Thiourea Research Articles

Indirect photolysis of cysteine and thiourea in the aquatic environment

The aim of this research is to study the thiourea (TU) and cysteine (Cys) photochemical transformations in aqueous solutions on model systems in order to estimate their role in the processes arising in the aquatic system. So, both thiols, TU and Cys, have been subjected to indirect photolysis with OH radicals, generated by the photodissociation of hydrogen peroxide on irradiation with different artificial light sources. It has been found that the indirect photolysis rates of TU and Cys depend on the chemical nature and initial concentrations of the substrate as well as H2O2. TU and Cys undergo photochemical transformations via very complex radical mechanisms.

Bridge molecule thiourea enforced polyaniline growing on activated carbon fiber for wearable braidable-supercapacitor

The bridge molecule thiourea (TU) enforced polyaniline (PANI) growing on activated carbon fiber (ACF) is applied to synthesize polyaniline-thiourea-activated carbon fiber (PANI-TU-ACF) through surface activation, hydrothermal treatment and electrochemical deposition processes for wearable braidable-supercapacitor. Experimental measurement and theoretical calculation demonstrate that PANI-TU-ACF involves amide bonding interface between ACF and TU and hydrogen bonding interface between TU and PANI, thus confirming the formation of bridging structure. The absorption spectrum red-shift of N–H vibration peak keeps in agreement with the declined bonding energy of N–H bond achieved by partial atom potential simulation calculation, which proves the formation of hydrogen bonding in PANI-TU-ACF. PANI-TU-ACF exhibits larger N(E) value and lower HOMO-LUMO energy gap than PANI-ACF, indicating its higher electrical conductivity. PANI-TU-PANI shows more lowered interface energy than PANI-ACF, suggesting its higher stability. PANI-TU-ACF electrode delivers excellent capacitance of 563.8F/g at 1 A/g and cycling stability of 89.1 % for 2000 cycles. Wearable braidable-supercapacitor based on PANI-TU-ACF electrode delivers energy density of 62.9 Wh kg−1 at power density of 800 W kg−1, maintains high capacitance retention of 90.13 % after 2000 charging/discharging cycles. The interfacial bonding strengthened PANI-TU-ACF with excellent performance displays potential in wearable supercapacitors.

Over 13% Efficient, Ambient Air‐Processed CuIn(S,Se)2 Solar Cells via Compositional Engineering of Molecular Inks

A dimethylformamide (DMF) and thiourea (TU)‐based ink deposition route is used to fabricate narrow bandgap (≈1.0 eV) CuIn(S,Se)2 (CISSe) films with Cu‐poor ([Cu]/[In] = 0.85), stoichiometric ([Cu]/[In] = 1.0), and Cu‐rich ([Cu]/[In] = 1.15) compositions for photovoltaic applications. Characterization of KCN‐ or (NH4)2S‐treated Cu‐rich absorber films using X‐ray diffraction and scanning electron microscopy confirms the removal of copper‐selenide phases from the film surface, while electron backscatter diffraction measurements and depth‐dependent energy‐dispersive X‐ray spectroscopy indicate remnant copper‐selenides in the absorber layer bulk. Contrary to best practice for vacuum‐processed cells, optimum [Cu]/[In] ratios appear to be stoichiometric, rather than Cu‐poor, in DMF–TU‐based CISSe devices. Accordingly, stoichiometric film compositions yield large‐grained (≈2 μm) absorber layers with smooth absorber surfaces (root mean square roughness <20 nm) and active area device efficiencies of 13.2% (without antireflective coating). Notably, these devices reach 70.0% of the Shockley–Queisser limit open‐circuit voltage (i.e., 526 mV at Eg of 1.01 eV), which is among the highest for ink‐based CISSe devices.

Synthesis and characterization of GA-AgNPs for highly sensitive and selective dual colorimetric detection of thiourea and thiophenol with DFT approach

This work reported a very simple, low cost and easy green method of synthesis of silver nanoparticles (GA-AgNPs) using gallic acid (GA) extracted from Terminalia chebula to detect the soil pollutants thiourea (TU) and thiophenol (TP). The GA-AgNPs were properly characterized by different techniques involving XRD, UV-Visible spectra, XPS, FE-SEM, and Raman spectroscopy. This synthesized GA-AgNPs was used as an effective colorimetric sensor and was even employed in real soil samples. Colorimetric detection was observed in a UV-visible spectrometer by analyzing the change in surface plasmon resonance of NPs when subjected to TU and TP. The result obtained was quick and visibly detectable by the naked eye. The colorimetric study resulted in a good linear relationship and the limit of detection (LoD) was calculated to be 5.79 nM for TU and 0.13 µM for TP. A color detector smartphone application was also used to detect the intensity of color change with variations in different concentrations of TU and TP. This system approach was also applied to real soil samples. Additionally, HPLC was used to validate the presence of TU and TP in the soil and to evaluate their recovery percentage. Density functional theory (DFT) analysis was done to support the plausible mechanism of the interaction between NPs and the sensing molecules. Moreover, the synthesized NPs showed excellent selectivity towards TU and TP in the presence of a wide range of interferences.

