Dear Prof. William Frost Berkowitz & Manohar Sehgal

Hi,

First of all I appreciate your wonderful convincing technique of TEMPO separation along with valuable reference it’s your greatness you guys contributing significantly and guiding the new scientist/researcher in this field.

I am new in area of Organic radicals and Polymer Chemistry, need your guideline.

My Question is I want synthesize the successful formation of biopolymer e.g. PEG-co-PAA, but all time esterformation peak in NMR missing or not well defined, I tried it multiple time, can you guide me please? Following article I followed for final product synthesis process.

Synthesis of PAA-PEG2000. PAA (14 mg, 8 μmol) was dissolved in 8 mL of a 100 mM potassium phosphate buffer (KPO4) at pH 6.0. EDC (192 mg, 1 mmol) and NHS (24 mg, 200 μmol) were dissolved in 2 mL of KPO4 and added to the above solution. The formation of activated NHS ester groups is indicated by a slight clouding of the reaction mixture. After 20 min of stirring at room temperature, 200 mg (100 μmol) of PEG2000 in 8 mL of KPO4 was

added and the reaction mixture was adjusted to pH 8.2 by titration with 1 M NaOH. At this pH, the NHS ester functionalities will react with amino groups to form stable amide bonds. The reaction was allowed to proceed for 4 h at room temperature, after which the reaction mixture was dialyzed for 24 h against deionized water. Andrea Seehuber et al. ,Langmuir (2012), 28, 8700−8710, ; Doi.org/10.1021/la2050652  

Thank you.

Warmest Regards,

Dr Alam

How TEMPO can be removed from organic reaction mixture without column chromatography?. Available from: https://www.researchgate.net/post/How_TEMPO_can_be_removed_from_organic_reaction_mixture_without_column_chromatography1#5976ecd396b7e4d7cb25dff6 [accessed Jul 27, 2017].