SEM III
CHE3C03 ORGANIC CHEMISTRY
Module 1
Organic Chemistry-
Some Basic Concepts
Sr.Lovely Jacob A
Dept.of Chemistry
Little flower College, Guruvayoor
Lovely Jacob A,Asst, Profe.in
Chemistry,Little flower College, Guruvayoor
Prepare for your exams
Study with the several resources on Docsity
Earn points to download
Earn points by helping other students or get them with a premium plan
Guidelines and tips
Prepare for your exams
Study with the several resources on Docsity
Earn points to download
Earn points by helping other students or get them with a premium plan
Community
Ask the community
Ask the community for help and clear up your study doubts
University Rankings
Discover the best universities in your country according to Docsity users
Free resources
Our save-the-student-ebooks!
Download our free guides on studying techniques, anxiety management strategies, and thesis advice from Docsity tutors
SEM III CHE3C03 ORGANIC CHEMISTRY, Lecture notes of Organic Chemistry
Heterolytic fission is a type of bond fission in which a covalent bond between two chemical species is broken in an unequal manner,.
Typology: Lecture notes
2021/2022
1 / 74
This page cannot be seen from the preview
Don't miss anything!
Related documents
Partial preview of the text
Download SEM III CHE3C03 ORGANIC CHEMISTRY and more Lecture notes Organic Chemistry in PDF only on Docsity!
SEM III
CHE3C03 ORGANIC CHEMISTRY
Module 1
Organic Chemistry-
Some Basic Concepts
Sr.Lovely Jacob A
Dept.of Chemistry
Little flower College, Guruvayoor
Lovely Jacob A,Asst, Profe.in
BOND FISSION
1. HOMOLYSIS
2. HETEROLYSIS
Lovely Jacob A,Asst, Profe.in
Lovely Jacob A,Asst, Profe.in
HETEROLYSIS Heterolytic fission is a type of bond fission in which a covalent bond between two chemical species is broken in an unequal manner, resulting in the bond pair of electrons being retained by one of the chemical species Lovely Jacob A,Asst, Profe.in
Lovely Jacob A,Asst, Profe.in
Lovely Jacob A,Asst, Profe.in
Large amount of energy is required to spark the homolytic fission of a molecule.
- When the molecule is subjected to ultraviolet radiation
- When the molecule is subjected to the required amount of heat in order to overcome the required bond dissociation energy for the homolytic fission
- When carbon compounds are subjected to extremely high temperatures in the absence of oxygen in order to facilitate the pyrolysis of the molecule Heterolytic fission usually requires a lower bond dissociation energy than homolytic fission. Lovely Jacob A,Asst, Profe.in
Electrophile and Nucleophile A nucleophile is a chemical species which, in relation to a response, gives an electron pair to form a chemical bond. A nucleophile is usually charged negatively or neutral with a lone couple of donable electrons. H 2 O, - OMe or - OtBu are some of the examples. Overall, the electron-rich is a nucleophile. Any molecule, ion or atom that is in some manner deficient in electron can act as an electrophile. Electrophiles are generally charged positively or are neutral species with empty orbitals attracted to a centre wealthy in electrons.
What is Electrophile? Positively loaded or neutral species are called electrophiles that are deficient in electrons and can accept a couple of electrons. These are also called species that love electron (philic).
- The term electrophile can be split into “electro” derived from electron and “phile” which means loving.
- They are electron deficient and hence electrons loving.
- They are positively charged or neutrally charged.
- They attract electrons. Movement of electrons depends on the density.
- They move from high-density area to low density area.
- They undergo electrophilic addition and electrophilic substitution reactions.
- An electrophile is also called as Lewis acid.(Acid is a proton donor or electron acceptor) Lovely Jacob A,Asst, Profe.in
Lovely Jacob A,Asst, Profe.in
Lovely Jacob A,Asst, Profe.in
1. Electrophilic Reagents
- T hey are also called as electrophile.
- Electrophile has electron deficient atom or vacant orbital or incomplete octate at the valence shell.
- These species carry either positive charge or electron deficient molecules. So a reagent which can accept an electron pair in a reaction is called an electrophile. Generally these contain two electrons less than the octet. These attack regions of high electron density in the substrate molecule to complete the octet. These are represented by E+.
- Electrophiles are lewis acid (A Lewis acid is therefore any substance, such as the H
ion, that can accept a pair of nonbonding electrons. In other words, a Lewis acid is an electron-pair acceptor.)
- An electrophile is a species that accepts a pair of electrons to form a new covalent bond
- There are 2 types of electrophiles.
- (a) Neutral electrophile : These species carry neither positive charge nor negative charge
- Example: AlCl 3 , BF 3 , Carbene, Nitrene, free radicals SO 3 , , Acid chlorides etc.
- (b) Positive electrophile : they are also called Positively charged Electrophile
- Examples: H
, H 3 O
, Cl
, Br
, NO 2
, NO
, Carbonium ion, nitrosonium ion, diazonium ion
- Note: cation of IA group and IIA group like Na
, Mg ++ , Ca ++ and also NH 4
are not Positive electrophile Lovely Jacob A,Asst, Profe.in
2. Nucleophilic reagents
- T hey are also called as nucleophile
- A nucleophile is a chemical species that donates an electron pair to an electrophile to form a chemical bond in relation to a reaction.
- All molecules or ions with a free pair of electrons or at least one pi bond can act as nucleophiles. Because nucleophiles donate electrons, they are by definition Lewis bases.
- They have electron rich atoms and lone pairs of electron so they are negatively charged species
- Nucleophiles are from “nucleus loving”, or “positive-charge loving
- A nucleophile is a reactant that provides a pair of electrons to form a new covalent bond.
- There are 2 types nucleophiles.
- (a) Neutral nucleophile :
- NH 3 , RNH 2 , H–O–H , R–OH , R–O–R , R–S–R.
- Important Note:
- LiAlH 4 : it can donate H ion with a lone pair of electron
- LiBH 4 : it can donate H ion with a lone pair of electron
- RMgX: Grignard Reagent: here R acts as a nucleophile but Mg++^ is not an electrophile
- (b) Negative nucleophile :
- Examples: Cl
(chloride ion), Br
( Bromide ion), I
(Iodide ion), OH
, CN
Carbanions like CH 3
, CH 3 CH 2
etc. Lovely Jacob A,Asst, Profe.in