| Popis: |
The addition of HCl to 1,2,3-pentatriene has been studied in 95 vol. % aqueous ethanol containing 4−10 mol/1 HCl. The reaction involves rate-determining proton attack at the terminal methylene group with formation of 1,2- and 1,4-adducts. Subsequently, the 1,2-adduct is converted into a di-adduct. The reaction shows pseudo-first-order kinetics. Log k1 is linear in H0 with a slope equal to −1.18 ± 0.01. The average value of the kinetic isotope effect kH/kD is 1.7. A change in nucleophile (ClO4−, SO24−, Br−) does not affect the rate. The addition of HCl is a two-step process with a carbocation intermediate. In all probability, alcohol and water are not covalently present in the transition state of the rate-determining step. |
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