Q8(b)(i). Structure of the halogenated ester
A halogenated ester shows M⁺ peak at m/z 166 (10%) and M+2 peak at m/z 168 (9.8%) in the mass spectrum. ¹H NMR spectrum of this compound shows two triplets and a singlet at δ 2.9, 3.6 and 3.8 ppm, respectively, in the intensity ratio 1 : 1 : 1.5. Deduce the structure of the compound. Justify your answer.
Answer in brief
Methyl 3-bromopropanoate, BrCH₂CH₂CO₂CH₃.
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CoversM+2 peakbromine isotope patternmethyl 3-bromopropanoatestructure elucidation¹H NMR
All parts of Question 8
- 8(a)(i) Coupling constants of the lettered protons5 marks
- 8(a)(ii) Chemical shifts of Hᵃ and Hᵇ5 marks
- 8(a)(iii) Number of ¹H NMR signals5 marks
- 8(b)(i) Structure of the halogenated ester10 marks
- 8(b)(ii) C₆H₁₂ alkenes with peaks at m/z 42 and 565 marks
- 8(c)(i) Characteristic fragment ions10 marks
- 8(c)(ii) Structure of C₄H₅NO₂10 marks