Sinapinic acid

• Trans-3 ,5 -dimethoxy- 4-hydroxycinnamic acid
• (E ) -3,5 -dimethoxy- 4-hydroxycinnamic acid
• (2E ) -3 - ( 4-hydroxy- 3 ,5- dimethoxyphenyl )-2 -propenoic acid

Fixed

202 ° C

Decomposition

Sparingly soluble in water; soluble in methanol (1.04 mol / l ) in ethanol ( 0.79 mol / l) and dissolved in THF ( 0.446 mol / l).

Attention

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Sinapic acid ( trans-3 ,5 -dimethoxy -4 -hydroxycinnamic acid ) belongs to the group of phenylpropanoids or phenolic acids, more of cinnamic acid derivatives. With bases it forms part crystallizable salts which decompose in air.

Occurrence in nature

Sinapic acid is found in nature mainly in rapeseed. The total content of phenolic acids in rapeseed meal is considerably higher than in other oil plants (e.g., peanut: 63.6 mg / 100 g, rape: 639.9 mg / 100 g). The largest proportion of phenolic acids in rapeseed makes 70-85 % from the sinapinic or their esters. In the plant, the sinapinic acid is produced as a product of Zimtsäurebiosynthese. Starting from the amino acid phenylalanine is formed by deamination using the enzyme phenylalanine - ammonia - lyase ( EC 4.3.1.5 ) cinnamic acid. From this arises via caffeic acid, ferulic acid and 5- hydroxyferulic acid sinapic acid.

Use

In analytical chemistry, it is next α - cyano-4- hydroxycinnamic acid ( HCCA ) and 2,5- dihydroxybenzoic acid (DHB ) as the matrix of organic substance in the MALDI-MS (Matrix Assisted Laser Desorption Ionization Mass Spectrometry ) is used.