Assessment of Type 2 Diabetes Risk in General Population using Bitter Taste Sensitivity Status to Phenylthiocarbamide - A Pilot Study

Eating habits and genetic factors contribute to diseases such as obesity and Type 2 Diabetes Mellitus (T2DM). Variation in bitter taste perception has been linked with intake of alcohol, coffee, vegetable, and smoking habit as well as with adiposity, a risk factor for diabetes development. Therefore, it was hypothesized that bitter taste perception could lead to differences in eating/drinking behavior among individuals, which may lead T2DM development later in the life. Bitter taste sensitivity was assessed using paper strips having supra-threshold concentration of Phenyl Thio Carbamide (PTC). Lifestyle variables were assessed using standard anthropometry measurements and a questionnaire. T2DM risk was assessed using a point based system developed by Finnish Diabetes Association (FINDRISC score). SPSS software was used for statistical analysis. A total of 498 volunteers from New Delhi region participated in the present study, where the mean age of PTC tasters was 24 ± 12 years and for non-tasters was 29 ± 16 years. PTC taster status was significantly correlated with age (p ≤ 0.01), weight (p ≤ 0.05), BMI (p ≤ 0.05) and waste circumference (p ≤ 0.05). A positive correlation was observed for type of chocolate liking (r = 0.113, p ≤ 0.001) and for T2DM risk (p ≤ 0.012) with PTC non-taster status. Logistic regression analysis showed that PTC non-taster individuals are at a higher risk (OR: 1.558, 95% CI: 1.037-2.342, p=0.033) for developing T2DM in the next ten years. Present results have shown that bitter taste sensitivity modulates liking towards certain food and non-tasters for PTC have a higher BMI, weight and are at a higher risk for T2DM development. PTC tasting could be employed as a method for assessing risk of diabetes in healthy individuals. We recommend large scale screening among young adults to promote awareness and early prevention measures.

Four cyclometalated iridium(III) complex-based chemosensors for turn-on response to thiourea in fruit juice and their application in test strips

Excessive thiourea(TU) was demonstrated to be harmful to both environmental system and human body, so it is essential to create selective and sensitive sensors to detect TU. Herein, Four iridium(III) complexes, [(fppy)2Ir(PD)]PF6 (Ir-fppy, fppy = 2-(4-fluorophenyl)pyridine), [(fpiq)2Ir(PD)]PF6 (Ir-fpiq, fpiq = 1-(4-fluorophenyl)isoquinoline), [(dfppy)2Ir(PD)]PF6 (Ir-dfppy, dfppy = 2-(3,5-difluorophenyl)pyridine) and [(dfpiq)2Ir(PD)]PF6 (Ir-dfpiq, dfpiq = 1-(3,5-difluorophenyl)isoquinoline) bearing 1,10-phenanthroline-5,6-dione (PD) as ancillary ligands, were designed and synthesized, and employed as efficient chemosensors to identify thiourea. These iridium(III) complexes exhibited emission peaks between 541 nm and 583 nm with PLQY ranging from 0.12 to 0.26 and lifetime in the range of 2.65–2.74 μs. All the four iridium(III) complexes showed significant turn-on response to TU with low limit of detect on the order of 10−8 M. Furthermore, these iridium(III) complexes-based chemosensors exhibited excellent recoveries toward TU in various juice samples including orange, kiwi fruit and lemon juice. Four complexes-composite test strips showed marker color change after adding TU.

