Dec 14, 2009
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is this true statement? one of the book I am using states

• Intermolecular hydrogen bonding increase it boiling point, but intramolecular hydrogen bonding decrease it boiling point. so phenol with two hydroxy group on ortho position can easily form intramolecular hydrogen bond, so have a lower boiling point than two hydroxy group on meta position.

I thought both hydrogen bonding, no matter intra or inter molecular form increase its boiling point, but the statement made me get confused.
 

Nat426

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Off the top of my head i would agree with the statement. If the hydrogen bonding is happening within the molecule i would assume it is unavailable to bond with a different molecule. Let me know if anyone agrees/disagrees but that would be my reasoning behind it.
 

Cool Beans

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Off the top of my head i would agree with the statement. If the hydrogen bonding is happening within the molecule i would assume it is unavailable to bond with a different molecule. Let me know if anyone agrees/disagrees but that would be my reasoning behind it.
Nat426,
You hit it on the head and I agree with you. But fyi kpark102, this is probably a little beyond the scope of the DAT.
 
Apr 1, 2010
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Isnt it because of 2 electronegativity from Oxygen kind of cancel each of them out?

cuz I know for carboxylic acid, monocarbox has higher BP than dicarbox because of above reason
 

dentalWorks

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is this true statement? one of the book I am using states

• Intermolecular hydrogen bonding increase it boiling point, but intramolecular hydrogen bonding decrease it boiling point. so phenol with two hydroxy group on ortho position can easily form intramolecular hydrogen bond, so have a lower boiling point than two hydroxy group on meta position.

I thought both hydrogen bonding, no matter intra or inter molecular form increase its boiling point, but the statement made me get confused.
Whoa... Don't confuse the 2 types of interactions.. I'll copy paste something I wrote a while back:

"Well, there is a difference between intermolecular and intramolecular forces.
Inter = usually weak interactions between molecules (example would be the H-bonding happening between 2 water molecules)
Intra = usually this refers to ionic compounds or covalent bonds. It is referring to electrons either being transfered (as in NaCl) or just shared (as CH4) gas."


Basically, think "intra" = strong forces
and "inter" = weak forces, the stuff that effects boiling / melting points