jackie 發問於 科學及數學化學 · 10 年前

AL chem:carbonyl cpd +NaHSO3,急

AL chem:carbonyl cpd +NaHSO3

有條題目問how to purify the aldehyde cpd

in addition to recrystallization,

i found that marking provides an alternative method:

make use of reaction of carbonyl cpd +NaHSO3

我記得書有講過,但極不詳細

我想知道點用呢個方法和過程去purify 個compound

(可能out ,但我想知)

1 個解答

評分
  • ?
    Lv 7
    10 年前
    最愛解答

    in fact, the reaction is as simple as that, need not too much details to describe.

    for aldehydes (except ethanal and methanal) and methylketones, saturated NaHSO3 solution is added.

    the addition product has low solubility in water, which leads to precipitation of solid/crystals. (the addition products of methanal and ethanal are, however, reasonably soluble in water, making separation difficult)

    filter them out, wash, and do extra recrystallization if required.

    the reaction between NaHSO3 and aldehydes / methylketones is reversible. heat the product in inorganic acid / alkali, which restores the original aldehyde/ketone. do a phase separation to obtain the aldehydes / ketones if wanted.

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