Nitration is the class of chemical processes that introduces the nitro group into an organic chemical compound. The term nitration is also sometimes used incorrectly to represent different processes, such as the formation of nitrate esters among nitric acid and alcohols, which further take place in synthesising nitroglycerin. However, the main difference between the final structure of nitrates and nitro compounds is the nitrogen atom forms a chemical bond with a non-oxygen atom, such as the carbon or other nitrogen atoms. In the case of organic nitrates, the nitrogen is usually bonded with an oxygen atom, which further has a bond to a carbon atom.
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Nitration Mechanism
As such, in Organic Chemistry, nitration is a process, in which there is the replacement of a hydrogen atom (organic compound) with one or more nitro groups (single bond NO2).
The reaction usually occurs at high temperatures, or we can say that the reaction is exothermic. Additionally, nitration reactions can be hazardous when performed on large scales in batches.
A large amount of heat is released, and multiple nitrations can occur, which can be really problematic. Therefore, nitration reaction is usually controlled by some sort of systematic cooling that is particularly designed to take away the excess generated energy.
Besides, the ability to control exotherms in-flow allows improved selectivity and safety. As such, there have been many nitration reactions performed using continuous flow.
By-products are also usually formed where some products can also be highly explosive.
Most of the nitration reactions are conducted at low temperatures, mainly for safety reasons. Sometimes, nitration reaction is carried out with aliphatic compound also. Nonetheless, nitration of aromatics is more commercially important.
Forms of Nitration
Aromatic Nitration
This is a typical form of nitration synthesis wherein the “mixed acid”, a mixture of concentrated nitric acid and sulfuric acid, is applied.
The reaction between the mixture results in the formation of the nitronium ion (NO2+), which is the active species in aromatic nitration. Interestingly, this active ingredient also affects nitration without the need for mixed acid.
On the other hand, during mixed-acid syntheses, sulfuric acid is not consumed. It rather acts as a catalyst and water absorbent. In the case of nitration of benzene, which we will look at in detail below, the reaction is typically conducted at a warm temperature of 50 °C.
The process is an example of electrophilic aromatic substitution,
Today, there are several mechanisms that have been proposed, such as the one involving single electron transfer (SET). But the above-mentioned is a common and popular reaction discussed in the syllabus.
Ipso Nitration
The phrase ipso nitration was first stated by Perrin and Skinner in 1971 during their investigation into chloroanisole nitration. Ipso nitration basically involves compounds such as aryl chlorides, triflates and nonaflates. For instance, in a nitration protocol, 4-chloro-n-butylbenzene is reacted with sodium nitrite in t-butanol. This is done in the presence of 0.5 mol% Pd2(dba)3, a biaryl phosphine ligand and a phase-transfer catalyst (PTC) to form 4-nitro-n-butylbenzene.
Applications of Nitration
With the help of a nitration reaction, nitrogen is added to a benzene ring which can be used extensively in substitution reactions. The nitro group usually acts as a ring deactivator. As the ring consists of nitrogen, it is very useful because it can be used as a directing group or a masked amino group. The products of aromatic nitrations are very important intermediates in industrial chemistry.
Nitration finds various industrial applications, and the most critical by volume is the production of nitroaromatic compounds such as nitrobenzene. Nitration reactions are used notably in the production of explosives, like the conversion of toluene to trinitrotoluene and the conversion of guanidine to nitroguanidine. They are basically used widely as precursors and chemical intermediates.
Electrophilic Substitution Reaction between Benzene and Nitric Acid
Benzene is treated with a solution of concentrated sulfuric acid and concentrated nitric acid at a temperature not more than 50oC. As the temperature rises, there exist higher chances of obtaining more than one nitro group -NO2 being substituted in the ring.
Then, nitrobenzene is formed.
The concentrated sulfuric acid acts as a catalyst.
The Formation of Electrophile
An electrophile is the nitryl cation or the nitronium ion, NO2+, formed by the reaction between sulphuric acid and nitric acid. The nitronium ion is formed by the protonation of nitric acid by sulfuric acid, causing the loss of a water molecule and the formation of the ion.
Electrophilic Substitution Mechanism
The nitronium ion is a good electrophile, and thus it is attacked by benzene to produce nitrobenzene.
During electrophilic aromatic substitution, an acid-base reaction occurs. A weak base (water or HSO4– ion left after protonation of HNO3) removes a proton from carbon-bearing the nitro group, breaking C–H and re-forming C–C pi. Therefore, aromaticity is restored.
On the other hand, nitration is one of the popular organic reactions that is discussed in Chemistry.
