AMINES HYDROXYNITRILES

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Elizabeth McCoy
6 years ago
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1 AMINES ACYL CHLORIDES HYDROXYNITRILES ALDEHYDE/KETONE REDUCTION

2 Amines are nitrogen- containing organic compounds derived from ammonia, where one or more of the hydrogen atoms has been replaced by an alkyl or aryl group. ammonia methylamine phenylamine

3 Primary amines Seconday amines TerMary amines Quaternary ammonium ion What is happening to the hydrogen number around the Nitrogen atom as you move across the page camonic surfactant e.g. hair condimoner

4 Amines are named using the suffix amine. methylamine ethylamine propylamine If two idenmcal R groups are apached, the prefix di is used, and if three idenmcal groups are present, then tri is used. diethylamine triethylamine

5 If other funcmonal groups are present in the molecule, the presence of amine groups is denoted using the amino prefix. 2- aminoethanoic acid 3- aminopropanoic acid 1,2- diaminopentane

6 AliphaMc and aromamc amines l l they act as nucleophiles and take part in reacmons involving donamon of the lone pair they act as Brønsted Lowry bases (H + acceptors). Aroma8c amines contain a benzene ring directly apached to the NH 2 group. The delocalized system of the benzene group is able to incorporate the lone pair of electrons from the nitrogen atom, meaning that aromamc amines have different propermes to aliphamc amines.

7 ReacMons of amines as bases Amines accept protons (H + ) from acids to form salts: ethylamine ethylammonium chloride Quaternary ammonium ion CH 3 CH 2 NH 2(aq) + HCl (aq) CH 3 CH 2 NH 3 Cl - (aq) + H 2 O (l) +

8 RelaMve base strength The strengths of weak bases are measured on the pkb scale. The smaller the number on this scale, the stronger the base is. What is the trend? Compound pk b NH CH 3 NH (CH 3 ) 2 NH 3.27 C 6 H 5 NH Can you explain the trend in terms of the availability of lone pair of electrons on the nitrogen for donamon to the hydrogen ion?

9 R group has a posimve inducmve effect and increases the electron density on the N atom. Thus N lone pair is more available to be donated to a proton, hence amine molecule can funcmon as a strong base. Benzene group withdraws electron density from the nitrogen atom and incorporates this into the delocalised electron system within the benzene ring. Thus, N lone pair is less available to be donated to a proton and therefore funcmons as a weak base. Strength of base (strongest to weakest order) R- - à NH 2 more than NH 3 more than C 6 H ß - - NH 2 Basic Buffer= aliphamc amine + strong acid (e.g. HCl) or amine salt or NH 4 Cl

10 Nucleophilic subs8tu8on with excess NH 3 and haloalkane promotes primary amine forma8on

11 Nucleophilic subs8tu8on with excess NH 3 and haloalkane promotes primary amine forma8on δ+ excess NH 3 δ Reac,on does not stop at first amine product. The primary amine itself undergoes nucleophilic subs,tu,on with haloalkane

12 Secondary/TerMary amines Primary amine δ+ δ- Secondary amine

13 Secondary/TerMary amines subsmtuted amines are more nucleophilic than NH 3 (due to alkyl inducmve effect) Primary amine δ+ δ- Secondary amine Excess NH 3 favours 1 amine producmon Excess Haloalkane favours 3 and 4 amine producmon

14 Amine + Haloalkane (R- X) Via nucleophilic subsmtumon mechanism: NH R- X à 1 Amine 1 Amine + 1 R- X à 2 Amine 2 Amine + 1 R- X à 3 Amine 3 Amine + 1 R- X à promoted if excess NH 3 promoted if excess R- X

15 of nitrile Making aliphamc amines

16 Making aliphamc amines of nitrile Nucleophilic subsmtumon involving the haloalkane and NH 3 generates a mixture of 1, 2, 3, 4 amines due to further subsmtumon reacmons involving the product(s) and haloalkane

18 A: KCN, aqueous/ethanolic; intermediate CH 3 CH 2 CN propanenitrile; then, H 2 /Ni catalyst B: NH 3, excess NH 3 Route A disadvantage: toxic KCN or expensive LiAlH 4 or H 2 explosive Route B: impure product, further subsmtumon likely

19 Making ethylamine from methane

20 Making ethylamine from methane CH 4 CH 3 Cl CH 3 CN CH 3 CH 2 NH 2 1. Cl 2, uv light, free radical subsmtumon 2. Ethanolic and aqueous KCN, reflux, nucleophilic subsmtumon 3. Either H 2 /Nickel catalymc hydrogenamon or LiAlH 4

