How many chiral centres are present in the molecule #H_3C-CHBr-CHBr-CHBrCH_3#? How many diastereomers will this structure generate?

1 Answer
anor277
Jan 29, 2018

You gots THREE chiral centres...

Explanation:

A meso-compound is a symmetric #RS# species....such that upon inversion #RS-=SR#, and the structures are superposable. Here you gots THREE chiral centres....

#H_3stackrel(1)C-CHBr-CHBr-CHBr-stackrel(5)CH_3#

Now clearly, #2R, 3S, 4S!=2S, 3R, 4R#....

....and this is not really a suitable problem for 2nd year organic, because with three chiral centres there is a lot of geometry to consider and represent.

On the other hand for #"2,4-dibromopentane"#

#H_3stackrel(1)C-CHBr-CH_2-CHBr-stackrel(5)CH_3#....

....there are three diastereomers, #"RR"#, #"SS"#, and the meso #"RS"-="SR"#

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