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Not sure what happens here when vanillin reacts with acetic anhydride n the presence of an acid...
The NMR of the acid product shows peaks at - ppm (integration) -
2.1 (6.37)
2.3 (2.90)
3.8 (3.00)
7.1 (3.22)
7.6 (1.08)
im really bad at NMRs... so im not getting too far with this..
thanks!
The NMR of the acid product shows peaks at - ppm (integration) -
2.1 (6.37)
2.3 (2.90)
3.8 (3.00)
7.1 (3.22)
7.6 (1.08)
im really bad at NMRs... so im not getting too far with this..
thanks!
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Re: Esterification of Vanillin In Presence of Acid
Mon, July 21, 2008 - 2:13 AMWhat is the multiplet of each of those peaks?... understand the multiplet relationships is what tells the structure on a primary level (peak splitting is needed for a deeper understanding). -
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Re: Esterification of Vanillin In Presence of Acid
Mon, July 21, 2008 - 3:00 AM2.1 (6.37)
2.3 (2.90)
3.8 (3.00)
7.1 (3.22)
7.6 (1.08)
they all look like singlets to me... -
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Re: Esterification of Vanillin In Presence of Acid
Mon, July 21, 2008 - 8:55 AMHow did you purify the sample?
In the aromatic region 7.6 is the proton between the formyl and methoxide groups. This is a singlet.
7.1 is also aromatic protons, but should be a doublet and count 2 protons, not 3, so something is wrong with the integration.
3.8 is the methoxide protons (3) and should be a singlet.
2.3 were the hydroxyl group was converted into an acetate ester (3 protons and a singlet)
~10-11 is were the formyl proton should be, but these often don't show up well (a singlet of 1 proton).
At 2.1, you have a singlet of 6 protons which matches the methyl protons on acetic acid or acetic anhydride. It is possible but unlikely that the formyl group was converted into a hemi-acetate (2 ester groups on the same carbon). I say unlikely because you normally need a strong electron withdrawing group (like CF3) also attached to the same carbon to stablize the hemi-acetate....
Go to www.sigmaaldrich.com/spectra...1609.PDF to see a FT-NMR of vanillin (the top is a carbon FT-NMR). Use that as a point of comparison. -
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Re: Esterification of Vanillin In Presence of Acid
Wed, July 23, 2008 - 12:31 AMThis is a fun reaction. have you looked up the other posts this tribe has come up with regarding the esterification of vanillin? -
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Re: Esterification of Vanillin In Presence of Acid
Wed, July 23, 2008 - 1:01 AMI actaully forget whether or not it will do anything beyond forming the ester in acid conditions.
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