22 Op8on 1 Op8on 2 Op8on 3 diethylamine Step 1 HBr electrophilic addimon CH 3 CH 2 Br H 2, Ni addimon (catalymc, H 2 ) C 2 H 6 H 2 O, H 3 PO 4 electrophilic addimon C 2 H 5 OH Step 2 excess NH 3, nucleophilic subsmtumon CH 3 CH 2 NH 2 Br 2 free radical subsmtumon CH 3 CH 2 Br KBr, conc H 2 SO 4 nucleophilic subsmtumon CH 3 CH 2 Br Step 3 CH 3 CH 2 Br nucleophilic subsmtumon (CH 3 CH 2 ) 2 NH NH 3 OR CH 3 CH 2 NH 2 nucleophilic subsmtumon (CH 3 CH 2 ) 2 NH NH 3 OR CH 3 CH 2 NH 2 nucleophilic subsmtumon (CH 3 CH 2 ) 2 NH

24 CH 3 CN CH 3 CH 2 NH 2 Secondary amine Step 1: Ethanolic/(aq) KCN Step 2: H 2 /Ni OR LiAlH 4 Step 3: CH 3 Br Nucelophilic subsmtumon

25 Cl 2 uv light

26 conc H 2 SO 4 and conc HNO 3, C HNO 3 + H 2 SO 4 à NO HSO H 2 O Electrophilic subsmtumon Sn HCl Cl 2 uv light excess NH 3

27 Sn HCl Cl 2 uv light excess NH 3

29 Nucleophilic subs8tu8on of (chloromethyl)benzene to produce phenylmethylamine δ+ δ- excess NH 3 (chloromethyl)benzene phenylmethlyamine

30 Nucleophilic subs8tu8on of (chloromethyl)benzene to produce phenylmethylamine δ+ δ- excess NH 3 (chloromethyl)benzene phenylmethlyamine

31 Making butane- 1,4- diamine

32 Making butane- 1,4- diamine Bromine(aq) electrophilic addimon LiAlH ethanolic/aq KCN 4 reflux H 2 /Ni BrCH 2 CH 2 Br NCCH 2 CH 2 CN H 2 N(CH 2 ) 4 NH 2 nucleophilic catalymc subsmtumon hydrogenamon 1,2- dibromoethane S N 2 S N 1

33 Long answer quesmons

35 Acyl chloride addimon- eliminamon reacmons Nitriles (HA, RCHO/RCOR, catalymc hydrogenamon) NaBH 4 with RCHO/RCOR

36 Acyl chloride and primary amine Nucleophilic addimon- eliminamon δ+ δ + HCl N- subs8tuted amide N- methylpropanamide

37 Acyl chloride and primary amine Nucleophilic addimon- eliminamon δ+ δ +HCl N- subs8tuted amide

38 ReducMon of ketone by NaBH 4 (H ) to secondary alcohol (sodium tetrahydridoborate (III)) Nucleophilic addimon δ+ δ H + from solvent opmcally acmve 2 alcohol Nucelophile is apacking a planar C=O bond of asymmetrical ketone (or aldehyde) APack is equally likely from above or below the planar C=O group Product is a racemix mixture containing equal amounts of enanmomers op8cally inac8ve

39 ALDEHYDE δ+ CN FormaMon of hydroxynitrile by acidified KCN Nucleophilic addimon δ H CN H H + from solvent CN H opmcally acmve hydroxynitrile Nucelophile is apacking a planar C=O bond of asymmetrical ketone (or aldehyde) APack is equally likely from above or below the planar C=O group Product is a racemix mixture containing equal amounts of enanmomers op8cally inac8ve

40 ALDEHYDE δ+ CN FormaMon of hydroxynitrile by acidified KCN Nucleophilic addimon δ H CN H H + from solvent CN H opmcally acmve hydroxynitrile Nucelophile is apacking a planar C=O bond of asymmetrical ketone (or aldehyde) APack is equally likely from above or below the planar C=O group Product is a racemix mixture containing equal amounts of enanmomers op8cally inac8ve

41 KETONE δ+ FormaMon of hydroxynitrile by acidified KCN Nucleophilic addimon δ CN CN H + from solvent CN opmcally acmve hydroxynitrile Nucelophile is apacking a planar C=O bond of asymmetrical ketone (or aldehyde) APack is equally likely from above or below the planar C=O group Product is a racemix mixture containing equal amounts of enanmomers op8cally inac8ve

Mechanisms. . CCl2 F + Cl.

Mechanisms. . CCl2 F + Cl. Mechanisms 1) Free radical substitution Alkane à halogenoalkane Initiation: Propagation: Termination: Overall: 2) Ozone depletion UV light breaks the C Cl bond releasing chlorine radical CFCl 3 F à. CCl2