Zadanie 6a
Wzorowane na: Chemistry HL Paper 2, November 2023, TZ2, 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 synthesised from but-1-ene in a two-stage process. In the first stage the alkene reacts with water in the presence of sulfuric acid to form the intermediate compound [X]; in the second stage [X] is converted into butanone by reagent B.
(i) Draw the structural formula of [X].
(ii) Outline why compound [X] exists as a pair of stereoisomers.
(iii) State what type of reagent B is.
(iv) Determine the compound formed in small amounts as a minor product of the two stages, and outline why it forms.
Sprawdź rozwiązanieUkryj rozwiązanieKlucz i punktacja
Odpowiedź z klucza
(i) CH3CH(OH)CH2CH3 «butan-2-ol» ✔
(ii) it contains a chiral / asymmetric carbon atom «bonded to four different groups»
OR
its mirror image is non-superimposable ✔
(iii) an oxidizing agent / oxidant ✔
(iv) butanal, CH3CH2CH2CHO ✔
OR
butanoic acid, CH3CH2CH2COOH ✔
water can also add the other way round, giving the primary alcohol butan-1-ol «via the less stable primary carbocation» as a minor product ✔
Schemat punktowania
(i) [1]: accept a skeletal or full structural formula. (ii) [1]. (iii) [1]: a named oxidizing agent such as acidified potassium dichromate(VI) or potassium manganate(VII) is also accepted; do not accept a reducing agent. (iv) [2]: M1 for butanal or butanoic acid, M2 for the reason; accept “anti-Markovnikov addition” for M2.