Biodegradable Surface Active D-Glucose Based Quaternary Ammonium Ionic Liquids in the Solventless Synthesis of Chloroprene

Abstract

Five ionic liquids based on a quaternary ammonium core substituted with a D-glucose moiety and alkyl chains of varying length were synthesized as prospective phase-transfer catalysts. The catalytic activity of the obtained ionic liquids was tested in the dehydrochlorination of 3,4-dichloro-1-butene to chloroprene. The reaction proceeded in a two-phase system in the presence of an aqueous solution of sodium hydroxide. The results showed that the longer the alkyl chain in the cation, the higher the activity of the ionic liquid as a phase-transfer catalyst. The tested ionic liquids gave an easily recyclable system compared to classical phase-transfer catalysts that were soluble in the reaction system, with no leaching observed over five cycles (chloroprene yield >99%). The cytotoxicity and biodegradability of a series of synthesized ionic liquids based on D-glucose were determined so that a preliminary hazard assessment could be undertaken.

Insights into the Properties and Potential Applications of Renewable Carbohydrate-Based Ionic Liquids: A Review

“…The length of the carbon chain is another factor that can influence the cytotoxicity of ILs. This effect was discussed in aforementioned work by Erfurt et al [ 54 ], where glucose-based ILs modified at anomeric position with various alkyl substituents ( 4a – c ) were examined. Derivatives with the shortest alkyl chain ( 4a ) showed the lowest cytotoxicity against rat leukemia cells, in fact it revealed no effect on the viability of cells up to 0.584 mM concentration.…”

“…However, the biodegradability of carbohydrate ILs is dependent on the length of the alkyl chain in the cation. In a series of quaternary ammonium salts based on d -glucose cation, where alkyl chains of various length were introduced (–CH 3 , –C 12 H 25 , –C 16 H 33 , 4a , 4b , 4c , respectively), a derivative with the shortest alkyl chain ( 4a ) was found to be readily biodegradable (74–83%), while 4b with C12 was close to fulfill the ready biodegradability criterion (60%), reaching 57% [ 54 ]. In contrast, ILs with –C 16 H 33 substituent ( 4c ) showed a longer lag phase of 10 days, after which it started to degrade, not reaching a plateau during the experiment time though.…”

“…In addition to [Ch]ILs, carbohydrates have also gained attention as starting materials for synthesizing non-toxic and biocompatible ILs. Carbohydrate-derived ILs generally exhibit very low (eco)toxicity towards bacteria [ 37 ], fungi [ 37 ], human cancer cells [ 17 ], mouse cells [ 13 , 39 ], rat cells [ 54 ], and zebrafish eggs [ 17 ], indicating a promising biocompatible character.…”

“…Very recently Chrobok’s group [ 54 ] presented also the application of glucose-derived ILs, modified with long alkyl chains on the quaternary ammonium group as PTC catalysts for the synthesis of 2-chloro-1,3-butadiene (chloroprene) in a two-phase system. The authors presented the influence of alkyl chain length of ammonium bromides on the conversion of 3,4-dichloro-1-butene, with the highest activity reported for IL bearing a C12 alkyl chain.…”

Antibacterial, Antifungal and Ecotoxic Effects of Ammonium and Imidazolium Ionic Liquids Synthesized in Microwaves

“…Stolte et al [37] tested the toxicity of a number of imidazolium salts. Cao et al, Erfurt et al [38,39] studied cytotoxicity of selected ILs. However, the imidazolium and ammonium ILs presented in this work were not completely studied.…”