Hi !

If you use TsCl the sulfone wiil be absorbed  strong in UV ! 

Hi !

You may try Folin-Ciocalteau (FC) reagent used for the detection of polyphenols under basic conditions.

Hi Paiva!

Thank you for your suggestion, I'm going to try and then I will tell you. By the way, Do you know if pyridine it's essential for this reaction?

Hi Brother!

Sometimes  ! but you can use triethylamine ! 

Hugs!

Dear Carmen,

The essential point here is to use dry components (i.e. alcohol and a solvent), otherwise you will have to add a large excess of the reagent like TsCl which is water-sensitive. You can perform this reaction in dry pyridine. Or use a dry neutral solvent like acetonitrile in the presence of triethylamine or N-methylmorpholine. Typically you can add 2 eq. of the reagent and 2.2-2.5 eq. of TEA. You can use also a benzoyl chloride or similar aromatic chloroanhydrides under similar conditions.

There are also reagents of other types for alcohol derivatization resulting in UV-absorbing products. For example, phthalic anhydride is very suitable.

Best wishes,

Igor

Dear Igor,

Thank you very much for your suggestions they were very useful. Indeed when I used a dry pyridine the results were more replicable. Now I’m going to check some others reagents to see which one is more suitable…The principal problems on my samples are the solubility, the impurities (some fatty acids of very long chain and some aldehydes). I'm already characterized by GC-MS, but I can’t use it for common quality control.

Thank again

Dear Carmen,

What you need are UV absorbing reagents that react with -OH groups.  According to the "Handbook of Derivatives for Chromatography", in addition to those mentioned already above, Phenyl Isocyanate (PIC) is another option and it says has been used for aliphatic alcohols, but it looks like only up to C7.  It could be worth a try though. 

It says the alcohol (0.5 - 10mg) was dissolved in 1ml of dimethyl formamide (DMF) and 0.5ml of PIC added, mixed vigorously and allowed to stand 15 mins.  Excess reagent was destroyed by adding 0.5ml methanol.  Derivatives were separated on a C18 column at 50 degrees C and detected at 230nm.  

The thing is you are dealing with alcohols with very long aliphatic chains and need to be able to get them well dispersed and solubilized first prior to derivatization.  I am thinking that you may need an additional co-solvent and/or use elevated temperature to get them into solution.

Keep us posted.  If I come up with any other potentially viable ideas I will let you know.

Buena suerte,

Tom