Ammonium acid formate bicarbonate

Synonym Ammonia Water Amfbnioformaldehyde Ammonium Acetate Ammonium Acid Fluoride Ammonium Amidosulfonate Ammonium Amidosulphate Ammonium Benzoate Ammonium Bicarbonate Ammonium Bichromate Ammonium Bifluoride Ammonium Carbonate Ammonium Chloride Ammonium Citrate Ammonium Citrate, Dibasic Ammonium Decaborate Octahydrate Ammonium Dichromate Ammonium Disulfate-Nickelate (II) Ammonium Ferric Citrate Ammonium Ferric Oxalate Trihydrate Ammonium Ferrous Sulfate Ammonium Fluoride Ammonium Fluosilicate Ammonium Formate Ammonium Gluconate Ammonium Hydrogen Carbonate Ammonium Hydrogen Fluoride Ammonium Hydrogen Sulfide Solution Ammonium Hydroxide Ammonium Hypo Ammonium Hyposulfite Ammonium Iodide Ammonium Iron Sulfate Ammonium Lactate Ammonium Lactate Syrup Ammonium Lauryl Sulfate Ammonium Molybdate Ammonium Muriate Ammonium Nickel Sulfate Ammonium Nitrate Ammonium Nitrate-Urea Solution Ammonium Oleate... 

The ion suppression might be due to gas-phase reneutralrzation of the ion-evaporated anions. The response of raffinose is also enhanced by ammoninm formate and bicarbonate. Ammonium biphosphate suppresses the response of all acidic compounds. In the positive-ion mode, some compoimds, e.g., propranolol, terfenadine, and leserpine, show enhanced response at acid concentrations below 0.5%, while others show response suppression, e.g., risperidone. Surprisingly, the response of some bases, e.g., risperidone and terfenadine, is enhanced by addition of ammonium hydroxide. The response of pipenzolate, a quaternary ammonium compound, is not significantly influenced by additives, except TEA. Most basic compounds are suppressed by the addition of ammonium formate, bicarbonate, and biphosphonate [102]. 

Because formic acid has a A a of 1.8 x 10 , the pH of a formic acid/formate buffer would be around 4, whereas the carbonic acid/bicarbonate buffer would be around pH 7 and the ammonium/ammonia buffer around 10. Thus, we can calculate the [H30 ] and pH of a formic acid/formate buffer that uses 0.1 M solutions of the weak acid and... 

The PNA chain was linked to the peptide spacer glutamic acid-(y-tert-butyl ester)-(fi-aminohexanoic acid)-(fi-aminohexanoic acid) (Glu [OtBuj-fiAhx-fiAhx) via an enzymatically cleavable Glu-Lys handle. The Glu [OtBuj-fiAhx-fiAhx spacer was coupled to the amino-functionalized membrane by standard Fmoc-Chemistry. Then the membranes were mounted in an ASP 222 Automated SPOT Robot and a grid of the desired format was dispensed at each position. The free amino groups outside the spotted areas were capped and further chain elongation was performed with Fmoc-protected PNA monomers to synthesize the desired PNA oligomers (18). After completion of the synthesis, the PNA oligomers were cleaved from the solid support by incubation with bovine trypsin solution in ammonium bicarbonate at 37 °C for 3 h. 

One of the first compounds to be introduced to the clinic, aztreonam (40-9), has been produced by total synthesis. Constmction of the chiral azetidone starts with amide formation of L-threonine (40-1) via its acid chloride treatment with ammonia leads to the corresponding amide (40-2). The primary amino group in that product is then protected as its carbobenzyloxy derivative (40-3). Reaction of that product with methanesulfonyl chloride affords the mesylate (40-4). Treatment of that intermediate with the pyridine sulfur trioxide complex leads to the formation of the A -sulfonated amide (40-5). Potassium bicarbonate is sufficiently basic to ionize the very acidic proton on the amide the resulting anion then displaces the adjacent mesylate to form the desired azetidone the product is isolated as its tetrabutyl ammonium salt (40-6). Catalytic hydrogenation over palladium removes the carbobenzyloxy protecting group to afford the free primary amine (40-7). The... 

