Ammonium additives

M ammonium acetate, which yields [NH4] +, clustered [NH4] + and [CH3COO] ions protonation to [M + H] + or ammonium addition to [M + NH4] + is observed and the spectra are similar to ammonia Cl or field desorption spectra327,374 possible reactions between gas-phase ions and analyte molecules have been investigated374. The ionization mechanism is still not entirely understood, nor is the influence of a number of experimental parameters such as the nature and concentration of the electrolyte, the flow rate and the thermospray temperature375. Thermospray ionization exhibits better sensitivity than conventional Cl and is widely used in pesticide residue analyses327,336,337,340. 

Effects of ammonium on mammalian cell cultures. (A) Effects of ammonium generated by glutamine metabolism. (B) Effects of ammonium generated by glutamine decomposition or by ammonium addition in the culture medium. 

Hernandez-Orte, R, Bely M., Cacho, J., Ferreira, V. (2006) Impact of ammonium additions on volatile acidity ethanol, and aromatic compound production by different Saccharomyces cerevisiae strains during fermentation in controlled synthetic media. Australian Journal of Grape and Wine Research, 12, 150-160. 

The system produces protenation, ammonium addition and protonbound solvent molecular clusters. The ionization procedure with this system was reported to be very soft resulting in very few molecular fragment ions being formed. The system was used very successfully in... 

Nold S. C., Boschker H. T. S., Pel R., and Laanbroek H. J. (1999) Ammonium addition inhibits C-methane incorporation into methanotroph membrane lipids in a freshwater sediment. FEMS Microbiol. Ecol. 29, 81—89. 

The base used is most often benzyltrimelhyl-ammonium hydroxide, but aqueous or ethano-lic alkali is suitable. In addition to compounds... 

Addition of ammonium hydroxide to a solution of an aluminium salt gives a white gelatinous precipitate of aluminium hydroxide, Al(OH)3, insoluble in excess. Sodium hydroxide gives the same precipitate, but in this case, it does dissolve in excess. 

Addition of ammonium hydroxide to an aluminium salt in solution in presence of alizarin, gives a pink precipitate. 

Hence, if chlorine is passed into a cold suspension (in hydrochloric acid) of lead(II) chloride, lead(IV) chloride is formed. Addition of ammonium chloride gives the complex salt ammonium hexachloro-plumbate(lV) as a yellow precipitate ... 

Aqueous ammonia can also behave as a weak base giving hydroxide ions in solution. However, addition of aqueous ammonia to a solution of a cation which normally forms an insoluble hydroxide may not always precipitate the latter, because (a) the ammonia may form a complex ammine with the cation and (b) because the concentration of hydroxide ions available in aqueous ammonia may be insufficient to exceed the solubility product of the cation hydroxide. Effects (a) and (b) may operate simultaneously. The hydroxyl ion concentration of aqueous ammonia can be further reduced by the addition of ammonium chloride hence this mixture can be used to precipitate the hydroxides of, for example, aluminium and chrom-ium(III) but not nickel(II) or cobalt(II). 

Addition of sulphide ion to a solution of a zinc salt containing ammonia and ammonium chloride gives a white precipitate of zinc sulphide. 

Add 15 g. of finely powdered ammonium carbonate gradually to 50 ml. of glacial acetic acid contained in a 150 ml. round-bottomed flask, shaking the mixture during the addition to ensure a steady evolution of carbon dioxide. When all the carbonate has... 

The glycine so obtained is almost pure. To remove traces of ammonium chloride, however, dissolve the glycine in 30 ml. of water, and then reprecipitate by the addition of 200 ml. of methanol. Cool the product in ice-water with stirring, and then... 

Formamide. Commercial formamide may contain excess of formic acid. It is purified by passing ammonia gas into the mixture until a slight alkaline reaction is obtained. The ammonium formate thus formed is precipitated by the addition of acetone the filtrate, after drying over anhydrous magnesium sulphate, is distilled under reduced pressure. Pure formamide has b.p. IO571I mm. 

In aqueous solution at 100° the change is reversible and equilibrium is reached when 95 per cent, of the ammonium cyanate has changed into urea. Urea is less soluble in water than is ammonium sulphate, hence if the solution is evaporated, urea commences to separate, the equilibrium is disturbed, more ammonium cyanate is converted into urea to maintain the equilibrium and evfflitually the change into urea becomes almost complete. The urea is isolated from the residue by extraction with boiling methyl or ethyl alcohol. The mechanism of the reaction which is generally accepted involves the dissociation of the ammonium cyanate into ammonia and cyanic acid, and the addition of ammonia to the latter ... 

The formation of ethyl isopropylidene cyanoacetate is an example of the Knoevenagel reaction (see Discussion before Section IV,123). With higher ketones a mixture of ammonium acetate and acetic acid is an effective catalyst the water formed is removed by azeotropic distillation with benzene. The essential step in the reaction with aqueous potassium cyanide is the addition of the cyanide ion to the p-end of the ap-double bond ... 

In a 2 litre bolt-head flask, equipped with an efficient mechanical stirrer, place 60-5 g. (50 ml.) of pure nitrobenzene and a solution of 30 g. of ammonium chloride in 1 litre of water. Stir vigorously and add 75 g. of a good quality zinc powder (about 90 per cent, purity) in small portions over a period of 5 minutes. The main reaction occurs about 5 minutes after the addition and the temperature rises. When the temperature reaches about 65°, add enough ice to the weU-stirred mixture to reduce the temperature to 50-55°. Filter the solution through a Buchner funnel twenty minutes after the first portion of zinc powder was introduced wash the zinc oxide residues with 600-700 ml. of boiling water. 

The conversion of a carbonyl compound by ammonium polysulphide solution into an amide with the same number of carbon atoms is known as the Willgerodt reaction. The procedure has been improved by the addition of about 40 per cent, of dioxan or of pyridine to increase the mutual solubility of the ketone and aqueous ammonium polysulphide the requisite temperature is lowered to about and the yield is generally better. 

For ammonium surfactants there is evidence for the existence of an additional specific interaction between the headgroups of the surfactant and the aromatic solubilisate . This is in line with the observation that partition coefficients for benzene in CTAB solutions are much higher than those for... 

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