Triethylamine Buffer

Basic compounds Amines Phosphate buffer, triethylamine (buffered to pH 3.0)... 

Benzimidazole Reversed-phase-C 18, methanol-phosphate buffer-triethylamine UV 50 ppb 124... 

Mobile phase MeCN 10 mM phosphate buffer triethylamine 80 20 0.1, pH adjusted to... 

Mobile phase MeCN 10 mM phosphate buffer triethylamine 80 20 0.1, pH adjusted to 4.0 with 85% phosphoric acid Flow rate 2 Ii jection volume 100 Detector UV 224... 

Amano PS3o phosphate buffer triethylamine Triton X-100 Ar A N O... 

Mobile phase MeCN 50 mM phosphate buffer triethylamine 27 73 0.05, adjusted to pH... 

If the reaction proves difficult the TLC plate should first be dipped in 1 % solution of triethylamine in acetone or in a solution of 1 to 2 drops sodium hydroxid solution (c = 10 mol/1) in methanol to optimize the pH for the reaction. This effect can also be achieved by employing borate buffer, pH = 11, instead of acetone in the spray reagent [10,11]. 

Solvolyses of these cyclic vinyl triflates at 100 in 50% aqueous ethanol, buffered with triethylamine, lead exclusively to the corresponding cyclo-alkanones. Treatment of 176 with buffered CH3COOD gave a mixture of cyclohexanone (85%) and 1-cyclohexenyl acetate (15%). Mass spectral analysis of this cyclohexanone product showed that the amount of deuterium incorporation was identical to that amount observed when cyclohexanone was treated with CH3COOD under the same conditions. This result rules out an addition-elimination mechanism, at least in the case of 174, and since concerted elimination is highly unlikely in small ring systems, it suggests a unimolecular ionization and formation of a vinyl cation intermediate in the solvolysis of cyclic triflates (170). The observed solvent m values, 174 m =. 64 175 m =. 66 and 16 m =. 16, are in accord with a unimolecular solvolysis. 

If the analyte contains either an acidic or a basic functionality, adjusting the pH of the extraction solvent to make the analyte either ionic or nonionic may be advantageous. To make an analyte that contains an acidic or basic functionality nonionic for extraction into a nonpolar solvent, a small amount (5% or less) of an organic acid (such as acetic acid or trifluoroacetic acid) or organic base (triethylamine) along with methanol (about 10%) can be added to diethyl ether or ethyl acetate. Conversely, buffered solutions can be used to control the pH precisely in such a way as to control the charge on an analyte and thus improve its extraction efficiency into polar solvents. 

The steroids aldosterone, cortisone, cortisol, 11-P-hydroxyandrostenedione, corticosterone, and rostenedione, 11-desoxycorticosterone, 17-hydroxy-progesterone, and progesterone have been performed on Ultrasphere ODS using methanokwater.19 Ranitidine N-[2-[[[5-[(dimethylamino)methyl]-2-furanyl]-methyl]thio]ethyl]-N1-methyl-2-nitro-l,l-ethenediamine has been separated using a p-Bondapak C18 column operated with acetoni-trile methanol water buffered with triethylamine phosphate.117 Pyridoxal-5 -phosphate and other B6 vitamers, including pyridoxamine phosphate, pyri-doxal, pyridoxine, and 4-pyridoxic acid, were separated as bisulfite adducts... 

Dissolve the amine-containing PAM AM dendrimer in methanol or a buffered aqueous medium at a pH of 7-9 (e.g., 50mM sodium phosphate, pH 7.5) and at a concentration of at least lOmg/ml. Note that Singh (1998) used a concentration of llOmg/ml in methanol, but other dendrimer concentrations should work equally well. For nonaqueous reactions, the addition of a proton acceptor may aid in driving the reaction to maximal yields (i.e., triethylamine or dimethylaminopyridine). 

Triethylamine may act to buffer the pH, which changes as formic acid is consumed during the reaction. An excess of formic acid over substrate is often used. Though not essential (as will be discussed later), it is sometimes preferable to charge TEAF during the reaction in order to ensure a high yield of product. 

The crude material was purified by flash chromatography over silica gel (100 g), buffered with 1 % triethylamine, using M-hexane-diethyl ether (3 1) as eluent to give (25, 3,S)-3-propyloxiranemethanol as a colourless oil (2g, 15.3 mmol, 80%). 

At times it is necessary to add reagents such as buffers, ion-pairing reagents, or other modifiers such as triethylamine to the mobile phase to improve reproducibility, selectivity, or peak shape. 

FIGURE 1.30 Micro-HPLC separation of all 4 stereoisomers of the dipeptide alanyl-alanine as FMOC derivatives (a) and DNP-derivatives (b), respectively, on a 0-9-(tert-butylcarbamoyl)quinine-based CSP. Experimental conditions Column dimension, 150 X 0.5 mm ID mobile phase (a) acetonitrile-methanol (80 20 v/v) containing 400 mM acetic acid and 4 mM triethylamine, and (b) methanol-0.5 M ammonium acetate buffer (80 20 v/v) (pHa 6.0) flow rate, 10 ixLmin temperature, 25 C injection volume, 250 nL detection, UV at 250 nm. (Reproduced fromC. Czerwenka et al., J. Pharm. Biomed. Anal., 30 1789 (2003). With permission.)... 

FIGURE 7.4 Microcoil CE-NMR spectra of triethylamine methyl peak in 1 M borate buffer with increasing applied voltage 0.0-9.0 kV by increments of 1.0 kV. Inset is a schematic of electrophoretic current-induced magnetic field. (Reproduced from Jayawickrama, D. A., Sweedler, J. V. J. Chromatogr. A 2003, 1000, 819-840, with permission from Elsevier.)... 

The same buffer may be used for separation of aliphatic amines such as methyl-, dimethyl-, trimethyl-, ethyl-, propyl-, diethyl-, triethylamine, morpholine, etc. 

Examples of possible intramolecular general acid-base catalysis were reported by Kupchan et al. (1962). The methanolysis of coprostanol acetate and coprostane 3/3, 5/3-diol 3-monoacetate [12] in aqueous methanol was conducted in triethylamine-triethyl-ammonium acetate buffer. The rates of methanolysis at constant... 

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