Photo-on-Demand Base-Catalyzed Phosgenation Reactions with Chloroform: Synthesis of Arylcarbonate and Halocarbonate Esters
Yuka HashimotoSasuga HosokawaFengying LiangYuto SuzukiNamin DaiGegen TanaKazuo EdaToshifumi KakiuchiTakashi OkazoeH. HaradaAkihiko Tsuda
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Abstract:
Carbonate esters are utilized as solvents and reagents for C1 building blocks in organic synthesis. This study reports a novel photo-on-demand in situ synthesis of carbonate esters with CHCl3 solutions containing a mixture of an aromatic or haloalkyl alcohol having relatively high acidity, and an organic base. We found that the acid–base interaction of the alcohol and base in the CHCl3 solution plays a key role in enabling the photochemical reaction. This reaction allows practical syntheses of diphenyl carbonate derivatives, haloalkyl carbonates, and polycarbonates, which are important chemicals and materials in industry.Keywords:
Base (topology)
Organic base
Organic Synthesis
Propylene carbonate
Dyes of sulfonphthalein series undergo combination with various organic bases to form salts soluble in organic solvents and are utilized for colorimetric determination of organic bases.Some modifications were made in the existing method to simplify the procedure and make the method more practicable. In this modified method, the Bromocresol Green salt of the organic bases formed in aqueous phase is extracted with chloroform, the chloroform layer, which is colored yellow, is separated, and addition of ethanolic solution of triethanolamine to it changes its color to blue. This blue chloroform solution is submitted to the measurement of absorbance at 630mμ.
Bromocresol green
Absorbance
Triethanolamine
Colorimetry
Bromocresol purple
Colorimetric analysis
Organic base
Colored
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The use of chloroform as an adjunct to the practice of endodontics has been a matter of debate. In the present study the chloroform uptake of gutta-percha cones was determined by a gravimetric assay for different times of chloroform dip. In conjunction with an assessment of the amount of gutta-percha dissolved during dip, this provided an estimate of the amount of chloroform that patients are exposed to in clinical conditions. An assay was also performed of the chloroform concentration in the air in a dental office. Chloroform uptake was shown to increase with an increasing dipping time. There also seems to be a difference in this uptake between pure chloroform and a chloroform preparation with colophonium. The concentration levels of chloroform evaporated during the practice of chloroform dip within a dental office do not exceed the safety limits.
Gutta-percha
Gravimetric analysis
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Potassium fluoride on alumina (KF/Al2O3) is a versatile base developed by Ando et al. for alkylation reactions. [1] Over the years the reagent has found applications in a large number of organic reactions such as elimination, [2] addition, [3] condensation, [4] epoxidation, [5] palladium-catalyzed coupling [6] and the synthesis of heterocyclic compounds. [7] The KF/Al2O3 system has been able to replace organic bases in many reactions, but still its enhanced source of basicity as compared to non-supported KF remains a matter of debate in literature. [8] Recently, Blass has reviewed [9] KF/Al2O3 mediated organic synthesis.
Potassium fluoride
Organic Synthesis
Organic base
Base (topology)
Condensation reaction
Organic reaction
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Diazotization diazonium salt is the importance of the chemical nature very lively,diazonium salt can be carried out many reactionsinto a variety of reactions can occur in many kinds of compounds,as an organic synthesis intermediate diazonium salt.in organic synthesis occupies an extremely important position.
Organic Synthesis
Diazonium Compounds
Organic base
Organic reaction
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정수처리 공정에서 소독 부산물로서 생성되는 THM 성분 중 chloroform의 제거에 TiO2 광촉매 반응을 적용하였다.
TiO2 광촉매에 조사되는 자외선 파장 변화에 따른 chloroform의 제거율은 반응시간 1시간에 UV-C에서 49.6%, UV-B에서 47.6%, UV-A에서 34.8%로 나타났다. 또한 TiO2 광촉매에 의한 순수한 chloroform의 제거율은 UV-A 파장에서 6.3%로 나타났다. Chloroform 초기농도 1mg/L, 10mg/L, 100mg/L에서 제거율은 각각 40.6%, 34.8%, 31.7%로 나타났다. pH 변화에 따른 chloroform의 제거율은 pH가 3, 5, 7, 9, 11에서 각각 25.4%, 33.1%, 34.8%, 40.6%, 46.7%로 나타났다. 따라서 pH 변화에 따른 chloroform의 제거율은 알칼리성이 강할수록 증가하는 경향을 보이고 있다.