Besides, both aromatic and aliphatic compounds can be nitrated by different methods, such as heterolytic (nucleophilic and electrophilic) and radical nitrations.
Aliphatic is a free radical, and aromatic nitration is the most frequent electrophilic. Nitroaromatic compounds are mostly used as intermediates in the synthesis of pharmaceuticals, plants, dyestuffs, and insecticides.
Environmental Concerns
As for the environmental issues of nitration processes, apart from its explosive properties, it is related to the occurrence of acid vapours which are largely nitric or sulfuric acid from the reaction.
There can be some other unreacted nitrating agents also that are used to carry the nitration reaction to completion. There are also cases resulting in the emission of VOCs or other gas streams containing the various oxides of nitrogen.
If we talk about water pollutants, the nitration of aromatic feedstocks may result in the generation of large quantities of waste-mixed acid. This requires proper neutralisation and disposal or even recovery (using the distillation process) and reuse.
The products and by-products are usually slow to biodegrade and toxic. Now, this will require additional treatment of the waste products.
Neeraj Anand, Param Anand
Er. Neeraj K.Anand is a freelance mentor and writer who specializes in Engineering & Science subjects. Neeraj Anand received a B.Tech degree in Electronics and Communication Engineering from N.I.T Warangal & M.Tech Post Graduation from IETE, New Delhi. He has over 30 years of teaching experience and serves as the Head of Department of ANAND CLASSES. He concentrated all his energy and experiences in academics and subsequently grew up as one of the best mentors in the country for students aspiring for success in competitive examinations.
In parallel, he started a Technical Publication "ANAND TECHNICAL PUBLISHERS" in 2002 and Educational Newspaper "NATIONAL EDUCATION NEWS" in 2014 at Jalandhar. Now he is a Director of leading publication "ANAND TECHNICAL PUBLISHERS", "ANAND CLASSES" and "NATIONAL EDUCATION NEWS".
He has published more than hundred books in the field of Physics, Mathematics, Computers and Information Technology. Besides this he has written many books to help students prepare for IIT-JEE and AIPMT entrance exams. He is an executive member of the IEEE (Institute of Electrical & Electronics Engineers. USA) and honorary member of many Indian scientific societies such as Institution of Electronics & Telecommunication Engineers, Aeronautical Society of India, Bioinformatics Institute of India, Institution of Engineers. He has got award from American Biographical Institute Board of International Research in the year 2005.
CBSE Class 11 Chemistry Syllabus is a vast which needs a clear understanding of the concepts and topics. Knowing CBSE Class 11 Chemistry syllabus helps students to understand the course structure of Chemistry.
Unit-wise CBSE Class 11 Syllabus for Chemistry
Below is a list of detailed information on each unit for Class 11 Students.
UNIT I – Some Basic Concepts of Chemistry
General Introduction: Importance and scope of Chemistry.
Nature of matter, laws of chemical combination, Dalton’s atomic theory: concept of elements, atoms and molecules.
Atomic and molecular masses, mole concept and molar mass, percentage composition, empirical and molecular formula, chemical reactions, stoichiometry and calculations based on stoichiometry.
UNIT II – Structure of Atom
Discovery of Electron, Proton and Neutron, atomic number, isotopes and isobars. Thomson’s model and its limitations. Rutherford’s model and its limitations, Bohr’s model and its limitations, concept of shells and subshells, dual nature of matter and light, de Broglie’s relationship, Heisenberg uncertainty principle, concept of orbitals, quantum numbers, shapes of s, p and d orbitals, rules for filling electrons in orbitals – Aufbau principle, Pauli’s exclusion principle and Hund’s rule, electronic configuration of atoms, stability of half-filled and completely filled orbitals.
UNIT III – Classification of Elements and Periodicity in Properties
Significance of classification, brief history of the development of periodic table, modern periodic law and the present form of periodic table, periodic trends in properties of elements -atomic radii, ionic radii, inert gas radii, Ionization enthalpy, electron gain enthalpy, electronegativity, valency. Nomenclature of elements with atomic number greater than 100.
UNIT IV – Chemical Bonding and Molecular Structure
Valence electrons, ionic bond, covalent bond, bond parameters, Lewis structure, polar character of covalent bond, covalent character of ionic bond, valence bond theory, resonance, geometry of covalent molecules, VSEPR theory, concept of hybridization, involving s, p and d orbitals and shapes of some simple molecules, molecular orbital theory of homonuclear diatomic molecules(qualitative idea only), Hydrogen bond.
