Chemistry · Class 12 Science
Ch 13Organic Nitrogen Compounds — Class 12 Chemistry, concept-first.
Organic compounds containing nitrogen are essential to life. Amines, the organic derivatives of ammonia, play a central role in bioregulation and neurotransmission -- dopamine and histamine are both amines.
Key concepts
Hover a concept to preview it and jump to its most relevant Q&A.
Reactions of Nitrobenzene
Nitrobenzene's own chemistry extends the general nitro-reduction ladder and adds ring-specific electrophilic substitution.
Most relevant Q&A
- Which of the following reagents can be used to convert nitrobenzene to aniline? a) Sn / HCl b) Zn-Hg / NaOH c) Zn / NH4Cl d) All of theseFree
- How will you convert nitrobenzene into i. 1,3,5-trinitrobenzene ii. o- and p-nitrophenol iii. m-nitroaniline iv. azoxybenzene v. hydrazobenz…Preview
- Nitrobenzene, on reaction with conc. HNO3 / conc. H2SO4 at 80-100 degree C, forms which one of the following products? a) 1,4-dinitrobenzene…Preview
- The product obtained when nitrobenzene is reduced using Zn/NaOH is : (a) azobenzene (b) aniline (c) hydrazobenzene (d) azoxy benzenePreview
- Nitrobenzene on reduction with Zn/NaOH gives : (a) $C_6H_5-N=N-C_6H_5$ (b) $C_6H_5-NH-NH-C_6H_5$ (c) $C_6H_5NHOH$ (d) $C_6H_5-N=N-C_6H_5$ wi…Preview
Chapter contents
The NCERT structure, section by section. Open a section to see its questions, then read the concept-first solution.
Introduction
Organic compounds containing nitrogen are essential to life. Amines, the organic derivatives of ammonia, play a central role in bioregulation and neurotransmission -- dopamine and histamine are both a…
Nitro Compounds
Nitro compounds are considered derivatives of hydrocarbons: replacing one hydrogen atom of a hydrocarbon with the -NO2 group gives the resulting organic compound its name -- a nitro compound.
Classification of Nitro Compounds
Nitro compounds (organic compounds containing the -NO2 group) split first into aliphatic nitro compounds and aromatic nitro compounds.
Nomenclature of Nitroalkanes
In IUPAC nomenclature, nitroalkanes are named by adding the prefix 'nitro' before the name of the parent alkane, with a locant number showing the position of the -NO2 group on the longest chain contai…
Isomerism in Nitroalkanes
Nitroalkanes show chain isomerism (differing in the length/branching of the carbon chain, e.g. 1-nitrobutane vs 2-methyl-1-nitropropane), position isomerism (differing only in where -NO2 sits on an ot…
Acidic Nature of Nitroalkanes
The alpha-hydrogen of a primary or secondary nitroalkane shows acidic character because the strongly electron-withdrawing -NO2 group pulls electron density away, stabilising the conjugate base once th…
Preparation of Nitroalkanes
Five distinct routes give nitroalkanes. (1) FROM ALKYL HALIDES (laboratory method): an alkyl bromide or iodide heated with an ethanolic solution of potassium nitrite (KNO2) displaces the halide via an…
Preparation of Nitroarenes
Two routes give nitroarenes. (1) DIRECT NITRATION: benzene heated at 330 K with a nitrating mixture (concentrated HNO3 + concentrated H2SO4) undergoes electrophilic substitution to give nitrobenzene (…
Physical Properties of Nitroalkanes
The lower nitroalkanes are colourless, pleasant-smelling liquids that are only sparingly soluble in water but dissolve readily in organic solvents such as benzene and acetone.
Chemical Properties of Nitroalkanes
Nitroalkanes undergo three principal reaction classes. (i) REDUCTION: the nitro group reduces stepwise -- nitro (R-NO2) to nitroso (R-N=O) to N-alkylhydroxylamine (R-NHOH) to the primary amine (R-NH2)…
Chemical Properties of Nitrobenzene
Nitrobenzene's chemistry mirrors and extends the general nitroalkane reduction ladder, plus adds its own electrophilic aromatic substitution chemistry.
Amines -- Classification
Amines are the organic derivatives of ammonia, formed by replacing one, two or three hydrogens with alkyl or aryl groups.
