Zadanie 4b
Wzorowane na: Chemistry HL Paper 2, May 2026, TZ2, pytanie 4(b). Treść, dane i kontekst są zmienione; sprawdzane umiejętności, format i punktacja jak w oryginale.
Darmowe konto pozwoli wrócić do niego później.
Polecenie
1-Bromobutane, CH3CH2CH2CH2Br, is used as a solvent and as a building block for other organic compounds.
(i) Predict the organic compound produced from 1-bromobutane and hydroxide ions.
(ii) Deduce the type of reaction in (i) and give a reason for your answer.
(iii) Sketch the mechanism for the reaction of 1-bromobutane with hydroxide ions, showing the movement of electron pairs with curly arrows.
Sprawdź rozwiązanieUkryj rozwiązanieKlucz CKE i punktacja
Odpowiedź z klucza
(i) butan-1-ol / 1-butanol ✔
(ii) nucleophilic substitution AND OH− / hydroxide ion is a nucleophile / donates an electron pair
OR nucleophilic substitution AND Br− / bromide ion is replaced by OH− / hydroxide ion ✔
(iii) curly arrow from the lone pair / negative charge on O in HO− to the C atom attached to Br ✔
curly arrow from the C–Br bond to Br ✔
transition state showing the negative charge AND partial bonds «HO···C···Br, with HO and Br on opposite sides of the carbon atom» ✔
Schemat punktowania
(i) [1] accept the structural formula but not the molecular formula. (ii) [1] accept ‘SN2 AND 1-bromobutane is a primary halogenoalkane’. (iii) [3] award [3] for a correct mechanism using any primary halogenoalkane; do not allow a curly arrow starting on H of HO−; accept the curly arrow from the C–Br bond to Br drawn either on the halogenoalkane or in the transition state; do not penalize if HO and Br are not at 180°, or the square bracket is missing, in M3; do not award M3 if an O–C bond is drawn as a full bond; award [2 max] for a correctly drawn SN1 mechanism.