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How would you draw a six-carbon alkyne that can exist as a diastereomer?

Answer 1

Jacob Anderson

A six carbon alkyne that can exist as a diastereomer is 1-ethynyl-2-methylcyclopropane.

One way for a compound to have diastereomers is to have two chiral centres.

The only way we can do this with a six-carbon alkyne is to have a cyclopropane ring.

Then we can add an ethynyl and a methyl group to generate two chiral centres.

1-ethynyl-2-methylcyclopropane

Since there are two chiral centres and no plane of symmetry, there are #2^2 = 4# stereoisomers.

Their structures are

Any isomer in one row is a diastereomer of the two isomers in the other row.

Isomers in the same row are a pair of enantiomers.

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Answer 2

Maya Allen

A six-carbon alkyne with a diastereomer can be represented as follows:

[ \begin{array}{ccccccc} & H & | & H & | & H & \ H-C=C-C=C-C \quad \text{(Original Alkyne)} & | & | & | \ & H & | & H & | & H & \end{array} ]

To create a diastereomer, swap the positions of two nonadjacent substituents. For instance, interchange the positions of two hydrogen atoms on different carbon atoms.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.