Hydrochloric acid between

Szejtli has pointed out that investigation of log fc as a function of Ho is possible only with concentrations of hydrochloric acid between 0.1 and 0.5 N. At lower concentrations, Ho becomes equal to the pH and, at acid concentrations at which Ho can be determined accurately, that is above 0.5 N, pH cannot be determined directly. 

Acidification of the solvent is specially important in the case of anthocyanins, since it would determine extraction of the flavylium cation that is stable at acid pH however, care should be taken since too strong acid conditions may cause the hydrolysis of acylated anthocyanins, and thus reduction of the concentration of hydrochloric acid (between 0.1 % and 1 % HCl in methanol) or the use of acetic acid, or weaker acids like tartaric, oxalic, or citric acids have shown good results. ... 

Preparation by direct nitrosation [2068] of 4-hydroxy-acetophe-none with aqueous sodium nitrite solution in dilute hydrochloric acid between 0 and 5° [2069],... 

Also obtained by degradation of 7,7 -diacetoxy-4,4 -dimethyl-3,4-dihydro-4,6 -bicoumarin with aluminium chloride in dilute hydrochloric acid between 135° and 170° for 2 h (5%) [5654]. 

On acetylation it gives acetanilide. Nitrated with some decomposition to a mixture of 2-and 4-nitroanilines. It is basic and gives water-soluble salts with mineral acids. Heating aniline sulphate at 190 C gives sulphanilic add. When heated with alkyl chlorides or aliphatic alcohols mono- and di-alkyl derivatives are obtained, e.g. dimethylaniline. Treatment with trichloroethylene gives phenylglycine. With glycerol and sulphuric acid (Skraup s reaction) quinoline is obtained, while quinaldine can be prepared by the reaction between aniline, paraldehyde and hydrochloric acid. 

Molisch s test A general test for carbohydrates. The carbohydrate is dissolved in water, alcoholic 1-naphthol added, and concentrated sulphuric acid poured down the side of the tube. A deep violet ring is formed at the junction of the liquids. A modification, the rapid furfural test , is used to distinguish between glucose and fructose. A mixture of the sugar, 1-naphthol, and concentrated hydrochloric acid is boiled. With fructose and saccharides containing fructose a violet colour is produced immediately the solution boils. With glucose the appearance of the colour is slower. 

Dissolve 15 ml. (15-4 g.) of aniline in a mixture of 40 ml. of concentrated hydrochloric acid and 40 ml. of water contained in a 250 ml. conical flask. Place a thermometer in the solution, immerse the flask in a mixture of ice and water, and cool until the temperature of the stirred solution reaches 5°. Dissolve I2 5 g. of powdered sodium nitrite in 30 ml. of water, and add this solution in small quantities (about 2-3 ml. at a time) to the cold aniline hydrochloride solution, meanwhile keeping the latter well stirred by means of a thermometer. Heat is evolved by the reaction, and therefore a short interval should be allowed between consecutive additions of the sodium nitrite, partly to allow the temperature to fall again to 5°, and partly to ensure that the nitrous acid formed reacts as completely as possible with the aniline. The temperature must not be allowed to rise above 10°, otherwise appreciable decomposition of the diazonium compound to phenol will occur on the other hand, the temperature... 

Prepare a solution of benzencdiazonium chloride from 20 ml, (20 5 g.) of aniline precisely as in the preparation of chlorobenzene (p. 189), i.e, by dissolving the aniline in a mixture of 50 ml. of concentrated hydrochloric acid and 50 ml. of water, cooling to 5°, and then cautiously adding a solution of 17 g. of sodium nitrite in 40 ml. of water to the well-cooled and stirred aniline hydrochloride solution so that the temperature of the mixture remains between 5° and 10°. 

This tube is connected %vith rubber tubing of about 6 mm. bore to the carbon dioxide Kipp, via a wash-bottle containing sodium carbonate solution (to remove any dilute hydrochloric acid spray). It is very important, when the apparatus is in use, that there should be no constriction or bend in the rubber tube between the tap C and the wash-bottle. If these precautions are taken, a slow, e en, and easily controlled flow of gas can be obtained. 

