IDENTIFICATION TEST OF ORGANIC COMPOUNDS

CHEMICAL TEST OF ORGANIC COMPOUNDS Identification Test

ALKANE Observation: Brown turns to colourless. General Equation: R–H + Br2 hv R–Br + HBr Note: CCl4 is still needed as solvent for reaction under sunlight.

ALKENE 1) Halogenation of Alkenes, Br2 in Inert Solvent (CCl4 or CH2Cl2) Observation: Brown colour turns to colourless. General equation: CC + Br2 CCl4 CC Room temperature Br Br Dark

ALKENE 2) Reaction of alkenes with basic, dilute, cold KMnO4  Baeyer’s test C C + KMnO4 OH-, cold CC + MnO2 (purple) dilute OH OH (brown precipitate) 1,2-diols @ glycols Observation: Purple colour of KMnO4 decolourised and brown precipitate formed.

ALKENE 3) Reactions of alkenes with acidified, hot, concentrated KMnO4 R1 R3 R1 R3 C=C KMnO4(conc), C=O + O=C H+, heat R2 R2 H H [O] R3 Observation: O=C Purple colour of KMnO4 decolourize. OH

ARENE 1) Reactions of benzene with HNO3 conc and H2SO4 conc, heat General equation: HONO2 (conc.) NO2 H2SO4 (conc.), Δ + H2O Observation: A pale yellow solution is formed.

ARENE 2) Reactions of toluene with Br2 under uv light General equation: R RX X2, uv Observation: Brown colour of Br 2 turns colourless

ARENE 3) Reactions of toluene with KMnO4 / H+, ∆ General equation: R COOH KMno4, H+, heat @ Na2Cr2O7, H+, heat Observation: Purple colour of KMnO4 decolourize.

HALOALKANE 1) Reactions of H-X with R-OH, AgNO3/ OH- to produce haloalkane. General equation: H-X + R-OH → R-X + H2O Observation: R-Cl : white precipitate R-Br : pale yellow precipitate R-I : yellow precipitate

ALCOHOL 1) Reactions of R-OH with Na General equation: R-OH + Na → RONa + ½H2 Observation: A pop sound by the wooden splinter

ALCOHOL 2) Lucas reagent, concentrated HCl/ZnCl2 (between 1, 2 and 3 alcohol) General CH2OH HCl (conc.), ZnCl2 equation: OH HCl (conc.), ZnCl2 CH2Cl CH3 HCl (conc.), ZnCl2 + H2O OH Cl + H2O + H2O CH3 Cl

ALCOHOL 2) Lucas reagent, concentrated HCl/ZnCl2 (between 1, 2 and 3 alcohol) Classes of Observation alcohol The solution does not turn cloudy Primary, The solution turn cloudy within 5 1°ROH minutes Secondary, The solution turn cloudy 2°ROH immediately Tertiary, 3°ROH

ALCOHOL 3) Reactions of R-OH with PCl5 General equation: R-OH + PCl5 → RCl + PCl3 + HCl Observation: Acidic white fumes produced

ALCOHOL 4) KMnO4/H+ or K2Cr2O7 /H+ (between 1 and 3, and 2 and 3 alcohols) General ROH 1o KMnO4, H+ RCOOH equation: heat ROH 2o K2Cr2O7, H+ RCR heat ROH 3o Na2Cr2O7, H+ O heat NO REACTION

ALCOHOL 4) KMnO4/H+ or K2Cr2O7 /H+ (between 1 and 3, and 2 and 3 alcohols) Class of alcohol and observation Primary, 1° KMnO4 purple turns to colorless K2Cr2O7orange turns to green Secondary, 2° (Same observation as for primary ROH) Tertiary, 3° (The color of oxidizing agent is remains)

ALCOHOL 5) Reactions of R-OH with I2 and NaOH H R C CH3 + I2 + NaOH OH O R C ONa + NaI + H2O + CHI3 YELLOW PRECIPITATE

PHENOL 1) Reactions with NaOH General equation: C6H5-OH + NaOH C6H5-O-Na+ + H2O Observation: One layer of solution formed

PHENOL 2) Reactions with Br2 in H2O General equation: OH Br Br OH Br2/H2O Br Observation: Brown colour of Br 2 turns colourless White precipitate forms

PHENOL 3) Reactions with FeCl3 (Phenol Test) General equation: OH OH + FeCl3 FeCl3 Observation: Turn the yellow FeCl3 into purple solution.

PHENOL 4) Reactions with HNO3 conc General equation: OH OH concentrated O2N NO2 HNO3 NO2 (conc.) Observation: Yellow precipitate formed.

KETONE/ ALDEHYDE 1) Brady’s Reagent; 2,4 –dinitrophenylhydrazine (2,4-DNPH) O + H2N N NO2 C 2,4-dinitrophenylhydrazine RR H O2N RCNN NO2 RH O2N Observation: Yellow precipitate / Orange crystal formed for aliphatic compound.

