Compound A is pentan-1-ol (CH3−CH2−CH2−CH2−CH2−OH) and Compound B is pent-1-ene (CH2=CH−CH2−CH2−CH3).
The conversion of an alcohol to an alkene is a dehydration reaction, which requires an acidic dehydrating agent such as concentrated H2SO4 or H3PO4. Thus, reagent D is concentrated H2SO4 or H3PO4.
Compound C is butane-1,3-diol (HO−CH2−CH2−CH(OH)−CH3).
When C is treated with excess dehydrating agent (reagent D), both hydroxyl groups undergo elimination (dehydration). The elimination of two water molecules yields a conjugated diene, which is highly stable due to resonance.
The product E formed is 1,3-butadiene (CH2=CH−CH=CH2).
Answer:
| D | E |
| Conc. H2SO4 or H3PO4 | CH2= CH − CH = CH2 |