UNIT V – Chemical Thermodynamics
Concepts of System and types of systems, surroundings, work, heat, energy, extensive and intensive properties, state functions. First law of thermodynamics – internal energy and enthalpy, measurement of U and H, Hess’s law of constant heat summation, enthalpy of bond dissociation, combustion, formation, atomization, sublimation, phase transition, ionization, solution and dilution. Second law of Thermodynamics (brief introduction) Introduction of entropy as a state function, Gibb’s energy change for spontaneous and nonspontaneous processes. Third law of thermodynamics (brief introduction).
UNIT VI – Equilibrium
Equilibrium in physical and chemical processes, dynamic nature of equilibrium, law of mass action, equilibrium constant, factors affecting equilibrium – Le Chatelier’s principle, ionic equilibrium- ionization of acids and bases, strong and weak electrolytes, degree of ionization, ionization of poly basic acids, acid strength, concept of pH, hydrolysis of salts (elementary idea), buffer solution, Henderson Equation, solubility product, common ion effect (with illustrative examples).
UNIT VII – Redox Reactions
Concept of oxidation and reduction, redox reactions, oxidation number, balancing redox reactions, in terms of loss and gain of electrons and change in oxidation number, applications of redox reactions.
UNIT VIII – Organic Chemistry: Some basic Principles and Techniques
General introduction, classification and IUPAC nomenclature of organic compounds. Electronic displacements in a covalent bond: inductive effect, electromeric effect, resonance and hyper conjugation. Homolytic and heterolytic fission of a covalent bond: free radicals, carbocations, carbanions, electrophiles and nucleophiles, types of organic reactions.
UNIT IX – Hydrocarbons
Classification of Hydrocarbons Aliphatic Hydrocarbons: Alkanes – Nomenclature, isomerism, conformation (ethane only), physical properties, chemical reactions. Alkenes – Nomenclature, structure of double bond (ethene), geometrical isomerism, physical properties, methods of preparation, chemical reactions: addition of hydrogen, halogen, water, hydrogen halides (Markovnikov’s addition and peroxide effect), ozonolysis, oxidation, mechanism of electrophilic addition. Alkynes – Nomenclature, structure of triple bond (ethyne), physical properties, methods of preparation, chemical reactions: acidic character of alkynes, addition reaction of – hydrogen, halogens, hydrogen halides and water.
Aromatic Hydrocarbons:
Introduction, IUPAC nomenclature, benzene: resonance, aromaticity, chemical properties: mechanism of electrophilic substitution. Nitration, sulphonation, halogenation, Friedel Craft’s alkylation and acylation, directive influence of functional group in monosubstituted benzene. Carcinogenicity and toxicity.
To know the CBSE Syllabus for all the classes from 1 to 12, visit the Syllabus page of CBSE. Meanwhile, to get the Practical Syllabus of Class 11 Chemistry, read on to find out more about the syllabus and related information in this page.
CBSE Class 11 Chemistry Practical Syllabus with Marking Scheme
In Chemistry subject, practical also plays a vital role in improving their academic scores in the subject. The overall weightage of Chemistry practical mentioned in the CBSE Class 11 Chemistry syllabus is 30 marks. So, students must try their best to score well in practicals along with theory. It will help in increasing their overall academic score.
CBSE Class 11 Chemistry Practical Syllabus
The experiments will be conducted under the supervision of subject teacher. CBSE Chemistry Practicals is for 30 marks. This contribute to the overall practical marks for the subject.
The table below consists of evaluation scheme of practical exams.
Evaluation Scheme
Marks
Volumetric Analysis
08
Salt Analysis
08
Content Based Experiment
06
Project Work
04
Class record and viva
04
Total
30
CBSE Syllabus for Class 11 Chemistry Practical
Micro-chemical methods are available for several of the practical experiments. Wherever possible such techniques should be used.
A. Basic Laboratory Techniques 1. Cutting glass tube and glass rod 2. Bending a glass tube 3. Drawing out a glass jet 4. Boring a cork
B. Characterization and Purification of Chemical Substances 1. Determination of melting point of an organic compound. 2. Determination of boiling point of an organic compound. 3. Crystallization of impure sample of any one of the following: Alum, Copper Sulphate, Benzoic Acid.
C. Experiments based on pH
1. Any one of the following experiments:
Determination of pH of some solutions obtained from fruit juices, solution of known and varied concentrations of acids, bases and salts using pH paper or universal indicator.
Comparing the pH of solutions of strong and weak acids of same concentration.
Study the pH change in the titration of a strong base using universal indicator.
2. Study the pH change by common-ion in case of weak acids and weak bases.
D. Chemical Equilibrium One of the following experiments:
1. Study the shift in equilibrium between ferric ions and thiocyanate ions by increasing/decreasing the concentration of either of the ions. 2. Study the shift in equilibrium between [Co(H2O)6] 2+ and chloride ions by changing the concentration of either of the ions.
