Extremely Rapid Polythioether Synthesis in the Presence of TBD

Abstract

A straightforward, novel, and extremely rapid method is developed for the synthesis of polythioether based on the reaction of dimethyl acetylenedicarboxylate with electron-deficient triple bond and 1,6-hexanedithiol in CHCl 3 using an organobase 1,5,7-triazabicyclo[4.4.0]dec-5ene at room temperature. The influence of various parameters, such as concentration of monomers, solvent, catalyst, and reaction time, on the polymerization was investigated through kinetic studies. Polythioether with molecular weight up to ∼50 kDa was quantitatively achieved in 1 min, under the optimum experimental conditions. Various dithiol compounds were then reacted with dimethyl acetylenedicarboxylate to enhance polymer diversity. Following, three propiolate compounds were reacted with 1,6-hexanedithiol to explore their ability for polythioether synthesis, but low to moderate molecular weights were achieved compared to those with dimethyl acetylenedicarboxylate. The versatility of these polythioethers was shown by postpolymerization functionalization studies. Considering the huge demand for rapid polymerizations in high efficiency under mild reaction conditions, the current study will offer remarkable opportunities toward the design of new polymeric materials.

Rapid Hyperbranched Polythioether Synthesis Through Thiol‐Michael Addition Reaction

“…Recently, our group focused on the use of highly basic and as well as a nucleophilic catalyst, 1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene (TBD) in the extremely rapid synthesis of polythioethers and the postfunctionalization of unsaturated polyester backbones . More recently, we showed that dimethyl acetylenedicarboxylate (DMADC) and various dithiols could be polymerized in the presence of TBD to give a series of linear polythioethers.…”

“…It was observed that this reduction tendency continued until 30 min and remained the same after that time. We observed similar behavior in our previous work on a dithiol addition to DMADC leading to linear polythioether . The M w values of the linear polythioethers just started to decline after 1 min while 10 or 15% TBD was used for the polymerization of DMADC (1.0 M) and hexanedithiol (1.0 M) in 2 mL of CHCl 3 at room temperature.…”

“…In contrast, HB polythioether ( 2 ) reaction proceeds much more slowly than that of HB polythioether (1) . It should be noted here that methylpropiolate has only one electron‐withdrawing carbonyl group in its structure, which makes the triple bond less electron deficient than that of DMADC, and thus simultaneous thiol additions, due to the resonance fact, take place on the same C of the triple bond carbons . Therefore, after the first thiol addition to the alkyne, the second thiol addition to the remaining double bond carbon which has already contain a sulfur atom makes the second Michael addition harder, resulting in slower polymerization.…”

Covalent Adaptable Networks with Tunable Exchange Rates Based on Reversible Thiol–yne Cross‐Linking

“…In these studies,T BD was chosen as an on-nucleophilic,s trong, non-volatile and lipophilic base that is compatible with polymer formulations and their envisaged thermal reprocessing,a nd also immediately gave very good results on small molecule level. [35] Even though the forward reactions to yield the thioacetal adduct are spontaneous and thermodynamically favored, Anslyn reported that dynamic thiol exchange can happen upon the addition of alternative thiols and triethylamine in solution via the suspected retro-Michael reaction (2')i n Scheme 2. [24] As our objective was to explore the utility of this reversible reaction in the context of CANs with dynamic thiol-yne derived thioacetal linkages,w ef irst synthesized as eries of small molecule TA-X compounds following the Angewandte Chemie Forschungsartikel 3638 www.angewandte.de synthetic procedure depicted above (1 mol %TBD in chloroform).…”

Aliphatic Polyester/polyhedral Oligomeric Silsesquioxanes Hybrid Networks via Copper‐free 1,3‐dipolar Cycloaddition Click Reaction

“…The strain‐promoted azide‐alkyne cycloaddition reaction between azides and strained alkynes, was developed by Bertozzi and coworkers, is widely applied for bioconjugation of live organisms. Recently, Tang and coworkers, Schubert et al, and Durmaz and coworkers groups have developed alternative copper‐free 1,3‐dipolar cycloaddition reactions between azides and electron‐deficient alkynes under mild conditions. The key of this click reaction is that the usage of adjacent electron‐withdrawing functional group makes the alkynes very electron deficient and suitable for cycloaddition reaction with azide to produce a triazole at room temperature under mild reaction conditions without using a metal catalyst.…”