Hydroxycinnamate

The stabili2ation of polyolefins used to insulate copper conductors requires the use of a long-term antioxidant plus a copper deactivator. Both A[,Ar-bis(3,5-di-/ A-butyl-4-hydroxycinnamoyl)hydra2ine (29) and 2,2 -oxamidobisethyl(3,5-di-/ A-butyl-4-hydroxycinnamate) (30) are bifimctional. They are persistent antioxidants that have built-in metal deactivators. Oxalyl bis(ben2yhdenehydra2ide) (28) is an effective copper deactivator when part of an additive package that includes an antioxidant. 

Hydroxycinnamic acid (p-coumaric acid) [501-98-4] M 164.2, m 210-213 , 214-215 , 215 pK 4.64, pKj 9.45. Crystd from H2O (charcoal). Needles from cone aqueous solutions as the anhydrous acid, but from hot dilute solutions the monohydrate acid separates on slow cooling. The acid (33g) has been recrystd from 2.5L of H2O (1.5g charcoal) yielding 28.4g of recrystd acid, m 207°. It is insol in CgH6 or pet ether. The UV in 95% EtOH has 223 and 286nm (e 14,450 and 19000 M cm ). [UV Wheeler and Covarrubias J Org Chem 28 2015 7965 Corti Helv Chim Acta 32 681 1949.]... 

Chemical Name Methyireserpate 3 -methoxy-4 -hydroxycinnamate Common Name —... 

The chloroform layer was dried over sodium sulfate, and the solvent was evaporated, so that there was obtained a brown amorphous matter. This was recrystalllzed from chloroform-hexane, and there was then obtained 1.0 g (78% of yield) of methyireserpate 3 -methoxy-4 -hydroxycinnamate which was characterized as pale yellow needles having a melting point of 259°C to 260°C. 

When the substituent groups in the polyphosphazenes were azobenzene [719] or spiropyran [720] derivatives, photochromic polymers were obtained, showing reversible light-induced trans-cis isomerization or merocyanine formation, respectively. Only photocrosslinking processes by [2+2] photo-addition reactions to cyclobutane rings could be observed when the substituent groups on the phosphazene backbone were 4-hydroxycinnamates [721-723] or 4-hydroxychalcones [722-724]. 

The decarboxylation of 4-hydroxycinnamic acid to 4-hydroxystyrene, and of fernlic acid (3-methoxy-4-hydroxycinnamic acid) to 4-vinylgnaiacol by several strains of Haf-nia alvei and H. protea, and by single strains of Enterobacter cloacae and K. aerogenes (Fignre 2.7d) (Findsay and Priest 1975). The decarboxylase has been pnrihed from Bacillus pumilis (Degrassi et al. 1995). 

The metabolism of ferulic acid (3-methoxy-4-hydroxycinnamic acid) by Ent. cloacae to a nnmber of products including phenylpropionate and benzoate (Fignre 2.8) (Grbic-Galic 1986). 

Decarboxylation of aromatic carboxylic acids has been encountered extensively in facultatively anaerobic Enterobacteriaceae. For example, 4-hydroxycinnamic acid is... 

FIGURE 8.32 Decarboxylation of ferulic acid (3-methoxy-4-hydroxycinnamic acid). 

Despite the large number whole-cell MALDI protocols that have been tested a single approach has not yet been widely adopted. There remain different and sometimes conflicting reports in the literature regarding optimum methodologies.3 In addition to the ferulic acid matrix mentioned above sinapinic acid, a-yano-4-hydroxycinnamic acid, 2,4-hydroxyphenyl benzoic... 

The MALDI-TOF technique was first developed for the analysis of large biomolecules (Karas and others 1987). This technique presents some interesting characteristics. Of these, the high speed of analysis and the sensitivity of the technique have been pointed out as important advantages compared with other methods. In MALDI the samples are cocrystallized with a matrix that is usually composed of organic compounds, such as 3,5-dimethoxy-4-hydroxycinnamic acid (sinapic acid), 2, 4, 6 -trihydroxyacetophenone, a-cyano-4-hydroxycinnamic acid (alpha-cyano or alpha-matrix), and 2,5-dihydroxybenzoic acid (DHB). After the cocrystallization, the laser is fired and the matrix absorbs energy and allows a soft ionization of the samples. Afterward the ions are analyzed by a TOF mass spectrometer. 

