Triethylamine concentration

The first-order experimental rate coefficient, k = k1+k4[Et3N], was found to be independent of the triethylamine concentration indicating that the contribution of reaction (4) is negligible. A previous study using trimethylamine6 showed that the analogue of reaction (4) was much faster than reaction (1). 

When the intensity of the 222 nm CD band, also a parameter of the helix content, is plotted as a function of triethylamine concentration, it can be observed that triethylamine induces a transition from coil to helix in the polypeptide chains (Figure 15). The most remarkable aspect is that the amount of NEt3 needed to induce the transition is different for the dark-adapted sample and the illuminated one. Two separate curves are hence observed exposure to light and darkness conditions at solvent compositions in the range between the two curves produces reversible... 

Cobalt Naphthenate. Cobalt naphthenate behaved in much the same way as cobalt chloride, but at equivalent metal concentrations the soluble salt gave much faster rates. As the triethylamine concentration was increased, the 1 2 contents increased from 21 to 39% at the expense of cis structure. The trans contents remained constant at 30 3% (Table VII) until a ratio of NEt3/Co of about 4 was reached (dependent on the cobalt concentration (Table VIII)) when high trans polymer was obtained. 

Fig. 5. Semilogarithmic plots for polymerization of formaldehyde at —30°C (1) catalyst calcium stearate, concentration 4x10" molel (2) catalyst tetrabutyl-ammonium laurate, concentration 2 x 10" mole 1" (3) catalyst triethylamine, concentration 3 x 10" mole 1". g is the degree of conversion.

In a closer study of the amine-catalyzed reaction of phenyl isocyanate with alcohols in toluene solution, Burkus 38) found that contrary to Baker s results observed in dibutyl ether solution, the second-order rate constant was not a linear function of the triethylamine concentration. 

In order to explain the linearity in dibutyl ether and the nonlinearity in toluene of the second-order rate constant as a function of the triethylamine concentration, Burkus considers the role of the solvent. In dibutyl ether the solvent-alcohol interaction causes the absence of monomeric alcohol. The addition of the base does not affect the nature of the alcohol... 

The antihistamines synopen and ephedrine were separated and eluted in < 10 min on a diol column (A = 254 nm) using a 30/70 methanol/water (10 mM triethylamine to pH 4 with H3PO4) mobile phase. For the most reproducible results the authors correctly noted that the pH of the solution should be monitored in the aqueous phase and then added to the organic. An extensive table of the effects of changing triethylamine concentration, pH, and percent methanol on the retention of the analytes is also presented [545]. 

Figure 3 The effect of triethylamine concentration on the molecular weight of the polymer formed in 1 hr. at from equival-...

An excimer is a special case of exciplex—a complex between an excited-state molecule and a ground-state molecule, where the two molecules have different identities. Exciplex formation has been used as a model bimolecular process in the study of solute-solute clustering in supercritical fluid solutions. Brennecke et al. reported the investigation of naphthalene-triethylamine exciplex formation in supercritical CO2 at 35 C and 50°C (166). Their results show that the exciplex emission can be observed, even at low triethylamine concentrations (5 X 10 -5 X 10 M). Similarly, Inomata et al. investigated the formation of pyrene-dimethylaniline excimer in supercritical CO2 at 45°C (169). They... 

The distillate was dissolved in a mixture of 350 ml of dry diethyl ether and 45 g of dry triethylamine (dried over powdered KQH). Trimethylchlorosilane (45 g) was added in 20 min with cooling at about 10°C. After standing for 1 h at room temperature the precipitate was sucked off on a dry sintered-glass funnel and rinsed with pentane. The filtrate was concentrated in a water-pump vacuum- The small amount of salt which precipitated during this operation was removed by a second suction filtration. Subsequent distillation afforded the trimethyl silyl ether, b.p. 100°C/15 mmHg, 1.4330, in 944 yield. 

To a mixture of 100 ml of dry dichloromethane, 0.10 mol of propargyl alcohol and 0.11 mol of triethylamine was added a solution of 0.05 mol of Ph2PCl in 75 ml of dichloromethane in 3 min between -80 and -90°C. The cooling bath was removed, and when the temperature had reached 10°C, the reaction mixture was poured into a solution of 2.5 ml of 362 HCl in 100 ml of water. After vigorous shaking the lower layer was separated and the aqueous layer was extracted twice with 25-ml portions of dichloromethane. The combined solutions were washed twice with water, dried over magnesium sulfate and then concentrated in a water-pump vacuum, giving almost pure allenyl phosphine oxide as a white solid, m.p. 98-100 5, in almost 1002 yield. 

