Chemistry (petroleum related)

Fontaine · #1 09-18-2008, 07:59 PM

i was asked which is more soluble in water, salicylic acid or aspirin....I found out that the answer is infact aspirin at 10mg/mL, but i need a good explanation as to why....i was hoping some TB'ers could help out a young fella?

thanks.

**bassybill** · #2 09-19-2008, 01:07 AM

Just from looking at the structural formulae, it looks likely that the aspirin moelcule would have a greater dipole moment than that of salicylic acid (the oxygens in the side chain sticking out make it more asymmetrical in terms of charge distribution). This increased polarity will make it interact more strongly with molecules of a polar solvent such as water and increase the solubility.

Atoz · #3 09-19-2008, 02:52 AM

The salicylic acid might also be more likely to form a dimer with the hydroxyls hydrogen bonding, making it less soluble in water than aspirin.

Or... I could be out to lunch on that.

Fontaine · #4 09-19-2008, 04:41 AM

i actually determined i was wrong, it was the salicylic acid due to it having 2 alcohols on its benzene ring compared to aspirin which only has 1 coming off the benzene ring.

thanks for the help anyway guys.

**bassybill** · #5 09-19-2008, 05:56 AM

Wait, what?

The solubility data I looked up said that aspirin was the more soluble of these two compounds, which is quite surprising and this was what I thought was the reason for the question in the first place.

Fontaine · #6 09-19-2008, 07:04 AM

Quote:

Originally Posted by bassybill

Wait, what?

The solubility data I looked up said that aspirin was the more soluble of these two compounds, which is quite surprising and this was what I thought was the reason for the question in the first place.

i thought the same as well, but apparently, its not. I'm still a bit confused.