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Can $\ce{CH3-CHCl-CH3}$ and $\ce{CH3COCl}$ give the iodoform test?

I thought $\ce{CH3COCl}$ having the keto-methyl group would show the iodoform test, while $\ce{CH3-CHCl-CH3}$ will not since it's not a secondary alcohol but an alkyl halide.

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    $\begingroup$ acetyl chloride will become acetate under alkaline conditions. $\endgroup$
    – user55119
    Commented Dec 30, 2019 at 18:27
  • $\begingroup$ @user55119 the keto methyl group would still be there(?) $\endgroup$
    – Tapi
    Commented Dec 30, 2019 at 18:29
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    $\begingroup$ Hydroxide adds to the carbonyl and eliminates chloride. The acetic acid formed is deprotonated by base to acetate. No iodoform reaction of acetate! All carbonyl groups are not created equal. Secondary methyl carbinols are oxidized by I2/NaOH to give the iodoform test via oxidation to acetone. To the extent that SN2 displacement of 2-chloropropane occurs, which is likely very little, 2-propanol is formed. Elimination (E2) is likely the major reaction. $\endgroup$
    – user55119
    Commented Dec 30, 2019 at 18:40
  • $\begingroup$ @user55119 Okay, thanks. So, 2-chloropropane also doesn't give the iodoform test. $\endgroup$
    – Tapi
    Commented Dec 30, 2019 at 18:46
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    $\begingroup$ 2-Chloropropane itself does not give a positive iodoform test. If you learn the mechanism, then the answer would be self-evident. $\endgroup$
    – user55119
    Commented Dec 30, 2019 at 19:03

1 Answer 1

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As mentioned by user55119, ethanoyl chloride will not give iodoform test, because acid derivatives will show nucleophilic substitution reactions. Resulting will be acetate ion, which is no more a good nucleophile. For a more detailed answer check out here.

2-chloropropane will show iodoform test, since through bimolecular substitution reaction $(\mathrm{S_N2}),$ chlorine will be replaced by $\ce{-OH}$ group. Propan-2-ol so formed will be oxidised to acetone, which will show iodoform test.

Remember that only $\ce{CH3COR}$, (where $\ce{R}$ can be alkyl or aryl part) or which can be converted to it, give haloform tests, until steric hindrance prevent even some of these compounds to react.

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  • $\begingroup$ As also mentioned, isopropyl chloride generally won't turn into propanol. $\endgroup$
    – Mithoron
    Commented Dec 31, 2019 at 21:18

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