Synergistic inhibition effect of imidazoline and thiourea on pitting corrosion of Q235 carbon steel

Pitting corrosion is a significant issue which significantly shorten the service life of carbon steel. In this study, imidazoline and thiourea are combined to assess the synergistic in the localized corrosion of Q235 carbon steel by a combined system. In detail, five different proportions of corrosion inhibitors are used in the simulated corrosion solution (5 wt. % NaCl + 0.5 wt. % CH3COOH + 1.0 wt. % Na2S) in the closed area to investigate the corrosion inhibition performance of Q235 steel at 80 °C. The corrosion behavior of the steel in the simulated solution was investigated using potentiodynamic polarization test and electrochemical impedance spectroscopy test. Due to the combination of imidazoline (IM) and thiourea (TU) corrosion inhibitors, the corrosion inhibitors in the simulated solution of the occlusion zone reduce the migration of corrosive anions to the occlusion zone and slowed the acidification of the solution resulting in lower concentrations of Cl- and S2- to varying degrees and reaching a higher pH of the solution. As a result, the compounded corrosion inhibitors exhibit improved corrosion inhibition rate (80 mg/L IM+20 mg/L TU (86.91 %), 50 mg/L IM+ 50 mg/L TU (95.67 %), 20 mg/L IM+ 80 mg/L TU (86.16 %)) to Q235 steel, which is superior to that using imidazoline (63.42 %) or thiourea (92.77 %) alone. This enhanced performances fully prove the synergistic effect of imidazoline with thiourea.

N-P-based inhibitors for PCDD/Fs suppression with model fly ash: Inhibition mechanism during de novo synthesis

Chemical inhibitors are essential for controlling polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) formation during municipal solid waste incineration, while conventional N-S-based inhibitors emit secondary pollutants such as NOx and SO2. Developing novel inhibitors is crucial to reduce secondary pollution. Here, the N-P-based inhibitors diammonium hydrogen phosphate (DAP) and ammonium polyphosphate (APP) were proposed to explore the inhibition effects and mechanisms of PCDD/Fs. The findings demonstrated that using DAP at a 1% mass ratio in the model fly ash (MFA) significantly increased I-TEQ inhibition efficiency to 98.8%, a 27.4% improvement compared to the standard inhibitor, thiourea (TUA). The inhibition mechanisms were investigated through experiments and density functional theory (DFT) calculations. We observed that the phase transition (from CuCl2 to CuHPO4, Cu2P2O7) weakened the catalytic action of CuCl2, while the chlorination action of CuCl2 was also blocked during PCDD/F formation. TGA-MS results showed DAP and APP released NH3, which consumed Cl2 and impeded the chlorination process. Furthermore, they were more eco-friendly than TUA, as they did not emit NOx or SO2. Additionally, DFT calculations revealed that inhibitors impaired the catalysis process, ranked by binding energy to the catalyst: Ebenzene-b (−0.59 eV) > EHPO4-b (−3.15 eV) > ENH4-b (−3.24 eV) > EP2O7-b (−4.67 eV) > ECH4N2S-b (−11.38 eV). Moreover, economic feasibility analysis indicated that the DAP and APP had large cost advantages over the TUA, reducing costs by 67.7% and 19.8%, respectively. The proposed strategy, which achieved superior inhibition effects for PCDD/Fs and reduction of inhibitor costs, appears promising for industrial application.

THE "PHOTOSYNTHESIS–GROWTH–STRESS MEMORY" RELATIONSHIP IN PLANTS UNDER CONDITIONS OF MOISTURE FLUCTUATION AND RECURRENT DROUGHT: MANAGEMENT OPTIONS

The effect of co-activation of the stress-memory formation potential under repeated drought of Glycine max (Merr.) L. plants was recorded using cytokinin (CK), thiourea (TH) and, especially, complex preparation Polyel. Glycine max plants (Merr.) L. of Moldovitsa, Nadejda and Magia varieties, exposed to two cycles of "drought–rehydration" at the "first trifoliate leaf" and "flowering - pods formation” phases served as test subjects. The tolerance-inducing effect manifests itself by maintaining the content of assimilatory pigments, photosynthesis and growth processes at a significantly higher level. After the restoration of the optimal moisture background, plants pre-treated with CK, TH and the preparation Polyel, which endured moderate stress in the initial stages of ontogenesis, had restored functional processes. The information obtained in this work certainly opens the management perspective of the ability to form stress memory, adaptation and tolerance of plants to the unfavourable fluctuation of humidity and recurrent drought. The management possibilities of plant adaptation and tolerance are discussed.

