Primuline
Encyclopedia
Primuline is a dye
containing the benzothiazole
ring system. Primuline itself is also known as Direct yellow 7, Carnotine, or C.I. 49010.
The primulines are considered derivatives of dehydrothiotoluidine (aminobenzenyltoluylmercaptan), which is obtained when para-toluidine
is heated with sulfur
for eighteen hours at 180-190 °C and then for a further six hours at 200-220 °C
Dehydrothiotoluidine is not itself a dye-stuff, but if the heating is carried out at a higher temperature in the presence of more sulfur, then a base is formed, which gives primuline yellow upon sulfonation.
Primuline yellow is a mixture of sodium salts and probably contains at least three thiazole rings in combination. It is a substantive cotton
dye of rather fugitive shade, but can be diazo
tized on the fibre and then developed with other components, yielding a series of ingrain colors.
Primuline is usually available as a sodium salt. Primuline is fluorescent.
Thioflavin T is obtained by the methylation
of dehydrothiotoluidine with methanol
in the presence of hydrochloric acid
. Thioflavin S results from the methylation of dehydrothiotoluidine with sulfonic acid
. This sulfonic acid on oxidation with bleaching powder or with lead peroxide, in alkaline solution yields chloramine yellow, which dyes cotton
a beautiful yellow.
Dye
A dye is a colored substance that has an affinity to the substrate to which it is being applied. The dye is generally applied in an aqueous solution, and requires a mordant to improve the fastness of the dye on the fiber....
containing the benzothiazole
Benzothiazole
Benzothiazole is an aromatic heterocyclic compound with the chemical formula . It is colorless, slightly viscous liquid. Although the parent compound, benzothiazole is not widely used, many of its derivatives are found in commercial products or in nature...
ring system. Primuline itself is also known as Direct yellow 7, Carnotine, or C.I. 49010.
The primulines are considered derivatives of dehydrothiotoluidine (aminobenzenyltoluylmercaptan), which is obtained when para-toluidine
Toluidine
There are three isomers of toluidine, which are organic compounds. These isomers are o-toluidine, m-toluidine, and p-toluidine. The o- stands for ortho- , m- stands for meta- , and p- stands for para-...
is heated with sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...
for eighteen hours at 180-190 °C and then for a further six hours at 200-220 °C
Dehydrothiotoluidine is not itself a dye-stuff, but if the heating is carried out at a higher temperature in the presence of more sulfur, then a base is formed, which gives primuline yellow upon sulfonation.
Primuline yellow is a mixture of sodium salts and probably contains at least three thiazole rings in combination. It is a substantive cotton
Cotton
Cotton is a soft, fluffy staple fiber that grows in a boll, or protective capsule, around the seeds of cotton plants of the genus Gossypium. The fiber is almost pure cellulose. The botanical purpose of cotton fiber is to aid in seed dispersal....
dye of rather fugitive shade, but can be diazo
Diazo
Diazo refers to a type of organic compound called diazo compound that has two linked nitrogen atoms as a terminal functional group. The general formula is R2C=N2. The simplest example of a diazo compound is diazomethane...
tized on the fibre and then developed with other components, yielding a series of ingrain colors.
Primuline is usually available as a sodium salt. Primuline is fluorescent.
Thioflavin T is obtained by the methylation
Methylation
In the chemical sciences, methylation denotes the addition of a methyl group to a substrate or the substitution of an atom or group by a methyl group. Methylation is a form of alkylation with, to be specific, a methyl group, rather than a larger carbon chain, replacing a hydrogen atom...
of dehydrothiotoluidine with methanol
Methanol
Methanol, also known as methyl alcohol, wood alcohol, wood naphtha or wood spirits, is a chemical with the formula CH3OH . It is the simplest alcohol, and is a light, volatile, colorless, flammable liquid with a distinctive odor very similar to, but slightly sweeter than, ethanol...
in the presence of hydrochloric acid
Hydrochloric acid
Hydrochloric acid is a solution of hydrogen chloride in water, that is a highly corrosive, strong mineral acid with many industrial uses. It is found naturally in gastric acid....
. Thioflavin S results from the methylation of dehydrothiotoluidine with sulfonic acid
Sulfonic acid
Sulfonic acid usually refers to a member of the class of organosulfur compounds with the general formula RS2–OH, where R is an alkyl or aryl. The formal part of acid, HS2–OH, are formally derivatives of the "parent" inorganic compound with the formula HSO2.-Preparation:Sulfonic acid is...
. This sulfonic acid on oxidation with bleaching powder or with lead peroxide, in alkaline solution yields chloramine yellow, which dyes cotton
Cotton
Cotton is a soft, fluffy staple fiber that grows in a boll, or protective capsule, around the seeds of cotton plants of the genus Gossypium. The fiber is almost pure cellulose. The botanical purpose of cotton fiber is to aid in seed dispersal....
a beautiful yellow.