CLASS 12 a



SOLVING PROBLEMS BASED ON ORGANIC CONVERSIONS IN SUBTLEST WAYS AND SHORTEST POSSIBLE TIME

Presented By:-

Lokesh suredia PGT(Chemistry)

KV SAC Vastrapur (Ahemdabad)

INTRODUCTION : Students memorise all organic reactions but unable to rearrange all these reactions and solve problems based on organic conversions. This is an effort to systematize and rearrange the organic reactions to solve problems based on organic conversions.

METHOD:- Organic conversions are classified as:-

A. Aliphatic conversions.

B. Aromatic conversions

(A) ALIPHATIC CONVERSIONS: Aliphatic conversions further classified as

Step-up conversions

(i) By Wurtz reaction:

(ii) Through cyanide:

(iii) Through Grignard reagent:

(iv) Through Alkyne:

(b) Step-down conversions

(i) Through carboxylic acid:

(ii) By Hofmann bromamide reaction:

KEY FOR CONVERSIONS

(By Lokesh Suredia)

|Sl No |Reagent |Group Out |Group In |Remark |

|1 |KMnO4 / H+ |-CH2OH |-COOH |Strong Oxidation (20 alc( ketone) |

|2 |LiAlH4 |-COOH |-CH2OH |Strong Reduction (ketone ( 20 alc) |

|3 |Cu / 573 K or CrO3 |-CH2OH |-CHO |Dehydrogenation |

|4 |PCl5 or SOCl2 |-OH |-Cl | |

|5 |Cl2 / Δ or Cl2 / UV |-H |-Cl |Free radical substitution |

|6 |Aq NaOH / KOH |-X |-OH |Nucleophilic substitution |

|7 |KCN |-X |-CN |Step Up |

|8 |AgCN |-X |-NC | |

|9 |Alcoholic KOH |-HX |= |Dehydrohalogenation (Stzf) |

|10 |Mg / dry ether | |Mg |R-X ( R-MgX |

|11 |HBr |>=< |H, Br |Merkovnikov |

|12 |H2 / Pd-BaSO4 |-COCl |-CHO |Rosenmund Reduction |

|13 |Zn-Hg / HCl |>C=O |-CH2- |Clemmension Reduction |

|14 |NH3 / Δ |-COOH |-CONH2 |-COOH + NH3 ( -COONH4 |

|15 |Br2 / NaOH or NaOBr |-CONH2 |-NH2 |Step Down ( Hoffmann) |

|16 |HNO2 or NaNO2/HCl |-NH2 |-OH |HONO |

|17 |CHCl3 / alc KOH |-NH2 |-NC |Carbyl amine |

|18 |P2O5 |-CONH2 |-CN |Dehydration |

|19 |H3O+ |-CN |-COOH |Hydrolysis |

|20 |OH- |-CN |-CONH2 | |

|21 |LiAlH4 |-CN |-CH2NH2 |Reduction |

|22 |Red P / Cl2 |α-H of acid |-Cl |HVZ Reaction |

| | In benzene ring |

|23 |Fe / X2 /dark |-H |-X |Halogination |

|24 |CH3Cl / AlCl3(anhyd) |-H |-CH3 |Friedel Craft alkylation |

|25 |CH3COCl / AlCl3(anhyd) |-H |-COCH3 |Friedel Craft acylation |

|26 |Conc.HNO3/con.H2SO4 |-H |-NO2 |Nitration |

|27 |Conc H2SO4 |-H |-SO3H |Sulphonation |

|28 |KMnO4 / H+ |-R |-COOH |Oxidation |

|29 |CrO2Cl2 / H+ |-CH3 |-CHO |Mild oxidation(Etard Reaction) |

|30 |Sn / HCl or Fe/HCl |-NO2 |-NH2 |Reduction |

|31 |NaOH / 623K / 300 atm |-Cl |-OH | |

|32 |Zn dust / Δ |-OH |-H | |

|33 |NaNO2 / dil HCl / 273-278 K |-NH2 |-N2+Cl- |Diazo reaction |

|34 |CuCl / HCl or Cu/HCl |-N2+Cl- |-Cl |Sandmeyer or Gattermann |

|35 |CuBr / HBr or Cu/HBr |-N2+Cl- |-Br |Sandmeyer or Gattermann |

|36 |CuCN / KCN |-N2+Cl- |-CN |Sandmeyer |

|37 |KI |-N2+Cl- |-I | |

|38 |HBF4 / Δ |-N2+Cl- |-F | |

