Amines Plymstock School P.J.McCormack

15 November, 2018 Amines P.J.McCormack

Learning Outcomes. By the end of the lesson I will be able to.... 15 November, 2018 Learning Outcomes. By the end of the lesson I will be able to.... All.. Explain why amines are basic Draw the structure of a primary secondary and tertiary amine Most.. Describe the reactions of amines with acids to for salts Describe the preparation of amines reaction from halogenoalkanes Describe the preparation of aromatic amines from nitrobenzene Some.. Describe the synthesis of azo dyes and the full chemical equations for each step. Low High Key Words: alkali, trend electron configuration P.J.McCormack

15 November, 2018 Structures of Amines There are three classes of amines – primary, secondary and tertiary Secondary – dimethyl amine Primary – methyl amine Tertiary – trimethyl amine Quaternary – Tetramethyl ammonium chloride P.J.McCormack

Basic Behaviour of Amines 15 November, 2018 Basic Behaviour of Amines Like ammonia amines are weak bases. They react with water as follows: CH3CH2NH2 + H2O CH3CH2N+H3 + OH- The production of hydroxide ions (OH-) causes the aqueous solution to be alkaline. P.J.McCormack

Basic Behaviour of Amines 15 November, 2018 Basic Behaviour of Amines The production of hydroxide ions (OH-) causes the aqueous solution to be alkaline. As with all bases, amines will react with acids to form salts: CH3CH2NH2 + HCl  CH3CH2N+H3Cl- ethylammonium chloride (CH3CH2)2NH + HCl  (CH3CH2)2N+Cl- diethylammonium chloride (CH3CH2)3N + HCl  (CH3CH2)3N+Cl- triethylammonium chloride P.J.McCormack

Basic Behaviour of Amines 15 November, 2018 Basic Behaviour of Amines In each of the reactions above the mine accepts an H+ ion from the hydrochloric acid (proton acceptor). The lone pair of electrons on the nitrogen atom in the amine forms a dative covalent bond with the H+ ion, e.g. P.J.McCormack

Basic Behaviour of Amines 15 November, 2018 Basic Behaviour of Amines The strength of the amine as a base depends on three things: the availability of the nitrogen’s lone pair to bond with the H+ the stability of the positive ion formed the solubility of the amine. Amine Kb /mol dm-3 Ethylamine 5.1 x 10-4 Diethylamine 10.0 x 10-4 Triethylamine 5.6 x 10-4 Phenylamine 4.2 x 10-10 P.J.McCormack

Diazonium Salt Formation 15 November, 2018 Diazonium Salt Formation This reaction, called a diazotisation reaction is very important in the manufacture of dyes. Essentially it is a reaction between phenylamine and nitric(III) acid, HNO2, or nitrous acid. The nitric(III) acid is made by adding sodium nitrate(III), NaNO2, to concentrated hydrochloric acid. NaNO2 + HCl  HNO2 + NaCl P.J.McCormack

Preparation of Amines Ammonia can be added to a halogenoalkane: 15 November, 2018 Preparation of Amines Ammonia can be added to a halogenoalkane: A better way is the reduction of a nitro-compound or a nitrile: CH3CH2NO2 + 6[H]  CH3CH2NH2 + 2H2O LiAlH4 in ether then H2O CH3CN + 4[H]  CH3CH2NH2 Na/ethanol P.J.McCormack

Preparation of Phenylamine 15 November, 2018 Preparation of Phenylamine Phenylamine is prepared by reducing nitrobenzene: The reduction is carried out using tin and concentrated hydrochloric acid P.J.McCormack

15 November, 2018 Coupling Reaction In industry the diazonium ion is used to react with other benzene compounds to form brightly coloured azo dyes. An example of the production of one azo dye is as follows: P.J.McCormack

15 November, 2018 BoB.Ex You have 90 seconds to list as many facts as you can about groups 1 metals and their compounds. P.J.McCormack

Lesson 2 Objective 15 November, 2018 Describe and explain the trends in chemical and physical properties down Group 1. http://www.youtube.com/watch?v=nsbXp64YPRQ P.J.McCormack