- #1
Vishesh Jain
- 9
- 0
Homework Statement
The textbook "Organic Chemistry by O P Tandon" says that the tropylium cation (cycloheptatri-2,4,6-enyl cation) is more stable than the triphenylmethyl cation ( Ph3C+) (phase/solvent not mentioned). Is this correct assuming it's in a non-polar medium ? On a related note, are compounds such as Ph3C+ and the benzyl carbocation C6H5CH2+ aromatic ?The Attempt at a Solution
[/B]
I have learned that the 3 phenyl rings in Ph3C+ are not coplanar. (https://socratic.org/questions/what-is-the-most-stable-carbocation) So the 6 pi electrons of each ring are delocalized over the ring and the carbon attached to the ring (total 7 carbons). And in tropylium cation, the 6 pi electrons are delocalised over 7 C atoms, all part of the ring. Does that make a difference ? isn't Ph3C+ still aromatic ? Repulsion among the 3 phenyl rings could be a factor
In compounds like Ph3C+ & benzyl carbocation, the conjugation of 6 pi electrons forms a closed loop ... even though one carbon is outside the ring, so they should be aromatic (according to "requirements for aromaticity" defined in http://www.chem.ucla.edu/~harding/notes/notes_14C_intaroma02.pdf ). I hope this reasoning for the 2nd question is correct..