Salicylaldehyde
- 2 -hydroxybenzaldehyde
- 2- Formylphenol
Colorless to yellowish liquid with bittermandelartigem odor and burning taste
Liquid
1.17 g · cm -3 ( 20 ° C)
-7 ° C
197 ° C
0,77 hPa ( 25 ° C)
6.79
- Poorly in water ( 14 g · l-1 at 20 ° C)
- Miscible with ethanol and diethyl ether
1.5734
Attention
520 mg · kg -1 ( LD50, rat, oral)
Template: Infobox chemical / molecular formula search available
Salicylaldehyde is a naturally occurring in some plant and insect chemical compound which is today widely used as perfume and in the pharmaceutical and chemical industry will use. It is derived from both the benzaldehyde and phenol. The structure consists of a benzene ring with an added aldehyde ( -CHO) and hydroxy group (-OH) as a substituent. Salicylaldehyde belongs to the group of hydroxybenzaldehydes.
History
At about 1838 succeeded the Swiss pharmacists and pharmacists Johann Pagenstecherstraße to gain from the flowers of meadowsweet salicylaldehyde.
Occurrence
Insects (leaf beetles) produce this compound in special glands against predators from salicin their host plants. It is still in the swamp - Staude Spier or meadowsweet ( Filipendula ulmaria, formerly Spiraea ulmaria ) ago.
Production and representation
Previously salicylaldehyde by the Reimer -Tiemann reaction was (1876, early carbene ) won. Here, chloroform, potassium hydroxide and phenol are used as starting materials. Today is used as an improvement on a phase-transfer catalysis.
Properties
Salicylaldehyde has compared to the phenol (9.99 ) has a much lower pK a values of 6.79; the electron-withdrawing aldehyde group ( -M effect) increase the acidity; the phenolic OH bond is increasingly polarized.
Use
Salicylaldehyde is used as an intermediate in the dye and pharmaceutical industries as well as in 10 % alcoholic solution for the detection of ketones (eg acetone in the urine ) and fusel oils in alcohol. In addition, it is for the preparation of coumarin ( Perkin reaction ) and Schiff bases, such as the complexing agent N, N' -bis (salicylidene ) ethylene diamine (abbreviation: salen), the cobalt (II ) complex ( salcomine ) can reversibly bind oxygen used. It is also used as a fragrance in perfumes.