Aromatic chem questions
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Compare benzene and the theoretical molecule cyclohexa-1,3,5-triene in terms of: * stability * shape * carbon–carbon bond lengths. For each of these properties, suggest reasons for any differences. (5)
M1 Benzene is more stable than cyclohexatriene M2 The enthalpy of hydrogenation of benzene is (152 kJ mol-1) less/less exothermic M3 Due to the delocalisation of electrons in benzene M4 Both are planar/hexagonal M5 Benzene has equal C-C bond lengths or regular hexagon whereas Cyclohexa-1,3,5-triene has bonds of different/varied length or the hexagon is distorted/irregular
Give an equation to show the formation of the reactive intermediate from these two reagents. Between HNO3 and H2SO4
HNO3 + H2SO4 → H2NO3^+ + HSO4- then H2NO3+ → NO2+ + H2O OR HNO3 + H2SO4 → H2O + NO2+ + HSO4-
Use of phenyl amine
Manufacture of dyes OR (cationic) surfactants
Benzene reacts with methanoyl chloride (HCOCl) in the presence of a catalyst. (a) Give an equation for the overall reaction when benzene reacts with methanoyl chloride. Name the organic product
C6H6 + HCOCl → C6H5CHO + HCl Or shown as structural formulae 1 Benzaldehyde
Give an equation to show how the catalyst is used to form the electrophile, [HCO]+
HCOCl + AlCl3 → [HCO]+ + [AlCl4]−
Name the reagent for step 4. State a necessary condition for step 4. Context it is a methyl benzene turning into methyl benzene but replaces one hydrogen on the methyl with Cl so it is chloromethylbenzene
UV light
Amine A is formed in step 2 and amine B is formed in step 5. Explain why the yield of B in step 5 is less than the yield of A in step 2.
In Step 5 further substitution / gives other amine products 1 In Step 2 only one amine
Explain why amine B is a stronger base than amine A
In B Alkyl group is electron donating or positive inductive effect Or In A lone pair (on N partially) delocalised 1 Lone pair on N more available Lone pair on N less available