Enhanced Performance and Stability of Fully Printed Perovskite Solar Cells and Modules by Ternary Additives under High Humidity

To scale up from perovskite solar cells (PSCs) to perovskite solar modules (PSMs), a printing technique with an economical, uncomplicated fabrication process is required to meet the industrial market requirements. Equally important are the high photovoltaic (PV) performance and long-term device stability needed for successful commercialization of the technology. In this study, the effect of ternary additives consisting of guanidinium thiocyanate (GT), thiourea (TU), and urea (U) in MAPbI3 films on power conversion efficiency (PCE) as well as device stability was investigated for the first time based on the experimental results. GT helped influence perovskite crystal grain enlargement, while TU facilitated the perovskite crystal growth, leading to an increase in the current density. Moreover, the use of U was found to reduce the loss in open-circuit voltage as well as the hysteresis of PSC devices. An optimal composition of the ternary additives (1:1:2 molar ratio of GT, TU, and U) resulted in the outstanding performance of fully printed PSCs, showing a PCE of 16.40%, which was significantly higher than that of the pristine device (8.01%). In addition, the unencapsulated device prepared using the ternary additives showed great stability over 1000 h with a PCE retention of 100%, while the PCE of the unencapsulated pristine device decreased by 41.79%. For the large-scale PSM, the ternary additives yielded a significant enhancement of 11.60% PCE, which was over 3 times higher than that for the PSM without additives, as well as 100% retention after 2000 h of both desiccator and ambient storage.

Selective gold recovery from pregnant thiocyanate leach solution using ion exchange resins

Gold leaching using thiocyanate in acidic media is an alternative to cyanidation which is less toxic and can be done sequentially in one system without further preparation such as neutralization after acidic (bio)oxidation. Previous research activity in gold-thiocyanate leaching and gold recovery from thiocyanate pregnant leach solution (PLS) is limited. The current study deals with the selective recovery of gold over copper from synthetic and real thiocyanate PLS using ion exchange resins. Consequently, selective adsorption of Au(I) by ion exchange resins and selective Au(I) elution by proper eluent is proposed to obtain a high-purity Au(I) solution. First, the functionality of MTA 5011 and Amberjet 4200 resins at ambient temperature, and pH 2 for 24 h shaking at different resin mass (g) to PLS (L) ratios with synthetic PLS was compared. Then, 100 g/L MTA 5011 was chosen as the optimum resin/PLS (g/L) ratio for the highest separation with 99% gold and 12% copper extraction. Moreover, it was observed that over 24 h adsorption by 100 g/L MTA 5011, the copper extraction decreased, causing an increase in gold adsorption. Among the different reagents that were employed for gold elution, a solution of 0.01 M thiourea (TU) and 0.1 M H2SO4 was the most efficient with 70% gold and 4% copper elution. Adsorption experiments with MTA 5011 were repeated on the original thiocyanate PLS obtained after pyrite biooxidation and thiocyanate leaching using 0.2 M NaSCN and 0.01 M Fe3+. It was determined that the adsorption using 100 g/L MTA 5011 extracted ca. 99% gold and 5% copper, and for elution, a mixed solution of 0.01 M TU and 0.1 M H2SO4 recovered 99.2% gold and < 1% copper which validated the results from the synthetic PLS.

Thyroid Hormone Signaling Is Required for Dynamic Variation in Opsins in the Retina during Metamorphosis of the Japanese Flounder (Paralichthys olivaceus)

In the present study, we investigated the function of thyroid hormones (TH) in visual remodeling during Japanese flounder (Paralichthys olivaceus) metamorphosis through cellular molecular biology experiments. Our results showed that the expression of the five opsin genes of the flounder were highest in eye tissue and varied with the metamorphosis process. The expression of rh1, sws2aβ and lws was positively regulated by exogenous TH, but inhibited by thiourea (TU) compared to the control group. In addition, there was a significant increase in sws2aβ and lws in the rescue experiments performed with TU-treated larvae (p < 0.05). Meanwhile, T3 levels in flounder larvae were increased by TH and decreased by TU. Based on the differences in the expression of the three isoforms of the thyroid hormone receptor (TR) (Trαa, Trαb and Trβ), we further hypothesized that T3 may directly or indirectly regulate the expression of sws2aβ through Trαa. This study demonstrates the regulatory role of TH in opsins during flounder metamorphosis and provides a basis for further investigation on the molecular mechanisms underlying the development of the retinal photoreceptor system in flounders.

