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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: coolguy99 on March 01, 2010, 11:17:09 PM

Title: Melting Point/Boiling Point question
Post by: coolguy99 on March 01, 2010, 11:17:09 PM
Fairly simple question for you great minds out there,

which has a higher melting point and which has a higher boiling point?

Primary Amide vs. Carboxylic Acid

those were the choices.

I'm thinking Primary Amide? Less electronegative, so more hydrogen bonding, so higher mp? Or is that off?
Title: Re: Melting Point/Boiling Point question
Post by: Ajax on March 03, 2010, 04:27:09 PM
Amide is a type of bond whereas carboxylic acid is a group. if you mean amine then the answer is carboxylic acid; IE methanoic acid has a higher boiling point than methylamine....
Title: Re: Melting Point/Boiling Point question
Post by: cth on March 03, 2010, 05:02:38 PM
Amide is a type of bond whereas carboxylic acid is a group.

No, amides are a chemical group http://en.wikipedia.org/wiki/Amide


which has a higher melting point and which has a higher boiling point?

Primary Amide vs. Carboxylic Acid

You just have to compare the melting points of two related compounds:
http://en.wikipedia.org/wiki/Acetamide
http://en.wikipedia.org/wiki/Acetic_acid
The amide has boiling and melting points much higher than acetic acid. Carboxylic acids tend to form dimers through hydrogen bonds, while amide have more hydrogen atoms available for more hydrogen bonds with neighboring molecules.