A mixture of 0.10 mol of the acetylenic alcohol, 0.12 mol of triethylamine and 200 ml of dichloromethane (note 1) was cooled to -50°C. Methanesulfinyl chloride (0.12 mol) (for its preparation from CH3SSCH3, (08300)30 and chlorine, see Ref. 73) was added in 10 min at -40 to -50°0. A white precipitate was formed immediately. After the addition the cooling bath was removed and the temperature was allowed to rise to -20°0, then the mixture was vigorously shaken or stirred with 100 ml of water. The lower layer was separated off and the aqueous layer was extracted twice with 10-ml portions of CH2CI2. The combined solutions were dried over magnesium sulfate and concentrated in a water-pump vacuum (note 2). The yields of the products, which are pure enough (usually 96%) for further conversions, are normally almost quantitative. 

Formic acid behaves differently. The expected octadienyl formate is not formed. The reaction of butadiene carried out in formic acid and triethylamine affords 1,7-octadiene (41) as the major product and 1,6-octadiene as a minor product[41-43], Formic acid is a hydride source. It is known that the Pd hydride formed from palladium formate attacks the substituted side of tt-allylpalladium to form the terminal alkene[44] (see Section 2.8). The reductive dimerization of isoprene in formic acid in the presence of Et3N using tri(i)-tolyl)phosphine at room temperature afforded a mixture of dimers in 87% yield, which contained 71% of the head-to-tail dimers 42a and 42b. The mixture was treated with concentrated HCl to give an easily separable chloro derivative 43. By this means, a- and d-citronellol (44 and 45) were pre-pared[45]. 

Fig. 1. Time courses of the chemiluminescence intensity from oxalate—hydrogen peroxide systems in ethyl acetate as solvent, 0.7 mM TCPO. The curves correspond to the following concentrations of triethylamine (TEA) catalyst A, 0.05 mM B, 0.10 mM and C, 0.20 mM (70).

N -Heterocyclic Sulfanilamides. The parent sulfanilamide is manufactured by the reaction of A/-acetylsulfanilyl chloride with excess concentrated aqueous ammonia, and hydrolysis of the product. Most heterocycHc amines are less reactive, and the condensation with the sulfonyl chloride is usually done in anhydrous media in the presence of an acid-binding agent. Use of anhydrous conditions avoids hydrolytic destmction of the sulfonyl chloride. The solvent and acid-binding functions are commonly filled by pyridine, or by mixtures of pyridine and acetone. Tertiary amines, such as triethylamine, may be substituted for pyridine. The majority of A/ -heterocycHc sulfanilamides are made by simple condensation with A/-acetylsulfanilyl chloride and hydrolysis. 

Benzyl chloride undergoes self-condensation relatively easily at high temperatures or in the presence of trace metallic impurities. The risk of decomposition during distillation is reduced by the use of various additives including lactams (43) and amines (44,45). Lime, sodium carbonate, and triethylamine are used as stabilizers during storage and shipment. Other soluble organic compounds that are reported to function as stabilizers in low concentration include DMF (46), arylamines (47), and triphenylphosphine (48). 

A 600-mL, three-necked, round-bottomed flask 1s equipped with a mechanical stirrer, a short gas inlet tube, and an efficient reflux condenser fitted with a potassium hydroxide drying tube. The flask is charged with 13.4 g (0.05 mol) of 3-ben2y1-5-(2-hydroxyethyl)-4-methyl-l,3-th1azol1um chloride (Note 11, 72.1 g (1.0 mol) of butyraldehyde (Note 2). 30.3 g (0.3 mol) of triethylamine (Note 2), and 300 raL of absolute ethanol. A slow stream of nitrogen (Note 3) is begun, and the mixture is stirred and heated In an oil bath at 80°C. After 1.5 hr the reaction mixture is cooled to room temperature and concentrated by rotary evaporation. The residual yellow liquid Is poured Into 500 mL of water contained 1n a separatory funnel, and the flask is rinsed with 150 mL of dichloromethane which is then used to extract the aqueous mixture. The aqueous layer is extracted with a second 150-mL portion of... 

