lithium-chloride and lithium-bromide

Halopyridines are key building blocks for synthesizing pharmaceuticals, agrochemicals, and ligands for metal complexes, but strategies to selectively halogenate pyridine C-H precursors are lacking. We designed a set of heterocyclic phosphines that are installed at the 4-position of pyridines as phosphonium salts and then displaced with halide nucleophiles. A broad range of unactivated pyridines can be halogenated, and the method is viable for late-stage halogenation of complex pharmaceuticals. Computational studies indicate that C-halogen bond formation occurs via an S

Topics: Bromides; Density Functional Theory; Halogenation; Indicators and Reagents; Iodides; Lithium Chloride; Lithium Compounds; Models, Chemical; Onium Compounds; Phosphines; Pyridines

Reactions of lithium halide (LiX, X = F, Cl, Br and I) and methyl halide (CH₃X, X = F, Cl, Br and I) have been investigated at the B3LYP/6-31G(d) level of theory using the microhydration model. Beginning with hydrated lithium ion, four or two water molecules have been conveniently introduced to these aqueous-phase halogen-exchange S(N)2 reactions. These water molecules coordinated with the center metal lithium ion, and also interacted with entering and leaving halogen anion via hydrogen bond in complexes and transition state, which to some extent compensated hydration of halogen anion. At 298 K the reaction profiles all involve central barriers ΔE ( cent ) which are found to decrease in the order F > Cl > Br > I. The same trend is also found for the overall barriers (ΔE(ovr)) of the title reaction. In the S(N)2 reaction of sodium iodide and methyl iodide, the activation energy agrees well with the aqueous conductometric investigation.

Topics: Anions; Bromides; Computer Simulation; Fluorides; Hydrocarbons, Brominated; Hydrocarbons, Fluorinated; Hydrocarbons, Halogenated; Hydrocarbons, Iodinated; Hydrogen Bonding; Lithium Chloride; Lithium Compounds; Methyl Chloride; Models, Chemical; Models, Molecular; Molecular Conformation; Molecular Structure; Thermodynamics; Water

Antidepressant drug imipramine hydrochloride (IMP) is amphiphilic which shows surfactant-like behavior in aqueous solutions. We have studied the effect of adding electrolytes and non-electrolytes on the micellar behavior of IMP by making cloud point (CP) and dye solubilization measurements. The CP of a 100mM IMP solution (prepared in 10mM sodium phosphate (SP) buffer) was found to decrease with increasing pH, both in the absence as well as presence of added salts. Increase in pH increased the visible absorbance of Sudan III dye solubilized in the drug micelles, implying micellar growth. Addition of increasing amounts of salts to 100mM IMP solutions (at pH 6.7) caused continuous increase in CP due to micellar growth. On the basis of these studies, the binding-effect orders of counter- and co-ions have been deduced, respectively, as: Br(-)>Cl(-)>F(-) and Li(+)

Topics: Azo Compounds; Bromides; Coloring Agents; Electrolytes; Emulsions; Hydrogen-Ion Concentration; Imipramine; Lithium Chloride; Lithium Compounds; Micelles; Potassium Chloride; Potassium Compounds; Quaternary Ammonium Compounds; Sodium Chloride; Sodium Compounds; Sodium Fluoride; Solubility; Solutions; Thiourea; Urea

Lithium salts can impair the central nervous system and kidney function and disturb the biological oxidation as well as desamidization of biologically active amines. The suggested MAC for lithium and its salts in the air of working area is 0.05 mg/m3 (aerosol, 2nd jeopardy grade).

Topics: Adult; Air Pollutants, Occupational; Animals; Bromides; Female; Humans; Hygiene; Lethal Dose 50; Lithium; Lithium Carbonate; Lithium Chloride; Lithium Compounds; Maximum Allowable Concentration; Phosphates; Pregnancy; Sulfates

The denaturation of ribonuclease A by guanidine hydrochloride, lithium bromide, and lithium chloride and by mixed denaturants consisting of guanidine hydrochloride and one of the denaturants lithium chloride, lithium bromide, and sodium bromide was followed by difference spectral measurements at pH 4.8 and 25 degrees C. Both components of mixed denaturant systems enhance each other's effect in unfolding the protein. The effect of lithium bromide on the midpoint of guanidine hydrochloride denaturation transition is approximately the sum of the effects of the constituent ions. For all the mixed denaturants tested, the dependence of the free energy change on denaturation is linear. The conformational free energy associated with the guanidine hydrochloride denaturation transition in water is 7.5 +/- 0.1 kcal mol-1, and it is unchanged in the presence of low concentrations of lithium bromide, lithium chloride, and sodium bromide which by themselves are not concentrated enough to unfold the protein. The conformational free energy associated with the lithium bromide denaturation transition in water is 11.7 +/- 0.3 kcal mol-1, and it is not affected by the presence of low concentrations of guanidine hydrochloride which by themselves do not disrupt the structure of native ribonuclease A.

Topics: Animals; Bromides; Calorimetry; Cattle; Chlorides; Guanidine; Guanidines; Kinetics; Lithium; Lithium Chloride; Lithium Compounds; Pancreas; Protein Denaturation; Ribonuclease, Pancreatic; Sodium; Sodium Compounds; Thermodynamics

Topics: Animals; Bromides; Chlorides; Fertilization; Humans; Lithium Chloride; Lithium Compounds; Ovum; Sea Urchins; Thiocyanates