A chemist found that a mixture of four components (Compounds A-D) could be separ

Question

A chemist found that a mixture of four components (Compounds A-D) could be separated on a silica gel TLC plate using 10% diethyl ether in hexanes as the eluting solvent (see "original mixture" far left plate in the figure below). The mixture was then chromatographed on a silica gel column eluted with this same solvent mixture and 11 fractions of 15 mL each were collected. Thin-layer chromatographic analysis of the various fractions (1-11) under the conditions stated above gave the results shown in the figure below: Compound AO Compound B O Compound C Compound DO Mix 1 2 3 4 5 6 7 8 9 10 11 (a) According to these results which fractions should be combined to give pure samples of A, B, C, and D? (b) Which fractions contain more than one component? Indicate for these 'mixed' fraction numbers what components of the original mixture are present (c) In a real life situation, where these compounds are economically valuable to your industry, what should be done with the mixed fractions discussed in answer 4a above?

Explanation / Answer

a)Fractions 1 and Fraction 2 combineds give compound A. Fraction 5 and Fraction 6 combineds give pure compound B. Fraction 8 is having pure compound C and Fraction 10 is having pure compound D.

b) Fractions three and four is mixture of A and B. Fraction 7 is a mixture of B and C. Fraction 9 is a mixture of C and D.

c)These mixted fractions are again subjected to column chramatography. or These compounds are seperated by HPLC.

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