Paradox of thiourea: A false-positive and promoter for electrochemical nitrogen reduction on nickel sulfide catalysts

Electrochemical nitrogen reduction reaction (NRR) is an environmentally friendly process for ammonia synthesis. An unusually high NH3 production rate (86.91 ± 9.29 μg h−1 cm−2) and Faradaic efficiency (F.E.) (57.17 ± 4.14 %) was observed in electrochemical tests on NiS catalysts synthesized using thiourea (TU). Through joint experiment-theory work, we demonstrate the paradoxical catalytic effect of TU as a false positive from TU-derived thiocyanate reduction and a promoter via the generation of catalytically active carbon sites after TU reduction on the NiS surface (with an effective NH3 rate of 52 ± 5.57 μg h−1 cm−2). TU reduction leads to the substitution of an S atom to a reactive C atom with fewer valence electrons, facilitating a more facile NRR pathway. This study presents a new possibility for NRR catalysts based on metal-nonmetal compounds (e.g., sulfides, chalcogenides, or nitrides) by nonmetal dopants with fewer valence electrons to create new catalytically active sites.

High Performance and Reusable SAW Sensor Coated with Thiourea-Decorated POSS with Different Functional Groups for DMMP Detection

A colorless, odorless G nerve agent, a type of chemical transfer agent (CWA) that causes significant loss of life, is being studied for quick and accurate detection. In this study, detection materials with different functional groups were synthesized based on thiourea (TU)-decorated polyhedral oligomeric silsesquioxane (POSS) to study the most suitable material for the detection of dimethyl methylphosphonate (DMMP), a simulant of neural agents. The sensing material was coated on a SAW sensor with a resonance frequency of 250 MHz based on ST-quartz, the DMMP exposure experiment was conducted, and the performance of the sensing material was compared through frequency shift before and after exposure. Coating materials with excellent reactivity with DMMP and appropriate coating concentration for each material were identified at a concentration of 10 ppm. Among them, POSS-TU with 3,5-bis(trifluoromethyl)phenyl as a functional group showed the largest frequency shift characteristics, and it was used in low concentration (1, 5, and 10 ppm) DMMP detection experiments to confirm linear frequency shift characteristics according to low concentration. Finally, through a selectivity experiment with other gases, it was confirmed that the amount of frequency shift in other gases except DMMP was small, making it an excellent DMMP sensing material.

Turning on the Antimicrobial Activity of Gold Nanoclusters Against Multidrug‐Resistant Bacteria**

AbstractIn this work, we show that the addition of thiourea (TU) initiated broad‐spectrum antimicrobial activity of otherwise inactive D‐maltose‐capped gold nanoclusters (AuNC‐Mal). For example, AuNC‐Mal/TU was effective against multidrug‐resistant Pseudomonas aeruginosa with a minimum inhibitory concentration (MIC) of 1 μg mL−1 (2.5 μM [Au]) while having 30–60 times lower in vitro cytotoxicity against mammalian cells. The reaction of AuNC‐Mal and TU generated the antimicrobial species of [Au(TU)2]+ and smaller AuNCs. TU increased the accumulation of Au in bacteria and helped maintain the oxidation state as AuI (vs. AuIII). The modes of action included the inhibition of thioredoxin reductase, interference with the CuI regulation and depletion of ATP. Moreover, the antimicrobial activity did not change in the presence of colistin or carbonyl cyanide 3‐chlorophenylhydrazone, suggesting that AuNC‐Mal/TU was indifferent to the outer membrane barrier and to bacterial efflux pumps.

Turning on the Antimicrobial Activity of Gold Nanoclusters Against Multidrug-Resistant Bacteria.

In this work, we show that the addition of thiourea (TU) initiated broad-spectrum antimicrobial activity of otherwise inactive D-maltose-capped gold nanoclusters (AuNC-Mal). For example, AuNC-Mal/TU was effective against multidrug-resistant Pseudomonas aeruginosa with a minimum inhibitory concentration (MIC) of 1 μg mL-1 (2.5 μM [Au]) while having 30-60 times lower in vitro cytotoxicity against mammalian cells. The reaction of AuNC-Mal and TU generated the antimicrobial species of [Au(TU)2 ]+ and smaller AuNCs. TU increased the accumulation of Au in bacteria and helped maintain the oxidation state as AuI (vs. AuIII ). The modes of action included the inhibition of thioredoxin reductase, interference with the CuI regulation and depletion of ATP. Moreover, the antimicrobial activity did not change in the presence of colistin or carbonyl cyanide 3-chlorophenylhydrazone, suggesting that AuNC-Mal/TU was indifferent to the outer membrane barrier and to bacterial efflux pumps.