Nomenclature of Amines
Amines are named two ways. In the COMMON system, an aliphatic amine is named by prefixing the alkyl group to 'amine' (isopropylamine, benzylamine), with di-/tri-/tetra- prefixes for two, three or four…
Structure of Amines
Like ammonia, the nitrogen of an amine is trivalent, carries one lone pair of electrons, and is sp3-hybridised: three of the four sp3 orbitals overlap with hydrogen or alkyl-group orbitals, while the…
General Methods of Preparation of Amines
Both aliphatic and aromatic amines are built by five general strategies. (1) FROM NITRO COMPOUNDS: reduction with H2/Ni (or Sn/HCl, or Pd/H2) converts a nitroalkane or nitroarene into the correspondin…
Physical Properties of Amines
PHYSICAL STATE AND SMELL: the lower aliphatic amines (C1-C2) are colourless gases with an ammonia-like smell; those with four or more carbons are volatile liquids with a fish-like smell.
Basicity of Amines
The lone pair on the amine nitrogen makes amines both basic and nucleophilic -- they react with acids to form salts (e.g. aniline + HCl gives anilinium chloride, C6H5-NH3+Cl-).
Chemical Reactions of Amines
(1) ALKYLATION: an amine reacts with an alkyl halide (e.g. CH3Br) in successive substitutions, climbing 1 degree to 2 degree to 3 degree amine and finally to a quaternary ammonium salt as more equival…
Diazonium Salts
Aromatic amines, treated with NaNO2 + HCl (nitrous acid generated in situ), give diazonium salts, Ar-N2+X-.
Introduction to Diazonium Salts
Diazonium salts are prepared from aromatic amines and are used immediately because they are stable for only a short time -- their reactive -N2+ group, formally derived by diazotisation of the ring's -…
Resonance Structure of Diazonium Salts
The arenediazonium cation is stabilised by delocalisation of its positive charge over the aromatic ring: the terminal nitrogen's positive charge can be drawn as resonating onto the ring's ortho and pa…
Preparation of Diazonium Salts
Benzenediazonium chloride is prepared by reacting aniline with nitrous acid (itself generated in situ from NaNO2 + HCl) at a low temperature of 273-278 K -- keeping the temperature this low is essenti…
Physical Properties of Diazonium Salts
Benzenediazonium chloride is a colourless, crystalline solid. It is readily soluble in water and stable in COLD water, but reacts with WARM water (hydrolysing to phenol, as covered under its replaceme…
Chemical Reactions of Diazonium Salts
Benzenediazonium chloride undergoes two broad classes of reaction. A. REPLACEMENT REACTIONS (involving LOSS of nitrogen, N2 gas): the diazonium group is displaced by a nucleophile such as X-, CN-, H-,…
Cyanides and Isocyanides
Cyanides and isocyanides are the two families of alkyl derivatives of hydrocyanic acid (HCN), which itself exists in two tautomeric forms: hydrogen cyanide (H-CN) and hydrogen isocyanide (H-NC, with t…
Introduction to Cyanides and Isocyanides
Cyanides and isocyanides are the derivatives of hydrocyanic acid's two tautomeric forms, hydrogen cyanide and hydrogen isocyanide.
Preparation of Cyanides
Four routes give alkyl cyanides. (1) FROM ALKYL HALIDES: treating an alkyl halide with NaCN or KCN in solution gives the alkyl cyanide, forming a NEW carbon-carbon bond (e.g.
Properties of Cyanides
The lower alkyl cyanides (up to about C14) are colourless liquids with a strong, characteristic sweet smell; the higher members are crystalline solids.
Chemical Properties of Cyanides
(1) HYDROLYSIS: boiling a cyanide with alkali or dilute mineral acid hydrolyses it to a carboxylic acid, via a two-stage mechanism -- PARTIAL hydrolysis (H2O2/OH-) stops at the amide (e.g.
Nomenclature of Alkyl Isocyanides
Isocyanides are commonly named as 'alkyl isocyanides' (methyl isocyanide, ethyl isocyanide, phenyl isocyanide), while the IUPAC system instead calls them 'alkylcarbylamines' -- so methyl isocyanide is…
Preparation of Isocyanides
Three routes give isocyanides. (1) FROM PRIMARY AMINES (the carbylamine reaction): both aromatic and aliphatic primary amines, treated with CHCl3 in the presence of KOH, give the corresponding carbyla…
Properties of Isocyanides
Isocyanides are colourless, highly unpleasant-smelling, volatile liquids -- considerably MORE poisonous than the corresponding cyanides, so much so that even a faint carbylamine-like odour during a sy…
Chemical Properties of Isocyanides
(1) HYDROLYSIS: unlike cyanides, alkyl isocyanides are NOT hydrolysed by alkalies; dilute MINERAL acids, however, hydrolyse them to a primary amine + formic acid, e.g.
