Zadanie 8d
Wzorowane na: Chemistry HL Paper 2, May 2022, TZ2, pytanie 8(d). Treść, dane i kontekst są zmienione; sprawdzane umiejętności, format i punktacja jak w oryginale.
Darmowe konto pozwoli wrócić do niego później.
Informacja do zadań 8a-8f.
Carbon occurs as several allotropes and forms an enormous variety of organic compounds.
Polecenie
(i) Write the equation for the reaction between hex-3-ene and hydrogen bromide.
(ii) State the type of reaction in (i).
(iii) Suggest two differences between the NMR spectra of hex-3-ene and of the organic product in (i). Use section 21 of the data booklet.
(iv) Predict, giving a reason, the major product of the reaction between pent-1-ene and hydrogen chloride.
Sprawdź rozwiązanieUkryj rozwiązanieKlucz i punktacja
Odpowiedź z klucza
(i) CH3CH2CH=CHCH2CH3 + HBr → CH3CH2CHBrCH2CH2CH3
correct reactants ✔
correct product ✔
(ii) «electrophilic» addition ✔
(iii) any two of:
hex-3-ene: 3 signals AND 3-bromohexane: 6 signals ✔
hex-3-ene: «area ratio» 3 : 2 : 1 AND 3-bromohexane: «area ratio» 3 : 3 : 2 : 2 : 2 : 1 ✔
hex-3-ene: «has a signal at» 4.5–6.0 ppm «and the product does not» ✔
3-bromohexane: «has a signal at» 3.5–4.4 ppm «and hex-3-ene does not» ✔
(iv) CH3CH2CH2CHClCH3 ✔
the «secondary» carbocation CH3CH2CH2CH+CH3 is more stable than the primary carbocation ✔
Schemat punktowania
(i) M1 and M2 as shown; accept molecular formulas C6H12 + HBr → C6H13Br for both marks. (ii) do not accept nucleophilic or free-radical addition. (iii) [1] each, maximum [2]. (iv) M1: 2-chloropentane (name or formula); M2: reason based on carbocation stability; do not accept «Markovnikov's rule» without a reference to carbocation stability.