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Chemical Synthesis and Crystal Growth Techniques
Published in Jean-Pierre Farges, Organic Conductors, 2022
Bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF or ET) was first synthesized in 1978, starting from dithiolate salt (6) [20]. The l,3-dithiole-2 thione-4,5-dithiolate anion (6) is obtained by the chemical [Na or K in dimethylformainide (DMF)] [21] or electrochemical (acetonitrile) [22] reduction of carbon disulfide. Since the trithiocarbonate anion (7) is also produced, various procedures have been developed for purifying and storing the dithiolate anion (Scheme 2). Treatment of the reduction products with zinc chloride and tetraethylammonium bromide produces an insoluble tetraethylammonium zincate salt (8) that can be isolated and converted to a stable dibenzoate (9) [23], Alkoxide regenerates the dithiolate anion when required in purified form. If desired, l,3-dithiole-2-thiones can be converted to l,3-dithiole-2-ones with mercuric acetate [24] to take advantage of the generally improved coupling yields with the 2-ones [8]. One of the most straightforward routes to BEDT-TTF, however, is to conduct the sodium reduction of carbon disulfide in DMF, rigorously remove the DMF, dissolve the reaction products in methanol, and alkylate the dithiolate anion in methanol with ethylene dibromide. The sequence takes place in a single reaction vessel and does not require the isolation of the dithiolate anion (6). 1,3-Dithiole [4,5-b][1,4]dithiin-2-thione (11) is obtained in 52% yield and can be converted to BEDT-TTF in one more step with neat, freshly distilled triethyl phosphite [25].
2 into Industrial Products
Published in Ashok Kumar, Swati Sharma, 2 Utilization, 2020
Ramya Thangamani, Lakshmanaperumal Vidhya, Sunita Varjani
The oxalic acid is generally produced from oxalate salt; however, it can also be produced under laboratory conditions by the cationic reduction of CO2 in an electrolytic cell. The porous membrane separates the anode and cathode compartments, and the catholyte acts as an organic solvent. The preferred solutes for the catholyte are tetraethylammonium bromide, tetrabutylammonium iodide, tetrabutylammonium perchlorate, tetraethylammonium perchlorate, and tetraethylammonium p-toluenesulfonate. When the anolyte remains the same electrolyte and the solvent as the catholyte, the coulombic yields are as high as 75%. However, close to 97% of sodium oxalate is also obtained when the aqueous solution of sodium salt is used as the anolyte. This process involved in the synthesis of alkali metal salts of glycolic acid, ethylene glycol, alkali metal salts of nitrilotriacetic acid by the hydrogenation of oxalic acid or an alkali metal hydrogen oxalate, alkali metal salts of diglycolic acid and alkali metal salts of glycine may sometimes contain ammonia or otherwise oxalic acid or alkali metal hydrogen oxalate that contains less than two moles of water.
Dermal Uptake
Published in Stephen S. Olin, Exposure to Contaminants in Drinking Water, 2020
Annette L. Bunge, James N. McDougal
Some chemicals found in water are always ions (e.g., paraquat or tetraethylammonium bromide). Other chemicals (weak acids or bases) can exist in either their ionized or unionized form depending on their pH. Still other chemicals are never unionized, but may be uncharged (i.e., zwitterionic or net neutral) at some pH values. For chemicals with one dominant acid-base reaction, the fraction of chemical that is unionized (i.e., fui) can be determined from the acid dissociation constant (i.e., pKa) and the pH of the water in which the chemical is dissolved: () fui=11+10g
Investigation of surface adsorption and thermodynamic properties of 1-tetradecyl-3-methylimidazolium bromide in the absence and presence of tetrabutylammonium bromide in aqueous medium
Published in Journal of Dispersion Science and Technology, 2022
Harsh Kumar, Gagandeep Kaur, Shweta Sharma
The values of CMC of [C14mim][Br] in the presence of (0, 1, 2, and 5) mM tetrabutylammonium bromide (C4H9)4NBr at different temperatures (298.15, 308.15, and 318.15) K obtained from conductivity measurement can be further compared with those in the presence of (0, 1, 2, and 5) mM tetraethylammonium bromide (C2H5)4NBr at different temperatures (298.15, 308.15, and 318.15) K[44] as reported in Table 3. It can be observed from the table that the addition of both the tetraalkylammonium salts leads to the decrease in value of CMC of [C14mim][Br], but the lowering in the value of CMC is more in case of addition of (C4H9)4NBr as compared to (C2H5)4NBr. This may be due to the fact that the (C4H9)4NBr having longer alkyl chain exhibits stronger hydrophobicity as compared to (C2H5)4NBr, which in turn promotes the aggregation of [C14mim][Br] powerfully leading to more reduction in value of CMC.
Methods for the direct synthesis of thioesters from aldehydes: a focus review
Published in Journal of Sulfur Chemistry, 2020
Noor H. Jabarullah, Kittisak Jermsittiparsert, Pavel A. Melnikov, Andino Maseleno, Akram Hosseinian, Esmail Vessally
Almost simultaneously, Zhu and co-workers reported a convenient metal-free cross-dehydrogenative coupling of a diverse set of aldehydes 19 with thiols 20 using tetraethylammonium bromide (TEAB) as an efficient homogeneous catalyst in DCE under an inert atmosphere [44]. Among the various common oxidants like tBuOOH, TBHP, H2O2, K2S2O8, PhI(OAc)2, ozone; K2S2O8 was the most efficient for this transformation. Under the optimized reaction conditions, various aliphatic, aromatic, and heteroaromatic aldehydes were tolerated well and gave the desired thioesters 21 in good to excellent yields (Scheme 8). However, 3-pyridinecarboxaldehyde failed to produce any product. According to the authors proposed mechanism (Scheme 9), this reaction starts with the generation of the tetraethylammonium sulfate radical anion via the interaction of K2S2O8 with Et4NBr. Next, the reaction of this radical with the aldehyde 19 and the thiol 20 affords an acyl radical A and a thiyl radical B. Finally, cross-coupling of the radicals A with B leads to the formation of the expected thioester 21.
Fluorescent liquid crystals with rod-shaped π-conjugated hydrocarbon core
Published in Liquid Crystals, 2019
Jens Buchs, André Geßner, Benjamin Heyne, Dietmar Janietz, Hans Sawade
1.7 g (6 mmol) of 1,4-dibromo-naphthalene is dissolved in 35 ml of N-methyl-2-pyrrolidone. 3.9 g (15 mmol) of 4-(6-acetoxy-hexyloxy)-styrene, 4.9 g (60 mmol) of dry sodium acetate, 6.3 g (30 mmol) of tetraethylammonium bromide and 0.3 g (1.2 mmol) of triphenylphosphine are added. The suspension is degassed several times and flushed with argon. After that a catalytic amount (135 mg; 0.6 mmol) of palladium acetate is added. The mixture is heated to 125°C and stirred for 24 h. After the reaction is completed (TLC), the cooled mixture is poured into water. The solid is filtered off and washed with ethanol. A residual of palladium is removed by filtration on silica using chloroform/ethyl acetate 10:1 as eluent. After removing of the solvent by distillation on an evaporator, the raw product is purified by crystallisation from ethyl methyl ketone.