Uses of Organic Nitrogen Compounds
NITROALKANES: nitromethane is used as a fuel for cars; chloropicrin (CCl3NO2) is used as an insecticide; nitroethane is used as a fuel additive and as a precursor to explosives, and is a good solvent…
Summary Flow Charts -- Organic Nitrogen Compound Chemistry
The chapter's closing flow-chart page ties together the preparation and reaction webs built section by section.
EVALUATION
43 QThe chapter-end assessment: 25 objective 'Choose the correct answer' questions spanning nitro-compound reduction/reactivity, amine preparation and basicity, diazonium-salt replacement/coupling chemist…
+−Choose the Best Answer25 questions
- Q1Which of the following reagents can be used to convert nitrobenzene to aniline? a) Sn / HCl b) Zn-Hg / NaOH c) Zn / NH4Cl d) All of theseFree
- Q2The method by which aniline CANNOT be prepared is a) degradation of benzamide with Br2 / NaOH b) potassium salt of phthalimide treated with…Free
- Q3Which one of the following will NOT undergo Hofmann bromamide reaction? a) CH3-CO-NH-CH3 b) CH3-CH2-CO-NH2 c) CH3-CO-NH2 d) C6H5-CO-NH2Free
- Q4Assertion: Acetamide on reaction with KOH and bromine gives acetic acid. Reason: Bromine catalyses hydrolysis of acetamide. a) if both asser…Preview
- Q5CH3CH2Br is treated in sequence: (i) aq. NaOH/heat gives A; (ii) A + KMnO4/H+/heat gives B; (iii) B + NH3/heat gives C; (iv) C + Br2/NaOH/he…Preview
- Q6Which one of the following nitro compounds does NOT react with nitrous acid? a) CH3-CH2-CH2-NO2 b) (CH3)2CH-CH2-NO2 c) (CH3)3C-NO2 d) CH3-CO…Preview
- Q7Aniline + benzoyl chloride, in the presence of NaOH, gives C6H5-NH-CO-C6H5 (N-phenylbenzamide). This reaction is known as a) Friedel-Crafts…Preview
- Q8The product formed by the reaction of an aldehyde with a primary amine (NEET) is a) carboxylic acid b) aromatic acid c) Schiff's base d) ket…Preview
- Q9Which of the following reactions is NOT correct? a) CH3CH2NH2 + HNO2 gives CH3CH2OH + N2 b) (CH3)2N-C6H5 + NaNO2/HCl gives (CH3)2N-C6H4-N=NC…Preview
- Q10When aniline reacts with acetic anhydride, the product formed is a) o-aminoacetophenone b) m-aminoacetophenone c) p-aminoacetophenone d) ace…Preview
- Q11The order of basic strength for methyl-substituted amines in aqueous solution is a) N(CH3)3 > N(CH3)2H > N(CH3)H2 > NH3 b) N(CH3)H2 > N(CH3)…Preview
- Q12A benzenediazonium salt bearing -NO2 and -Br substituents on the ring reacts with a reagent A to give a product retaining both the -NO2 and…Preview
- Q13C6H5NO2 --Fe/HCl--> A --NaNO2/HCl, 273 K--> B --H2O, 283 K--> C. 'C' is a) C6H5-OH b) C6H5-CH2OH c) C6H5-CHO d) C6H5-NH2Preview
- Q14Nitrobenzene, on reaction with conc. HNO3 / conc. H2SO4 at 80-100 degree C, forms which one of the following products? a) 1,4-dinitrobenzene…Preview
- Q15C5H13N reacts with HNO2 to give an optically active compound. The compound is a) pentan-1-amine b) pentan-2-amine c) N,N-dimethylpropan-2-am…Preview
- Q16Secondary nitroalkanes react with nitrous acid to form a a) red solution b) blue solution c) green solution d) yellow solutionPreview
- Q17Which of the following amines does NOT undergo acetylation? a) t-butylamine b) ethylamine c) diethylamine d) triethylaminePreview
- Q18Which one of the following is most basic? a) 2,4-dichloroaniline b) 2,4-dimethylaniline c) 2,4-dinitroaniline d) 2,4-dibromoanilinePreview
- Q19When ethyl nitrite (CH3CH2-O-N=O) is reduced with Sn / HCl, the pair of compounds formed are a) ethanol, hydroxylamine hydrochloride b) etha…Preview
