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Which of the following does not given iodoform test :A. 2-pentanoneB. ethanolC. ethanalD. 3-pentanone |
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Answer» Correct Answer - D the compounds which contain either `CH_(3)-CO-`group or `CH_(3)-underset(OH)underset(|)(C)H` group give postiive Iodoform test In 2-pentanone, `(CH_(3)CH_(2)CH_(2)COCH_(3)),CH_(3)CHO and C_(2)H_(5)OH`, required groups are present, thus they give iodoform as follows `CH_(3)-COCH_(2)-CH_(2)CH_(3)+3I_(2)+4NaOHtounderset("Iodoform (yellow ppt.)")(CHI_(3))darr+CH_(3)CH_(2)CH_(2)COONa+3NaI+3H_(2)O` `CH_(3)CHO+3I_(2)+4NaOHto underset("Iodoform (Yellow ppt.)")CHI_(3))darr+HCOONa+3NaI+3H_(2)O` `C_(2)H_(5)OHoverset(I_(2))toCH_(3)CHO` `CH_(3)CHO+3I_(2)+4NaOHtounderset("Iodoform")(C HI_(3))darr+HCOONa+3NaI+3H_(2)O` But due to absence of `CH_(3)-underset(OH)underset(|)(C)H` or `CH_(3)-underset(|)(C)=` Group in 3-pentanone, it does not give iodoform `underset("3-pentanone")(CH_(3)-CH_(2)-overset(O)overset(||)(C)-CH_(2))-CH_(3)+I_(2)+NaOHto` No reaction. |
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