* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Amines and amides
Survey
Document related concepts
Physical organic chemistry wikipedia , lookup
Bottromycin wikipedia , lookup
George S. Hammond wikipedia , lookup
Asymmetric induction wikipedia , lookup
Wolff rearrangement wikipedia , lookup
Baylis–Hillman reaction wikipedia , lookup
Aza-Cope rearrangement wikipedia , lookup
Hydroformylation wikipedia , lookup
Wolff–Kishner reduction wikipedia , lookup
Tiffeneau–Demjanov rearrangement wikipedia , lookup
Hofmann–Löffler reaction wikipedia , lookup
Strychnine total synthesis wikipedia , lookup
Transcript
Amines and Amides Amines are the organic chemistry equivalents of NH3, alkyl groups take the place of one, two or three hydrogen atoms… H-N-H R-N-H R-N-H H H R’ ammonia primary amine R-N-R’ secondary amine R’’ tertiary amine 1. Nomenclature: primary amines use the suffix “amine” e.g methylamine, ethylamine. Simple secondary and tertiary amines use prefix “di” and “tri” e.g dimethylamine and triethylamine. H 3C CH3 CH3 N N H H3 C CH3 Note: alkyl groups in secondary and tertiary amines need not be the same!! Higher homologues use CH3CH(NH2)CH2CH2CH3 prefix “amino” e.g 2-aminopentane, Some diamines have very derivative names indicating where they are found e.g putrescine [H2N(CH2)4NH2] and cadaverine [H2N(CH2)5NH2]! These are the amines responsible for the terrible smell of rotting meat. 2. Key properties: If it smells of “fish” or “rotting flesh” chances are you have an amine!! Amines behave in a similar way to NH3 but their behaviour is modified by the alkyl groups. .. H-N-H H 2.1 Bonding: cf NH3 Lone pair is responsible for: Solubility in H2O / base properties /ligand behaviour / nucleophile properties 2.2 Solubility. of Amines Like NH3 amines can H-bond, because of this small amines are soluble in water. Large amines disrupt H-bonding in water. 2.3 Amines as bases: Lone pair on N can take part in dative covalent bonds. When electron pair is donated to H+, ammonia acts as a proton acceptor i.e a base. NH3(aq) + H2O(l) NH4+(aq) + OH-(aq) Ammonium ion Similarly with amines: CH3CH2CH2NH2(aq) + H2O(l) CH3CH2CH2NH3+(aq) + OH-(aq) The presence of the OH-(aq) ion means that aqueous solutions of amines are ALKALINE. Like NH3 amines react with acids, H3O+ ion is more effective proton donor than H2O, therefore reaction goes to completion therefore amines lose their smell (thank goodness!!) NH2 (aq) + H3O+(aq) NH3 + (aq) + H2O(l) 2.4 Amines as ligands Lone pair strikes again ! if NH3 is added to a solution of CuSO4 we get the following complex: [Cu(NH3)4(H2O)2]2+(aq), If butylamine is added instead we would obtain [Cu(C4H9NH2)4(H2O)2]2+(aq) 2.5 Amines as Nucleophiles: R-Cl + NH3 R-NH3+Cl R-NH2 + H+ + Cl- Product is an amine, but amines are nucleophiles. So amijes undergo substitution reactions with halogenoalkanes to form 2ry and 3ry amines! + H R’-Cl + R-NH2 R’-N-H R’-N-H Cl- + H+ + Cl- R 2ry amine Similar reaction if use an acyl chloride [RCOCl] O O + NH3 + HCl R-C R-C Cl NH2 primary amide R With a 1ry amine: R-C O Cl + R’-NH2 R-C O N-R’ + HCl H 2 amide ry Amides: Contain functional group R-C O NH2 -C O N- Amide group or “peptide link” H 1ry amides are formed by reaction of ammonia with an acyl chloride (see above) named after corresponding carboxylic acid: CH3-C O CH3-C OH O CH3-C Cl NH2 ethanamide ethanoyl chloride ethanoic acid O Hydrolysis of amides: This reaction involves breaking the C-N bond at the carbonyl carbon. a. acid hydrolysis: forms “ammonium” ion and carboxylic acid b. alkaline hydrolysis: forms carboxylate ion and amine Condensation Polymers As we have seen –COOH (and COCl) react with amines to form 2ry amides A Condensation reaction is one in which two molecules combine to form a larger molecule with the elimination of a small molecule. -C O O H + H2 O -C-N- N+ OH H H 2ry amide If we react a di-acid with a diamine we get condensation polymerisation with the formation of polyamides or nylons. O O O O -C- -C-NH -N-CH -C-NH -NH