Triethylamine titration

The checkers purchased [(COD)RuCl2]n from Fluka (purum quality), BINAP from Aldrich (97 %), and toluene (HPLC grade) and triethylamine (reagent grade) from Fisher Scientific the latter was distilled from CaH2 under Ar prior to use. The submitters dried toluene and triethylamine over 4 A molecular sieves. Karl-Fischer titration indicated <200 pg/mL water. 

Fig. 7.8 Conductimetric titration of 3,5-dinitro-benzoic acid (HA) with triethylamine. (I)...

Eastham and Derwent474 have also studied the kinetics of the perchloric acid-catalyzed reaction of ethylene oxide with pyridine. In excess of pyridine the rate was found to be dependent on the Conor Titrations of ethylene oxide and perchloric add. Addition of stronger bases,. g. ammonia, triethylamine, or benzylamiae, depressed the vum of cleavage, presumably by competing with ethylene oxide for thr-available proton source, believed to be pyridinium perchlorate in this case. Other acids examined included nitric acid and hydroiodie irireaction rate depended to a certain extent... 

Acetonitrile or methanol-50 mM acetic acid (80 20), pH 6 (titrated with triethylamine or ammonia)... 

Total Acid Titrations. A sample (ca. 2.5 grams) was removed from the solution, weighed to an accuracy of 0.05 gram, and diluted with 100 ml. of tetrahydrofuran. Triethylamine (2 ml.) was added, and the solution was stirred for 1 minute. A few drops of phenolphthalein indi-... 

Both carboxylic acid and peracid are formed during ozonolysis of disubstituted double bonds. The analytical procedure for acid analysis measures the total carboxylic acid and peracid after reduction of peracid to acid with triethylamine, followed by titration with standard base. Results for polymer ozonizations measuring total acid formed as a function of time at 0°C. are shown in Figures 3 and 4, respectively. These show that total acid formation is divided into two stages, which can be separated experimentally by the breakthrough of ozone into the potassium... 

Figures 3 and 4 illustrate that there is a temperature dependence in acid formation under our experimental conditions because Figure 3 shows —59 mmoles of acid at the end of aldehyde oxidation whereas Figure 4 shows only 50 mmoles of acid. However, temperature dependence occurs only in the aldehyde-oxidation phase since the two plots for acid formation before ozone breakthrough are essentially identical. Furthermore, the temperature of ozonization does not affect final acid formation if the solutions are allowed to warm up with no immediate triethylamine treatment. Thus, upon warming to room temperature the final acid values for 0° and — — 25 °C. titration experiments are in the range 65-70 mmoles total acid. (In the —25°C. titration experiments care was taken to treat the cold ozonized cement with triethylamine as soon as the cement was removed from the reactor. The cement was not allowed to warm up before triethylamine treatment. As discussed later, triethylamine reduces a species which is capable of forming acid.)...

The temperature dependence of acid formation can be explained by formation of this peroxide with its subsequent decomposition to two molecules of acid. Since the end of the reaction seems to be temperature independent (as measured by the change in slope), aldehyde oxidation stops at the same time in both cases low temperature favors the preservation of the hemiacetal type of peroxide, and thus less acid formation is seen. Treatment of the cold cement with triethylamine prevents formation of acid on warming by reducing peroxidic material (either peracid or hemiperacetal) to acid and aldehyde, and as a result less acid is titrated. However, when the solution is warmed with no reducing agent... 

Poisons can be used to titrate the active sites many Lewis bases chemisorb strongly onto sites and block polymerization. For example, Hogan [40-42] added triethylamine to a reactor in which polymerization was already occurring on Cr/silica. The polymerization could be retarded or even stopped by the addition of trace amounts of the amine. In one experiment, he injected 0.057 mol of NEt3 per mol of Cr after polymerization had reached a nearly constant rate. The activity immediately dropped by 32%. In a second run, he injected 0.108 mol of NEt3 per mol of Cr,... 

It is absolutely imperative that the solution of butyllithium be accurately titrated. If an excess of butyllithium (or LDA) is used, reduced yields will result as a consequence of a decomposition reaction that releases pseudoephedrine. This is easily monitored by TLC analysis (5% methanol, 5% triethylamine, and 90% dichloromethane eluent UV and ninhydrin visualization). It should be noted that even optimal reaction conditions produce small amounts of this cleavage product (2-4%) however, the amount of cleavage is greatly enhanced in the presence of excess base. To titrate the alkyllithium solution we recommend the method of Watson and Eastham.4 A standard solution of 1.00 M 2-butanol (freshly distilled from calcium hydride) in toluene (freshly distilled from calcium hydride) is prepared in a volumetric... 

