Colour reactions

The colour reactions with the enzyme peroxidase and HjO permit all the above amines to be distinguished from one another in very dilute solution (P- 523)-... 

No colour reaction with bleaching powder cf. amines). 

Method 2. Transfer the dark-coloured reaction product to a separatory funnel and shake successively with water, with sufficient 5-10 per cent, sodium hydroxide solution to ensure that the washings are alkaline to litmus, and finally with water. Dry with anhydrous magnesium sulphate or calcium chloride. Filter through a fluted filter paper into a small distilling flask and distil slowly. Collect the crude bromobenzene at 150-170° pour the residue whilst still hot into a small porcelain basin. Redistil the hquid of b.p. 150-170° (3) and collect the bromobenzene at 154-157° the yield is about 60 g. 

By using an aromatic aldehyde carrying an electron-releasing group the intermediate cation can be stabilized. This is the basis of the widely-used Ehrlich colour reaction for pyrroles, indoles and furans which have a free reactive nuclear position (Scheme 21). 

The study of colour reactions of flocculants with organic reagents of various classes revealed that they can be used for determination of residual amount of flocculants in various types of waters. Best spectrofotometric char acteristics were demonstrated of flocculants with the sulphophthalein reagents and dioxyazocompounds. 

Procedures of the beta-galactosidase activity measuring using colour reaction with ONPG and X-Gal without cells permeabilization were developed and the detection limit at the level of 4 ppb has been achieved. The influence of the foreign ions (phosphate, sulphate, carbonate et. al) was studied. 

The other class of primary antioxidants are the phenols (hindered phenols, hindered bisphenols, hindered thiobisphenols, polyhydroxy phenols) (Fig. 34). Phenolic antioxidants are generally used when the discolouration of the amine antioxidants cannot be tolerated. Phenols may produce coloured reaction products (yellow, tan or pink) but the discolouration is significantly less than produced with amines. 

Phenylglycollyltropeine Mandelyltropeine, homatropine), CigHjiOjN. This is largely used as a substitute for atropine. It crystallises in prisms, m.p. 95-5-98-5°. The hydrobromide, the salt usually employed in medicine, is a crystalline powder, m.p. 217-8° (dec.) the hydrochloride, m.p. 224-5°, and the salicylate are also used. All tl ee are freely soluble in water. The methobromide has m.p. 192-6°. The aurichloride, B. HAUCI4, forms prisms and is sparingly soluble in water. Homatropine, unlike atropine, does not give the Vitali colour reaction (p. 70). Its mydriatic effect is more rapid and transient than that of atropine. 

As regards general methods for distinguishing between the alkaloids of opium, mention may be made of the following Kofler and Kofler s study of the micro-sublimation of these alkaloids and the characters of the micro-sublimates the comparison by Maplethorpe and Evers of the picrates of a series of opium bases, comparison of the colour reactions of a series of opium alkaloids, and their behaviour with specific reagents and precipitants. ... 

Tuduranine, CjgHjgOgN. This member of the aporphine group (p. 306) is the most recent addition to Sinomenium alkaloids and was isolated by Goto from the mother liquors of sinomenine. It is crystalline, has m.p. 125° (with softening at 105°), and yields a sparingly soluble hydrochloride, m.p. 286° (dec.), [a] f — 148° (dilute MeOH), is freely soluble in alkali, and gives feeble ferric chloride and diazo-colour reactions and a fuchsin-red colour with formaldehyde and sulphuric acid. It behaves as a secondary base and yields a diacetyl derivative, m.p. 170°, [a] / — 321-71° (MeOH), which does not form a methiodide, but can be hydrolysed to A -acetyl-tuduranine, m.p. 277°, — 395-24°, and this can be methylated to... 

Glaucidine (item 56 list, p. 173), composition unknown m.p. 209-10°, gives the characteristic colour reactions of glaueine. It is a phenolic base and on methylation gives a product of which the hydrogen tartrate closely resembles that of glaueine. ... 

Alkaloids of Pot Curare. This variety of curare is a dark brown, comparatively dry extract. According to Boehm, it contains protocurine, colourless hair-like needles, m.p. 306° (dec.), a base of low toxicity and yielding crystalline salts. A second alkaloid of similar type is protocuridine prisms, m.p. 274-6°, sparingly soluble in all ordinary solvents. The poisonous constituent is protocurarine, a red powder, easily soluble in water, and giving characteristic colour reactions with nitric acid and with oxidising agents in sulphuric acid, this latter reaction indicating a Strychnos spp. as a possible botanical source. 

Both are unmelted at 320°, form the characteristic, sparingly soluble nitrate, and give with sulphuric acid the specific colour reaction, cheriy-red changing to blue on warming. 

As these substances are difficult to isolate and to distinguish, particular importance attaches to their colour reactions and to their relative paralysing potencies these and other data for the ten alkaloids are summarised in the table (p. 384), the paralysing potencies being given in micro-grammes (y) per frog. 

Karrer and Schmid have noted that the dimeride of C-curarine I does not give the characteristic colour reactions of this alkaloid with acids, but still gives that with ceric sulphate and potassium dichromate (p. 384). 

Alkaloid A. This forms a chloride, [CjoHjaONjJ+Cl", HjO, isomeric with the chlorides of toxiferine, C-eurarine I and C-curarine III the picrate has m.p. 269° (dec.). The chloride differs from the isomerides named, in potency, colour reactions and ultra-violet absorption spectrum. The chloride in 2N-sulphuric acid gives a carmine-red colour with potassium dichromate. 

Name of Base Formula Potency expressed as y (0-001 mgm.) Colour Reactions Melting point of Plcrate... 

According to Hesse, conquinamine, an isomeride of quinamine (see table below) jdelds, on appropriate treatment, quinamicine and apoquin-amine. Raymond-Hamet has shown that cinchonamine (below) and aricine (table, p. 466) give indole colour reactions and in that respect resemble quinamine. 

EtOH). No methoxyl is present. It forms a series of crystalline double chlorides with cadmium, zinc or copper, does not give the thalleioquin reaction, and solutions of its sulphate are not fluorescent. It is diacidie and forms two series of salts of which the nitrate, B. HNOj, crystallises in minute prisms, m.p. 196°, insoluble in water. Cinchonamine hydrochloride, B. HCl, laminae or B. HCl. HjO, cubical crystals, has been suggested for use in the estimation of nitrates. When warmed with strong nitric acid the alkaloid furnishes dinitrocinchonamine. It gives an amorphous, monoacetyl derivative, and forms a methiodide, m.p. 208 , which with silver oxide yields an amorphous methylcinchonamine. Raymond-Hamet found that cinchonamine ves typical indole colour reactions and is probably an indole alkaloid. This seems to have been... 

Name and Formula Crystalline Form Optical Rotation [[Pg.467]

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