Fill in the best correct answer. i) Which of the following compounds has an (E)-
ID: 939070 • Letter: F
Question
Fill in the best correct answer. i) Which of the following compounds has an (E)-alkene group? ii) Which of the following is NOT an electrophibc species? iii) Separation of a racemic mixture with standard punfication techniques, such as silica gel chromatography, is only possible once the enantiomers have been converted to. A) diastereomeric compounds B) meso compounds C) achiral compounds D) nucleophiles iv) Which of the following reaction conditions would react with 3-methyl-1-butene to give a major product that results from a carbocation rearrangement?Explanation / Answer
(i) According to, Cahn-Ingold-Prelog priority rules ,The two attached atoms are C and H, so since the atomic numbers C > H then the -CH3 group is higher priority. Therefore the two high priority groups are on the opposite side, then this is (2E)-2-chloro-but-2-ene.
correct answer is (C) (2E)-2-chloro-but-2-ene.
(II) An electrophile is a reagent attracted to electrons. They are positively charged or neutral species having vacant orbitals that are attracted to an electron rich centre. They accepts an electron pair in order to bond to a nucleophile. CH3Li is a nucleophile not electrophile.
correct answer is (C) CH3Li.
(iii) Reaction of a racemic mixture with an enantiomerically pure chiral reagent gives a mixture of diastereomers, which can be separated. For example, if a racemic mixture of a chiral alcohol is reacted with a enantiomerically pure carboxylic acid, the result is a mixture of diastereomers.
correct answer is (A) Diastereomeric compounds.
(iv) When 3-methyl-1-butene undergoes acid-catalyzed hydration, rearrangement occurs because carbocation intermediates are involved. Oxymercuration–reduction gives addition without rearrangement because the intermediate is a cyclic mercurinium ion, which does not rearrange. 3-METHYL-2-BUTANOL is the major product of the reaction.
correct answer is (B) Hg(OAc)2 with H2O followed by NaBH4.
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