JEE Advanced 2024 Revision Notes for Practical Organic Chemistry

Physical Properties:

A knowledge of whether a given compound is liquid or solid (if solid, then crystalline or amorphous) is of great help in its identification (this can by a consulting table of the known compound).

Colour:

The colour of the original sample is noted. Some compound show colour due to impurities, which is frequently produced as a result of their slow oxidation by moist air (freshly distilled anilines is nearly colourless but goes reddish-brown when kept for a longer time), while many other shows colour due to the presence of chromophore groups in them.

A brief summary of conclusions that can be drawn by the observation of colour is given here:

Odour: Many types of organic compounds have characteristics odour and so the ability to detect and remember an Adour is helpful in qualitative analysis, some of the odour characteristics of compounds are given here

Action of Heat:

Ignition Test: Place a little of the substance (0.1g) on a piece of porcelain and then heat it over a low flame, raising the temperature gradually. Observe whether the compound is volatile; inflammable( if so, nature of the flame); or melts, decomposes or a residue is left, if a residue is left, it is cooled and a drop of distilled ${H_2}O$ is added to the residue and tested with litmus paper (or ph.ph.indicator). then a little of dil.Hcl is added to see whether ay gas is evolved or not

Heating with Soda-Lime: Mix well the compound (0.5gm) with powdered soda-lime(1g) in a dry test tube, cover with a layer of soda-lime and heat first gently and then strongly, notice any odour or change in colour.

Ammonia Odour:
$RCOON{H_4} + NaOH/CaO \to RCOONa + N{H_3} \uparrow  + {H_2}O$

$RCOON{H_2} + NaOH/CaO \to RCOONa + N{H_3} \uparrow$

$RCO - NH - RCO + NaOH/CaO \to RCOONa + N{H_3} \uparrow$

Chloroform Odour

\[CC{l_3}CHO.{H_2}O + NaOH/CaO \to CHCC{l_3} + HCOONa\]

Treatment with conc. ${H_2}S{O_4}$ acid: To a small quantity (0.1g) of the substance contained in a dry test tube, add about 1ml of conc. ${H_2}S{O_4}$ acid and note the reaction first while the mixture is cold and then after it had been gently warmed.

Solubility and Reverse Precipitation:

Acidity Test:

Procedure: To obtain a neutral $FeC{l_3}$ soln., add a few drops of$N{H_4}OH$ soln. to $FeC{l_3}$ soln. till a form and filter. Add a few drops of this $FeC{l_3}$ soln. to dilute solution of the substance (neutral solution in case of acids).

Test for Functional Group:

Test of Unsaturation

1. Addition of ${H_2}$, 1π ≡ mole ${H_2}$

2. Addition of $B{r_2}/CC{l_4}$ or Bromine water Phenolic compounds give light yellow ppt with $B{r_2}$ water.

3. Aromatic amines gives ppt with $B{r_2}/{H_2}O$

4. Bayer's Reagent discharge the colour of dil, cold, alkaline $KMn{O_4}$ to pink or brown

5. Terminal alkynes gives red/brown ppt with $CuC{l_2}/N{H_4}OH$ due to Copper alkylidene 

6. Terminal alkyne gives white ppt with tollens reagent Silver alkylidene. 

7. Undergoes ozonolysis.

Test of OH-Group

1. Evolves ${H_2}$ gas with Na metal.

2. Gives red solution with ceric ammonium nitrate.

3. Gives ester with acetic anhydrides, acid chloride, acids.

4. Gives halides with $PC{l_5},P{X_3}$anhydride $ZnC{l_2}$ / conc. HCI or $SOC{l_2}$.

5. Lucas’s test (anhydrous. $ZnC{l_2}$ / Conc. HCI)

3⁰ → Formation of turbidity → immediate

2⁰ → Formation of turbidity within 5 minutes

3⁰ → No turbidity

Test of Phenolic Group

1. Soluble in NaOH -  Insoluble in $NaHC{O_3}$ (Picric acid is only alcohol soluble in $NaHC{O_3}$)

2. Phenol gives red colour with alc. $FeC{l_3}$

3. Phenols — undergoes acetylation & Methylation.

Test of Ether Linkage

1. Ethers - insoluble in ${H_2}O$

2. With HI - gives alcohol and alkyl Iodide

3. With excess HI - only alkyl Iodide

Test of Carbonyl Groups

1. Phenyl hydrazine &HCI → brown crystalline compound of phenyl hydrazone.

2. 2,4-DNPH (Brady's reagent) → Red ppt 

3. $N{H_2}OH/{H^ + }$ → Oxime 

4. Reduced to alkanes by

Wolf- Kirshner reduction → $N{H_2}N{H_2}/KOH$
Clamminess’s reduction → Zn(Hg)/HCl

Test of Aldehydes Only

1. Red ppt with Fehling solution → $C{u_2}O$

2. Red ppt with Benedict's solution → $C{u_2}O$

3. Silver mirror (Ag) with Tollen's Reagent.

4. Pink colour with Schiff's reagent.

5. Aldol condensation - Aldehydes with α−Hydrogen with dil base - NaOH

6. Cannizzaro Reaction - aldehydes without no α−hydrogen with conc. NaOH/KOH.

Test of Ketones

1. Wine red colour with sod. Nitroprusside

2. aliphatic methyl ketones give ppt with $NaHS{O_3}$. 