|39 |H3PO2 or CH3CH2OH |-N2+Cl- |-H | |

|40 |H2O / 283 K |-N2+Cl- |-OH | |

|41 |HBF4/ NaNO2, Cu / Δ |-N2+Cl- |-NO2 | |

|42 |C6H5-OH |-N2+Cl- |-N=N-C6H5-OH |Coupling ( p-hydroxy) |

|43 |C6H5-NH2 |-N2+Cl- |-N=N-C6H5-NH2 |Coupling ( p-amino) |

Reactions of Grignard Reagent

|Grignard reagent + |Any one below + H2O ( |Product |

|R-MgX |H2O or ROH or RNH2 |R-H |

| |H-CHO |R-CH2-OH (10 alc) |

| |R-CHO |R-CH(OH)-R (20 alc) |

| |R-CO-R |R2C(OH)-R (30 alc) |

| |CO2 |R-COOH |

| |R-CN |R-CO-R |

| |HCOOR |Aldehyde |

| |RCOOR |Ketone |

NB: i) During reaction generally changes take place in the functional group only so see the functional

group very carefully.

ii) Remember structural formula of all the common organic compounds ( with their IUPAC and common

names)

iii) Wurtz Reaction and Aldol Condensation are not included in the table although they are

very important for conversions so study them .

iv) By taking examples practice all the above cases ( from 1 to 43 and Grignard)

v) Practice only from NCERT book.

vi) Start practicing NOW !

How to use the table? See below.

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Directional Properties of groups in benzene ring for electrophilic substitution

Ortho-para directing group: -R , -OH, -NH2, -X, -OR, -NHR, -NR2, -NHCOCH3, -CH2Cl, -SH, - Ph

Meta-directing group: -NO2 , -CHO , -COOH , COOR , -CN , -SO3H , -COCH3 , -CCl3 , -NH3+ ,

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(C) Conversions of same no. of carbon atoms

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(B) Aromatic Conversions

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CONCLUSION:-

Now students are able to solve the problems based on organic conversions by using this method in shortest possible time. They can also solve the problems of what happens when? Complete the reactions etc, which cover the major aspect of organic chemistry. These conversion charts make organic chemistry interesting for the students. Teacher can also use it as a teaching aid.

-------------------------------------------------------****************------- ASSIGNMENT FOR CLASS –XII Sc (CHEMISTRY) ORGANIC CONVERSION---(2 to 3 marks)

CONVERT THE FOLLOWING:-

Q.I# Aniline to (a) benzoic acid (b) benzonitrile (c) iodobenzene (d)phenol (e) acetanilide (f) p-nitroaniline (g) sulphanilic acid

Q.II# Benzonitrile to (a)actophenone (b) benzoic acid (c) benzamide (d) 1-phenyl methanamine (e) aniline

Q.III# Phenol to (a) salicylic acid (b) salicylaldehyde (c) toluene (d) acetophenone (e) aspirin

Q.IV# Acetylene to (a) Lactic acid (b) Acetaldehyde (c) Acetic acid

Q.V# Benzaldehyde to (a) α-hydroxy phenyl acetic acid (b) Benzophenone (c) 3-phenylpropan-1-ol

(d) Benzyl alcohol

Q.VI# Hept-1-ene to (a) Heptanal (b) Hexanal (c) Hexanoic acid (d) Heptanoic acid .

