UV spectra were measured for the aliphatc saturated aldehydes and ketones as their 2, 4-DNPHs. Maximum of absorption spectrum was indicated at 358mμ and 363mμ in their ethanol solution, respectively, and the absorption curve of aldehydes 2, 4-DNPHs was similar to the pattern of ketones 2, 4-DNPHs.
Therfore, the mixture in neutral ethanol solution, was possible to determine for the total carbonul compounds, but determination of aldehyde 2, 4-DNPHs in the presence of ketone 2, 4-DNPHs was impossible. When, this neutra solution of aldehydes and ketones 2, 4-DNPHs were made alkaline absorption maximum in UV region was disappeared, instead, a maxium of absorption spectrum was appeared in visible region (Max. at 440mμ ). The absorption appeared at 440mμ was quite similar to its of UV region.
The color-fading against lapst time was only existed in aldehyde 2, 4-DNPHs at visible region, but this was not seen in ketone 2, 4-DNPHs. The color-fading velosity was proportional to the molar concentration of aldehyde 2, 4-DNPHs.
It was found that mixture of aldehydes and ketones could be determined by absorption spectra of the neutral solution in UV region and color-fading velosity in the visible region from alkaline solution.
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