Discovery of Anodic Thiourea Oxidation as a Sustainable Counter Reaction to Boost Electro-Reductive Organic Transformations

In the reductive electrochemistry, the oxidative counter reaction remains one of the main bottlenecks for efficient cathodic organic transformations, but it has received less attention. Herein, anodic thiourea (TU) oxidation is reported as a sustainable oxidative counter reaction, which takes place at a low potential with a relative high current density. Mechanistic studies suggest that the anodic TU oxidation is initiated by a single electron-transfer (SET) process with the formation of formamidine disulfide cation as the main intermediate. In practice, the anodic TU oxidation counterbalances a series of SET reductive transformations at the cathode, and the protocol features sustainable condition, minimized waste, convenient setup, and excellent scalability, which highlights the underexplored potential of TU oxidation as an alternative counter reaction for the reductive electrochemistry.

Dual Effects of Slow Recrystallization and Defects Passivation Achieve Efficient Tin‐Based Perovskite Solar Cells with Good Stability Up to One Year

AbstractTin‐based perovskite solar cells (TPSCs) have become a star candidate in lead‐free perovskite cells due to their excellent optoelectronic properties and low toxicity. However, there are a lot of problems such as uncontrollable crystallizationprocess, easy oxidation of Sn2+ and high defect density have not been completely resolved in TPSCs. Here, the thiourea (TU) and amidine thiourea (ASU) are added into the perovskite precursor to regulate the microstructure, inhibit the oxidation of Sn2+ and promote charge transfer. The characterization results demonstrate that the TU additive can not only improve the micrograph, crystallinity and antioxidant, but also significantly induce recrystallization and passivate trap states. Thus, the TPSCs with TU (TU‐modified TPSCs) show a significantly higher power conversion efficienc (PCE) and better stability than those of the TPSCs with ASU (ASU‐modified PSCs) and reference TPSCs. After stored in N2 atmosphere for 8 months, the unencapsulated TU‐modified PSCs achieve a champion PCE of 10.9% with an open‐circuit voltage of 0.79 V. Furthermore, the unsealed TU‐modified PSCs can maintain 115% of its initial efficiency after stored in N2 atmosphere for one year. This is the longest lifetime of unencapsulated pure TPSCs in N2 atmosphere.

Polyhydroxyurethane covalent adaptable networks: looking for suitable catalysts

Various bases (DMAP, DBU, TBD, t-BuOK), acid (p-TSA), thiourea (TU) and organometallic Lewis acid (DBTDL) were investigated as potential catalysts for the preparation of polyhydroxyurethane covalent adaptable networks.

Facile and efficient acylation of chitin in deep eutectic solvents

This study investigates acylation of chitin in deep eutectic solvents (DESs) as analogous solvents of ionic liquids (ILs), because we have already reported that such reaction smoothly progresses using acyl chlorides in the presence of pyridine/N,N-dimethyl-4-aminopyridine (DMAP) as base/catalyst in the IL, that dissolves chitin. In addition to a DES composed of 1-allyl-3-methylimidazolium chloride (AMIMCl) and thiourea (TUA) as hydrogen bond acceptor and donor (HBA and HBD), respectively, which we previously reported to dissolve chitin, several DESs were prepared from AMIMCl and different HBDs, that is, urea (UA), acetylthiourea (AcTUA), acetylurea (AcUA), and 1,1,3,3-tetramethylguanidine (TMG). These DESs were found to also dissolve chitin. Hexanoylation of chitin in the AMIMCl/TUA-DES under the same conditions, as those previously performed in the IL, i.e., using hexanoyl chloride in the presence of pyridine/DMAP at 100 ​°C for 24 ​h, gave the product with the low degree of substitution (DS). As this was speculated to be due to the high nucleophilicity of TUA, which had a potential to react with hexanoyl chloride, the other HBDs with lower nucleophilicity, mentioned above, were employed to be combined with AMIMCl in the DESs. When hexanoylation of chitin was carried out in the DESs composed of UA, AcTUA, AcUA, and TMG under the same conditions as above, the higher DS products were obtained. In particular, the reaction in the AMIMCl/TMG-DES efficiently occurred in the absence of pyridine/DMAP to produce the high DS product, probably owing to the high basicity and low nucleophilicity of TMG. The structure of the chitin hexanoate produced was evaluated by the IR and 1H NMR measurements. Accordingly, acylation of chitin using various acyl chlorides was performed in the AMIMCl/TMG-DES under the conditions without the use of pyridine/DMAP to give the corresponding chitin acylates with the high DSs. This study achieves the facile and efficient acylation method of chitin in the DES.