Water-soluble bases

Group II. The classes 1 to 5 are usually soluble in dilute alkali and acid. Useful information may, however, be obtained by examining the behaviour of Sails to alkaline or acidic solvents. With a salt of a water-soluble base, the characteristic odour of an amine is usually apparent when it is treated with dilute alkali likewise, the salt of a water soluble, weak acid is decomposed by dilute hydrochloric acid or by concentrated sulphuric acid. The water-soluble salt of a water-insoluble acid or base will give a precipitate of either the free acid or the free base when treated with dilute acid or dilute alkali. The salts of sulphonic acids and of quaternary bases (R4NOH) are unaflFected by dilute sodium hydroxide or hydrochloric acid. 

Step 2. Extraction of the basic components. Extract the ethereal solution (Ej) with 15 ml. portions of 5 per cent, hydrochloric acid until all the basic components have been removed two or three portions of acid are usually sufficient. Preserve the residual ethereal solution (E2) for the separation of the neutral components. Wa.sh the combined acid extracts with 15-20 ml. of ether discard the ether extract as in Step 1. Make the acid extract alkaline with 10-20 per cent, sodium hydroxide solution if any basic component separates, extract it with ether, evaporate the ether, and characterise the residue. If a water-soluble base is also present, it may be recognised by its characteristic ammoniacal odour it may be isolated from the solution remaining after the separation of the insoluble base by ether extraction by distilling the aqueous solution as long as the distillate is alkahne to htmus. Identify the base with the aid of phenyl iso-thiocyanate (compare Section 111,123) or by other means. 

The process of isolation finally adopted by the former authors consists in precipitating as reineckates the water-soluble bases contained in a methyl alcoholic extract of the curare. The mixed reineckates are further purified, by solution in acetone and precipitation with water as often as may be necessary. The product so cleaned represents the bulk of the biological activity of the crude drug the mother liquors may contain curine (p. 374), which indicates a menisperm as one of the components of such curares. The mixed reineckates are then fractionated chromato-graphically over alumina and the components isolated as chlorides by the use of silver sulphate and barium chloride in succession. This process has been modified in detail by Schmid and Karrer, who have also found that with their curare, the more soluble reineckate fraction includes less potent quaternary alkaloids. 

Base A compound that will react with (neutralize) hydrogen ions to produce water. It is the opposite of an acid. A water-soluble base is an alkali. 

Ointments are semisolid preparations that are intended for external use. Ointments may contain either finely powdered drugs or their mixtures, liquids, and other drug forms incorporated into appropriate bases. They are applied to the skin for their physical effects as emollients (which make the skin more pliable), protectants, lubricants, and drying agents. Ointment bases are also used as vehicles in which to incorporate topical medications which exert specific effect. There are four types of ointment bases, namely, oleaginous, absorption, water removable, and water soluble bases. 

The drug substance was a water-soluble base in salt form with a pK of about 9 that was also soluble in most organic solvents. The polymer in the tablet was, however, soluble only in an organic medium like methanol. Other organic solvents such as acetonitrile and dimethylformamide were... 

Distinctions between water-soluble fractions of mixed hydrocarbons may be made by using solvent extraction of the water-soluble base/neutral and acid fractions with methylene chloride (EPA 1991c Thomas and Delfino 1991a). This separation of base/neutral and acid fractions will permit the GC resolution of the type of water soluble hydrocarbons present in the aqueous phase. Hexane has also been used as a solvent (DellAcqua and Bush 1973), as has pentane (Coleman et al. 1984). 

The use of water-soluble bases may result in some irritation because, as they take up water and dissolve, they may produce slight dehydration of the rectal mucosa. They are widely used, however, and release the drug by dissolving and mixing with the aqueous body fluids. PEG suppository bases and glycerinated gelatin are the most popular in this class. 

In the formulations presented here, mixtures of the polyethylene glycols, Lutrol E 400, Macrogol 1500, Macro-gol 4000, and Macrogol 6000, are intended as water-soluble base for suppositories and ovula. 

Extracts dried on to a water-soluble base are useful in the preparation of powdered drinks. Soft extracts tend to contain about 70% solid matter and can be mixed into a slun y with the substrate and spray-dried or dried in a vacuum oven. The substrate is usually essential to prevent the dried extract from reabsorbing moisture and turning back into a hard or sticky mass. The dried extracts can be dry-blended with other ingredients in a powdered drink formulation. 

Treat the solution (R i) remaining in the distilling flask after the volatile acidic and neutral compounds have been removed with 10-20 per cent sodium hydroxide solution until distinctly alkaline. If a solid separates, filter it off and identify it. Distil the alkaline solution until no more volatile bases pass over (distillate no longer turbid, or not basic to litmus water-soluble bases also possess characteristic odours) add more water to the contents of the flask if the solution becomes too concentrated during this distillation. [Set aside the solution in the distilling flask (S2) for Step 3.] If the volatile basic compounds are insoluble in water, remove them by extraction with two 20 ml portions of ether, and identify the bases (compare Sections 9.6.21, p. 1273 and 9.6.22, p. 1278) after evaporation of the ether. The water-soluble amines may be identified with phenyl isothiocyanate it is best to concentrate the bases by redistilling and collecting the first half of the distillate separately. 

However, although several methods exist for estimating water solubility based on regression of water solubility against octanol/water partition coefficient, most have used data sets that do not include nonionic dyes. 

This is actually quite remarkable—by adding just a little bit of a very water-soluble base (NH3 in this case), the pH of the rain goes almost back to that of pure rain. 

Among the water-soluble bases of Aspidosperma polyneuron there has been isolated an ester which after methanolysis yielded the known compound 3-carbomethoxyharman (CCCXXXIX) which was recognized by its NMR- and mass spectra (180, 181, Tables IV and V). The natural alkaloid is presumably a glycosidic ester of the corresponding acid. 

Water-soluble bases do not contain any oily or oleaginous phase. Solids can be easily incorporated into these bases. They may be completely removed from the skin due to their water solubility. Polyethylene glycol (PEG) ointment National Formulary (NF) is an example of a water-soluble base. 

Ointments Hydrocarbon (oily), adsorptive water-washable, or water-soluble bases emulsifying agents, glycols, medicating agent External... 

Vitamin B was found in the 1940s during the unraveling of the mysteries of the nitrogen-base B vitamin complex. A diet-induced peUagra-Hke condition in rats was shown to be cured by a water-soluble base, later differentiated from the known vitamins B and named vitamin B by Gyoigy... 

IVIVCs are often indicated only for obtaining oral formulations. Various data have been presented in the cases of less-classical formulations such as intrauterine devices, chewing gums, ocular inserts, suppositories, etc. For example, for suppositories two main types of formulations exist one based on hydrophilic excipients and the second on lipophilic excipients. The first step is the dissolution of the mass. This means a fusion of the lipophilic base at human body temperature (36-39.5°C) or dissolution for the water-soluble base (even with a high melting point) in the rectal fluid. 

Ointments utilize certain bases that act as vehicles to deliver the drug and to impart emollient and lubricant properties to the preparation. Usually, but not always, they contain medicinal substances. Properties of ointments may vary from product to product depending on their specific use, ease, and extent of application. In general, ointment bases may be classified into four general groups hydrocarbon, absorption, water-removable, and water-soluble bases. 

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