Protocatechualdehyde
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| General | |||||||||||||||||||
| Surname | Protocatechualdehyde | ||||||||||||||||||
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| Molecular formula | C 7 H 6 O 3 | ||||||||||||||||||
| Brief description |
beige solid |
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| properties | |||||||||||||||||||
| Molar mass | 138.12 g mol −1 | ||||||||||||||||||
| Physical state |
firmly |
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| Melting point |
150-157 ° C |
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| solubility |
poor in water (6.3 g l −1 at 20 ° C) |
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| As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . | |||||||||||||||||||
Protocatechualdehyde ( 3,4-dihydroxybenzaldehyde ) is an aromatic aldehyde . It occurs glycosidically bound in vanilla . It also arises from the decomposition of the aromatic substance piperonal (= "methylene protocatechualdehyde") through the action of atmospheric oxygen, light and heat. The material is an intermediate in the preparation of the substances vanillin , ethyl vanillin and piperonal as well as the carrier substance ( neurotransmitter ) dopamine . Protocatechualdehyde can be enzymatically oxidized to protocatechuic acid.
Extraction and presentation
Protocatechualdehyde can be produced from catechol , from piperonal and by demethylating vanillin. Whereas in the past the production from piperonal was the usual approach, today it is mainly made from vanillin:
- Autoclaving at 160–170 ° C of vanillin with dilute hydrochloric acid .
- Cooking vanillin with anhydrous aluminum chloride and pyridine .
- Implementation of vanillin with anhydrous aluminum bromide and nitrobenzene .
- Conversion of vanillin with mercury-activated aluminum and elemental bromine in nitrobenzene .
Individual evidence
- ↑ Entry on PROTOCATECHUICALDEHYDE in the CosIng database of the EU Commission, accessed on May 14, 2020.
- ↑ a b c d data sheet 3,4-dihydroxybenzaldehyde from Sigma-Aldrich , accessed on May 14, 2017 ( PDF ).
- ↑ Data sheet 3,4-dihydroxybenzaldehyde (PDF) from Merck , accessed on May 14, 2020.
- ↑ Georgios I. Panoutsopoulos, Christine Beedham: Enzymatic Oxidation of Vanillin, Isovanillin and Protocatechuic Aldehyde with Freshly Prepared Guinea Pig Liver Slices , in: Cell Physiol Biochem , 2005 , 15 (1-4) , pp. 89-98; PMID 15665519 ; PDF .
- ↑ Fragrance Lexicon: Protocatechualdehyde ( Memento of March 17, 2004 in the Internet Archive )
- ^ Karl Hell, Carl Haussermann: New Concise Dictionary of Chemistry , 784 (1875).
- ↑ Robert G. Lange: Cleavage of Alkyl o -hydroxyphenyl Ethers , in: J. Org. Chem. , 1962 , 27 (6) , pp. 2037-2039; doi : 10.1021 / jo01053a030 .
- ^ A. Pearl, DL Beyer: Reactions of Vanillin and its Derived Compounds. XXII. Ethers of Protocatechuic Acid and their Ethyl Esters , in: J. Am. Chem. Soc. , 1953 , 75 (11) , pp. 2630-2633; doi : 10.1021 / ja01107a022 .
- ↑ US patent US2975214.
Web links
- Fragrance lexicon: Protocatechualdehyde ( Memento from March 17, 2004 in the Internet Archive )