Volatile buffers were reconsidered for the modified method. Triethylamine was ruled out primarily because it could not be obtained in high purity and because the secondary and primary amines contaminating it could potentially react with solutes present in the water sample. Preliminary evidence of reaction between ethidium bromide and triethylammonium bicarbonate was obtained, but the reaction product was not characterized. The components of volatile buffers that appeared acceptable on the basis of chemical purity were ammonia, acetic acid, and formic acid. A few exploratory experiments were conducted involving the elution by ammonium formate and ammonium acetate of EB or quinaldic acid exchanged onto AG MP-50 or IRA 900. These experiments showed that 1 M ammonium formate in water was a very poor eluent, but that EB could be eluted from AG MP-50 with 1 M ammonium formate in methanol. Elution was essentially complete with 6 bed volumes of the methanolic eluent, whereas neither methanol alone nor aqueous 1 M ammonium formate was able to elute this solute. This situation pointed out the necessity for a counterion to displace exchanged solutes and, additionally, indicated that the displaced solute be highly soluble in the eluting solvent. 

To HEPES buffer (100 mL, 200 mM, pH 7.5) were added ManNAc 15 (1.44 g, 6 mmol), PEP sodium salt (1.88 g, 8 mmol), pyruvic acid sodium salt (1.32 g, 12 mmol), CMP (0.64 g, 2 mmol), ATP (11 mg, 0.02 mmol), pyruvate kinase (300 U), myokinase (750 U), inorganic pyrophosphatase (3 U), /V-acctylneuraminic acid aldolase (100 U), and CMP-sialic acid synthetase (1.6 U). The reaction mixture was stirred at room temperature for 2 days under argon, until CMP was consumed. The reaction mixture was concentrated by lyophilization and directly applied to a Bio-Gel P-2 column (200-400 mesh, 3 x 90 cm), and eluted with water at a flow rate of 9 mL/h at 4°C. The CMP-NeuAc fractions were pooled, applied to Dowex-1 (formate form), and eluted with an ammonium bicarbonate gradient (0.1-0.5 M). The CMP-NeuAc fractions free of the nucleotides were pooled and lyophilized. Excess ammonium bicarbonate was removed by addition of Dowex 50W-X8 (H+ form) to the stirred solution of the residual powder until pH 7.5. The resin was filtered off and the filtrate was lyophilized to yield the ammonium salt of CMP-NeuAc 17 (1.28 g, 88%). 

Other physical phenomena that may be associated, at least partially, with complex formation are the effect of a salt on the viscosity of aqueous solutions of a sugar and the effect of carbohydrates on the electrical conductivity of aqueous solutions of electrolytes. Measurements have been made of the increase in viscosity of aqueous sucrose solutions caused by the presence of potassium acetate, potassium chloride, potassium oxalate, and the potassium and calcium salt of 5-oxo-2-pyrrolidinecarboxylic acid.81 Potassium acetate has a greater effect than potassium chloride, and calcium ion is more effective than potassium ion. Conductivities of 0.01-0.05 N aqueous solutions of potassium chloride, sodium chloride, potassium sulfate, sodium sulfate, sodium carbonate, potassium bicarbonate, potassium hydroxide, and sodium hydroxide, ammonium hydroxide, and calcium sulfate, in both the presence and absence of sucrose, have been determined by Selix.88 At a sucrose concentration of 15° Brix (15.9 g. of sucrose/100 ml. of solution), an increase of 1° Brix in sucrose causes a 4% decrease in conductivity. Landt and Bodea88 studied dilute aqueous solutions of potassium chloride, sodium chloride, barium chloride, and tetra-... 

In a closed system equipped with an oil bubbler, 30 ml of tetrahydrofuran were added to a mixture of 4-amino-5-chloro-2-methoxybenzoic acid, 2.02 g (0.010 mole) and l,l -carbonyldiimidazole, 1.62 g (0.010 mole) with stirring. When evolution of carbon dioxide ceased, nitrogen was bubbled through the reaction mixture for 1 hr. A solution of 3-aminoquinuclidine, 1.26 g (0.010 mole) in 10 ml tetrahydrofuran was added dropwise to the stirred reaction mixture and stirring at room temperature continued for 3 hrs. TLC analysis (3% cone, ammonium hydroxide solution in methanol) showed some product formation. The mixture was heated at reflux temperature for 18 hours and then concentraded to an oil. TLC analysis showed the presence of the product, imidazole and 3-aminoquinuclidine. The oil was dissolved in methylene chloride (75 ml) and washed twice with 50 ml portions of aqueous sodium bicarbonate solution. The methylene chloride layer was dried over anhydrous magnesium sulfate and concentrated to yield 2.0 g (67%) of a glassy amorphous solid, the free base of the title compound. 

