Oksimerkürasyon reaksiyonuyla etkili bir şekilde keton uçlu PEG sentezi

For the longest time, effective, easy and inexpensive formation of one terminal group to another reactive terminal group is a desirable case not only in organic chemistry but in polymer chemistry as well. For this instance, researches are made either to find a new technique for polymers or to adapt and modify organic chemistry reactions in order to apply then in polymer chemistry. Ketones are desirable terminal groups in polymer chemistry since they can form imine forms when they react with terminal amine functionalized protein or peptides. But inevitably, alkyne functioned polymers are being used in such manner via CuAAC "Click" reactions to give biomolecule- polymer binding. Unfortunately, CuAAC reactions are limited to use to give such products due to the usage of Cu as the catalyst which has severe effects on human body functions. Hydration of alkynes is an easy way to obtain ketone function. This reaction is done by a mercury (II salt as a catalyst and acidic media, known as oxymercuration reactions. In addition, using such inexpensive chemicals and in a short period of time (4 hours), alkyne function can successfully changes to ketone function, quantitavely. Further observations showed that it is also possible to get rid of mercury (II) salts easily during the work-up processes, which provides the pathway to use oxymercuration reactions in biological aspects. In this work, we have chosen to use commercially available alkyne functionalized polyethylene glycol (PEG), which is also bio-compatible. Experimental works showed that when applied heat or worked in room temperature, it is possible to observe alkyne to ketone formation with high yields. Also, it was made clear that ketone functionalized PEG can successfully forms imines when reacted with an amine functionalized structure in our model reaction. Firstly, PEG-OH was reacted with 4-pentionic acid, giving PEG-Alkyne which is bio-compatible. Then, optimum reaction conditions were tried to be found in order to form the ketone conversion. But unlike in the organic synthesis, sulfuric acid and hydrochloric acid is found to be ineffective in this reaction, because both hydrolyzed the polymer structure. Instead, para-toluene sulfonic acid was used since its low toxicity, inexpensiveness and effectiveness in this reaction. Different equivalents and temperatures were tried with the most compatible mercury salt and acid, found to be the optimum reaction condition was 0.25 equivalent of p-TSA, HgSO4 in 50oC and 0.50 equivalent of p-TSA, HgSO4 in room temperature and observed quantitave formation. In light of these informations, optimum reaction time was observed as 4 hours from the kinetic studies. In light of this information firstly, two different electronic structıred alkyne terminated PEG was synthesised and alkyne- ketone conversion optimum reaction conditions were studied.