Photographic processing or photographic development is the chemical means by which photographic film or paper is treated after photographic exposure to produce a negative or positive image. Photographic processing transforms the latent image into a visible image, makes this permanent and renders it insensitive to light.
In chemistry, azide is a linear, polyatomic anion with the formula N−3 and structure −N=N+=N−. It is the conjugate base of hydrazoic acid HN3. Organic azides are organic compounds with the formula RN3, containing the azide functional group. The dominant application of azides is as a propellant in air bags.
The quinones are a class of organic compounds that are formally "derived from aromatic compounds [such as benzene or naphthalene] by conversion of an even number of –CH= groups into –C(=O)– groups with any necessary rearrangement of double bonds", resulting in "a fully conjugated cyclic dione structure". The archetypical member of the class is 1,4-benzoquinone or cyclohexadienedione, often called simply "quinone". Other important examples are 1,2-benzoquinone (ortho-quinone), 1,4-naphthoquinone and 9,10-anthraquinone.
In the processing of photographic films, plates or papers, the photographic developer is one or more chemicals that convert the latent image to a visible image. Developing agents achieve this conversion by reducing the silver halides, which are pale-colored, into silver metal, which is black when in the form of fine particles. The conversion occurs within the gelatine matrix. The special feature of photography is that the developer acts more quickly on those particles of silver halide that have been exposed to light. When left in developer, all the silver halides will eventually be reduced and turn black. Generally, the longer a developer is allowed to work, the darker the image.
Cinnamaldehyde is an organic compound with the formula or C₆H₅CH=CHCHO. Occurring naturally as predominantly the trans (E) isomer, it gives cinnamon its flavor and odor. It is a phenylpropanoid that is naturally synthesized by the shikimate pathway. This pale yellow, viscous liquid occurs in the bark of cinnamon trees and other species of the genus Cinnamomum. It is an essential oil. The bark of cinnamon tree contains high concentrations of cinnamaldehyde.
Zileuton (trade name Zyflo) is an orally active inhibitor of 5-lipoxygenase, and thus inhibits leukotrienes (LTB4, LTC4, LTD4, and LTE4) formation, used for the maintenance treatment of asthma. Zileuton was introduced in 1996 by Abbott Laboratories and is now marketed in two formulations by Cornerstone Therapeutics Inc. under the brand names Zyflo and Zyflo CR. The original immediate-release formulation, Zyflo, is taken four times per day. The extended-release formulation, Zyflo CR, is taken twice daily.
Metol (or Elon) is a trade name for the organic compound with the formula [HOC6H4NH2(CH3)]2HSO4. It is the sulfate salt of N-methylaminophenol. This colourless salt is a popular photographic developer used in monochrome photography.
Hydroquinone, also known as benzene-1,4-diol or quinol, is an aromatic organic compound that is a type of phenol, a derivative of benzene, having the chemical formula C6H4(OH)2. It has two hydroxyl groups bonded to a benzene ring in a para position. It is a white granular solid. Substituted derivatives of this parent compound are also referred to as hydroquinones. The name "hydroquinone" was coined by Friedrich Wöhler in 1843.
Pyrogallol is an organic compound with the formula C6H3(OH)3. It is a water-soluble, white solid although samples are typically brownish because of its sensitivity toward oxygen. It is one of three isomers of benzenetriols.
1,4-Benzoquinone, commonly known as para-quinone, is a chemical compound with the formula C6H4O2. In a pure state, it forms bright-yellow crystals with a characteristic irritating odor, resembling that of chlorine, bleach, and hot plastic or formaldehyde. This six-membered ring compound is the oxidized derivative of 1,4-hydroquinone. The molecule is multifunctional: it exhibits properties of a ketone, being able to form oximes; an oxidant, forming the dihydroxy derivative; and an alkene, undergoing addition reactions, especially those typical for α,β-unsaturated ketones. 1,4-Benzoquinone is sensitive toward both strong mineral acids and alkali, which cause condensation and decomposition of the compound.
The Dakin oxidation (or Dakin reaction) is an organic redox reaction in which an ortho- or para-hydroxylated phenyl aldehyde (2-hydroxybenzaldehyde or 4-hydroxybenzaldehyde) or ketone reacts with hydrogen peroxide (H2O2) in base to form a benzenediol and a carboxylate. Overall, the carbonyl group is oxidised, whereas the H2O2 is reduced.
β-Arbutin, also known by its International Nomenclature of Cosmetic Ingredients (INCI) name, arbutin, is a glycosylated derivative of hydroquinone. β-Arbutin is naturally present in the leaves and bark of a variety of plants, notably the bearberry plant, Arctostaphylos uva-ursi. Utilized as a biosynthetic active ingredient in topical treatments for skin lightening, β-arbutin is aimed at addressing hyperpigmentation issues. Its mechanism of action involves inhibiting the activity of tyrosinase, an essential enzyme for melanin synthesis in the human skin, thereby leading to a reduction in hyperpigmentation. It is important to distinguish β-arbutin from its structurally similar stereoisomer, α-arbutin, which exhibits similar effects in clinical applications.
Valerophenone, or butyl phenyl ketone, is an aromatic ketone with the formula C6H5C(O)C4H9. It is a colorless liquid that is soluble in organic solvents. It is usually prepared by the acylation of benzene using valeryl chloride.
Boswellic acids are a series of pentacyclic terpenoid molecules that are produced by plants in the genus Boswellia. Like many other terpenes, boswellic acids appear in the resin of the plant that exudes them; it is estimated that they make up 30% of the resin of Boswellia serrata. While boswellic acids are a major component of the resin, the steam or hydro distilled frankincense essential oil does not contain any boswellic acid as these components are non-volatile and too large to come over in the steam distillation process.
Photographic developer solutions may contain more than one developing agents, such as Metol and hydroquinone, or Phenidone and hydroquinone. This is because they work together to a synergistic effect, called superadditive development.
Arachidonate 5-lipoxygenase inhibitors are compounds that slow or stop the action of the arachidonate 5-lipoxygenase enzyme, which is responsible for the production of inflammatory leukotrienes. The overproduction of leukotrienes is a major cause of inflammation in asthma, allergic rhinitis, and osteoarthritis.
ALOX15 is, like other lipoxygenases, a seminal enzyme in the metabolism of polyunsaturated fatty acids to a wide range of physiologically and pathologically important products. ▼ Gene Function
FX-55 is an 'eco-friendly' photographic developer for monochrome film devised by Geoffrey Crawley. It was first published in Amateur Photographer.
In polymer chemistry, polymerisation inhibitors are chemical compounds added to monomers to prevent their self-polymerisation. Unsaturated monomers such as acrylates, vinyl chloride, butadiene and styrene require inhibitors for both processing and safe transport and storage. Many monomers are purified industrially by distillation, which can lead to thermally-initiated polymerisation. Styrene, for example, is distilled at temperatures above 100 °C whereupon it undergoes thermal polymerisation at a rate of ~2% per hour. This polymerisation is undesirable, as it can foul the fractionating tower; it is also typically exothermic, which can lead to a runaway reaction and potential explosion if left unchecked. Once initiated, polymerisation is typically radical in mechanism and as such many polymerisation inhibitors act as radical scavengers.
Furegrelate, also known as 5-(3-pyridinylmethyl)benzofurancarboxylic acid, is a chemical compound with thromboxane enzyme inhibiting properties that was originally developed by Pharmacia Corporation as a drug to treat arrhythmias, ischaemic heart disorders, and thrombosis but was discontinued. It is commercially available in the form furegrelate sodium salt.