3. On Reduction → gives 2⁰ alcohol.

Test of Carboxylic Acid

(a) With $NaHC{O_3}$ → effervescence of $C{O_2}$

(b) $PC{l_5},PC{l_{3,}}SOC{l_2}$ acid chloride

(c) Amides with NH₃/∆

(d) Acetic acid gives blood red colour with $FeC{l_3}$

(e) HCOOH → also gives oxidation with

Test for Dibasic Acid

1. Oxalic acid . $CO + C{O_2} + {H_2}O$

2. Malonic acid → $C{H_3}COOH + CO$

3. Succinic acid → Succinic anhydrides.

4. Maleic acid → Maleic anhydrides

5. Glutaric acid →  Lactones

6. Adipic acid → Cyclol pentanone

Test of -hydroxy acid → on heating gives Lactides

Test of hydroxy acid → on heating undergoes dehydration to give unsaturated acid.

$R - CH = C{H_2} - COOH + {H_2}O$

Test for Halo Acid

1. α−halo acids α−hydroxy acid

2. β−halo acid β−hydro acid 

3. γ and higher halo acids lactones

Test of  Esters:

1. Esters are neutral, water-insoluble compound, with fruity smell

2. Ester on reduction with $LiAl{H_4}$ or $Na/{C_2}{H_5}OH$ gives two moles of alcohol. Ester on hydrolysis (saponification)gives acid and alcohol.

Test of Anhydrides:

1. Anhydrides react with water to form two acids.

2. Anhydrides react with $PC{l_5}$ to form acid chloride.

3. with NH3-form amide and acid,

4. On reduction with $LiAl{H_4}$-gives two moles of alcohol.

Test of Aliphatic Halogen Compounds

All halides (except vinyl). when heated with aq. NaOH followed by acidification and with AgN03 gives white, light Yellow or dark yellow ppt. 

Test for Amines :

1. All amines are basic in nature.

2. All amines are soluble in acids.

3. Reacts with excess RCI to form quaternary ammonium halides.

4. With NaNO/Cl or $HN{O_2}$

Reaction Given by Only Primary and Secondary Amine.

1. 1°& 2° amines are acetylated acid benzoylated.

2. Evolve ${H_2}$ gas with Na metal.

3. Gives alkane with G.R.

4. Gives N-halogenated amines with halogen/NaOH.

Reaction Given by 10 Amines Only.

1. Carbyl amine test all 1°amines when heated with $CHC{l_3}$ and alc. KOH form isocyanides (Foul smelling odour).

2. Haloform mustard oil reaction — 1°amine when heated with $C{S_2}$ and $HgC{l_2}$ form isothiocyanates having smell of mustard oil.

Test for Cyanides

1. Cyanides on reduction with $LiAl{H_4}/Na/{C_2}{H_5}OH$or ${H_2}/Ni$form 1° amines. 

2.  Cyanides on hydrolysis gives carboxylic acid and ammonia.

Test for Isocyanides

1. Isocyanides on reduction with $LiAl{H_4}/Na/{C_2}{H_5}OH$or ${H_2}/Ni$form secondary methyl amine. 

2. Isocyanides on hydrolysis gives p-amines and HCOOH.

Test for Aliphatic Nitro Compound

1. Reduction with Sn/HCl (acidic medium) -1° amine.

2. Reduction in neutral medium $Zn/N{H_4}Cl$or $Sn/CaC{l_2}$-Hydroxylamine

On O reaction with $NaN{O_2}$/conc. ${H_2}S{O_4}$
1⁰ − nitro − nitrolic acid − red soln. in NaOH 
2⁰ − nitro −  Pseudonitrol − blue soln.

Alkyl Nitrite : R-O-NO.

1. On Reduction gives alcohol (Sn/HCl)

2. On hydrolysis gives alcohol

Test for Amides

1. Smell of ammonia on heating.

2. Amides give 1⁰ amine with LiAlH

3. Amides gives cyanides with ${P_2}{O_5}$

Importance of Practical Organic Chemistry

This chapter focuses on explaining the different types of functional groups that help us to categorize organic compounds. It also explains how these functional groups and elements present in the organic compounds can be tested using various methods.

All these qualitative analysis methods are designed based on the chemical features of organic compounds. These methods have been designed to safely find out the types of elements and functional groups present in such compounds.

Students will be able to learn how the fundamental principles of organic chemistry are used to determine the properties of these compounds. The concepts covered in this chapter will have applications and relevance in organic chemistry, so students can refer to the Practical Organic Chemistry JEE Advanced revision notes to get an overall understanding of the chapter.

This chapter is important as it provides a clear view of the applications of properties of different organic compounds. These properties can be used to recognize the compounds by determining the results of such tests. The detection of elements and functional groups in compounds will give you better insights into such testing methods.

Benefits of Practical Organic Chemistry JEE Advanced Notes PDF

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