A-LevelChemistryIntroduction to organic chemistryOct/Nov 2009Paper 1 Q201 Mark
The presence of 11-cis retinal, C20H28O, in cells in the eye is important for vision. The structure of retinal includes an aldehyde group, a cyclohexene ring and a long aliphatic side chain, in which a carbon-carbon double bond exists between carbons numbered 11 and 12. Which pair of statements about 11-cis retinal could be correct?
Atotal number of >C=C< double bonds: 5, arrangement around the adjacent carbons 11 and 12: [Diagram showing R1 and R2 on the same side (cis) of the double bond]
Btotal number of >C=C< double bonds: 5, arrangement around the adjacent carbons 11 and 12: [Diagram showing R1 and R2 on opposite sides (trans) of the double bond]
Ctotal number of >C=C< double bonds: 6, arrangement around the adjacent carbons 11 and 12: [Diagram showing R1 and R2 on the same side (cis) of the double bond]
Dtotal number of >C=C< double bonds: 6, arrangement around the adjacent carbons 11 and 12: [Diagram showing R1 and R2 on opposite sides (trans) of the double bond]
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The correct answer is A. This question tests the candidate's understanding of introduction to organic chemistry within the Chemistrysyllabus. The examiner's mark scheme requires...
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