Zadanie 6a
Wzorowane na: Chemistry HL Paper 2, November 2023, TZ1, pytanie 6(a). Treść, dane i kontekst są zmienione; sprawdzane umiejętności, format i punktacja jak w oryginale.
Darmowe konto pozwoli wrócić do niego później.
Polecenie
Butanone can be synthesized from but-1-ene in a two-stage process. In the first stage but-1-ene reacts with water and sulfuric acid to form an intermediate compound X. In the second stage X reacts with reagent B to form butanone.
(i) Draw the structural formula of X.
(ii) Outline why X can exist as stereoisomers.
(iii) State what type of reagent B must be.
(iv) Determine the compound formed as a minor product of the whole two-stage synthesis, and outline why it forms.
Sprawdź rozwiązanieUkryj rozwiązanieKlucz i punktacja
Odpowiedź z klucza
(i) CH3CH(OH)CH2CH3 «butan-2-ol» ✔
(ii) X has a carbon atom bonded to four different groups «a chiral centre», so it has non-superimposable mirror images ✔
(iii) oxidizing agent ✔
«for example acidified potassium dichromate(VI)»
(iv) butan-1-ol
OR
butanal
OR
butanoic acid ✔
water can also add «to the carbon atom at the other end of the double bond», giving a primary alcohol / through the less stable primary carbocation, so only a small proportion forms ✔
Schemat punktowania
(i) [1]; accept the full structural or skeletal formula. (ii) [1]. (iii) [1]; accept a named oxidizing agent such as acidified potassium dichromate(VI) or potassium manganate(VII). (iv) M1: the minor product, accept butan-1-ol, butanal or butanoic acid; M2: reason, accept “the addition of water can occur in the opposite direction” or a reference to the lower stability of the primary carbocation.