Potassium cinnamate reactions

This article reports on the synthesis of photosensitive polymers with pendant cinnamic ester moieties and suitable photosensitizer groups by cationic copolymerizations of 2-(cinnamoyloxy)ethyl vinyl ether (CEVE) (12) with other vinyl ethers containing photosensitizer groups, and by cationic polymerization of 2-chloroethyl vinyl ether (CVE) followed by substitution reactions of the resulting poly (2-chloroethyl vinyl ether) (PCVE) with salts of photosensitizer compounds and potassium cinnamate using a phase transfer catalyst in an aprotic polar solvent. The photochemical reactivity of the obtained polymers was also investigated. 

Substitution reactions of the remaining pendant chloroethyl groups in PCVE-NPVE with 20 mol-% excess of potassium cinnamate were carried out using TBAB as a phase transfer catalyst in DMF at 100"C for 24 h. The reaction conditions and results are summarized in Table III. It should be noted that 100 mole % substitution occurred in all cases. 

These results suggest that the reaction conditions for the syntheses of PCEVE-NPVE and PCEVE-NNVE can be accomplished by the reactions of PCVE with any ratio of potassium cinnamate and PNP or PNN in one pot using a phase transfer catalyst. In addition, it is to be expected that PCEVE-NPVE and PCEVE-NNVE prepared from the reactions of PCVE have the same degree of polymerization if no side reactions occur during the substitution reactions. It is also expected that these copolymers are more random compared to the copolymers prepared from the cationic copolymerizations of the monomers, because the former is not affected by the monomer reactivity ratios. 

From all these results, it was concluded that polymers have high photochemical reactivity and high practical photosensitivity when synthesized by the cationic copolymerizations of CEVE with NNVE or NPVE, or by the reactions of PCVE with potassium cinnamate and PNN or PNP using phase transfer catalyst in DMF. 

Benzal chloride is hydrolyzed to benzaldehyde under both acid and alkaline conditions. Typical conditions include reaction with steam in the presence of ferric chloride or a zinc phosphate catalyst (22) and reaction at 100°C with water containing an organic amine (23). Cinnamic acid in low yield is formed by heating benzal chloride and potassium acetate with an amine as catalyst (24). 

Manufacture. The most widely employed method for the commercial synthesis of (H)-cinnamic acid uti1i2es ben2aldehyde, acetic anhydride, and anhydrous sodium or potassium acetate in a condensation reaction commonly referred to as the Perkin reaction (11). 

As with poly(vinyl alcohol), poly(vinyl cinnamate) is prepared by chemical modification of another polymer rather than from monomer . One process is to treat poly(vinyl alcohol) with cinnamoyl chloride and pyridine but this is rather slow. Use of the Schotten Baumann reaction will, however, allow esterification to proceed at a reasonable rate. In one example poly(vinyl alcohol) of degree of polymerisation 1400 and degree of saponification of 95% was dissolved in water. To this was added a concentrated potassium hydroxide solution and then cinnamoyl chloride in methyl ethyl ketone. The product was, in effect a vinyl alcohol-vinyl cinnamate copolymer Figure 14.8)... 

Furfural condenses with acetic anhydride and potassium acetate to give furylacrylic acid (compare Perkin reaction, Cinnamic Acid, Section IV, 124) ... 

Aromatic aldehydes lake up keiene in the presence of potassium acetate in the manner of a Perkin reaction. The producl is a cinnamic acid ... 

Compound 85 was dehydrogenated at 300° over palladium black under reduced pressure to a pyridine derivative 96 which was independently synthesized by the following route. Anisaldehyde (86) was treated with iodine monochloride in acetic acid to give the 3-iodo derivative 87. The Ullmann reaction of 87 in the presence of copper bronze afforded biphenyldialdehyde (88). The Knoevenagel condensation with malonic acid yielded the unsaturated diacid 91. The methyl ester (92) was also prepared alternatively by a condensation of 3-iodoanisaldehyde with malonic acid to give the iodo-cinnamic acid (89), followed by the Ullmann reaction of its methyl ester (90). The cinnamic diester was catalytically hydrogenated and reduced with lithium aluminium hydride to the diol 94. Reaction with phosphoryl chloride afforded an amorphous dichloro derivative (95) which was condensed with 2,6-lutidine in liquid ammonia in the presence of potassium amide to yield pyridine the derivative 96 in 27% yield (53). 

The bromination of cinnamic acid dissolved in carbon tetrachloride or other inert solvent.offers a convenient system for study. The dibromocinnamic acid produced remains in the carbon tetrachloride solution. The thermal reaction is so slow that it can barely be measured at room temperature and it is entirely negligible in comparison with the photochemical reaction at ordinary intensities. The quantum yield is so large that considerable reaction occurs even if the intensity of light is much reduced by the monochromator or other device for confining the light to a narrow range of frequencies. Furthermore, the reaction is easily and accurately followed by titration with sodium thiosulfate. Potassium iodide is added and the iodine liberated is a measure of the remaining bromine. 

Examples of the solvent-dependent competition between nucleophilic substitution and / -elimination reactions [i.e. SnI versus Ei and Sn2 versus E2) have already been given in Section 5.3.1 [cf. Table 5-7). A nice example of a dichotomic y9-elimination reaction, which can proceed via an Ei or E2 mechanism depending on the solvent used, is shown in Eq. (5-140a) cf. also Eqs. (5-20) and (5-21) in Section 5.3.1. The thermolysis of the potassium salt of racemic 2,3-dibromo-l-phenylpropanoic acid (A), prepared by bromine addition to ( )-cinnamic acid, yields, in polar solvents [e.g. water), apart from carbon dioxide and potassium bromide, the ( )-isomer of l-bromo-2-phenylethene, while in solvents with low or intermediate polarity e.g. butanone) it yields the (Z)-isomer [851]. 

The reaction is usually carried out be heating equimolar quantities of the aldehyde and salt with excess of the anhydride for 8 hours at 170-180°. Lower temperatures are often employed when potassium acetate or trialkylamines are used as condensing agents. Continuous removal of acetic acid during the reaction was found to have no effect on the yield of cinnamic acid. Substitution of diacetimide for acetic anhydride gives cinnamide (77%). ... 

This condensation is essentially an aldol-type reaction of an aldehyde with the methylene group of an anhydride. The sodium salt may be replaced by other basic catalysts such as potassium carbonate oi tertiary amines. If the acid residue in the anhydride is not the same as that in the sodium salt, an equilibrium between these substances may occur before condensation. Thus, a mixture of acetic anhydride and sodium butyrate or a mixture of butyric anhydride and sodium acetate gives cinnamic acid and a-ethylcinnamic acid in the same ratio. ... 

Moles of substituted coumarin is mixed with 65 mL of dimethyl sulfate and 70 mL. of 33% potassium hydroxide. The reaction is allowed to complete, cooled and mixed with more dimethyl sulfate and potassium hydroxide. The reaction mixture is refluxed with 150 mL of 33% potassium hydroxide for one hour. The reaction mixture is then methylated further with more dimethyl sulfate. Potassium hydroxide is added again and refluxed to hydrolyze the methyl estev that is formed. The solution is then mixed with 3 liters of water and filtered through charcoal. The mixture is chilled, mixed with hydi i) chloric acid to precipitate the cinnamic acid which is collected by vacuum filtration. 

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