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For converting $\ce{OH}$ of methylated polyethylene glycol. The first step is converting hydroxyl group to imidazole carbamate as an active intermediate. But what about the next step?

If I will add primary amine containing group to form carbamate linkage, how can I convert it to a free amine?

Reference: Zhou, S.; Wang, J.; Wang, G.; Jiang, Z.; Ren, H. An approach to developing high dielectric constant nanocomposites based on polyrotaxane derivative. European Polymer Journal 2017, 90, 312-322. DOI: 10.1016/j.eurpolymj.2017.03.037.

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  • $\begingroup$ I don't think it will convert to a free amine. If you add an amine, you will make a carbamate where PEG has acted as a carrier or intermediate. For what it's worth, if you want a hydroxyl to amine conversion, I would try diphenylphosphoryl azide. Then convert the azide to the amine by hydrogenation or triphenylphosphine. $\endgroup$ – Beerhunter Apr 4 '18 at 22:47
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Conversion of Hydroxyl group to free amine in polyethylene glycol: This is a case of converting a primary alcohol to a primary amine

$$\ce{R-CH2OH -> -> -> R-CH2NH2}$$

To my understanding, converting hydroxyl group to imidazole carbamate as an active intermediate is not the way to do this. First thing come to my mind was a named reaction called the Mitsunobu reaction. The Mitsunobu Reaction allows the conversion of primary and secondary alcohols to esters, phenyl ethers, thioethers and various other compounds including amines. The reaction uses triphenylphosphine ($\ce{Ph3P}$) and diethylazodicarboxylate ($\ce{DEAD}$) to activate hydroxyl group. Then, activated alcohol can undergo substitution reaction with a suitable nitrogen nucleophile (either phthalimide or hydrogen azide can be used) followed by reduction (in the case of azide formation) or acid or base hydrolysis (if phthalimide were used as nucleophile) to give primary amine groups.

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  • $\begingroup$ I actually know this method but i am asking about the other using CDI in the attached paper ? $\endgroup$ – Hossam Mar 31 '18 at 4:20

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