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aromatic chem
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Question | Answer |
---|---|
Properties of benzene | C6H6, unsaturated structure, cyclic. |
Why was Kekule's structure proposed? | hydrogenation of benzene suggests three C=C bonds |
What were the problems with Kekule's structure? | unsaturated; benzene does not undergo electrophilic addition, equal electron density and C-C bond lengths, hydration value is lower than experimental value. |
What is the shape of molecule for each carbon atom in the benzene ring | trigonal planar 120 |
How is benzene's delocalised electrons formed? | 3 of carbons electrons are bonded in sigma bonds, 4th is in a 2p orbital above and below the plane of C, p orbitals overlap with p orbitals on either side and producing pi bonds all over the ring, DELOCALISED ELECTRONS! |
What is required for the formation of the NO2+ ion? | concentrated H2SO4 concentrated HNO3 50degreesC |
What can be used as a halogen carrier in the formation of halogen+ | Fe FeBr3 AlBr3 |
How do we test for the presence of a carbonyl | 2,4 DNPH+methanol+sulphuric acid=Bradys reagent add to solution forming yellow/orange ppt if carbonyl group is present |
How do we determine if it is an aldehyde or a ketone | tollens reagent=NaOH(aq)+AgNO3(aq) and aq NH3 Aldehyde=silver mirror, oxidised to carboxylic acid Ketone= no reaction |
Identifying carbonyl compound | yellow/orange ppt. 2,4 DNPH, filtered and recrystallised, purified sample produced. filtered and dried. melting point measured and compared to database. |