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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: watizit97 on July 06, 2019, 03:01:44 AM

Title: Esterification of 4-Hydroxy-1-naphthalenesulfonic acid sodium salt
Post by: watizit97 on July 06, 2019, 03:01:44 AM

Hello.

I am just wondering whether it is possible to combine the hydroxy group of 4-Hydroxy-1-naphthalenesulfonic acid sodium salt to another compound with -COOH group via esterification?

Title: Re: Esterification of 4-Hydroxy-1-naphthalenesulfonic acid sodium salt
Post by: wildfyr on July 06, 2019, 10:53:54 AM

Certainly, should be conventional phebyl ester synthesis.

Title: Re: Esterification of 4-Hydroxy-1-naphthalenesulfonic acid sodium salt
Post by: hollytara on July 07, 2019, 03:21:03 PM

The tricky part is likely solubility.  You could use an acid chloride to react with the hydroxyl, but the salt may have limited solubility in the solvents we typically use for reactions of acid chloride + alcohol - you may have to use something more polar like DMF, NMP or DMSO. The salt it is more soluble in water, but esterification is hard to do in water, but it has been done - see Org Lett. 2012 Sep 21; 14(18): 4910–4913.

Title: Re: Esterification of 4-Hydroxy-1-naphthalenesulfonic acid sodium salt
Post by: rolnor on July 07, 2019, 04:42:28 PM

You can get a mixed sulphonic-carboxyl anhydrid but it will be easy to hydrolyse in the workup if you add MeOH after the esterification is finnished. You could make a Bu4N+-salt of the startingmaterial if solubility is poor.

Title: Re: Esterification of 4-Hydroxy-1-naphthalenesulfonic acid sodium salt
Post by: kriggy on July 09, 2019, 05:33:40 AM

DMF can cause problems when combined with acid chlorides via formation of vilsmayer reagent and futher side reactions. Why dont you use classic esterification conditions using dcc and DMAP in acetonitrile or other solvents? Also, if the salt is not soluble, the reaction can be done in suspension (did that in few cases when my acid chloride was not soluble enough)