resonance

[connie317]

I need some help with this please :why the OCCl2 does not have resonance?

 

how to know if a compound has resonance or not ?

[Suxamethonium]

Im going to assume OCCl₂ is phosgene.

 

Whilst this is not the be all and end all of resonance- a good hint to finding resonating structures is looking for double bonds, particularly double bonds with adjacent single bonds. An example is acetone, H₃CC(=O)CH₃ -You may want to draw it.

 

In an acid or base, protonation of the oxygen or deprotonation of a carbon occurs, and a charge is established. This is important because now electrons can flow through the molecule. Where the electrons flow single bonds become double bonds, and the double bonds become single bonds. This is because of the electrons moving in pi-orbitals. In order for this to happen there needs to be some degree of conjugation, unless its only moving through 1 bond.

 

In the acetone example, H₃CC(=O)CH₃ resonates to H₂C=C(OH)CH₃.

 

Likewise through conjugation:

 

^-O-CH=CH-CH=CH-CH=O could resonate to O=CH-CH=CH-CH=CH-O^-

 

As for phosgene, It doesn't resonate because theres no where for electrons come from.

 

O=CCl₂ does not go to ^-O-C(=Cl⁺)Cl - it deosnt look right for starters, and its too unfavourable to take electrons away from chlorine.

 

I'm struggling to explain it in text, can you present a few, more sepcific questions of what you don't quite understand? Maybe it will be easier for me to answer clearly.