온도 변화에 따른 chloroform의 제거율은 온도 10℃, 20℃, 30℃에서 각각 31.8%, 34.8%. 37.7%나타났다. 이것은 광촉매 반응이 광에 의한 활성화 과정이기 때문에 원칙적으로 승온을 필요로 하지 않고 상온에서 수행될 수 있기 때문이다. Chloroform 10mg/L 수용액에 과산화수소를 0mg/L, 50mg/L, 300mg/L, 500mg/L 주입하였을 경우 chloroform 제거율은 각각 34.8%, 41.8%, 31.5%, 30.4%로서 나타났다. 따라서 본 실험의 경우 과산화수소 50mg/L 주입했을 때의 chloroform의 제거율이 가장 높게 나타났다.
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Triflimide (HNTf2) is a commercially available and highly versatile super Brønsted acid. Owing to its strong acidity as well as good compatibility with organic solvents, it has been widely employed as an exceptional catalyst, promoter, or additive in a wide range of organic reactions. On many occasions, triflimide has been demonstrated to outperform triflic acid (TfOH). The uniquely outstanding performance of triflimide also benefits from the low nucleophilicity and noncoordinating property of its conjugate base (Tf2N–). Therefore, it has been employed as a precursor toward a variety of cationic metal complexes or organic intermediates with enhanced reactivity or catalytic activity. In this Review, we describe these features and applications of triflimide in organic synthesis, including its synthesis, physical properties, and role as catalyst or promoter in organic reactions. At the end of this Review, another closely related reagent, triflidic acid (HCTf3), is also briefly introduced.
Organic Synthesis
Cationic polymerization
Organic reaction
Triflic acid
Organic base
Reactivity
Brønsted–Lowry acid–base theory
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1,4-DiAzaBiCyclo[2.2.2.]octane (DABCO) is a good neucleophile and base in number of organic reactions and gaining particular importance as catalyst in synthetic organic chemistry. Catalytic applications of DABCO in various reactions such as cycloaddition reaction, coupling reaction, Baylis-Hillman reaction, Henry reaction, ring opening reaction etc. are noteworthy in synthesis of novel organic scaffold. In this article it is tried to overview the recent development of DABCO catalysed reaction as well as its use in heterocyclic synthesis.
DABCO
Organic Synthesis
Coupling reaction
Organic base
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The thermal chlorination of chloroform has been studied in the range 260–320°C, using chloroform to chlorine ratios from 10 down to ⅙. For high partial pressures of chloroform the reaction is independent of the chloroform and unimolecular with respect to chlorine. At lower chloroform pressures there is a small dependence on the chloroform in addition to the first-order dependence on chlorine. A mechanism similar to one postulated for the photochemical chlorination of chloroform is discussed and a comparison with the thermal hydrogen-chlorine mechanism leads to the significant conclusion that the reaction has a chain mechanism initiated by chlorine atoms originating on the walls. Production of the latter is interfered with by chloroform adsorption and possibly also by adsorption of reaction products. The chains are broken principally in the gas phase.
Chlorine atom
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A method was developed to detect the content of propylene carbonate in industrial poly (propylene carbonate) using gas chromatograph.This method has high practicability and reliability. It is desirable for industrial analysis.
Propylene carbonate
Gas Chromatography
Propylene oxide
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Organic catalysts have found wide applications in organic synthesis. Many organic reactions, which originally do not occur under normal conditions or are difficult to operate normally, have been successfully conducted under mild conditions in the presence of catalysts. In recent years, 2,4,6-trichloro-1,3,5-triazine (TCT, cyanuric chloride) has been used as organic catalyst in many organic synthesis, because it is stable, nonvolatile, inexpensive, commercially available, and easy to handle. On account of these properties it has been used as a green catalyst and sometimes is a catalyst of choice in organic reactions.
Cyanuric chloride
Organic Synthesis
Triazine
Organic base
Organic reaction
Cyanuric acid
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