Practical Organic Chemistry Revision Notes for JEE Preparation: Free PDF Download
There are various methods to do a qualitative analysis of organic compounds. There are hurdles that make the analysis of organic compounds quite difficult. In fact, many organic compounds fall into particular classifications. This chapter explains how organic compounds can be qualitatively analyzed using various methods. To understand the concepts of such tests, download and refer to the Practical Organic Chemistry JEE Advanced notes for free from Vedantu.
These notes are explained by the top subject matter experts at Vedantu to provide a better platform for JEE aspirants to learn and revise this chapter for their exams. Students will find the fundamental principles of qualitative analysis methods easier to understand by referring to these notes. They will also be able to resolve their doubts on this chapter on their own with the help of these revision notes.
JEE Advanced Revision Notes Chemistry 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:
Observation | Inference |
Orange-red | Nitroanilines, azo compound, β-naphthoquinone, alizarin |
Brown | Higher aromatic amines, diamines |
Pink | Naphthol’s |
Greenish-yellow | p-nitroso compounds, quinhydrone |
Colourless, turning reddish brown or pinkish(due to air oxidation) | Phenol, aniline, aminophenol’s, α-and-β-Naphthylamines |
Colourless, turning yellowish or yellow-brown | Anthracene, cinnamic acid, cresols, etc |
Colourless | Carbohydrates, aldehydes, ketones, acids, esters, alcohols, ethers, many hydrocarbon |
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
Observation | Inference |
Odour of better almond | Benzaldehyde, benzonitrile, nitrobenzene |
Mouse-like | Acetamide, acetonitrile |
Cinnamon-like | Cinnamic acid |
Pleasant-fruity | Ester |
Pleasant, sweet | Chloroform, diphenylamine, alcohols |
Garlic | Thiophenols, thioalcohols |
Phenolic (carbolic) | Many phenols |
Pungent, irritating | Lower acid, lower aldehydes, acid halides, thiocids |
Camphone-like | Pinacol, hexachloroethane |
Intensely disagreeable | Isocyanides |
Vinegar-like | Acetic acid, aspirin |
Cucumber-like | Chloral |
Pyridine-like | Heterocyclic bases |
Fish-like | Lower aliphatic amines, side-chain aromatic amine |
Odourless | Carbohydrates, aromatic acid, glycerol, solid aliphatic acid, etc |
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
Observation | Inference |
Burn with a smoky flame | Aromatic compound |
Burn with non-smoky flame | Aliphatic compounds |
Melts, darkness swells and then chars with the odour of burnt sugar | Sugar |
Chars without melting with the odour of burnt sugar | Starch, inulin, tartaric, citric, or their salts, lactate |
Residual ash | Organo metallic compound or metallic salts of acid |
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.
Observation | Inference |
Ammonia or ammoniacal vapour evolved | Ammonium salt of amides, amides, nitriles, aliphatic amino acids or poly nitro-compounds. |
Chloroform produced (gives a characteristic odour while cold) | Chloral hydrates |
Odour of burnt sugar | Carbohydrates or some aliphatic hydroxyl acid and their salts |
Phenolic odour | Phenolic acids or phenyl esters of carboxylic acids |
Benzene produced Odour of aromatic amine | Benzene carboxylic acid or their salts |
Odour of aromatic amine | Amine salts, aniliids or aromatic amino-carboxylic acid |
Colour changes yellow to brown and then black | Many aromatic nitro compounds |
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.
Observation | Inference |
Evolution of CO and $C{O_2}$ without charring but the mixture turns yellow | Citric acid and its salts |
Rapid charring with effervescence (evolution of Co and/or $C{O_2}$ and $S{O_2}$) | Carbohydrates, tartrates, lactates. |
Evolution of evolution of Co and $C{O_2}$ but no blackening | Oxalates |
Evolution of pungent vapour but no blackening and no marked effervescence | Many simple carboxylic acids and their salts |
Blackening without effervescence | Phenols |
Solubility and Reverse Precipitation:
Observation | Inference |
Soluble in 5% $NaC{O_3}$ soln. and reprecipitated by dil. HCl acid and not soluble in ${H_2}O$ | Aromatic carboxylic acid |
Soluble in 5% NaOH soln. (but insoluble in $N{a_2}C{O_3}$Soln. and ${H_2}O$) and reprecipitated by dil. HCI acid. | Water-insoluble phenol |
Soluble in dil. HCI (not soluble in ${H_2}O$) and reprecipitated by NaOH solution. | Organic base |
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).
Observation | Inference |
Intense purple, blue or red colour. | Phenol, phenolic acids, esters and amides |
Buff ppt (cleared by dil. HCI but replaced by a white ppt. of free acid. | Aromatic acid and succinate |
Greenish colour of ppt. | Catechol, Quinol or ß- naphthol |
Red colour (discharges on the addition of dil. HCI ) | Amino acids, formic or acetic acids. |
Greenish colour (the substance in dil. HCI) | Some amines |
Test for Functional Group:
Test of Unsaturation
Addition of ${H_2}$, 1π ≡ mole ${H_2}$
Addition of $B{r_2}/CC{l_4}$ or Bromine water Phenolic compounds give light yellow ppt with $B{r_2}$ water.
Aromatic amines gives ppt with $B{r_2}/{H_2}O$
Bayer's Reagent discharge the colour of dil, cold, alkaline $KMn{O_4}$ to pink or brown
Terminal alkynes gives red/brown ppt with $CuC{l_2}/N{H_4}OH$ due to Copper alkylidene
Terminal alkyne gives white ppt with tollens reagent Silver alkylidene.
