State the difference in the basicities of ammonia, NH3, propanamide, CH3CH2CONH2, and propylamine, CH3CH2CH2NH2. Explain your answer. weakest base < ................................................................ < ................................................................ < strongest base
- (a)State the difference in the basicities of ammonia, NH3, propanamide, CH3CH2CONH2, and propylamine, CH3CH2CH2NH2. Explain your answer. weakest base < ................................................................ < ................................................................ < strongest base[4]
- (b)Fig. 4.1 shows two different ways to synthesise propylamine. [Figure 4.1] Identify compounds K and L and reagent M from Fig. 4.1. K ....................................................................................................................................................................... L ....................................................................................................................................................................... M .......................................................................................................................................................................[3]
- (c)Compound N is shown in Fig. 4.2. [Figure 4.2] Compound N is treated with an excess of concentrated HCl(aq). N undergoes complete hydrolysis to form three organic products. The products are isolated from the reaction mixture at pH4. Draw the structures of the three organic products at pH4. Assume that the CH3O— group does not react.[4]
- (d)(i)Compound P can be synthesised from 1-methyl-4-nitrobenzene by the route shown in Fig. 4.3. [Figure 4.3] Step 1 is a reduction reaction. Complete the equation for this reaction. Use [H] to represent an atom of hydrogen from the reducing agent. C7H7NO2 + ......................................[1]
- (d)(ii)Complete Table 4.1 to give details of each step of the synthesis shown in Fig. 4.3. Table 4.1 step reagents and conditions type of reaction 1 reduction 2 3 4 condensation[6]
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Mark scheme
Marking points from the official mark scheme (Feb/Mar 2025). The mark or mark type is shown in brackets.
- [4] propanamide < ammonia < propylamine
- (basicity linked to) p orbital of N / lone pair on N AND being accept / donate to / coordinate to a proton/H+
- (propanamide) lone pair / p-orbital on N is delocalised AND into C=O group / over N-C-O group / across the two electronegative O & N
- (propylamine) R / alkyl / propyl group AND is electron donating / positive inductive effect
- [3] K = CH3CH2COCl / propanoyl chloride
- L = CH3CH2CN / propanenitrile
- M = LiAlH4 OR H2/Ni / correct names
- [4] M1: (un)protonated benzylamine
- M2: (un)protonated amine as above
- M3: ethanoic acid
- M4: all amine groups protonated (—NH3+) AND all acid groups as -COOH
- [1] C7H7NO2 + 6[H] → C7H7NH2 + 2H2O
- [6] step 1: reagents and conditions: Sn & conc. HCl (+ heat)
- step 2: reagents and conditions: CH3Br/CH3C1/CH3I (in ethanol); type of reaction: (nucleophilic) substitution
- step 3: reagents and conditions: hot MnO4-/KMnO4; type of reaction: oxidation
- step 4: reagents and conditions: HO. (+ conc. H2SO4); type of reaction: condensation
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