Mechanism of Organic Reactions

Paper Code: 
25CHY222
Credits: 
4
Contact Hours: 
60.00
Max. Marks: 
100.00
Objective: 

This course will enable the students to

get in-depth knowledge of different types of reaction mechanisms i.e. substitution, elimination and addition reactions of aliphatic and aromatic organic compounds

Course Outcomes: 

Course

Learning outcome

(at course level)

Learning and Teaching Strategies

Assessment Strategies

Course Code

Course

Title

 

25CHY222

 

Mechanism of Organic Reactions (Theory)

CO57 Explain the mechanistic and stereochemical aspects of the different reactions of organic compounds.

CO58 Appraise and differentiate between aromatic electrophilic and nucleophilic substitution reactions giving proper mechanism.

CO59 Elaborate and illustrate the mechanistic concepts of various substitution reactions.

CO60 Apply the basic principles involved in C-C and C-hetero multiple bond formation.

CO61 Explain the chemistry of enolates along with the stereoselective and condensation reactions. Contribute effectively in course-specific interaction.

CO62 Contribute effectively in course-specific interaction.

Approach in teaching:

Interactive lectures, tutorials, group discussions and e-learning.

 

Learning activities for the students:

Peer learning, e- learning, problem solving through tutorials and group discussions.

 

 

Written examinations,

Assignments, Quiz

 

 

12.00
Unit I: 
Substitution & Elimination

Aliphatic Nucleophilic Substitution Reactions: SN1, SN2, mixed SN1 and SN2, ion pair in SN1 mechanism, SNi mechanism, neighbouring group participation, regioselectivity, substitution at allylic and vinylic carbon atoms, ambident nucleophiles, effect of substrate structure, nucleophile, leaving group  and reaction medium on the reactivity.

Elimination Reactions: E2, E1, E1cB and E2C (syn elimination) mechanisms, E1–E2–E1cB spectrum, orientation of the double bond, regioselectivity, effect of substrate structure, attacking base, leaving group and reaction medium on reactivity, mechanism and orientation in pyrolytic elimination.

 

12.00
Unit II: 
Aromatic Substitution
  1. Aromatic Nucleophilic Substitution: SNAr, benzyne and SRN1 mechanism, effect of substrate structure, leaving group and attacking nucleophiles on reactivity.
  2. Typical reactions: Bucherer reaction, Rosenmund-von Braun reaction, Von-Richter, Sommelet-Hauser and Smiles rearrangement.
  3. Aromatic Electrophilic Substitution: Arenium ion mechanism, orientation and reactivity, energy profile diagrams , directive influence and its explanation in different substitutions, o/p ratio, ipso attack, substitution reactions involving diazonium ions, Vilsmeir-Haack reaction, Friedel-Craft reaction- alkylation, arylation (Scholl reaction), acylation (ring closer, Haworth reaction, Hoesch reaction).

 

 

12.00
Unit III: 
Aliphatic Electrophilic Substitution & Free Radical Substitution Reactions

Aliphatic electrophilic substitution: Bimolecular mechanisms (SE2 and SEi),  SE1 mechanism, substitution  accompanied  by  double  bond  shifts,  halogenation,  sulphonation, aliphatic diazonium coupling, direct amination, metalation with organometallic compounds, trans metalation with metal and metal halides, insertion by nitrenes, insertion by carbenes, acylation at an aliphatic carbon, effect of substrates, leaving group and solvent polarity on the reactivity.

FreeradicalsubstitutionFree radical substitutionatanaromaticsubstrate,neighbouringgroup participation and free radical rearrangements, reactivity for aliphatic and aromatic substrates, reactivity at bridgehead, reactivity of the attacking radical and effect of solvent on reactivity. Important reactions involving free radicals-Sandmeyer and Gattermann reaction,Hunsdiecker reaction, Gomberg-Bachmann reaction, coupling ofalkynes.

 

12.00
Unit IV: 
Addition to C-C & C-Hetero Multiple Bonds

Addition to C-C multiple bond: Mechanistic and stereochemical aspects of addition reaction involving electrophiles, nucleophiles and free radicals, regio and chemo selectivity, orientation and reactivity, addition to cyclopropane ring, hydrogenation of aromaticrings.

Addition to C-Hetero Multiple Bonds- mechanism of metal hydride reduction of saturated and unsaturated carbonyl compounds, acids, esters and nitriles, addition of Grignard reagents, organozinc, organocopper and organolithium reagents to carbonyl and unsaturated carbonyl systems.

 

12.00
Unit V: 
Enolate Chemistry

Formation of enolates, kinetic and thermodynamic control, 1,2 vs 1,4 addition, HSAB principle, reactions of enolate anions with electrophiles. O and C alkylation.

Enolate condensation reactions- synthetic applications of inter and intramolecular Aldol, Claisen, Dieckmann, Knoevenagel and Stobbe’s condensations.

Stereoselective enolate reactions: Diastereoselection, Zimmermann-Traxler model, Evans mode. Baylis- Hillmann reaction and Robinson annulation.

 

Essential Readings: 
  1. Advanced Organic Chemistry: Reactions, Mechanisms and Structure, Seventh Edition; J. March; John Wiley and Sons Asia Private Limited, New Delhi, 2015.
  2. A Guidebook to Mechanism in Organic Chemistry, Sixth Edition; P. Sykes; Pearson Education, Delhi, 2011.
  3. Organic Chemistry: Vol. I and II, Second Edition; Singh, Mukherjee, Kapoor; New Age International Private Limited, New Delhi, 2018.

 

 

References: 
  1. Advanced Organic Chemistry Part A & B, Fifth Edition; F. A. Carey and R. J. Sundberg; Springer, US, 2007.
  2. Principles of Organic Synthesis, Third Edition; R.O.C. Norman and J.M. Coxon; Chapman and Hall Ltd., London, 2003.
  3. Supplement for Basic Principles of Organic Chemistry, First Edition; J. D. Roberts and M. C. Caserio; W. A. Benzamin Inc., New York, 1965.

 

e-Resources:

  1. https://epgp.inflibnet.ac.in/Home/ViewSubject?catid=13G8VouhmrFfuhs6rkiyTA== (P-05 & P-09)
  2. https://www.accessscience.com/content/organic-reaction-mechanism/475400
  3. https://nptel.ac.in/courses/104101115

 

Academic Year: 
2025-2026
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