Cinnamic acid, 3,4-dimethoxy

For PMMA/additive dissolutions, it was not possible to identify any additive characteristic mass peaks, either by direct laser desorption or with matrix-assistance (dithranol, DHBA or sinapinic acid, 4-hydroxy-3,5-dimethoxy-cinnamic acid). This has again been ascribed to very strong interaction between PMMA and additives, which suppresses desorption of additive molecules. Also, partial depolymerisation of pho-tolytically labile PMMA by laser irradiation may play a role, which leads to saturation of the detector by PMMA fragment-ions and disappearance of additive mass peaks below noise level. Meyer-Dulheuer [55] has also reported MALDI-TOFMS analysis of a coating/2-ethylhexyldiphenylphosphate sample. Quantitative determination of the additives by means of MALDI-ToFMS proved impossible. Possibly the development of reproducible (automated) sample handling procedures or thin films might overcome this problem. 

The most common cinnamic acids are caffeic (3,4-dihydroxycinnamic acid), ferulic (3-methoxy-4-hydroxy), sinapic (3,5-dimethoxy-4-hydroxy) and p-coumaric (4-hydroxy) acid, Table 4 [13]. 

Unsaturated Lignin Model Compounds Double bonds in lignin model compounds are attacked by peracetate ions. Dehydro-di-woeugenol (XXI, Figure 12.9) reacted with epoxidation of the aliphatic double bond and formation of the diol. The double bonds in stilbenes [59] and coniferaldehyde [90] are also cleaved. FemUc acid (IVa) and its ethyl ester reacted slowly at 50°C the methyl ether, 3,4-dimethoxy cinnamic acid, was much less reactive and was almost quantitatively recovered [55]. The reactions of ferulic acid and its ethyl ester (both in the trans form) were accompanied by trans-cis isomerization, perhaps an indication of reversible phenoxy radical formation. HomovanilUc acid (XXXa) was also formed the proposed mechanism involved epoxidation of the a-P double bonds followed by decarboxylation. 

A cyclization of a dimethoxy cinnamic acid to a coumarin derivative is presented by... 

Cinnamic acid, 3,5-dimethoxy- sinapic acid 52. Phenol, 5-methyl-2-(l-methylethyl)- thymol... 

The most commonly used matrices for synthetic polymers are DHB (2,5-dihydroxybenzoic acid), HABA (2,(-4-hydroxyphenylazo)benzoic acid), lAA (3-j3-indoleacrylc acid), dithranol (1,8,9-trihydroxyanthracene), sinapinic acid (3,5-dimethoxy-4-hydroxy cinnamic acid), all trans-retinoic acid, and 5-chlorosalicylic acid. Exhaustive lists of useful matrices are available in the literature. ... 

SIA (4-Hydroxy-3,5-Dimethoxy-Cinnamic Acid) (Fig. 63.2) is a phenylpropanoid compound found in various herbal materials and high-bran cereals. It has been reported that sinapic acid has antioxidant efficacy as a metal chelator due to the orientation of functional groups. Administration of sinapic acid exhibited significant reversal of arsenic-induced toxicity in hepatic tissue [68]. 

The most common unsaturated aromatic carboxylic acid is cinnamic acid (8-73). In cinnamon and other spices the (E)-isomer predominates. Cinnamic acid oxidation products are 4-hydroxycinnamic acid (also known as 4-coumaric or p-coumaric acid) and 3,4-dihydroxycinnamic acids, which is called caffeic acid. A 3-methoxy derivative of caffeic acid is feruhc acid and the 3,5-dimethoxy derivative is known as sinapic acid. 

Qiao HY, Dahiya JP, Classen HL. 2008. Nutritional and physiological effects of dietary sinapic acid (4-hydroxy-3,5-dimethoxy-cinnamic acid) in broiler chickens and its metabolism in the digestive tract. Poultry Science, 87(4) 719-726. 

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