Zadanie 3c
Wzorowane na: Chemistry HL Paper 2, May 2023, TZ1, pytanie 3(c). Treść, dane i kontekst są zmienione; sprawdzane umiejętności, format i punktacja jak w oryginale.
Darmowe konto pozwoli wrócić do niego później.
Informacja do zadań 3b-3c.
1-Bromopropane can be converted into propanoic acid in a two-step process. In step 1 it is converted into propan-1-ol, and in step 2 the propan-1-ol is converted into propanoic acid.
Polecenie
(i) Identify the type of reaction that takes place in step 1.
(ii) Sketch the mechanism of the reaction in step 1, using curly arrows to show the movement of electron pairs.
(iii) Identify the products formed from the reaction of propan-1-ol and propanoic acid in the presence of an acid catalyst. Give the structural formula of the organic product.
Sprawdź rozwiązanieUkryj rozwiązanieKlucz i punktacja
Odpowiedź z klucza
(i) nucleophilic AND substitution ✔
(ii) curly arrow from the lone pair «or negative charge» on O of OH− to the carbon bonded to Br ✔
curly arrow from the C-Br bond to Br, showing Br leaving ✔
transition state drawn with partial bonds HO···C···Br, square brackets and the negative charge outside the brackets ✔
correct products: CH3CH2CH2OH and Br− ✔
(iii) CH3CH2COOCH2CH2CH3 «ester» AND H2O ✔
Schemat punktowania
(i) [1]: accept SN2; do not accept SN1 or hydrolysis alone. (ii) [4]: accept OH− with or without the lone pair; do not accept an arrow starting on H of OH−; accept curly arrows drawn on the transition state; do not penalize if HO, C and Br are not drawn at 180°; do not award M3 if an O-C bond is drawn as a full bond. A correct SN1 mechanism with an SN1 answer in (i) scores [3] at most because 1-bromopropane is a primary halogenoalkane. (iii) [1]: both products are needed; accept a condensed, full structural or skeletal formula of the ester; a name is not required; do not accept a reactant, or an isomeric ester such as ethyl butanoate.