Volatility of Deep Eutectic Solvent Choline Chloride:N-Methylacetamide at Ambient Temperature and Pressure

Abstract

Common organic volatile solvents would volatilize in air, thus causing air pollution and harming human health. Deep eutectic solvents (DESs) are one type of the green solvents with low volatility, deemed as the new solvents of the 21st century. Previous investigation showed that the DESs would undergo volatilization at high temperature and/or vacuum pressure. However, how DESs volatile at ambient temperature and pressure is unknown. Here the volatilization of DESs in air at ambient temperature and pressure was investigated by in situ FT−IR and 2D FT−IR. ChCl (choline chloride):Nmethylacetamide was taken as an example of DESs and we found that it underwent severely volatilization even at ambient temperature and pressure. Moreover, the dynamics process of the volatilization was investigated by 2D FT−IR. It was found that N-methylacetamide volatilizes from ChCl:N-methylacetamide by destroying the hydrogen bond between free NH group and ChCl in ChCl:N-methylacetamide during the first 60 min. H-bonded NH II with strong H-bonding interaction with ChCl also undergoes a remark alternation at this turning point at ca. 60 min. During the period from 60 and 190 min, there also exists free NH in the DES ChCl:N-methylacetamide. The shift of free NH group ceases after ca. 70 min. After 190 min, most of Nmethylacetamide in ChCl:N-methylacetamide have volatilized, only trace of N-methylacetamide is left, therefore, the shift of IR absorption peaks is negligible. This works shows that we should pay more attention to the volatilization of DESs even at ambient temperature and pressure.

Recent Developments on 1,3-Dipolar Cycloaddition Reactions by Catalysis in Green Solvents

“…They are a eutectic mixture composed of Lewis or Brönsted acid (hydrogen bond donor commonly defined as HBDs) and bases in the form of salts (hydrogen bond acceptors commonly defined as HBAs), that can contain different types of anions and cations. In Figure 4, the most common hydrogen bond donors and hydrogen bonds acceptors are reported [49,50]. The reaction between crotonaldheyde 67a and (Z)-N-benzylidene-1-phenylmethanamine oxide 66 was selected to study the effects of all organocatalysts and ionic liquids, comparing the results with those obtained in classical conditions (CH 2 Cl 2 ; 5 • C; 4 die).…”

“…They are a eutectic mixture composed of Lewis or Brönsted acid (hydrogen bond donor commonly defined as HBDs) and bases in the form of salts (hydrogen bond acceptors commonly defined as HBAs), that can contain different types of anions and cations. In Figure 4, the most common hydrogen bond donors and hydrogen bonds acceptors are reported [49,50]. This phase, composed of two or more components, generally does not form new chemical compounds through covalent bonds, but the main bonding interactions of non-covalent nature are: Hydrogen interactions, α-hole interactions, π-hole interactions, and other two recently discovered as ĸ-hole and µ-hole interactions [51].…”

“…The most common hydrogen bond donors (HBDs) and hydrogen bond acceptors (HBAs) of deep eutectic solvent (DES)[49,50].…”

Utilization of Deep Eutectic Solvents to Reduce the Release of Hazardous Gases to the Atmosphere: A Critical Review

“…Many researchers have indicated that DESs has minimal or negligible volatility relative to traditional organic solvents. However, recently, Chen et al [ 41 ] reported the volatilization of ChCl: N -methylacetamide (1:6) DES even at room temperature and pressure. Another study conducted by the same group [ 42 ] found that the polyethylene glycol (PEG)-based DESs showed volatilization under the same conditions.…”

“Inverted” Deep Eutectic Solvents Based on Host‐Guest Interactions

“…Although DESs are considered to have negligible vapor pressure, some systems will lose weight significantly at room temperature. [16] The internal reason is that these systems contain volatile components,a nd the essence of this process is volatilization rather than decomposition. The interaction sites in the system can be determined by analyzing the weightlessness process.…”