- Q20The IUPAC name for the amine (CH3CH2)2C(CH3)-N(CH3)2 -- a pentane chain carrying an ethyl-type arm on each side of C3, a methyl branch also…Preview
- Q214-Methoxybenzonitrile (p-CH3O-C6H4-CN) is treated with CH3MgBr, then hydrolysed with H3O+. Product 'P' in this reaction is a) p-CH3O-C6H4-CH…Preview
- Q22The ammonium salt of benzoic acid is heated strongly with P2O5, and the product so formed is reduced and then treated with NaNO2 / HCl at lo…Preview
- Q23Identify X in the sequence: m-chloroaniline --CHCl3/KOH--> (Y) --HCl, 300 K--> X + methanoic acid. a) m-chloroaniline (the original amine, r…Preview
- Q24Among the following, the reaction that proceeds through an electrophilic substitution is: a) C6H5-N2+Cl- + Cu2Cl2 gives C6H5-Cl + N2 b) benz…Preview
- Q25The major product of the following reaction: phthalic acid (benzene-1,2-dicarboxylic acid) + NH3, strongly heated, is a) a mono-amide of pht…Preview
+−Write Brief Answer18 questions
- Q1Write down the possible isomers of C4H9NO2 and give their IUPAC names.Free
- Q2There are two isomers with the formula C2H5NO2. How will you distinguish between them?Free
- Q3What happens when i. 2-Nitropropane is boiled with HCl? ii. Nitrobenzene undergoes electrolytic reduction in a strongly acidic medium? iii.…Free
- Q4How will you convert nitrobenzene into i. 1,3,5-trinitrobenzene ii. o- and p-nitrophenol iii. m-nitroaniline iv. azoxybenzene v. hydrazobenz…Preview
- Q5Identify compounds A, B and C in the following sequences of reactions: i) C6H5NO2 --Fe/HCl--> A --HNO2, 273 K--> B --C6H5OH--> C ii) C6H5N2+…Preview
- Q6Write short notes on the following: i. Hofmann's bromamide reaction ii. Ammonolysis iii. Gabriel phthalimide synthesis iv. Schotten-Baumann…Preview
- Q7How will you distinguish between primary, secondary and tertiary aliphatic amines?Preview
- Q8Account for the following: i. Aniline does not undergo Friedel-Crafts reaction. ii. Diazonium salts of aromatic amines are more stable than…Preview
- Q9Arrange the following: i. In increasing order of solubility in water: C6H5NH2, (C2H5)2NH, C2H5NH2 ii. In increasing order of basic strength:…Preview
- Q10How will you prepare propan-1-amine from i) butanenitrile ii) propanamide iii) 1-nitropropane?Preview
- Q11Identify A, B and C: CH3-NO2 --LiAlH4--> A --2 CH3CH2Br--> B --H2SO4--> CPreview
- Q12How will you convert diethylamine into i) N,N-diethylacetamide ii) N-nitrosodiethylamine?Preview
- Q13Identify A, B and C: salicylic acid (2-hydroxybenzoic acid, a ring bearing both -OH and -COOH) --SOCl2--> A --NH3--> B --LiAlH4--> (C)Preview
- Q14Identify A: aniline + benzaldehyde gives A.Preview
- Q15Complete the following reaction: an aromatic ketone/aldehyde + benzylamine (drawn as a ring-CH2-NH2 group), in the presence of a trace of H+…Preview
- Q16Predict A, B, C and D for the following reaction: phthalic anhydride (the cyclic anhydride drawn with two ring C=O groups bridged by O) + NH…Preview
- Q17A dibromo derivative (A) on treatment with KCN followed by acid hydrolysis and heating gives a monobasic acid (B) along with liberation of C…Preview
- Q18Identify A to E in the following sequence of reactions: toluene --CH3Cl/AlCl3--> A (major product) --HNO3/H2SO4--> B --Sn/HCl--> C --NaNO2/H…Preview
Sample & Board Papers
Sample papers and previous-year board questions for this subject.
