Reina Gómez
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View article: On the reaction mechanism of a colour test for uracil detection
On the reaction mechanism of a colour test for uracil detection Open
When uracil is dissolved in bromine water and excess of a solution of barium hydroxide is added, a purple precipitate or colour is developed. It was found that iso-dialuric and dialuric acid form purple precipitates with barium hydroxide. …
View article: The chemistry of Deniges test for adrenaline
The chemistry of Deniges test for adrenaline Open
The phenol groups in adrenaline are activated, step by step, by interaction with sodium acetate. A phenoxide reacts with mercuric chloride (SN2 reaction), giving an organomercurial intermediate. The second phenoxide ion reacts differently …
View article: The chemistry of the interaction of brucine with chlorine water
The chemistry of the interaction of brucine with chlorine water Open
In this communication the reaction route of the interaction of brucine with chlorine water is provided along with the reaction mechanism. The reaction is initiated by chlorination of the alkaloid by means of activated hypochlorous acid. Th…
View article: The chemistry of Obermayer test for indican in urine
The chemistry of Obermayer test for indican in urine Open
The purpose of this article is to provide the reaction mechanism of the process occurring during the Obermayer colour test for indican in urine. This test differs from cognate tests because no chemical oxidant is used in order to oxidise 3…
View article: On the chemistry of Jorissen test for morphine
On the chemistry of Jorissen test for morphine Open
The Jorissen’s test for morphine employs warm sulphuric acid both as solvent and reagent. Care must be taken in order to prevent morphine-apomorphine rearrangement. The species for sulphonation derives from sulphuric acidium ion whose dehy…
View article: On the chemistry of creatinine detection via oxaziridine intermediate
On the chemistry of creatinine detection via oxaziridine intermediate Open
In this communication the chemistry of the interaction of creatinine with mercuric cyanide in alkaline medium is described. The separation of elemental mercury is idoneous for a chemical test and also is a hint of what is happening at leas…
View article: On the chemical oxidation of berberine
On the chemical oxidation of berberine Open
Berberine is an antiseptic isolated from several plants. Klunge proposed a test for identification of this four ring isoquinoline alkaloid. He used a solution of berberine, chlorine water and hydrochloric acid or sulphuric acid, obtaining …
View article: On the Horsley’s test for morphine
On the Horsley’s test for morphine Open
In the Horsley test for morphine, to a hot solution of morphine acetate silver nitrate solution is added. Metallic silver is separated and the filtrate is coloured blood-red by nitric acid. In this communication the reactivity of both reag…
View article: On the interaction of uric acid with ammonium molybdate in acidic medium
On the interaction of uric acid with ammonium molybdate in acidic medium Open
This communication is a theoretical organic chemistry study on the interaction of uric acid with ammonium molybdate in acidic medium (Gigli test for uric acid). Colour tests give rapid, visible, results. However, it is interesting know wha…
View article: A novel transamination reaction in a murexide-like sequence for caffeine detection
A novel transamination reaction in a murexide-like sequence for caffeine detection Open
This communication is a theoretical organic chemistry study on the Hammarsten test for caffeine. He used chlorine water and ammonium hydroxide; a violet colour indicates presence of caffeine. Since a derivative of ammonium purpurate is for…
View article: The mechanism of Fleury test for morphine
The mechanism of Fleury test for morphine Open
The test under study is due to M. Fleury. He used morphine dissolved, at room temperature, in 1/20 N sulphuric acid; added some lead superoxide (lead dioxide), stirred for 8 min., let stand 4 min; the water-clear liquid was separated, and …
View article: A complete and sustained organic/inorganic reaction mechanism of Baeyer’s test
A complete and sustained organic/inorganic reaction mechanism of Baeyer’s test Open
The Baeyer’s test for unsaturation has been used in Qualitative Organic Analysis for a long time. However, if an alkaline reagent is used, compounds having an active hydrogen (carbon acids) also give a positive test with potassium permanga…
View article: On the formation of Oxydimorphine (pseudomorphine, 2.2’-bimorphine)
On the formation of Oxydimorphine (pseudomorphine, 2.2’-bimorphine) Open
In Beckurt’s test for alkaloids the substance for assay, generally a salt, is treated with a 0.1 N solution of potassium permanganate. In his study he used the hydrochloride of the alkaloid. In this communication the reactivity of both rea…
View article: On the mechanism of Siebold’s test for morphine
On the mechanism of Siebold’s test for morphine Open
In this communication the reaction course of Siebold’s test for morphine is provided. The test is based on the interaction of the alkaloid in sulphuric acid with potassium perchlorate. Perchloric acid is the intermediate that gives rise th…
View article: The oxidation mechanism of Morphine with Antimony trichloride
The oxidation mechanism of Morphine with Antimony trichloride Open
In this communication the oxidation route of morphine with antimony trichloride is provided. The deliquescent reagent is partially hydrolysed to antimonyl chloride with concomitant release of hydrogen chloride. The reactive species is obta…