KETONE/ALDEHYDE 2) Iodoform Test General equation: R C CH3 + I2 + NaOH OO R C ONa + NaI + H2O + CHI3 Observation: Yellow precipitate formed.

ALDEHYDE 1) Tollens’ Reagent; Ag(NH3)2+, OH-, ∆ General equation: R O + 2[Ag(NH3)2]+ OH- O C R C O-  + 2Ag + 4NH3 + 2H2O silver mirror H Observation: Silver mirror formed on the wall of the tube.

ALDEHYDE 2) Fehling’s/Benedict’s Reagent; Cu2+, OH-, ∆ R C O + Cu2+ O H Fehlings' Solution R C O- + Cu2O + H2O Copper(I) Oxide (Brick red precipitate) Observation: Brick red precipitate formed.

ALDEHYDE 3) Schiff’s Reagent Observation: Pinkish purple colour solution is formed.

ALDEHYDE 5) Oxidation with KMnO4 @K2Cr2O7 General equation: O O RC OH [O] RCH Observation: KMnO4 : purple to colourless K2Cr2O7 : orange to green

CARBOXYLIC ACID 1) Reaction with RO-H, H2SO4 conc., Δ General equation: OO ⇌H+ R C OH + H—OR’ R C OR' + H2O carboxylic acid alcohol ester Observation: Sweet and pleasant smell is formed.

CARBOXYLIC ACID 2)Reaction with Reactive Metals Na @ Mg General equation: Observation: H2 gas released gives pop sound by wooden splinter.

CARBOXYLIC ACID 3) Reaction with metal carbonates; Na2CO3 @ MgCO3 @ NaHCO3 Observation: CO2 gas released turn the lime water cloudy.

CARBOXYLIC ACID 4) Reaction with PCl5 @ SOCl2 O PCl5 R C Cl+ POCl3 + HCl O C O R OH SOCl2 R C Cl + SO2 + HCl Observation: White acidic fumes evolves.

AMINE 1) Hinsberg’s Test i. Benzyl sulphonyl chloride ii. Base – KOH iii. Acid – HCl Class of KOH HCl amine Clear solution Precipitate 1° amine formed Precipitate 2° amine remained No change No change 3° amine Clear solution

AMINE 2) Reaction with Nitrous Acid HONO @ HNO2, 0-5 ºC @ NaNO2, HCl, 0-5 ºC +HCl NaNO2 +HONO NaCl Class of Amine OBSERVATION 1° aliphatic amine 2° aliphatic amine Bubbles gas (N2 gas) 3° aliphatic amine Yellow oil 1° aromatic amine Clear solution (soluble salt formed) No bubble gas below 5°C 2° aromatic amine Yellow oil 3° aromatic amine Yellow precipitate

AMIINE (a) Primary aliphatic amines RCH 2CH2 NH 2 + NaNO2 HClRCH 2CH 2 + - Cl  N2 RCH = CH2 - H+  2 + H 2  + N 2 +H2O RCH  C +X- RCH 2CH 2OH RCH 2CH 2Cl Observation : Formation of gas bubbles (N2)

AMINE (b) Secondary aliphatic amines Secondary amines react with nitrous acid to form secondary N-nitrosamines as yellow oil which is stable under the reaction conditions. R2NH NaNO2, HCl R +NaCl H2O R NNO + cold secondary N-nitrosoamines (yellow oil)

AMINE (c) Tertiary aliphatic amines  When a tertiary aliphatic amine is mixed with nitrous acid, an equilibrium is established among the tertiary amine, its salt, and an N- nitrosoammonium compound. NaNO2, HCl +2R3N R3N N OCl R3NHCl cold Water soluble salt

AMINE (d) Primary aromatic amines Primary arylamines react with nitrous acid to give arenediazonium salts. NH2 N2+Cl- NaNO2, HCl + NaCl + H2O cold baernezneendeiadziaoznoiunmiumsasltalt

AMINE (e) Secondary aromatic amines Secondary aromatic amines react similar to secondary aliphatic amines. CRH3 NaNO2, HCl CRH3 NH N NO below 5 oC N-Methyl-N-nitrosoaniline (yellow oil)

AMINE (f) Tertiary aromatic amines Tertiary aromatic amines undergo substitution at the para position of the ring to from nitrosoaniline. CRH3 CRH3 N NaNO2, HCl O N N CRH3 CRH3 below 5 oC N,N-Dimethyl-4-nitrosoaniline (precipitate)

AMINE 3) Reaction of aniline with General equation: NH2 NH2 Br 3Br2(aq) Br + 3HBr room temperature Br Observation: Brown colour of Br2 decolourised.