E. Quantitative Estimation i. Using a mechanical balance/electronic balance. ii. Preparation of standard solution of Oxalic acid. iii. Determination of strength of a given solution of Sodium hydroxide by titrating it against standard solution of Oxalic acid. iv. Preparation of standard solution of Sodium carbonate. v. Determination of strength of a given solution of hydrochloric acid by titrating it against standard Sodium Carbonatesolution.
F. Qualitative Analysis 1) Determination of one anion and one cation in a given salt Cations‐ Pb2+, Cu2+, As3+, Al3+, Fe3+, Mn2+, Ni2+, Zn2+, Co2+, Ca2+, Sr2+, Ba2+, Mg2+, NH4+ Anions – (CO3)2‐ , S2‐, NO2‐ , SO32‐, SO2‐ , NO ‐ , Cl‐ , Br‐, I‐, PO43‐ , C2O2‐ ,CH3COO‐ (Note: Insoluble salts excluded)
2) Detection of ‐ Nitrogen, Sulphur, Chlorine in organic compounds.
G) PROJECTS Scientific investigations involving laboratory testing and collecting information from other sources.
A few suggested projects are as follows:
Checking the bacterial contamination in drinking water by testing sulphide ion
Study of the methods of purification of water.
Testing the hardness, presence of Iron, Fluoride, Chloride, etc., depending upon the regional variation in drinking water and study of causes of presence of these ions above permissible limit (if any).
Investigation of the foaming capacity of different washing soaps and the effect of addition of Sodium carbonate on it.
Study the acidity of different samples of tea leaves.
Determination of the rate of evaporation of different liquids Study the effect of acids and bases on the tensile strength of fibres.
Study of acidity of fruit and vegetable juices.
Note: Any other investigatory project, which involves about 10 periods of work, can be chosen with theapproval of the teacher.
Practical Examination for Visually Impaired Students of Class 11
Below is a list of practicals for the visually impaired students.
A. List of apparatus for identification for assessment in practicals (All experiments) Beaker, tripod stand, wire gauze, glass rod, funnel, filter paper, Bunsen burner, test tube, test tube stand, dropper, test tube holder, ignition tube, china dish, tongs, standard flask, pipette, burette, conical flask, clamp stand, dropper, wash bottle • Odour detection in qualitative analysis • Procedure/Setup of the apparatus
B. List of Experiments A. Characterization and Purification of Chemical Substances 1. Crystallization of an impure sample of any one of the following: copper sulphate, benzoic acid B. Experiments based on pH 1. Determination of pH of some solutions obtained from fruit juices, solutions of known and varied concentrations of acids, bases and salts using pH paper 2. Comparing the pH of solutions of strong and weak acids of same concentration.
C. Chemical Equilibrium 1. Study the shift in equilibrium between ferric ions and thiocyanate ions by increasing/decreasing the concentration of eitherions. 2. Study the shift in equilibrium between [Co(H2O)6]2+ and chloride ions by changing the concentration of either of the ions.
D. Quantitative estimation 1. Preparation of standard solution of oxalic acid. 2. Determination of molarity of a given solution of sodium hydroxide by titrating it against standard solution of oxalic acid.
E. Qualitative Analysis 1. Determination of one anion and one cation in a given salt 2. Cations – NH+4 Anions – (CO3)2-, S2-, (SO3)2-, Cl-, CH3COO- (Note: insoluble salts excluded) 3. Detection of Nitrogen in the given organic compound. 4. Detection of Halogen in the given organic compound.
Note: The above practicals may be carried out in an experiential manner rather than recording observations.
We hope students must have found this information on CBSE Syllabus useful for their studying Chemistry. Learn Maths & Science in interactive and fun loving ways with ANAND CLASSES (A School Of Competitions) App/Tablet.
Frequently Asked Questions on CBSE Class 11 Chemistry Syllabus
Q1
How many units are in the CBSE Class 11 Chemistry Syllabus?
There are 9 units in the CBSE Class 11 Chemistry Syllabus. Students can access various study materials for the chapters mentioned in this article for free at ANAND CLASSES (A School Of Competitions).
Q2
What is the total marks for practicals examination as per the CBSE Class 11 Chemistry Syllabus?
The total marks for the practicals as per the CBSE Class 11 Chemistry Syllabus is 30. It includes volumetric analysis, content-based experiment, salt analysis, class record, project work and viva.
Q3
Which chapter carries more weightage as per the CBSE Syllabus for Class 11 Chemistry?
The organic chemistry chapter carries more weightage as per the CBSE Syllabus for Class 11 Chemistry.
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