Cinnamic anhydride

More commonly a combination of techniques is used as illustrated by the following study. The reaction is the acylation of allylamine by rrans-cinnamic anhydride, Eq. (2-34). 

The initial anhydride concentration was about 3 x 10 M, and the amine concentration was much larger than this. The reaction was followed spectrophoto-metrically, and good first-order kinetics were observed hence, the reaction is first-order with respect to cinnamic anhydride. It was not convenient analytically to use the isolation technique to determine the order with respect to allylamine, because it is easier to observe the cinnamoyl group spectrophotometrically than to follow the loss of amine. Therefore, the preceding experiment was repeated at several amine concentrations, and from the first-order plots the pseudo-first-order rate constants were determined. These data are shown in Table 2-1. Letting A represent... 

Figure 6-4 is a plot according to Eq. (6-46) for the hydrolysis of trans-cinnamic anhydride in the presence of carbonate buffers. The nonzero slopes indicate the existence of buffer catalysis, and the increasing slope value with increasing pH shows that /cb must be larger than k. From the intercepts ko is obtained at each pH, and the plot according to Eq. (6-47) is shown in Fig. 6-5. This plot shows that k is negligible. With this information, Eq. (6-46) can be simplified to...

Figure 6-4. Plol of Eq. (6-46) for the hydrolysis of cinnamic anhydride at 25°C and ionic strength 0.1 M in carbonate buffers. fi, represents the total buffer concentration. From top to bottom, pH = 10.06, 9.76, and 9.14.

These are rate constants for the hydrolysis of cinnamic anhydride in bicarbonate-carbonate buffers. The pK of bicarbonate is 10.22. Find the rate constant for hydrolysis, at each pH, at zero buffer concentration. Analyze the data to determine if the acid or base component of the buffer, or both, are responsible for catalysis, and give the catalytic rate constant(s). 

The following data are for the hydrolysis of cinnamic anhydride in (2-amino-2-hydroxymethyl-1,3-propane diol buffers. Extrapolate them to zero buffer concentration, and, together with data from Problem 9, plot the pH-rate profile. Determine the order with respect to hydroxide, and calculate the rate constant for hydrolysis. 

These rate constants are for the hydrolysis of cinnamic anhydride in carbonate buffer, pH 8.45, total buffer concentration 0.024 M, in the presence of the catalysts pyridine, A -methylimidazole (NMIM), or 4-dimethylaminopyridine (DMAP). In the absence of added catalyst, but the presence of buffer, the rate constant was 0.005 24 s . You may assume that only the conjugate base form of each catalyst is catalytically effective. Calculate the catalytic rate constant for the three catalysts. What is the catalytic power of NMIM and of DMAP relative to pyridine ... 

Figure 7-4. Br nsted-type plot for reaction of aliphatic amines with cinnamic anhydride at 25°C in acetonitrile "" the pK values are for the conjugate acids in water. Open circles primary amines closed circles secondary amines.

These rate constants are for the cinnamoylation of hydroxy compounds by cinnamic anhydride catalyzed by A-methylimidazole. The reaction is first-order in each reactant. The kinetics were followed spectrophotometrically in acetonitrile solution. Analyze the data that is, attempt to account for the relationship between structure and reactivity. 

Cinnamic anhydride [538-56-7] M 278.4, m 136°. Crystd from benzene or toluene/pet ether (b 60-... 

Preparation 219.—Cinnamic Anhydride [Anhydride of Z-phenyl-2-propen acid],... 

The general formula for fulgides is represented as compound 1. Based on the absorption spectra data, 1-3 fulgide systems can be separated into two largely independent cinnamic anhydride-type chromophores. Freudenberg eta/.101 studied the absorption spectra of ethyl /rans-cinnamate 82 and diethyl-(E,E)-bisbenzylidene succinate 83 and found that the absorption spectrum of compound 83 was similar to that of compound 82, rather than 1,4-diphenylbutadiene. This indicated that compound 83 had two relatively independent chromophores, which was supported by Heller and Szewczyk.16 They demonstrated that the UV spectrum of (E,E)-bis-(a-phenylethylidene) succinic anhydride It was almost identical with a 1 1 mixture of (E,Z) and (E,E) isomers of the same fulgide. 

These rate constants are for the hydrolysis of cinnamic anhydride in carbonate ... 

Anhydride, C](HmO, cinnamic anhydride. Crystals, mp 136 . Practically insol in water. Freely sol in warm benzene slightly sot in ale. 

Cinnamyl-Z-ecgonine has been obtained by acylation of Z-ecgonine with cinnamic anhydride. Esterification of this cinnamyl-derivative with methanol gave cinnamylcocaine (103). After the physical properties of cinnamylcocaine had been established it was subsequently isolated from Java coca leaves (109) and from Erythroxylum monogynum Roxb. (77). It has been reported (77) that cinnamylcocaine is devoid of mydriatic and anaesthetic properties. 

Phenyl-2-propenolc anhydride Cinnamic anhydride C19H1403 638-66-7 278.302 nd (bzoral) pt (al) 136 vs bz... 

Scheme 9. A representation of the Perkin reaction between ethanoic anhydride (acetic anhydride, CH3CO2COCH3) and benzenecarboxaldehyde (benzaldehyde, C5H5CHO) in the presence of sodium ethanoate (sodium acetate, CH3C02Na) to yield the mixed acetic cinnamic anhydride. The upper part of the scheme indicates nonproductive exchange of ethanoate anion (acetate anion, CH3C02 ) with the anhydride.

Robinson cyclisation by using 3-acetyl-4-hydroxyquinolines and acid anhydrides in the presence of triethylamine [24], These cyclisations proceeded smoothly with benzoic anhydride but when furoic anhydride or cinnamic anhydride was used (XXXIV, R = Br, Cl, NO2 R = furyl or styryl and R = furoyl or cinnamoyl) were obtained. The phenyl-, furyl-, and styryl-pyranoquinolines gave characteristic colours with sulphuric acid pale yellow for phenyl, orange for furyl and deep red for the styrryl compounds. The ultraviolet absorption spectra were similar to those of corresponding naphtopyrans. 2-Phenylpyrano[3,2-c]quinoline-4-one was also obtained from the dehydrobromination with pyridine of 3-bromo-2-phenyl-2,3-dihydropyrano[3,2-c]quinoline-4-one [24]. Dihydropyrano[3,2-c]quinolines can be dehydrobrominated by iV-bromosuccinimide or selenium dioxide to the corresponding (XXXIV, R = R = H R = Ph) [24]. 

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