Conditions: r.t.p Observations: 1) orange bromine decolourises, 2) white ppt of 2,4,6 tri-halogenated phenylamine Halogen carrier catalyst NOT needed (unlike halogenation of benzene) since -NH2 is a strong electron-donating group, which activates the benzene ring of phenylamine and turns it into a much stronger nucleophile Looking for free chemistry resources? Vist our website at: https://www.makingsense-sg.com/free-t... to view other learning resources (content videos + free resources). Follow us on: Youtube - Making Sense Tuition Centre Tik tok - @makingsensechemistry Instagram - @makingsensechemistry Facebook - Making Sense, Singapore's Leading Chemistry Tuition The Best Chemistry tuition! #indigoeducationgroup #bestchemistrytuition  #makingsensechemistry #learningisfun #videolessons #educationalvideos #easyandfunlearning #nitrogencompounds #amines #phenylamine #nucleophiles #halogenation #chemicalproperties #chemicalreactions