MALDI mass spectrometry monitoring of cyclodextrin-oligolactide derivatives synthesis

This paper aims to expand the range of matrix assisted laser desorption mass spectrometry analysis (MALDI MS) as a tool to establish the reaction kinetics for a particular case study: the synthesis of beta-cyclodextrin-oligolactide (CDLA) derivatives through solution ring opening oligomerization (ROO) of D,L-lactide (LA) initiated by beta-cyclodextrin (beta-CD). Specifically, MALDI MS was used to estimate the molecular weight averages minute changes during the synthesis for a better understanding of the chemical process. The MALDI MS data was compared with 1H NMR for determining the DL-Lactide conversion rate and an excellent agreement level was established. The synthesis process was further studied by observing the effects of the reaction parameters with a special focus on the solvent influence. Thus, we observed that the ROO performed in dimethylformamide and Nmethyl-2-pyrrolidone proceeds faster in comparison with dimethylsulfoxide due to an activation process in the LA ring opening reaction. The activation is produced by the amines resulted from the cleavage of the amide bonds in the presence of the beta-CD or CDLA derivatives. The products of the degradation process were identified in the MS spectra and structurally confirmed through MS fragmentation experiments.

Automated summary

This paper explores the reaction kinetics and details of the synthesis of beta-cyclodextrin-oligolactide derivatives initiated by beta-cyclodextrin in D,L-lactide through MALDI MS analysis, comparing data with 1H NMR and studying the influence of solvents, revealing a faster reaction in specific solvents due to activation processes.