akimhaneul

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Donald Dunderland performs a column chromatography in the organic lab. Which compound would elute first?

a) COOCH3 attached to pentane ring
b) OH attached to pentane ring
c) Cooh attached to pentane ring
d) COH attached to pentane ring
e) two OH groups attached to pentane ring


Can someone explain the order? Why is C the most polar?
 

DMikes

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Column Chromatography is based on polarity.

A should elute first. It is an ester and is relatively non-polar.
C should elute last as it is the most polar.

Carboxylic acids, which is "COOH," are more polar than alcohols. Alcohols are more polar than esters. Etc.
 

akimhaneul

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Column Chromatography is based on polarity.

A should elute first. It is an ester and is relatively non-polar.
C should elute last as it is the most polar.

Carboxylic acids, which is "COOH," are more polar than alcohols. Alcohols are more polar than esters. Etc.

Why is ester non polar?

Why is carboxylic acid more polar than alcohols?
 
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Donald Dunderland performs a column chromatography in the organic lab. Which compound would elute first?

a) COOCH3 attached to pentane ring
b) OH attached to pentane ring
c) Cooh attached to pentane ring
d) COH attached to pentane ring
e) two OH groups attached to pentane ring


Can someone explain the order? Why is C the most polar?
Glad to see everyone is on the right track with this question. A carboxy acid has the greater amount of electron density residing on the oxygen atom, hence would have the largest dipole and be the most polar. This polar molecule will actually react with the material in the chromatographic column and adhere to it, thus will elute very slowly. The ester has some polarity as well.....BUT is the LEAST polar when compared to molecules like acids or alcohols. This is a VERY important problem, and worth remembering. Keep up the great work guys,,,,,we got this.

Dr. Romano
 
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Bersabeh

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Glad to see everyone is on the right track with this question. A carboxy acid has the greater amount of electron density residing on the oxygen atom, hence would have the largest dipole and be the most polar. This polar molecule will actually react with the material in the chromatographic column and adhere to it, thus will elute very slowly. The ester has some polarity as well.....BUT is the LEAST polar when compared to molecules like acids or alcohols. This is a VERY important problem, and worth remembering. Keep up the great work guys,,,,,we got this.

Dr. Romano
hahaha am glad. one quest down.
 
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