Most of electrodecarboxylations have been carried out with partially neutralized carboxylic acid. Alkaline and alkaline earth metal as well as ammonium (pyridinium) carboxylates work efficiently as supporting electrolytes. Some metal ions (such as Fe " and Co " ) are found to favor selectively radical reactions in electrodecarboxylation. Addition of certain salts, such as perchlorate, fluoroborate, sulfate, dihydrogen phosphate, bicarbonate, and fluoride, tends to inhibit the radical reaction and favor the formation of cation intermediates [28-31]. The remarkable effects of the salts are well explained in terms of competitive adsorption between the anions and carboxylates. 

The influence of various mobile-phase additives on separation and detection of proteins after RPLC-MS was systematically studied by Garcia et al. [44]. First, the response of myoglobin, cytochrome c, and bovine serum albumin (BSA) in ESI-MS was evaluated by column-bypass injections. The best response was achieved using 0.2% formic acid, followed by 0.3% acetic acid, 10 mmol/1 ammonium formate (pH 3), and 50 mmol/1 ammonium bicarbonate (pH 9). Poor responses were achieved with TFA, and 10 mmoPl ammonium formate or acetate (pH 6). Low additive concentrations were favourable, except for ammonium bicarbonate. Separation of these proteins in RPLC could only be achieved using TFA, formic and acetic acid as additive. Formic acid showed poor recovery of the proteins from the column, while TFA resulted in signal suppression. Therefore, the use of acetic acid was preferred. 

In deacylation, as the enzyme cleaved the phenylacyl group, phenylacetic acid was formed, which lowered the pH of the reaction medium. Base was added to maintain the starting pH. (Note Use of ammonium hydroxide led to the formation of desilylated byproducts desilylation was eliminated when bicarbonates were used.) This approach was not required in the acylation reaction. At pH above 7.5 the (R)-and (S)-amines are practically insoluble in water. Organic solvents were used to extract the free amines from the aqueous reaction medium at pH 8.0. p-Fluoro-benzoyl, 1-naphthoyl, and phenylacetyl derivatives of the racemic amine were prepared and their behavior on the chiral HPLC column was studied. Based on ease of preparation and HPLC analysis, the 1-naphthoyl derivatives (Fig. 7) were preferred. Reversed phase HPLC analysis on a Vydac-C18 analytical column used a gradient of acetonitrile (0.1% triethylamine) in water (0.05% phosphoric acid) to quantify the total amide in the reaction mixture. Chiral HPLC analysis on (S,S) Whelk-O Chiral column used isopropanol hexane (30 70) as a solvent system to separate and quantify the (R)- and (S)-enantiomers. 

With regard to the mobile phase composition, it has generally included methanol or acetonitrile and aqueous solution with a volatile acid, such as formic acid or acetic acid, or a base, such as ammonium acetate. However, a few works have included nonvolatile components such as sodium formate [33] or ammonium bicarbonate [39], which could lead to precipitates in the MS. In any case, the content of organic solvent is normally kept high to decrease the viscosity of the solvent and the pressure associated when working with these conditions. 

As in gas chromatography, a mass spectrometer is generally the most powerful detector for liquid chromatography because of its capability for both quantitative and qualitative analysis. The challenge in liquid chromatography is to remove solvent from analyte so as not to overwhelm Ihe vacuum system of the mass spectrometer. Electrospray shown at the opening of this chapter creates a fine mist from which solvent evaporates and leaves ionic solutes in the gas phase. Nonvolatile buffers, such as phosphate, cannot be used with mass spectrometric detection because they clog the entrance to the mass spectrometer. To obtain acidic pH, ammonium formate and ammonium acetate buffers can be used. For alkaline pH, ammonium bicarbonate is a volatile buffer. 

The first step is the urease-dependent catalysis of the generation of ammonia and carbamic acid. In the absence of buffer, the pH of the medium will rapidly reach the pKa of the NH4VNH3 couple, namely 9.25. The second step, the spontaneous breakdown of carbamate, produces ammonia and carbon dioxide. Both gases can diffuse across the inner membrane of the organism and then, in the periplasm, generation of bicarbonate by the periplasmic carbonic anhydrase and protonation of the ammonia results in the formation of ammonium bicarbonate, buffering the periplasm. 

Buffer systems for high-pH chromatography in the ESI mode include ammonium bicarbonate (1—10 mM, pH 10), ammonium hydroxide (0.1—1% pH 10), and ammonium formate adjusted to pH 9 with ammonium hydroxide. In the last case, the buffering capacity is due to the ammonia/ammonium equilibrium rather than the organic acid components and, as alluded to already, are thought to play an important part in gas-phase ionization at high pH. 

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