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Names | |||
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Preferred IUPAC name 2-Hydroxybenzaldehyde [1] | |||
Other names Salicylaldehyde Salicylic aldehyde o-Hydroxybenzaldehyde | |||
Identifiers | |||
3D model (JSmol) | |||
471388 | |||
ChEBI | |||
ChEMBL | |||
ChemSpider | |||
ECHA InfoCard | 100.001.783 | ||
EC Number |
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3273 | |||
KEGG | |||
PubChem CID | |||
UNII | |||
CompTox Dashboard (EPA) | |||
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Properties | |||
C7H6O2 | |||
Molar mass | 122.123 g·mol−1 | ||
Density | 1.146 g/cm3 | ||
Melting point | −7 °C (19 °F; 266 K) | ||
Boiling point | 196 to 197 °C (385 to 387 °F; 469 to 470 K) | ||
-64.4·10−6 cm3/mol | |||
Hazards [2] | |||
GHS labelling: | |||
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Warning | |||
H302, H315, H317, H319, H335, H411 | |||
P280, P305+P351+P338 | |||
Safety data sheet (SDS) | [2] | ||
Related compounds | |||
Related compounds | Salicylic acid Benzaldehyde Salicylaldoxime | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
Salicylic aldehyde (2-hydroxybenzaldehyde) is an organic compound with the formula C6H4OH(CHO). [3] [4] Along with 3-hydroxybenzaldehyde and 4-hydroxybenzaldehyde, it is one of the three isomers of hydroxybenzaldehyde. This colorless oily liquid has a bitter almond odor at higher concentration. Salicylaldehyde is a precursor to coumarin and a variety of chelating agents.
Salicylaldehyde is produced by condensation of phenol with formaldehyde to give hydroxybenzyl alcohol, which is oxidized to the aldehyde. [4] Salicylaldehydes in general are prepared by ortho-selective formylation reactions from the corresponding phenol, for instance by the Duff reaction, Reimer–Tiemann reaction, or by treatment with paraformaldehyde in the presence of magnesium chloride and a base. [5] [6]
Salicylaldehyde is a characteristic aroma component of buckwheat. [7] Salicylaldehyde also occurs in the larval defensive secretions of several leaf beetle species that belong the subtribe Chrysomelina. [8] An example for a leaf beetle species that produces salicylaldehyde is the red poplar leaf beetle Chrysomela populi .
Salicylaldehyde is mainly used commercially as a precursor to coumarin. The conversion entails condensation with acetic anhydride ("Perkin synthesis"). [4]
Elbs persulfate oxidation gives gentisaldehyde (2,5-dihydroxybenzaldehyde). [14] [15]
Due to the ortho positioning of the hydroxy- and aldehyde groups, an internal hydrogen bond is formed between the groups. The hydroxy group serves here as the hydrogen bond donor, and the aldehyde as hydrogen bond acceptor. This internal hydrogen is not found in the other hydroxybenzaldehyde isomers. When the aldehyde is reacted with an amine to form an imine, the internal hydrogen bond is even stronger. [16] In addition, tautomerisation further increases the stability of the compound. [17] The internal hydrogen bond also ensures that the aldehyde (or corresponding imine) is held into the same plane, making the whole molecule essentially flat. [18]
In organic chemistry, a ketone is an organic compound with the structure R−C(=O)−R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group −C(=O)−. The simplest ketone is acetone, with the formula (CH3)2CO. Many ketones are of great importance in biology and industry. Examples include many sugars (ketoses), many steroids, and the solvent acetone.
In organic chemistry, an imine is a functional group or organic compound containing a carbon–nitrogen double bond. The nitrogen atom can be attached to a hydrogen or an organic group (R). The carbon atom has two additional single bonds. Imines are common in synthetic and naturally occurring compounds and they participate in many reactions.
In organic chemistry, nitro compounds are organic compounds that contain one or more nitro functional groups. The nitro group is one of the most common explosophores used globally. The nitro group is also strongly electron-withdrawing. Because of this property, C−H bonds alpha (adjacent) to the nitro group can be acidic. For similar reasons, the presence of nitro groups in aromatic compounds retards electrophilic aromatic substitution but facilitates nucleophilic aromatic substitution. Nitro groups are rarely found in nature. They are almost invariably produced by nitration reactions starting with nitric acid.
