How many optically stereoisomers are possible for butene-2,3-diol ?A.

1.	How many optically stereoisomers are possible for butene-2,3-diol ?A. 1B. 2C. 3D. 4
Answer» Correct Answer - B Butane-2,3-diol has two asymmetric carbon atoms. `underset("Butane-2,3-diol")(CH_(3)-overset(OH)overset(\|)(CH)-overset(OH)overset(\|)(CH)-CH_(3))` Optically active stereoisomers are I and III `{:(" "CH_(3) " "CH_(3)" "CH_(3)),(" \| ""\| "" \| "),(" "OH-C-H" "H-C-OH" "H-C-OH), ( " \| "" \| "" \|" ),(" "H-C-OH" "OH-C-H" "H-C-OH),(" \|"" \|"" \|"),(" "CH_(3)" "CH_(3)" "CH_(3) ),(" (I) (II) (III)"):}` III is meso form and is not optically active.

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Reimer-Tiemann reaction introduces an aldehyde group on to the aromatic ring of phenol, ortho to the hydroxyl group. This reacrtion involves electrophilic aromatic subsititution. It is a general method for the synthesis of subsituted salicyladehydes as depiced below: Which one of the following reagents is used in the above reaction ?A. aq. `NaOH+CH_(3)Cl`B. aq. `NaOH+CH_(2)Cl_(2)`C. aq. `NaOH+CHCl_(3)`D. aq. `NaOH+C Cl_(4)`
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How many optically stereoisomers are possible for butene-2,3-diol ?A. 1B. 2C. 3D. 4

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