The procedure is not usually applicable to aminosulphonic acids owing to the interaction between the amino group and the phosphorus pentachloride. If, however, the chlorosulphonic acid is prepared by diazotisation and treatment with a solution of cuprous chloride in hydrochloric acid, the crystalline chlorosulphonamide and chlorosulphonanilide may be obtained in the usual way. With some compounds, the amino group may be protected by acetylation. Sulphonic acids derived from a phenol or naphthol cannot be converted into the sulphonyl chlorides by the phosphorus pentachloride method. 

Attention has previously (see Diazonium Sails) been drawn to the fact that unless an excess of hydrochloric (or mineral) acid is used in the diazotisation process, coupling occurs between the diazonium salt and the amine to give diazoamino compounds. Thus phenyldiazonium chloride and aniline yield diazoaminobenzene. This substance may be conveniently prepared by dissolving two equivalents of aniline in three equivalents of hydrochloric acid, and adding one equivalent of sodium nitrite in aqueous solution followed by two equivalents of sodium acetate ... 

The aniline hydrochloride may be prepared by treating 2 g. of aniline with an excess (about 3 ml.) of concentrated hydrochloric acid in a small beaker, cooling, filtering at the pump, washing with a small volume of ether, and drying between filter paper. 

The reason for this is that reaction (i) is usually much slower than (ii) and (iii) so that the main reaction appears to be (Iv) (compare the preparation of tertiary butyl chloride from tertiary butyl alcohol and concentrated hydrochloric acid, Section 111,33). If the reaction is carried out in the presence of P3rridine, the latter combines with the hydrogen chloride as it is formed, thus preventing reactions (ii) and (iii), and a good yield of the ester is generally obtained. The differentiation between primary, secondary and tertiary alcohols with the aid of the Lucas reagent is described in Section III,27,(vii). 

Attack on the electrophilic C-2 may occur as in the 2-aminothiazoles series, which probably explains the rearrangements observed in acidic medium (121, 711, 712, 723, 724), in aqueous medium with NaOAc (725), or with aqueous NaHCOj (725) (Scheme 232). That the initial attack probably involves the C-2 atom is substantiated by the fact that this rearrangement occurs under extremely mild conditions for 2-iinino-3-substituted-5-nitro-4-thiazolines (725). As the whole mechanism proposed (see p. 92) is reversible, when imino derivatives are submitted to such rearrangement conditions the rearrangement is expected to occur faster if steric interaction between 3- and 4-substituents exists in the 2-imino isomer. Another reaction may occur in acidic medium phenylimino-2-bipheny]-3,4-4-thiazoline hydrolyzed with hydrochloric acid gives the corresponding 4-thiazoline-2-one and aniline (717). 

THPC—Amide Process. The THPC—amide process is the first practical process based on THPC. It consists of a combination of THPC, TMM, and urea. In this process, there is the potential of polymer formation by THPC, melamine, and urea. There may also be some limited cross-linking between cellulose and the TMM system. The formulation also includes triethanolamine [102-71-6J, an acid scavenger, which slows polymerization at room temperature. Urea and triethanolamine react with the hydrochloric acid produced in the polymerization reaction, thus preventing acid damage to the fabric. This finish with suitable add-on passes the standard vertical flame test after repeated laundering (80). 

A persistent idea is that there is a very small number of flavor quaUties or characteristics, called primaries, each detected by a different kind of receptor site in the sensory organ. It is thought that each of these primary sites can be excited independently but that some chemicals can react with more than one site producing the perception of several flavor quaUties simultaneously (12). Sweet, sour, salty, bitter, and umami quaUties are generally accepted as five of the primaries for taste sucrose, hydrochloric acid, sodium chloride, quinine, and glutamate, respectively, are compounds that have these primary tastes. Sucrose is only sweet, quinine is only bitter, etc saccharin, however, is slightly bitter as well as sweet and its Stevens law exponent is 0.8, between that for purely sweet (1.5) and purely bitter (0.6) compounds (34). There is evidence that all compounds with the same primary taste characteristic have the same psychophysical exponent even though they may have different threshold values (24). The flavor of a complex food can be described as a combination of a smaller number of flavor primaries, each with an associated intensity. A flavor may be described as a vector in which the primaries make up the coordinates of the flavor space. 

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