Organic 2 Review Problem 108

Organic 2 Review Problem 108 - 92 P RACTICAL ORGANIC...

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92 PRACTICAL ORGANIC CHEMISTRY does not give iodoform in these circumstances and can thus be distinguished from ethanol. The reactions involved are similar in both cases, and closely parallel to those which give rise to chloroform. The sodium hypochlorite probably first oxidises the potassium iodide to potassium hypoiodite, which then oxidises the ethanol to acetaldehyde and then iodinates the latter to tri-iodo- CH 5 CH 2 OH > CH 3 CHO ^ CI 3 CHO acetaldehyde or iodal. Aqueous sodium hypochlorite always contains sodium hydroxide, which converts the tri-iodo-acetaldehyde to iodoform and sodium formate. CI 3 CHO -f NaOH -> CHI 3 + HCOONa If acetone is used there is no initial oxidation: tri-iodo-acetone is first formed and is then converted by the sodium hydroxide to iodoform and CI 3 COCH 3 -f NaOH -> CHI 3 + CH 3 COONa sodium acetate. Iodoform is obtained more readily and in greater yield from acetone and acetaldehyde than from ethanol, possibly because no initial oxidation is required. Iodoform is a disinfectant and can be used as an external antiseptic.
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