+−Show 26 questionsHide questions26 questions
- Q1When nitromethane is reduced with $Zn/NH_4Cl$, we get : (a) $CH_3NH_2$ (b) $C_2H_5NH_2$ (c) $CH_3NHOH$ (d) $C_2H_5COOH$Preview
- Q2The IUPAC name of dimethyl sec. butylamine is : (a) 2-amino-3-methyl butane (b) 2-(N-methyl amino) butane (c) 2-(N, N-dimethyl amino) butane…Preview
- Q3The basic character of amines is due to : (a) tetrahedral structure (b) presence of nitrogen atom (c) lone pair of electrons on nitrogen ato…Preview
- Q4How is methyl cyanide obtained from acetamide ?Preview
- Q5Write about Gabriel phthalimide synthesis.Preview
- Q6(a) How do primary, secondary and tertiary amines react with nitrous acid ? (b) Elucidate the structure of glucose.Preview
- Q7Oxidation of aniline with acidified potassium dichromate gives : (a) benzaldehyde (b) p-benzo quinone (c) benzyl alcohol (d) benzoic acidPreview
- Q8Nitromethane condenses with acetaldehyde to give : (a) 2-nitro-1-propanol (b) Nitro propane (c) 3-nitro propanol (d) 1-nitro-2-propanolPreview
- Q9The product obtained when nitrobenzene is reduced using Zn/NaOH is : (a) azobenzene (b) aniline (c) hydrazobenzene (d) azoxy benzenePreview
- Q10What is Malachite green ? How is it prepared ?Preview
- Q11$C_7H_7ON\ (A) \xrightarrow[KOH]{Br_2} B \xrightarrow{COCl_2} C$. Identify A, B and C.Preview
- Q12Write the chromogen, chromophore and auxochrome present in para hydroxy azo benzene.Preview
- Q13(a) Distinguish between primary, secondary and tertiary amines. (b) Write notes on Polysaccharides.Preview
- Q14Nitrobenzene on reduction with Zn/NaOH gives : (a) $C_6H_5-N=N-C_6H_5$ (b) $C_6H_5-NH-NH-C_6H_5$ (c) $C_6H_5NHOH$ (d) $C_6H_5-N=N-C_6H_5$ wi…Preview
- Q15Write any three characteristics of dyes.Preview
- Q16Which of the following reagent can be used to convert nitrobenzene to aniline ? (a) $ZnHg/NaOH$ (b) $Zn/NH_4Cl$ (c) $Sn/HCl$ (d) All of thes…Preview
- Q17Identify A and B in the following sequence of reactions. $CH_3-Br \xrightarrow{NaN_3} A \xrightarrow{LiAlH_4} B + N_2$Preview
- Q18Assertion : Hex-4-ennitrile on reaction with Di-isobutyl aluminium hydride followed by Hydrolysis gives Hex-4-enal. Reason : Di-isobutyl alu…Preview
- Q19Identify the compounds A and B in the following sequence of reactions. $CH_3CH_2NO_2 \xrightarrow{Sn/HCl} A \xrightarrow{CH_3COCl} B$Preview
- Q20When aniline reacts with acetic anhydride, the product formed is : (a) p-aminoacetophenone (b) o-aminoacetophenone (c) acetanilide (d) m-ami…Preview
- Q21Write the reaction of primary amine with Carbon disulphide ($CS_2$).Preview
- Q22(a) (i) How acetic acid is prepared from Grignard reagent ? (ii) What are bio-degradable polymers ? Give an example. **OR** (b) An organic C…Preview
- Q23The compound that reacts with nitrous acid to give yellow oily liquid is ________. (a) N-methylaniline (b) Nitro benzene (c) N,N-dimethyl an…Preview
- Q24Identify compounds A, B and C in the following sequence of reaction. $C_6H_5NO_2 \xrightarrow{Sn/HCl} A \xrightarrow[273\ K]{NaNO_2 + HCl} B…Preview
- Q25$C_6H_5NO_2 \xrightarrow{Sn/HCl} A \xrightarrow[273\ K]{NaNO_2/HCl} B \xrightarrow[283\ K]{H_2O} C$ 'C' is : (a) $C_6H_5CHO$ (b) $C_6H_5OH$…Preview
- Q26An organic compound (A) with molecular formula $C_2H_7N$ reacts with nitrous acid to form compound (B) which is unstable. Hence compound (B)…Preview