View article: On the interaction of morphine with Lugol’s iodine in alkaline medium
On the interaction of morphine with Lugol’s iodine in alkaline medium Open
The purpose of this communication is to clear up what is happening in the test tube during the interaction of an alkaline solution of morphine with Lugol’s iodine (Kippenberger test for morphine). The formation mode and reactivity of potas…
View article: The chemistry of Husemann’s test for morphine
The chemistry of Husemann’s test for morphine Open
In this article is cleared up what is happening in the test tube during the Husemann’s test for morphine. According to different experimental conditions, morphine in sulphuric acid is heated during half an hour, boiled, or heated at 150° d…
View article: On the Interaction of Noscapine (Narcotine) with Ammonium Tellurate in Sulphuric Acid
On the Interaction of Noscapine (Narcotine) with Ammonium Tellurate in Sulphuric Acid Open
The purpose of this study is to clear up what is happening in the test tube during the interaction of ammonium tellurate with noscapine in sulphuric acid (Brociner test). The approach is a Theoretical Organic Chemistry Study based on the c…
View article: Organometallic intermediates in Böttger test for glucose in urine
Organometallic intermediates in Böttger test for glucose in urine Open
The reaction mechanism in organometallic chemistry is not always correctly understood or it is missing. In this communication the reaction route in the Böttger test for glucose is provided. The reagent can be bismuth subnitrate or bismuth …
View article: The Chemistry of Hager’s Test for Brucine
The Chemistry of Hager’s Test for Brucine Open
The purpose of the article is clear up what is happening in the test tube during the Hager’s test for brucine, that is, throughout the interaction of brucine with manganese dioxide in acidic medium. The paper is a Theoretical Organic Chemi…
View article: The mechanism of the oxidation of narceine by means of selenous acid -sulphuric acid
The mechanism of the oxidation of narceine by means of selenous acid -sulphuric acid Open
The chemistry of selenous acid was misunderstood for many years, being explained by electron back donation. In this communication we disclose the reaction mechanism of the interaction of narceine with selenous acid in sulphuric acid. Narce…
View article: On Dulcin detection by electron transfer
On Dulcin detection by electron transfer Open
The artificial sweetener Dulcin has been detected by reaction with mercury nitrate (Jorissen test), with silver nitrate or with mercury chloride (Ruggeri test). With these reagents a violet colour is developed. Since there are few violet o…
View article: On the chemistry of Beckurt’s test for physostigmine: A novel hydride transfer
On the chemistry of Beckurt’s test for physostigmine: A novel hydride transfer Open
Beckurt treated physostigmine hydrochloride with dilute potassium permanganate solution and observed separation of manganese dioxide. Since at first sight there is no reaction site for this oxidation, it was interesting to clear up the rea…
View article: On the chemistry of the Archetti test for caffeine and uric acid
On the chemistry of the Archetti test for caffeine and uric acid Open
The Archetti colour test is based on the reduction of ferricyanide ions to ferrocyanide, giving Prussian blue. However, the oxidation sequence of reactions that take in the organic molecule has not been described. Some electroanalytical ex…
View article: The Mechanism of Frabot Test for Uric Acid
The Mechanism of Frabot Test for Uric Acid Open
Uric acid is an Analyte. Excess uric acid ─ hyperuricemia ─ leads to gout and renal stones. Frabot noted that uric acid added to an alkaline tungstate solution developed an intense blue colour. A colorimetric method widely utilized to quan…
View article: On the mechanism of the Tattersall test for morphine
On the mechanism of the Tattersall test for morphine Open
Being morphine a restricted drug, a rapid colour test for its detection is very useful. Tattersall employed as reagent trisodium ortho-arsenate in sulphuric acid. However, the more common disodiumhydrogen ortho-arsenate heptahydrate can be…
View article: On the mechanism of the Folin test for uric aci
On the mechanism of the Folin test for uric aci Open
The mechanism of the interaction of uric acid with sodium tungstate in phosphoric acid (Folin test) is described. This insight involves the following steps: addition of tungstic acid to the carbon-carbon double bond in uric acid. Protolysi…
View article: The Mechanism of Schiff Test for Uric Acid in Urine
The Mechanism of Schiff Test for Uric Acid in Urine Open
Uric acid in urine can be detected by reaction with silver nitrate in alkaline medium. A redox reaction occurs and black elemental silver is observed in the filter paper used in this test. However, the mechanism of the series of steps occu…
View article: The mechanism of Mecke’s test for opioids
The mechanism of Mecke’s test for opioids Open
Mecke colour test is an official assay for opioids, either for opium or for purified compounds. It employs a solution of selenious acid in sulphuric acid. However, organoselenium chemistry was misunderstood for many years. The reaction mec…
View article: The chemistry of Mandelin’s test for strychnine
The chemistry of Mandelin’s test for strychnine Open
Strychnine reacts with Mandelin’s reagent giving a violet-blue colouration which changes to orange-red and finally to yellow. The chromic acid test for strychnine was surpassed by Mandelin’s assay due to better reagent stability, lower det…