Crystal violet lactone
Encyclopedia
Crystal violet lactone is a leuco dye
, a lactone
derivate of crystal violet
10B. In pure state it is a slightly yellowish crystalline powder, soluble in nonpolar or slightly polar organic solvents.
The central carbon in the leuco
form is in a tetraedric configuration, forming four covalent bond
s.
In acidic environment the lactone
ring is broken, the central carbon loses one valence and becomes a resonance stabilized carbocation
(although it might be better to draw the resonance structure with the cation on nitrogen), this planar carbon interconnecting the π systems of the aromatic rings and the amino functional group
s to form one large conjugated system
acting as a chromophore
with strong absorption in visible spectrum
, giving this compound its distinctive color.
It was the first dye used in carbonless copy paper
s, and it is still widely used in this application. It is also the leuco dye
component in some thermochromic dyes, e.g. in the Hypercolor
line of clothing. One of its novel uses is a security marker for fuels
.
It may cause allergic contact dermatitis
in people handling the carbonless copy paper.
Leuco dye
A leuco dye is a dye whose molecules can acquire two forms, one of which is colorless.For example, the spiro form of an oxazine is a colorless leuco dye; the conjugated system of the oxazine and another aromatic part of the molecule is separated by an sp3-hybridized "spiro" carbon...
, a lactone
Lactone
In chemistry, a lactone is a cyclic ester which can be seen as the condensation product of an alcohol group -OH and a carboxylic acid group -COOH in the same molecule...
derivate of crystal violet
Crystal violet
Crystal violet or Gentian violet is a triarylmethane dye. The dye is used as a histological stain and in Gram’s method of classifying bacteria. Crystal violet has antibacterial, antifungal, and anthelmintic properties and was formerly important as a topical antiseptic...
10B. In pure state it is a slightly yellowish crystalline powder, soluble in nonpolar or slightly polar organic solvents.
The central carbon in the leuco
Leuco dye
A leuco dye is a dye whose molecules can acquire two forms, one of which is colorless.For example, the spiro form of an oxazine is a colorless leuco dye; the conjugated system of the oxazine and another aromatic part of the molecule is separated by an sp3-hybridized "spiro" carbon...
form is in a tetraedric configuration, forming four covalent bond
Covalent bond
A covalent bond is a form of chemical bonding that is characterized by the sharing of pairs of electrons between atoms. The stable balance of attractive and repulsive forces between atoms when they share electrons is known as covalent bonding....
s.
In acidic environment the lactone
Lactone
In chemistry, a lactone is a cyclic ester which can be seen as the condensation product of an alcohol group -OH and a carboxylic acid group -COOH in the same molecule...
ring is broken, the central carbon loses one valence and becomes a resonance stabilized carbocation
Carbocation
A carbocation is an ion with a positively-charged carbon atom. The charged carbon atom in a carbocation is a "sextet", i.e. it has only six electrons in its outer valence shell instead of the eight valence electrons that ensures maximum stability . Therefore carbocations are often reactive,...
(although it might be better to draw the resonance structure with the cation on nitrogen), this planar carbon interconnecting the π systems of the aromatic rings and the amino functional group
Functional group
In organic chemistry, functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. The same functional group will undergo the same or similar chemical reaction regardless of the size of the molecule it is a part of...
s to form one large conjugated system
Conjugated system
In chemistry, a conjugated system is a system of connected p-orbitals with delocalized electrons in compounds with alternating single and multiple bonds, which in general may lower the overall energy of the molecule and increase stability. Lone pairs, radicals or carbenium ions may be part of the...
acting as a chromophore
Chromophore
A chromophore is the part of a molecule responsible for its color. The color arises when a molecule absorbs certain wavelengths of visible light and transmits or reflects others. The chromophore is a region in the molecule where the energy difference between two different molecular orbitals falls...
with strong absorption in visible spectrum
Visible spectrum
The visible spectrum is the portion of the electromagnetic spectrum that is visible to the human eye. Electromagnetic radiation in this range of wavelengths is called visible light or simply light. A typical human eye will respond to wavelengths from about 390 to 750 nm. In terms of...
, giving this compound its distinctive color.
It was the first dye used in carbonless copy paper
Carbonless copy paper
Carbonless copy paper , non-carbon copy paper, or NCR paper is an alternative to carbon paper, used to make a copy of an original, handwritten document without the use of any electronics...
s, and it is still widely used in this application. It is also the leuco dye
Leuco dye
A leuco dye is a dye whose molecules can acquire two forms, one of which is colorless.For example, the spiro form of an oxazine is a colorless leuco dye; the conjugated system of the oxazine and another aromatic part of the molecule is separated by an sp3-hybridized "spiro" carbon...
component in some thermochromic dyes, e.g. in the Hypercolor
Hypercolor
Hypercolor was a line of clothing, mainly T-shirts and shorts, that changed color with heat.They were manufactured by Generra Sportswear Company of Seattle and marketed in the United States as Generra Hypercolor or Generra Hypergrafix and outside the US as Global Hypercolor...
line of clothing. One of its novel uses is a security marker for fuels
Fuel dyes
Fuel dyes are dyes added to fuels, as in some countries it is required by law to dye a low-tax fuel to deter its use in applications intended for higher-taxed ones...
.
It may cause allergic contact dermatitis
Contact dermatitis
Contact dermatitis is a term for a skin reaction resulting from exposure to allergens or irritants . Phototoxic dermatitis occurs when the allergen or irritant is activated by sunlight....
in people handling the carbonless copy paper.