Tuesday 22 November 2016

MCQ Multiple Choice Question on Polycyclic Aromatic Hydrocarbon

Polycyclic Aromatic Hydrocarbon

  1.  Which is the most probable main product of the following reaction ?
   




 Answer:- b.

Electrophilic substitution on naphthalene occurs preferentially at C1/ α carbon.

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2. Which is the most probable main product of the following electrophilic substitution reaction of napphthalene?




Answer:-a. 

The most reactive site of naphthalene is C1 and remember that amino NH2 group is an activating, o,p-directing group in aromatic electrophilic substitution reaction; consequently, nitration occurs predominantly at C4 in this reaction.

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3. Which is the most probable main product of the following reaction?

Answer:- d.

Electrophilic substitution on anthracene occurs preferentially at C 9 carbon.
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4.  Which is impossible as a resonance contributor of anthracene.

Answer:- b.

In this structure two carbon atoms with five valencies.

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5. Which of following is the most important resonance contributing structure of the naphthalenium ion intermediate in an electrophilic substitution reaction of naphthalene?


 

Answer:- a.

In this one of the benzene ring having benzenoid i.e sexted state, rest of structure not.






Thank you. 



 

Isomerism and its type



Structural Isomerism or Constitutional Isomerism

Structural Isomerism or Constitutional Isomerism










Stereoisomerism and its type






Conformation Isomerism and Conformation of n-butane

Point to be covered

  • Conformation Isomerism 
  • Conformation of n-butane
  • Projection of conformers








 

Conformation and conformational analysis of n-butane









 

Sunday 20 November 2016

Organometalic compound Organoboranes Reaction and Mechanisms

Organometalic compound 

Organoboranes Preparation, Reaction and Mechanisms


Organoboron compounds (organoboranes) are organic derivatives of borane (BH3) and contain carbon-boron bonds.
Organoboranes can be monoalkyl, dialkyl or trialkyl depending on the number of alkyl groups attached to boron . For the dialkyl and trialkylboranes, the alkyl groups may be the same or different.
  

Bonding and Structure of Organoboranes

The C-B bond in organoboranes has low polarity (the difference in electronegativity 2.55 for carbon and 2.04 for boron), and therefore alkyl boron compounds are generally covalent. 
 

Synthesis of Organoboranes



  1. Hydroboration Of alkenes
  2. Borylation of aryl halides
  3. Transmetallation

 1. Hydroboration Of alkenes


Hydroboration is addition of borane (BH3) to the double or triple bond to form either alkylboranes or alkenylboranes respectively. Reaction is carried out in THF solvent.



1. Organoboranes- Carbonylation 

The reaction of organoboranes with carbon monoxide is caebonylation