Q.VII # Acetaldehyde to (a) butan-2-one (b) but-1,3-diol (c) but-2-enal (d) butan-1-ol (e) butanoic acid (f) but-2-enoic acid (g) Lactic acid (h) nitropropene -1

Q.VIII # Benzene to (a) m-nitrobenzoic acid (b) phenyl acetic acid (c) p-nitro benzaldehyde (d) p-nitro benzoic acid (e) methyl benzoate (f) meta-nitroacetophenone

Q.IX # (a) Benzoic acid from chlorobenzene (b) t-butyl alcohol from acetone (c) ethanol to propan-2-ol

(d) Methyl cyanide to propanone-2 (e) Acetophenone to 2-phenyl-2-butanol

(f) Methanal to propan-1-ol (g) bromobenzene to 1-phenyl ethanol (h) Propanal to Butanone

Q.X # (1) Ethyl amine from acetaldehyde (2 ) Ethanoyl chloride to methyl nitrile

(3) 2-nitropropane to acetone (4) Hexanamide to hexanitrile

(5) Propene to acetone and vice versa (6) Toluene to benzaldehyde

(7) Ethylbromide to ethylamine (8) Anisole to p-methoxy acetophenone

(9) Benzoyl chloride to benzonitrile (10) n-propyl alcohol to hexane.

(11) Hexanoic acid to hexanenitrile (12) p-nitrobenzoic acid to p-nitroaniline

(13) benzoic acid to benzyl amine (14) Benzyl alcohol to phenylethanoic acid

(15) m-nitroaniline from nitrobenzene (16) p-toludine to 2-bromo-4-methyl aniline

(17) Ethanol to 1,2-ethanediol (18) Acetic acid to acetaldehyde

(19) Acetic acid to ethylamine (20) acetic acid to acetone

(21) Benzyl alcohol to Benzoic acid (22) Propanoic acid to Propenoic acid

(23) Cyclohexene to Hexane-1,6-dioic acid (24) p-methyl acetophenone to benzene-1,4-dicarboxylic acid

(25) Propanoyl chloride to Dipropyl amine (26) Benzoic acid to Benzaldehyde

(27) Acetophenone to ethyl benzene Q.XI# (a) Methyl amine to Ethyl amine and vice versa (b) propanoic acid to ethyl ammine

(c) ethyl bromide to propanamine (d) Acetyl chloride to methyl chloride.

IDENTIFY THE COMPOUNDS A,B,C etc.

1# An organic compound “A” which has characteristic odour, on treatment with NaOH forms two compounds “B” and “C” .Compound “B” has a molecular formula C7H8O which on oxidation gives back compound “A’.

Compound “C” is the sodium salt of an acid .”C” when heated with sodalime yields an aromatic hydrocarbon”D”.Deduce the structure A,B,C,D .

2# An organic compound “A” has a molecular formula C5H10O.It does not reduce Fehling’s Solution but forms a bisulphite compound .It also positive iodoform test.What is the possible structure of “A”? Explain your reasoning which helped to arrive at the structure.

3# A compound “A” has a molecular formula C5H10O gave a positive 2,4-DNP testbut a negative Tollen’s test.

It was oxidized to carboxylic acid “B” with molecular formula C3H6O2 when treated with alkaline KMnO4 under vigorous condition .Sodium salt of ‘B” gave a hydrocarbon “C” on Kolbe’s electrolytic reduction Identify A,B and C and write chemical equations for the reaction.

4# An organic compound “A” has a molecular formula C3H7O2N on reaction with Fe and Conc.HCl give a compound “B” of molecular formula C3H9N . Compound “B” on treatment with NaNO2 and HCl give another compound “C” of molecular formula C3H8O.The compound “C” gives effervescence with Na.On oxidation with CrO3, the compound “C” gives a saturated aldehyde containing three carbon atoms .Deduce the structures of “A”, “B” and “C” and write the chemical equations for the reactions involved.

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Example : See no 7 in the table

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