Compound T is made by a three-stage synthesis. [Figure X.X showing the synthesis pathway for Compound T from phenylethanoic acid]
- (a)In stage 1, phenylethanoic acid reacts with a suitable reagent to form compound R. [Figure showing phenylethanoic acid → R] Suggest a suitable reagent for stage 1.[1]
- (b)(i)In stage 2, compound R reacts with ethylamine to form compound S. [Figure showing R + C₂H₅NH₂ → S] Name the functional group formed in stage 2.[1]
- (b)(ii)Identify the other product formed in stage 2.[1]
- (c)(i)In stage 3, compound S reacts with a suitable reagent to form compound T. [Figure showing S → T] State the formula of a suitable reagent for stage 3.[1]
- (c)(ii)Name the type of reaction that occurs in stage 3.[1]
- (d)(i)The relative abundance of the molecular ion peak in the mass spectrum of ethylamine is 62. Calculate the relative abundance of the M+1 peak in the mass spectrum of ethylamine.[1]
- (d)(ii)The mass spectrum of compound T contains several fragments. The m/e values of two of these fragments are 29 and 91. Draw the structures of the ions responsible for these peaks.[2]
- (e)(i)The proton (¹H) NMR spectrum of compound T shows hydrogen atoms in different environments. Six of these environments are shown on the structure using letters a, b, c, d, e and f. [Figure X.X] Use the letters a, b, c, d, e and f to answer the questions that follow. The questions relate to the proton (¹H) NMR spectrum of T. Proton d does not cause splitting of the peaks for protons c or e under the conditions used. Each answer may be one, or more than one, of the letters a, b, c, d, e and f. Identify the proton or protons with a chemical shift (δ) in the range 6.0 to 9.0.[1]
- (e)(ii)Identify the proton or protons whose peak will disappear if D₂O is added.[1]
- (e)(iii)Identify the proton or protons whose peak is a triplet.[1]
- (e)(iv)Identify the proton or protons with the lowest chemical shift (δ).[1]
This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2021). The mark or mark type is shown in brackets.
- [1] PCl5 OR PCl3 OR SOCl2
- [1] amide
- [1] HCl/hydrogen chloride OR C2H5NH3Cl/ ethylammonium chloride
- [1] LiAlH4
- [1] reduction
- [1] relative abundance = 2 carbons x 1.1 x 0.62 = 1.36/1.4 min 2sf
- [1] CH3CH2+/C2H5+
- [1] C6H5CH2+
- [1] a
- [1] d
- [1] b, c, f
- [1] f
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