Most pharmacopoeias specify that ethambutol hydrochloride contains not less than 98.0% and not more than 100.5% of C10H24N2O2 2HCI, calculated on the dried basis. Pharmaceutical products such as tablets must contain not less than 95.0% and not more than 105.0% of the labeled amount.As for pyrazinamide, the main pharmacopoeia assay method for ethambutol is a titration method. However, an HPLC method is used for the assay of ethambutol HCl in tablets.This method requires that a liquid chromatograph equipped with a 200-nm detector and a 4.6 mm X 15 cm base-deactivated column that contains 5 p,m porous silica particles, 3-10 p,m in diameter, with chemically bonded nitrile groups (CN, LIO) is used. The mobile phase is a mixture of 1.0 ml of triethylamine and 1 L of water, adjusted with phosphoric acid to a pH of 7.0. The flow rate is about 1.0 ml/min. Separately inject equal volumes (about 50 p.1) of standard preparations and the assay preparations into the chromatograph, record the chromatograms, and measure the responses for the major peaks and calculate the quantity, in mg, of ethambutol hydrochloride present in the tablets from the peak responses obtained from the assay preparation and the standard preparation, respectively. The tailing factor must not be more than 2.0, and the relative standard deviation for replicate injections not more than 2.0%. 

Finally, streptomycin can be determined by titrating with a dye formed by coupling diazotizedp-rosaniline with l-naphthol-4-sulphonic acid.< > A sample, containing 1-3 mg of streptomycin, was titrated in 10 ml. of triethylamine citrate buffer at — 0-8 V with a O Ol M solution of the dye. 

A colloidal suspension of L-proline in dioxane added slowly together with a soln. of phosgene in dioxane to the same solvent, stirred 1 hr. at 45° until a clear soln. results, traces of reactant removed by filtration, degassed in vacuo at 35° for ca. 45 min., the amount of N-chloroformyl-L-proline formed estimated by titration of 1 ml. of the soln. with 0.1 A Ag-nitrate, an equivalent amount of triethylamine added, and stirred 30 min. at room temp. N-carboxy-L-proline anhydride. Y 88%. A. A. Randall, Soc. 1962, 374. 

The initiator mixture was extensively purified to remove monofunctional side-product. The initiator concentration was determined by potentiometric titration with HGl after removing triethylamine as much as possible. Isoprene and isoprene-dg and were dried over CaH2 and distilled in vacuo. Following treatment with sodium mirror and distillation, the final purification was carried out by having the monomers dispersed in n-butyllithium at 0 C and subsequently flash distilling out of n-butyllithium right before any significant... 

Except for microcalorimetric titrations, readers are referred to the literature [14]. Microcalorimetric experiments at 298.15 K were carried out using the titration vessel of the 2277 Thermal Activity Monitor. The vessel was filled with 2.8 mL of a solution of p-te/t-butylcalix[4]eirene in benzonitrile (5 x 10 mol dm ) or in nitrobenzene (5 x 10" or 9 x 10 mol dm ). Triethylamine solutions in the appropriate solvent (concentration range 0.07-0.95 mol dm ) were injected (16 injections 0.015-0.025 mL for each run) from a 0.5 mL gas-tight Hamilton syringe, attached to a computer-operated syringe drive at 5 minute intervals, p-tert-Butylphenol solutions were 0.04 mol dm in both solvents. A dynamic correction... 

In order to establish whether or not ions are formed as a result of the interaction of p-re/t-butylcalix[n]arene (n = 6,8) and amines (A = triethylamine, cryptand 22 and cryptand 222) in nitrobenzene, conductance measurements were carried out at 298.15 K. A representative example is given in Figure 1 in which the conductimetric titration curves for the hexamer and the different amines in PhN02 at the standard temperature are shown. 

Fig. 3. Microcalorimetric recorded graph for the titration of p-tc/t-butylcalix[4]arene and triethylamine in nitrobenzene at 298.13 K.

The amount of silane and triethylamine used should be approximately proportional to the surface area of the silica thus, if a silica of 50 m /g is coated then five times less reagents should be used. The epoxy group concentration on coated silica can be determined by titration of the hydroxyl ions released during the reaction of the epoxy groups with thiosulphate (4). To do this suspend up to 100 mg of dry epoxy-silica in 2 ml water and adjust the pH to 7.0. Add 1 ml of a 3 M solution of sodium thiosulphate, pH 7. 0, to initiate the reaction. During the course of the reaction ( — 60 min) maintain the pH at 7.0 by adding 0.1 M HCl. The consumption of HCl corresponds to the epoxy group content of the gel. 

Lewis titrated bases like pyridine and triethylamine with acids such as solutions of BCI3 and SnCU in carbon tetrachloride, and AgC104 dissolved in benzene. These solutions were titrated back and forth with the use of indicators such as thymol blue, butter yellow, and crystal violet. Crystal violet is an especially convenient indicator because of its solubility in a variety of solvents and because it usually gives the same color change in different solvents. 

---