ORGANIC CHEMISTRY- I (NATURE OF BONDING AND STEREOCHEMISTRY)- ANNULENES

ORGANIC CHEMISTRY- I (NATURE OF BONDING AND STEREOCHEMISTRY)- ANNULENES

**Annulenes are the completely conjugated monocyclic hydrocarbons containing an even number of carbon atoms. They have the general formula CnHn (when n is an even number) or Cn.Hn+1 (when n is an odd number) 

**The first 3 members of the series, (4]-, [6]-, and [8]-annulene but you must have used their name as 1,3- cyclobutadiene, benzene and 1,3,5,7- cyclooctatetraene. 

**Annulenes could be aromatic, anti aromatic or non-aromatic.

#[4] Annulene: anti-aromatic 

#[6] Annulene: aromatic 

#[81 Annulene: non-aromatic

#[10] Annulene: non-aromatic 

#[12] Annulene anti-aromatic 

#[14] Annulene: anti-aromatic.

#[18] Annulene: aromatic. 

**The following bridgehead [10] annulenes are aromatic: 

#9,10 methane [10] annulene 

#9,10 oxa [10] annulerne 

#9,10 aza [10] annulene 

**Preparation of [14] annulene, [18] annulene and 9,10-methane [10] annulene from simple and easily available molecules.

 

ORGANIC CHEMISTRY- I (NATURE OF BONDING AND STEREOCHEMISTRY)- AROMATICITY –PART-1

ORGANIC CHEMISTRY- I (NATURE OF BONDING AND STEREOCHEMISTRY)- AROMATICITY –PART-1

These compounds exhibit significantly high diamagnetic susceptibility. Cyclic electron delocalization also results in bond length equalization, abnormal chemical shifts and magnetic anisotropies, as well as chemical and physical properties which reflect energetic stabilization. On the other hand, compounds with high paramagnetic susceptibility may be antiaromatic. 

**Huckel's rule can be used to determine whether a molecule is aromatic or anti-aromatic by broadly two conditions. 

* It is cyclic, planar and has continuous delocalization of π electrons (electrons in p orbitals) with or without the participation of lone pair(s)/- charge/ + charge (i.e having electrons or vacant p orbital). 

* The delocalised π-electron cloud must contain a total of (4n+2)π electrons, where n is a whole number (i.e., n= 0,1,2,3 and so on) **If in the second condition there are 4n π electrons, it is anti-aromatic.

** If the first condition is not fully met,it is aliphatic. 

**The term non-aromatic is applicable to both aliphatic as well as anti-aromatic. **Aromaticity is the state of stability that any molecule would thrive to achieve. These molecules are cyclic, planar and have (4n+2)π electrons continuously delocalised in a cyclic manner.

 

NEIGHBORHOOD OF INFINITY, LIMIT AT INFINITY AND INFINITY AS AN ISOLATED SINGULARITY - MATHEMATICS - ADVANCED COMPLEX ANALYSIS

NEIGHBORHOOD OF INFINITY, LIMIT AT INFINITY AND INFINITY AS AN ISOLATED SINGULARITY - MATHEMATICS - ADVANCED COMPLEX ANALYSIS NEIGHBORHOOD OF INFINITY, LIMIT AT INFINITY AND INFINITY AS AN ISOLATED SINGULARITY - MATHEMATICS - ADVANCED COMPLEX ANALYSIS

CASORATI-WEIERSTRASS THEOREM; DEALING WITH THE POINT AT INFINITY - MATHEMATICS - ADVANCED COMPLEX ANALYSIS

CASORATI-WEIERSTRASS THEOREM; DEALING WITH THE POINT AT INFINITY - MATHEMATICS - ADVANCED COMPLEX ANALYSIS CASORATI-WEIERSTRASS THEOREM; DEALING WITH THE POINT AT INFINITY - MATHEMATICS - ADVANCED COMPLEX ANALYSIS