Salt retardation

Sulfamic acid and its salts retard the precipitation of barium sulfate and prevent precipitation of silver and mercury salts by alkah. It has been suggested that salts of the type AgNHSO K [15293-60 ] form with elemental metals or salts of mercury, gold, and silver (19). Upon heating such solutions, the metal deposits slowly ia mirror form on the wall of a glass container. Studies of chemical and electrochemical behavior of various metals ia sulfamic acid solutions are described ia Reference 20. 

Later in the 20th century, Vompe and Stepanov delineated efficient procedures for the preparation of the so-called Zincke salts (e.g., 1) from pyridines and 2,4-dinitrochlorobenzene, involving, for example, reflux in acetone. Vompe and Lukes also noted that electron-donating substituents on the pyridinium ring of the Zincke salt retarded reaction with amines at the 2-position of the pyridinium ring, sometimes leading instead to attack at the C-1 position of the 2,4-dinitrobenzene ring, with displacement of the pyridine. 

Organic metal salts retard the development of color in the thermal treatment of PVC, and their ability to react selectively with allylic and tertiary chlorine structures according to Eq. 23 has been demonstrated with model compounds [19,32,113,115]. 

Influence of the Monovalent Ions. The addition of ammonium salts retard the course of the deesterification by changing the reaction rate of hydrolysis and ammonolysis. By increasing the concentration of the ions the conversion of the ester groups is reduced from 83.3 % for 0,01 M to 62.8 % for 0.2 M (without added salt this value is 84.05 %), and the ratio hydrolysis ammonolysis is changed correspondingly from 53.8 76.2 to 37.3 62.7 (without added salt this ratio is 57.6 42.4). 

The ammonium salts retard the depolytmerization, which is expressed by an increasing of the ammonia concentration and reducing of the ammonium hydroxide. The addition of Na and ions leads to enhancing of the process, but in this case the values are not so close as it is in the other processes. From the investigated divalent ions, we found out that Mg " retard the depolymerization, while Ca " enhance it. Comparing the influence of the ions on the performing reactions, we will notice that these which enhance the ammonolysis retard the depolymerization, and these which enhance the hydrolysis enhance the depolymerization as well. 

Traces of ferric salts retard the dissolution of mercury in nitric acid, a phenomenon which is attributed5 to decomposition of the nitrous acid by the catalytic alternate reduction and oxidation of the iron-radicle. 

Under these reaction conditions, the use of ammonium and related onium salts with nucleophilic anions has been found effective at converting the HCl/SnCU-initiated, uncontrolled polymerizations into controlled/ living processes [105], Similar results are reported for TiCl4-based polymerizations [174,175], Effective salts include tetraalkylammonium and phosphonium salts R4N+Y and R4P+Y (Y = I, Br, Cl, CH3COO R = CH3, C2Hs, 71-C4H9, etc.). As added nucleophiles do in nonpolar solvents, the added salts retard the polymerization, narrow the MWD of the polymers, and render their M values directly proportional to conversion and close to the calculated values (one living chain per initiator molecule). 

ACID RETARDATION," "BASE RETARDATION," AND "SALT RETARDATION" PHENOMENA... 

The above-discussed acid retardation and base retardation in the immobiUzed Uquid phase could be compared with the so-called salting-out effects. However, this term is hardly applicable to the case of salt retardation, the first example of which was demonstrated by a successful removal of small amounts of NH4CI from a concentrated brine of (NH4)2S04. This practically important problem arises in the manufacture of caprolactam, where large amounts of sulfuric acid are converted into ammonium sulfate used for the preparation of the crystalline fertilizer. The new process of ISE on nanoporous NN-381 resin allowed an effective purification of very large volumes of concentrated sulfate brine, due to the fact that small ions of NH and Cl are efficiently squeezed into and retained in the finest pores of the sorbent [172]. We consider this salt retardation process as a convincing proof of our interpretation of the mechanisms of the new electrolyte separation process. 

Acid retardation base retardation, and salt retardation phenomena 475... 

The conversion of alcohols to iodides with inversion using triphenylphosphine-iodine-imidazole, or triphenylphosphine-2,4,5-tri-iodoimidazole, (4,157) has now been described in detail. The purity and yield of tertiary iodides (or bromides) prepared from the alcohols and aqueous HI (or HBr) at 0 can be improved by addition of lithium or calcium halides it is believed the metal salts retard competing hydrolysis of the tertiary halides. Secondary alkyl bromides have been prepared from the alcohols with retention of configuration via the inverted selenides (Scheme 35). Two other new reagents for the... 

Ammonium salts retard the precipitation. For amounts of nicotine above 50 mg per 100 ml, a concentration of ammonium chloride below 5 per cent will not interfere but smaller amounts of nicotine require longer... 

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