Undergoes ozonolysis.
Test of OH-Group
Evolves ${H_2}$ gas with Na metal.
Gives red solution with ceric ammonium nitrate.
Gives ester with acetic anhydrides, acid chloride, acids.
Gives halides with $PC{l_5},P{X_3}$anhydride $ZnC{l_2}$ / conc. HCI or $SOC{l_2}$.
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
Soluble in NaOH - Insoluble in $NaHC{O_3}$ (Picric acid is only alcohol soluble in $NaHC{O_3}$)
Phenol gives red colour with alc. $FeC{l_3}$
Phenols — undergoes acetylation & Methylation.
Test of Ether Linkage
Ethers - insoluble in ${H_2}O$
With HI - gives alcohol and alkyl Iodide
With excess HI - only alkyl Iodide
Test of Carbonyl Groups
Phenyl hydrazine &HCI → brown crystalline compound of phenyl hydrazone.
2,4-DNPH (Brady's reagent) → Red ppt
$N{H_2}OH/{H^ + }$ → Oxime
Reduced to alkanes by
Wolf- Kirshner reduction → $N{H_2}N{H_2}/KOH$
Clamminess’s reduction → Zn(Hg)/HCl
Test of Aldehydes Only
Red ppt with Fehling solution → $C{u_2}O$
Red ppt with Benedict's solution → $C{u_2}O$
Silver mirror (Ag) with Tollen's Reagent.
Pink colour with Schiff's reagent.
Aldol condensation - Aldehydes with α−Hydrogen with dil base - NaOH
Cannizzaro Reaction - aldehydes without no α−hydrogen with conc. NaOH/KOH.
Test of Ketones
Wine red colour with sod. Nitroprusside
aliphatic methyl ketones give ppt with $NaHS{O_3}$.
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
Tollen's Reagent
Fehling Solution
$HgC{l_2}$
$B{r_2}$
Test for Dibasic Acid
Oxalic acid . $CO + C{O_2} + {H_2}O$
Malonic acid → $C{H_3}COOH + CO$
Succinic acid → Succinic anhydrides.
Maleic acid → Maleic anhydrides
Glutaric acid → Lactones
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
α−halo acids α−hydroxy acid
β−halo acid β−hydro acid
γ and higher halo acids lactones
Test of Esters:
Esters are neutral, water-insoluble compound, with fruity smell
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:
Anhydrides react with water to form two acids.
Anhydrides react with $PC{l_5}$ to form acid chloride.
with NH3-form amide and acid,
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 :
All amines are basic in nature.
All amines are soluble in acids.
Reacts with excess RCI to form quaternary ammonium halides.
With NaNO/Cl or $HN{O_2}$
Reaction Given by Only Primary and Secondary Amine.
1°& 2° amines are acetylated acid benzoylated.
Evolve ${H_2}$ gas with Na metal.
Gives alkane with G.R.
Gives N-halogenated amines with halogen/NaOH.
Reaction Given by 10 Amines Only.
Carbyl amine test all 1°amines when heated with $CHC{l_3}$ and alc. KOH form isocyanides (Foul smelling odour).
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
Cyanides on reduction with $LiAl{H_4}/Na/{C_2}{H_5}OH$or ${H_2}/Ni$form 1° amines.
Cyanides on hydrolysis gives carboxylic acid and ammonia.
Test for Isocyanides
Isocyanides on reduction with $LiAl{H_4}/Na/{C_2}{H_5}OH$or ${H_2}/Ni$form secondary methyl amine.
Isocyanides on hydrolysis gives p-amines and HCOOH.
Test for Aliphatic Nitro Compound
Reduction with Sn/HCl (acidic medium) -1° amine.
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.
On Reduction gives alcohol (Sn/HCl)
On hydrolysis gives alcohol
Test for Amides
Smell of ammonia on heating.
Amides give 10 amine with LiAlH
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
These notes are compiled with the sole aim to make the fundamental principles simpler and easily understandable. You will be able to grab the concepts faster and remember them due to the easier format used in these notes.
Download the revision notes PDF and refer to it anytime you want. Make your study time more productive by adding these notes to your study material. Before solving questions related to this chapter, read these notes once and you will recall what you have studied easily.
The notes have organized the reactions and their outcomes in a specific way. Using this suitable format is a better way to revise and recall the concepts. There is no need to make notes when the experts have done it for you. So you can proceed to solve the sample questions given in the revision notes to check your knowledge.
Download Practical Organic Chemistry JEE Advanced Revision Notes Free PDF
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FAQs on JEE Advanced 2023 Revision Notes for Practical Organic Chemistry
1. Why sodium is used for qualitative analysis?
Sodium is a reactive alkaline metal. It is used to check the presence of halogens, nitrogen, and sulphur in organic compounds. Many organic compounds are not soluble in water. Sodium can be used to make salts of such compounds and make them water-soluble and make it easier to perform qualitative analysis.
2. How can we find out the presence of halogen in organic compounds?
Sodium is used in different methods to react with the constituent halogens in an organic compound. Sodium reacts with the halogens to form salts. These salts are then tested to find out which halogen is present.
3. Why should we study qualitative analysis of organic compounds?
The testing methods teach us about the chemical qualities of organic compounds.
4. What is a fusion tube?
It is a small tube made of glass for sodium fusion tests and to do qualitative analysis.