Phloroglucinol-hydrochloric acid

The Wiesner Reaction. The reaction of lignified tissue and phloroglucinol—hydrochloric acid gives a visible absorption spectmm with a maximum at 550 nm. This has been attributed to coniferaldehyde units in lignin as the groups responsible for the color formation. 

Nitric acid, Sulfuric acid, Phloroglucinol, Hydrochloric acid Sodium chlorate. Copper sulfate. Ammonium hydroxide. Alcohol Sodium chlorate. Copper sulfate. Ammonium hydroxide. Alcohol Sulfuric acid. Potassium nitrate, 1,3,5-Trifluorobenzene, Methylene chloride. Hexane, Charcoal, Sodium sulfate, 2-Amino-2-methylpropanone, Potassium hydrogen carbonate, 1,2-Dichloroethane, Trifluoroacetic acid. Urea, Dimethylformamide Nitric acid. Urine... 

Color Reaction with Phloroglucinol-Hydrochloric Acid... 

The phloroglucinol-hydrochloric acid reagent gives a specific, green color with heptuloses and can be used for their detection. With the orcinol spray, octuloses give a crimson color which fades rapidly to a permanent gray. ... 

There are also methods based on the detection of aldehydic substances, for the typical odor and flavor of rancidity seem to be associated with the liberation of aldehydic materials during the oxidative deterioration. The Kreis test (18), perhaps the best known of these methods, consists of treating the fat with concentrated hydrochloric acid and a solution of phloroglucinol. The red color formed is attributed to a condensation product of epihydrin aldehyde with phloroglucinol. Historically, the chief difficulty with this method has been that fats which are not rancid will often give a positive Kreis test. It has been shown that if this test is quantitatively correlated with the induction period... 

Furfural gives two characteristic colour reactions which serve for qualitative detection. With phloroglucinol and hydrochloric acid (1 part concentrated acid, 1 part water) a cherry-red colour is produced on boiling with a solution of aniline acetate a red colour is produced even in the cold. 

Dimeric aldehydes analogous to (II) and (VI) have in fact been isolated from incubates of coniferyl alcohol with laccase (58). There are only 3% such aldehydic groups in lignin 4) [cf. Unit 10 in Fig. 9] but these suffice to give a intense red color with phloroglucinol and concentrated hydrochloric acid, the conventional Wiesner test for lignin. 

Sodium azide, Lead acetate, Water Picric acid. Sodium hydroxide. Lead nitrate Styphinic acid. Sodium hydroxide, Lead-II-nitrate Styphinic acid. Magnesium carbonate. Lead nitrate. Nitric acid Phloroglucinol, Glacial acetic acid. Sodium nitrite. Lead nitrate Acetylene, Arsenic trichloride. Mercuric chloride. Hydrochloric acid... 

The reaction of 1,3,5-tribromobenzene with excess sodium methoxide in methanol—NJV-dimethylformamide and in the presence of a catalytic amount of cuprous iodide gives ca 90% yield phloroglucinol trimethyl ether (1,3,5-trimethoxybenzene). The latter is hydrolyzed with 35 wt % hydrochloric acid at room temperature to give a 90% yield of phloroglucinol (140—142). 

Dissolve 5 g phloroglucinol (1,3,5-trihydroxybenzene) and 1 g ascorbic acid in a minimum amount of methanol (60 ml) and transfer to a 100-ml volumetric flask. Add 0.5 ml of 10 N hydrochloric acid, fill to the mark with methanol, and mix well. Store up to 2 weeks at 4°C. Bring to room temperature before use. 

Pentosans. This determination is made by Tollens and Kriiger s method, which is based on the transformation of pentosans into furfural by distillation with hydrochloric acid and on subsequent precipitation of the furfural with phloroglucinoL The analysis comprises, therefore, two distinct operations ... 

Phloroglucinol and Concentrated Hydrochloric Acid, i gram of phloroglucinol is dissolved in 80 c.c. of alcohol. Fibres steeped for a few minutes in this reagent and then treated with concentrated hydrochloric acid, assume a bright reddish-violet coloration if lignified. 

With sodium polysulphide, sym-trinitrobenzene yields tetranitroazoxybenzene along with dinitroaniline. All three nitro groups can be reduced by tin or iron in hydrochloric acid, triaminobenzenc being formed, which is the starting material for the manufacture of phloroglucinol. sym-Trinitrobenzene can react with sodium borohydride to yield trinitrocyclohexane (Severin [66]). 

A sampling of the colors produced in the reaction of various phenols and amines with lignin is presented in Table 2.1.1. Phenolic compounds are applied as acidic aqueous solutions and aromatic amines as aqueous solutions of the corresponding hydrochloride or sulfate in the presence of acids. Of the phenols, phloroglucinol is the most important, and its solution in hydrochloric acid is known as the Wiesner reagent. 

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