The key reaction that links primary and secondary metabolism is provided by the enzyme phenylalanine ammonia lyase (PAL) which catalyzes the deamination of l-phenylalanine to form iran.v-cinnamic acid with the release of NH3 (see Fig. 3.3). Tyrosine is similarly deaminated by tyrosine ammonia lyase (TAL) to produce 4-hydroxycinnamic acid and NH3. The released NH3 is probably fixed by the glutamine synthetase reaction. These deaminations initiate the main phenylpropanoid pathway. 

A series of subsequent reactions after PAL first introduces a hydroxyl at the 4-position of the ring of cinnamic acid to form p- or 4-coumaric acid (i.e., 4-hydroxycinnamic acid). Addition of a second hydroxyl at the 3-position yields caffeic acid, whereas O-methylation of this hydroxyl group produces ferulic acid (see Fig. 3.3). Two additional enzymatic reactions are necessary to produce sinapic acid. These hy-drocinnamic acids are not found in significant amounts in plant tissue because they are rapidly converted to coenzyme A esters, or glucose esters. These activated intermediates form an important branch point because they can participate in a wide range of subsequent reactions. 

J. Gobom, M. Schuerenberg, M. Mueller, D. Theiss, H. Lehrach, and E. Nordhoff. a-Cyano-4-hydroxycinnamic Acid Affinity Sample Preparation. A Protocol for MALDI-MS Peptide Analysis in Proteomics. Anal. Chem., 73(2001) 434-438. 

Note It is commonplace to use acronyms rather than compound names for matrices. However, these are not always consistently used, e.g., a-CHC, 4-HCCA, CHCA, and CCA all refer to a-cyano-4-hydroxycinnamic acid. Others may be easily confused, e.g., nicotinic acid (NA) and 9-nitroanthracene (9-NA). 

Beavis, R.C. Chaudhary, T. Chait, B.T. a-Cyano-4-Hydroxycinnamic Acid As a Matrix for Matrix-Assisted Laser Desorp-tion-MS. Org. Mass Spectrom. 1992, 27, 156-158. 

Dry salt grass, Distichlis stricta, has high levels of phenolics after fruiting. Cinnamic acids and their vinyl phenols lower uterus weight, inhibit follicular development, and lead to cessation of reproductive activity in the montane vole Microtus montanus. Specific active compounds are 4-vinylguaiacol and 4-vinylphenol, and alsop-coumaric acid (4-hydroxycinnamic acid) (Berger etal, 1977). 

Alkaloids 36-41 were isolated from Lupinus luteus L. seedlings. They are considered to be lupinine esters with 4-hydroxycinnamic acids (94-100). The structures of these new alkaloids were elucidated on the basis of H NMR, MS, and chemical and enzymatic transformations. All these alkaloids were obtained from lupinine and hydroxycinnamic acid by two enzymatic systems (96-97) ligase catalyzed formation of the CoA-thioester, and transferase catalyzed lupinine ester formation from the CoA-thioester. 

Notes CHCA, ct-cyano-4-hydroxycinnamic acid DHB, 2,5-dihydroxybenzoic acid lAA, tra/jx-3-indoleacrylic acid THAP, 2,4,6-trihydroxyacetophenone monohydrate. 

In the last years, ILs have been applied as matrices for matrix-assisted laser desorption/ionization (MALDI) MS [42], thus expanding the use of MALDI. In Ref. 38 the suitability of alkylammonium- and alkylimidazolium salts of a-cyano-4-hydroxycinnamic acid was investigated as a MALDI matrix and at the same time as the additive of BGE. The alkylammonium salt produced better separation of phenolic compounds than the alkylimidazolium salt. The investigation suggests that it is possible to synthesize ILs suitable for electrophoretic analysis as well as for online MALDI-MS analysis. 

Most commonly used matrix systems are derivatives of benzoic acid (e.g., 2,5-dihydroxybenzoic acid (DHB), derivatives of cinnamic acid (e.g., a-cyano-4-hydroxycinnamic acid (CHCA) or sinapinic acid (SA) (Figure 14.6) as well as heteroaromatic compounds containing nitrogen but numberless other substances and substance classes have been applied as matrices [36]. 

Coumaric acid (or 4-hydroxycinnamic acid) R = H Caffeic acid (or 3,4-dihydroxycinnamic acid) R = OH Cinnamaldehyde... 

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