AMINES

Naming How many chains are coming off the Nitrogen atom in the amine Count the number of carbons in each chain Name each chain as a branch Add the word amine after the branch(es)

Name the following CH 3 NH 2 CH 3 CH 2 CH 2 CH 2 NH 2 CH 3 NHCH 3 CH 3 CH 2 NHCH 3 (CH 3 ) 3 N 1 C in branch Hence Methyl Hence Methylamine 1C in each branch Hence dimethyl Hence dimethylamine 4C in branch Hence Butyl Hence Butylamine 1C in first branch and 2 C in second branch Hence Ethylmethyl Hence Ethylmethylamine 1C in all three first branches Hence trimethyl Hence trimethylamine

Primary Secondary and Tertiary Count the number of branches off the Nitrogen in the amine Only 1C = If 2C = If 3 C = Primary amine Secondary amine tertiary amine Primary Secondary Tertiary

Structure of amines What are these? What is the bond angle? Lone Pair O What chemistry do we expect? Charge here on C Charge here on N

BP/MP? What can form between two Amine molecules? Can you draw it? What does this mean in terms of properties A hydrogen bond MP/Bp are higher than expected because the intermolecular force (H-Bond) is stronger than a typical VDW so more energy si required to break them.

Preparation of amines Nucleophilic substitution reaction between Ammonia and Halogenoalkanes dissolved in ethanol Write the equation for the formation of a.CH 3 NH 2 b.CH 3 CH 2 NH 2 c.CH 3 NHCH 3 CH 3 Cl + 2NH 3 CH 3 NH 2 + NH 4 Cl in ethanol CH 3 CH 2 Cl + 2NH 3 CH 3 CH 2 NH 2 + NH 4 Cl in ethanol 2CH 3 Cl + 3NH 3 CH 3 NHCH 3 + 2NH 4 Cl in ethanol NB: Amines will react with halogenoalkanes as well to form secondary amines The by product HCl will also react with ammonia to form Ammonium Chloride Click here for mechanism for the above reactions

Water soluble? What can form between two Amine molecules? What can form between two water molecules? What can form between an amine and a water molecule Can you draw them? A hydrogen bond The ability to form H-bonds with the water molecules means that amines dissolve in water

Acid or Base? What is present on the Nitrogen of the amine? What will be attracted to a Nitrogen atom? What can happen next? A lone pair AND a slight negative charge A hydrogen ions The lone pair of electrons on the Nitrogen are donated to the H + ion forming a dative covalent bond The ability accept an H+ ion means that Amines are BASES

Equations for base behaviour Addition of water Addition of H + Addition of HCl Addition of H 2 SO 4 RNH 2 + H 2 O  RNH OH - RNH 2 + H +  RNH 3 + RNH 2 + HCl  RNH Cl - 2RNH 2 + H 2 SO 4  2RNH SO 4 -2

Other reactions of amines What might happen when you add amines to a.Iodomethane (or other halogenoalkanes) a.Acetyl Chloride (CH 3 COCl) Substituted amines will form CH 3 I + 2RNH 2  RNHCH 3 + RNH 3 I Amides will form CH 3 COCl + 2RNH 2  RNHCOCH 3 + RNH 3 I

Phenylamine Questions to ask How is this molecule formed? What is the chemistry of this molecule? Why?

Preparation- How? Reduction of Nitrobenzene using Sn and Conc HCl Can you write an equation? + 6[H] + 2H 2 O

Reactions of Phenylamine Where will the lone pair be on the Nitrogen? How does this effect the basic nature of phenylamine Why? Incorporated into the pi cloud of the benzene ring. The p orbital on the Nitrogen overlaps with the P orbitals on the benzene ring Makes phenylamine less basic The lone pair is longer available to donate to an H + so phenylamine does not accept a proton as readily as other amines

Reactions of the benzene ring in Phenylamine What will be the effect on the electron density in the ring? Electron density will increase. Phenylamine will be able to polarise molecules or attract an electrophile What reactions will Phenylamine undergo? C 6 H 5 NH 2 + 3Br 2  C 6 H 2 Br 3 NH 2 + 3HBr C 6 H 5 NH 2 + dil HNO 3  C 6 H 2 (NO 2 ) 3 NH 2 + 3H 2 O NB THESE ARE SIMILIAR REACTIONS TO PHENOL

Ammonia with bromoethane Ethylamine CH 3 CH 2 Br+ NH 3 CH 3 CH 2 NH 2 + HBr Preparation of amines Further reactions with bromoetane Diethylamine CH 3 CH 2 Br+ CH 3 CH 2 NH 2 CH 3 CH 2 NHCH 3 CH 2 + HBr mechanism NB The HBr will be neutralised by excess ammonia or amine to form NH 4 Cl or RNH 3 Cl respectively but I wouldn’t include in a mechanism only the balanced equation

δ+ δ- CH 3 H Br C H - Ammonia with bromoethane Nucleophilic substitution mechanism ethylamine CH 3 H NH 2 C H HBr Will go to NH 3 Br with excess ammonia reaction equation N H H H CH 3 H N C H H H + H

δ+ δ- CH 3 H Br C H - Further reactions with bromoethane Nucleophilic substitution mechanism Diethylamine HBr Will go to RNH 2 Br with excess amine reaction equation N H H CH 3 CH 2 CH 3 H N C H H H + CH 3 CH 2 CH 3 H NH C H CH 3 CH 2

δ+ δ- CH 3 H Br C H - Further reactions with bromoethane Nucleophilic substitution mechanism triethylamine HBr Will go to RNH 2 Br with excess amine reaction equation N CH 3 CH 2 H CH 3 H N C H CH 3 CH 2 H + CH 3 H N C H CH 3 CH 2