Ehrlich's reagent
Encyclopedia
para-Dimethylaminobenzaldehyde is an organic compound containing amine
and aldehyde
moieties which is used in Ehrlich's reagent for determination of hydrazine.
in fresh, cool urine
.If urine sample is left to oxidize in air to form urobilin
the reagent
will not detect the urobilinogen. By adding few drops of reagent to 3 ml of urine in a test tube
one can see a change of color from above, to dark pink or red. The degree of color change is proportional to the amount of urobilinogen in the urine sample.
Ehrlich's reagent is a strong electrophile which reacts with the electron-rich α-carbon of indole rings to form a blue-coloured adduct. It can be used to detect the presence of indole alkaloids
. Not all indole alkaloids give a coloured adduct as result of steric hindrance which does not allow the reaction to proceed.
to form an azo-dye
, which has a distinct yellow color. It is therefore used for spectrophotometric determination of hydrazine in aqueous solutions at 457 nm.
, in a 1963 humorous essay entitled "You, too, can speak Gaelic,", reprinted in the anthology Adding a Dimension
among others, traces the etymology
of each component of the chemical name "paradimethylaminobenzaldehyde" (e.g. the syllable "-benz-" ultimately derives from the Arabic lubān jāwī (لبان خاوي, "frankincense from Java"). Asimov points out that the name can be pronounced to the tune of the familiar jig
"The Irish Washerwoman
," and relates an anecdote in which a receptionist of Irish descent, hearing him singing the syllables thus, mistook them for the original Gaelic
words to the jig. This essay likely inspired the filk song "The Chemist's Drinking Song," set to the tune of that jig, which begins "Paradimethylaminobenzaldehyde, / Sodium citrate, ammonium cyanide, / ..."
Amine
Amines are organic compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are derivatives of ammonia, wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group. Important amines include amino acids, biogenic amines,...
and aldehyde
Aldehyde
An aldehyde is an organic compound containing a formyl group. This functional group, with the structure R-CHO, consists of a carbonyl center bonded to hydrogen and an R group....
moieties which is used in Ehrlich's reagent for determination of hydrazine.
Urobilinogen determination
It is used in Ehrlich's reagent, which may be used as a TLC stain, or as a reagent to detect urobilinogenUrobilinogen
Urobilinogen is a colourless product of bilirubin reduction. It is formed in the intestines by bacterial action. Some urobilinogen is reabsorbed, taken up into the circulation and excreted by the kidney. This constitutes the normal "enterohepatic urobilinogen cycle".Increased amounts of bilirubin...
in fresh, cool urine
Urine
Urine is a typically sterile liquid by-product of the body that is secreted by the kidneys through a process called urination and excreted through the urethra. Cellular metabolism generates numerous by-products, many rich in nitrogen, that require elimination from the bloodstream...
.If urine sample is left to oxidize in air to form urobilin
Urobilin
Urobilin is a yellow linear tetrapyrrole, resulting from the breakdown of heme, a cyclic tetrapyrrole.Urobilin is produced when Urobilinogen is oxidized by intestinal bacteria; it can also be...
the reagent
Reagent
A reagent is a "substance or compound that is added to a system in order to bring about a chemical reaction, or added to see if a reaction occurs." Although the terms reactant and reagent are often used interchangeably, a reactant is less specifically a "substance that is consumed in the course of...
will not detect the urobilinogen. By adding few drops of reagent to 3 ml of urine in a test tube
Test tube
A test tube, also known as a culture tube or sample tube, is a common piece of laboratory glassware consisting of a finger-like length of glass or clear plastic tubing, open at the top, usually with a rounded U-shaped bottom....
one can see a change of color from above, to dark pink or red. The degree of color change is proportional to the amount of urobilinogen in the urine sample.
Ehrlich's reagent is a strong electrophile which reacts with the electron-rich α-carbon of indole rings to form a blue-coloured adduct. It can be used to detect the presence of indole alkaloids
Indole alkaloids
Indole alkaloids are a class of alkaloids containing a structural moiety of indole; many indole alkaloids also include isoprene groups. Containing more than 4100 known different compounds, it is one of the largest classes of alkaloids. Many of them possess significant physiological activity and...
. Not all indole alkaloids give a coloured adduct as result of steric hindrance which does not allow the reaction to proceed.
Hydrazine determination
p-Dimethylaminobenzaldehyde reacts with hydrazineHydrazine
Hydrazine is an inorganic compound with the formula N2H4. It is a colourless flammable liquid with an ammonia-like odor. Hydrazine is highly toxic and dangerously unstable unless handled in solution. Approximately 260,000 tons are manufactured annually...
to form an azo-dye
Azo compound
Azo compounds are compounds bearing the functional group R-N=N-R', in which R and R' can be either aryl or alkyl. IUPAC defines azo compounds as: "Derivatives of diazene , HN=NH, wherein both hydrogens are substituted by hydrocarbyl groups, e.g. PhN=NPh azobenzene or diphenyldiazene." The more...
, which has a distinct yellow color. It is therefore used for spectrophotometric determination of hydrazine in aqueous solutions at 457 nm.
Isaac Asimov essay
Isaac AsimovIsaac Asimov
Isaac Asimov was an American author and professor of biochemistry at Boston University, best known for his works of science fiction and for his popular science books. Asimov was one of the most prolific writers of all time, having written or edited more than 500 books and an estimated 90,000...
, in a 1963 humorous essay entitled "You, too, can speak Gaelic,", reprinted in the anthology Adding a Dimension
Adding a Dimension
Adding a Dimension is a collection of seventeen scientific essays by Isaac Asimov. It was the third of a series of books collecting essays from The Magazine of Fantasy and Science Fiction...
among others, traces the etymology
Etymology
Etymology is the study of the history of words, their origins, and how their form and meaning have changed over time.For languages with a long written history, etymologists make use of texts in these languages and texts about the languages to gather knowledge about how words were used during...
of each component of the chemical name "paradimethylaminobenzaldehyde" (e.g. the syllable "-benz-" ultimately derives from the Arabic lubān jāwī (لبان خاوي, "frankincense from Java"). Asimov points out that the name can be pronounced to the tune of the familiar jig
Jig
The Jig is a form of lively folk dance, as well as the accompanying dance tune, originating in England in the 16th century and today most associated with Irish dance music and Scottish country dance music...
"The Irish Washerwoman
The Irish Washerwoman
The Irish Washerwoman is a traditional Irish jig whose melody is familiar to many people in the British Isles and North America. It repeats its refrain several times, sometimes by gradually increasing in tempo until being played very fast before coming to a sudden stop. The tune has lyrics, but is...
," and relates an anecdote in which a receptionist of Irish descent, hearing him singing the syllables thus, mistook them for the original Gaelic
Irish language
Irish , also known as Irish Gaelic, is a Goidelic language of the Indo-European language family, originating in Ireland and historically spoken by the Irish people. Irish is now spoken as a first language by a minority of Irish people, as well as being a second language of a larger proportion of...
words to the jig. This essay likely inspired the filk song "The Chemist's Drinking Song," set to the tune of that jig, which begins "Paradimethylaminobenzaldehyde, / Sodium citrate, ammonium cyanide, / ..."