JEE chemistry

Explain enantiomers with the example of lactic acid — JEE Chemistry

LLucasBernard77 Asked 4mo ago 1,295 views 1 answer

Explain enantiomers with the example of lactic acid. Draw both structures and state which is optically active.

1 Answer

VAVidaara Admin ✓ Vidaara Team ✓ Accepted · 3mo ago ▲ 3

Lactic acid $(CH_3-CH(OH)-COOH)$ has one chiral centre (C-2). Two non-superimposable mirror images:

  • $(R)$-lactic acid: rotates plane-polarised light to the right (+)
  • $(S)$-lactic acid: rotates to the left (-)

Both are optically active. An equimolar mixture is a racemic mixture (optically inactive, $[\alpha] = 0$).

$$Both enantiomers rotate plane-polarised light equally but in opposite directions$$

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Discussion (5)

RJ
Saved me before my mock test. Much clearer than my coaching notes.
Rahul Joshi · 3mo ago
PI
Quick doubt: would this method still work if the numbers were not so clean?
Pooja Iyer · 3mo ago
SG
Can someone explain why we ignore the other root here?
Sneha Gupta · 3mo ago
RV
What changes if the medium/conditions were different?
Rohit Verma · 3mo ago
VA
Good follow-up questions — remember to always state your assumptions in the JEE subjective section.
Vidaara Admin · Vidaara Team · 3mo ago
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