Phloroglucinol test

W ood meal may be detected in mixtures by the microscope or by the phloroglucinol test. One gram of phloroglucinol is dissolved in 1 c.c. of alcohol, and 10 c.c. of syrupy phosphoric acid is aorcolain dish. Wood fibres show a rose colour changing to carmine. Apart from wood meal other forms of meal (corn, potato) arc similarly used. 

The biuret reaction [alkaline Cu(II)] and the arginine test [102] are used to detect peptides in nucleic acid preparations. Two other colour reactions permit either type of nucleic acid to be detected in the presence of the other one is due to Dische and the other is the phloroglucinol test of v. Etjler and Hahn. 

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... 

A solvent-free synthesis of flavones was recently reported by microwave-assisted reaction of phloroglucinol 231 and differently substituted /1-ketoesters 232 [148]. The reaction was simply carried out by mixing the phenol and the ester in an open test tube followed by irradiation for 2-3 min. The internal temperature reached 240 °C and yields were in the range from 68 to 96%. Scheme 85 describes the application of this procedure to the synthesis of the natural product chrysin 233. 

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. 

To ensure lot-to-lot consistency, standardization of extracts often relies on constituents as biomarkers for plant identity and potency. SJW Hypericum perforatum), a perennial shrub traditionally used as a mood enhancer and mild antidepressant, has been tested in dozens of clinical trials, with mixed results for efficacy. Some of its purported bioactive constituents include naphthodianthrones, including hypericin flavonoids phloroglucinols, including hyperforin and essential oils. For many years, hypericin was presumed to be the active component. As a result most extracts were standardized based on hypericin concentration. Recent data, however, support other components such as hyperforin and the flavanoids, that may also contribute to the therapeutic efficacy of the SJW extracts (33-35). Because these secondary components were previously unaccounted for in the standardization of the former clinical test articles, and because these constituents are chemically unrelated to and their content within the plant varies independently of hypericin, it has been argued that the potency of these constituents in any particular batch was unlikely to be similar to that of other batches. This variability between batches could explain the observed differences in the clinical trial results (36). 

Stabilization of nitric esters of polyhydric ales (such as mixts of NG with NGc) for use in Dynamites, was achieved by incorporating small amts of acetylacetone, benzoylacetone, or phloroglucinol. Mixt of NG 60 NGc 40% stabilized with 1% acetylacetone withstood Abel stability test for >300 mins]... 

The reaction of hemicellulose to heated, concentrated (12%) HC1 is a test of the former s presence. Detection is by the violet or red color developed by one or more of the reaction products (chiefly furfural) with orcinol or phloroglucinol. The coloration is either blue, greenish, or nonexistent with KI-I2 (Whistler and Smart, 1953). The quantity of furfural produced relates directly to the quantity of pentosan present (Smith and Montgomery, 1959). Under the same reaction conditions, hexoses produce hydroxyme-thylfurfural. Furfural is steam-distillable hydroxymethylfurfural is not. 

Chang H-m, Allan GG (1971) Oxidation In Sarkanen KV, Ludwig CH (eds) Lignins Occurrence, formation, structure and reactions Wiley-Interscience, New York, 457-471 DeBaun RM, Nord FF (1951) A quantitative phloroglucinol-HCl test in the evaluation of lignin preparations Tappi 34 71-73... 

Nierenstein s Reaction A This reaction is based on the change of colour of a solution of phloroglucinol in presence of acrolein. On treatment of the solution to be tested with 2-3 ml. 5% phloroglucinol and addition of 5-10 drops of alkali, and then boiling rapidly, the presence of acrolein is detected by a bluish-green colour. 

Properties of Pentosans (SECTIONS 365, 382, 656).— (a) Tests for lignin.—Dissolve a few drops of aniline in a few drops of dilute hydrochloric acid, and dilute with 5 cc. of water. Pour one-half of the solution onto a piece of paper made from wood-pulp (newspaper) and one-half onto a paper made from linen. Repeat the tests using a solution of phloroglucinol in dilute hydrochloric acid. 

It was found that carbazole and phloroglucinol are unsuitable for determining the heptose content of sugar mixtures because of interference from other sugars similar interference is encountered with resorcinol. With orcinol, cysteine, and diphenylamine, however, specific reactions can be obtained at selected wavelengths. Ketoheptoses (and keto sugars in general) react under milder acid conditions than the aldoses, and this property can be used for identification purposes. In the orcinol test, for... 

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