Figure 3-14. Absorbance-time plots for the reaction of carbon suboxide and triethylamine in ether solution in the presence of acetic anhydride. The initial C3O2 concentration was 2.03 X I0 - M the amine concentrations were 3 X lO " M, 5 x 10 M, and 7 X lO " M.

After the reaction, 1 ml of water was added to the reaction mixture, and the mixture was adjusted to a pH of 1,0 with concentrated hydrochloric acid while being cooled, and then stirred for 30 minutes. The insoluble matters were filtered off, and the filtrate was adjusted to a pH of 5.5 with triethylamine. This solution was concentrated under reduced pressure, and the residue was diluted with 20 ml of acetone to precipitate white crystals. The crystals were collected by filtration and washed with ethanol to obtain 1.46 g of white crystals of7-[D(-)-0 -emino-(4-hydroxyphenyl)acetamido]-3-methyl-3-cephem-4-carboxylicacid having a decomposition point of 197°C. 

Preparation of Alkaloid Mixture 50 ml of the concentrated benzene solution, obtained as described was rapidly stirred, and a saturated solution of hydrogen chloride in ether added to the concentrated benzene solution until no more precipitate was obtained. The resulting precipitate was recovered by filtration and comprised the crude hydrochlorides of the extracted alkaloids and the hydrochloride of any unrecovered triethylamine. This material was dried by heating at a temperature of about 75°C for 6 hours, the crude, dried precipitate ground with 50 ml of isopropanol and to this slurry was added 1,000 ml of water. The resulting mixture was filtered. To the clear filtrate, cooled to 5°C, there was slowly added with rapid stirring, a 10% aqueous solution of ammonium hydroxide, until complete precipitation was accomplished. The precipitate was filtered off, washed with water and dried by heating at about 75°C for 6 hours. 

A solution of 75 g (Mo mol) of 1,3-propanolamine and 202 g of triethylamine in 100 cc of absolute dioxane Is added dropwise at 25°C to 30°C while stirring well to a solution of 25.9 g (Vio mol) of N,N-bis-( -chloroethyl)-phosphorlc acid amide dichlorlde in 100 cc of absolute dioxane. After the reaction is complete, the product is separated from the precipitated triethylamine hydrochloride and the filtrate Is concentrated by evaporation In waterjet vacuum at 35°C. The residue Is dissolved in a large amount of ether and mixed to saturation with water. The N,N-bis-( -chloroethyl)-N,0-propylene phosphoric acid diamide crystallizes out of the ethereal solution, after it has stood for some time in a refrigerator, in the form of colorless water-soluble crystals. MP 48 C to 49°C. Yield 65% to 70% of the theoretical. 

A solution of bis-triethylamine phosphate was prepared by slowly adding 2.36 ml of B5% phosphoric acid to 20 ml of acetonitrile containing 9.9 ml of triethylamine at 20°C. This solution was added to a stirred solution of 4.70 g of 9a-fluoro-11(3,170,21 -trihydroxy-160-methyl-1,4-pregnadiene-3,20-dione 21 -methanesulfonate and 20 ml of acetonitrile. The mixture was heated under reflux for four hours and then evaporated under reduced pressure to a volume of 12 ml. This mixture was a concentrated solution of 9a-fluoro-11(3,170,21 -tri-hydroxy-160-methyl-1,4-pregnadiene-3,20-dione 21 -phosphate triethylamine salt with some inorganic phosphate. 

A mixture of 12.6 g of benzoyl chloride in 100 cc of ethylene chloride is added dropwise to a suspension of 25.6 g of 3ethylene chloride and 21.8 g of triethylamine within 18 minutes at room temperature while stirring. The mixture is stirred at room temperature for a further 14 hours, 200 cc of water are added, the organic phase is separated and concentrated to an oil in a vacuum. Upon adding ether/dimethoxy ethane to this oil, crude 6-ben zoy I-3absolute ethanol with the addition of a small amount of coal, the compound has a melting point of 125°C to 127°C (decomp.). Displacement of the halogen with hydrazine leads to the formation of endralazine. 

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