Cyclohexene is a hydrocarbon with the formula (CH2)4C2H2. It is an example of a cycloalkene. At room temperature, cyclohexene is a colorless liquid with a sharp odor. Among its uses, it is an intermediate in the commercial synthesis of nylon.
Benzofuran is the heterocyclic compound consisting of fused benzene and furan rings. This colourless liquid is a component of coal tar. Benzofuran is the structural nucleus of many related compounds with more complex structures. For example, psoralen is a benzofuran derivative that occurs in several plants.
In organic chemistry, enolates are organic anions derived from the deprotonation of carbonyl compounds. Rarely isolated, they are widely used as reagents in the synthesis of organic compounds.
In organic chemistry, the Knoevenagel condensation reaction is a type of chemical reaction named after German chemist Emil Knoevenagel. It is a modification of the aldol condensation.
The Vilsmeier–Haack reaction (also called the Vilsmeier reaction) is the chemical reaction of a substituted formamide (1) with phosphorus oxychloride and an electron-rich arene (3) to produce an aryl aldehyde or ketone (5):
The Duff reaction or hexamine aromatic formylation is a formylation reaction used in organic chemistry for the synthesis of benzaldehydes with hexamine as the formyl carbon source. The method is generally inefficient. The reaction is named after James Cooper Duff.
In organic chemistry, an iminium cation is a polyatomic ion with the general structure [R1R2C=NR3R4]+. They are common in synthetic chemistry and biology.
o-Phenylenediamine (OPD) is an organic compound with the formula C6H4(NH2)2. This aromatic diamine is an important precursor to many heterocyclic compounds. OPD is a white compound although samples appear darker owing to oxidation by air. It is isomeric with m-phenylenediamine and p-phenylenediamine.
The Reimer–Tiemann reaction is a chemical reaction used for the ortho-formylation of phenols. with the simplest example being the conversion of phenol to salicylaldehyde. The reaction was first reported by Karl Reimer and Ferdinand Tiemann.
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.
The Gattermann reaction (also known as the Gattermann formylation and the Gattermann salicylaldehyde synthesis) is a chemical reaction in which aromatic compounds are formylated by a mixture of hydrogen cyanide (HCN) and hydrogen chloride (HCl) in the presence of a Lewis acid catalyst such as aluminium chloride (AlCl3). It is named for the German chemist Ludwig Gattermann and is similar to the Friedel–Crafts reaction.
The Hoesch reaction or Houben–Hoesch reaction is an organic reaction in which a nitrile reacts with an arene compound to form an aryl ketone. The reaction is a type of Friedel-Crafts acylation with hydrogen chloride and a Lewis acid catalyst.
In nitrile reduction a nitrile is reduced to either an amine or an aldehyde with a suitable chemical reagent.
Rieche formylation is a type of formylation reaction. The substrates are electron rich aromatic compounds, such as mesitylene or phenols, with dichloromethyl methyl ether acting as the formyl source. The catalyst is titanium tetrachloride and the workup is acidic. The reaction is named after Alfred Rieche who discovered it in 1960.
Imidoyl chlorides are organic compounds that contain the functional group RC(NR')Cl. A double bond exist between the R'N and the carbon centre. These compounds are analogues of acyl chloride. Imidoyl chlorides tend to be highly reactive and are more commonly found as intermediates in a wide variety of synthetic procedures. Such procedures include Gattermann aldehyde synthesis, Houben-Hoesch ketone synthesis, and the Beckmann rearrangement. Their chemistry is related to that of enamines and their tautomers when the α hydrogen is next to the C=N bond. Many chlorinated N-heterocycles are formally imidoyl chlorides, e.g. 2-chloropyridine, 2, 4, and 6-chloropyrimidines.
Hydroxymethylation is a chemical reaction that installs the CH2OH group. The transformation can be implemented in many ways and applies to both industrial and biochemical processes.
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