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QUESTION 26 (5 marks) The mass and infrared spectra for an organic compound X with the empirical formula C;H O are shown. Mass spectrum 100 43 nN oo So on) & ÔøΩ Relative intensity 20 / 0.0 20 40 60 80 100 m/z Infrared spectrum S ÔøΩ oy (oe) Oo IN Relative transmittance 0.2 3000 2000 1000 Wavenumber (cm!) Analyse the spectra to deduce the structural formula of X. Explain your reasoning
QUESTION 13 Infrared spectrum Relative transmittance 3000 2000 1000 Wavenumber (cm7!) Determine the functional group present in the infrared spectrum. (A) ester (B) ketone (C) alcohol (D) carboxylic acid
QUESTION 23 (5 marks) Aspartame is a methyl ester of a dipeptide that hydrolyses to form methanol and two amino acids. The structure of aspartame is shown. O OCH3 Zz OH NHÔøΩ O a) Identify the two amino acids that form aspartame. [1 mark] A hydrolysed sample of aspartame was analysed with silica thin layer chromatography (TLC) using a mixture of butanol and ethanoic acid as the solvent. The TLC plate was then reacted with ninhydrin to produce spots. Key S = hydrolysed aspartame sample Spot A TTT > R = reference amino acid 1 Spot B R = reference amino acid 2 R; = isoleucine b) Determine which amino acid in aspartame corresponds to Spot A. Explain your reasoning. [3 marks] c) Explain why the reference amino acids are included on the TLC plate. [1 mark]
QUESTION 14 The mass spectrum for Compound X is found to have signals at the following m/z values. Mass spectrum 100 80 60 40 Relative intensity (%) 20 10 20 30 40 50 60 70 80 m/z Compound X is (A) butanal. (B) butanol. (C) butanone. (D) butanoic acid
QUESTION 6 (8 marks) Polypeptides and proteins are formed by condensation reactions of amino acids. a) Identify the type of bond formed when three amino acids are joined to form a tripeptide and state any other product/s formed. [2 marks] b) Determine the total number of tripeptides that can be formed containing histidine lysine and glycine and use the three-letter symbols for the amino acids to describe two of the tripeptides formed. [3 marks] c) Explain how the pH of the buffer solution can be used to separate histidine lysine and glycine through electrophoresis. [3 marks]
QUESTION 4 (8 marks) Compound C has the molecular formula C H O and is either an alcohol an aldehyde or a carboxylic acid. Compound C infrared spectrum JIY 0.8 oO = 0.6 pir 5 : ea 0.4 0.2 3000 2000 1000 Wavenumber (cm ') (a) Deduce the class of compound C. Explain your reasoning. [4 marks] (b) Deduce the structural formula and IUPAC name of two isomers of compound C. [2 marks] (c) Distinguish between structural and geometric isomers. [2 marks]
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