Coumarilic acids

There is a marked and unexplained difference in the stability of the dianions derived by deprotonation of coumarilic acid (207) and 4,6-dimethylcoumarilic acid (209) to thermal... 

Coumaranone-2-acetic acid, 4,6-dimethyl-synthesis, 3, 850 /3-Coumaranones synthesis, 4, 710 Coumaric acid synthesis, 3, 685 Coumarilic acid... 

This concept has also been applied to the acid-base equilibria of indole-2-carboxylic acids (15) and of coumarilic acids (16) and to the rates of saponification of their ethyl esters. The data were excellently... 

Coumalic acid, decarboxylation of, apparatus for, 46, 102 to give a-pyrone, 46,101 purification of, 46,102 Coumarilic acid, 46, 29 Coumarone, 46, 28... 

B. Coumarilic acid. In a 5-1. three-necked flask fitted with a mechanical stirrer and reflux condenser, 450 g. (8 moles) of solid potassium hydroxide is dissolved in 700 ml. of absolute alcohol. The solution is cooled to 15° by immersing the flask in an ice bath, and 215 g. (0.7 mole) of finely divided coumarin dibromide is added in 10- to 15-g. portions to the well-stirred basic solution. The rate of addition is controlled so that the temperature never rises above 20° the addition requires about 30 minutes. After all the dibromide has been added, the reaction mixture is refluxed, with stirring, for 30 minutes (Note 7). One and a half liters of water is added, and the resulting solution is steam-distilled until 2.5 1. of distillate has been collected (Note 8). The residue is cooled to room temperature by the addition of 1 kg. of cracked ice (Note 9) and is then acidified by the addition of 1.2 1. of 6 N hydrochloric acid. The crude coumarilic acid is collected on a filter and stirred with 600 ml. of cold water. The acid is separated from the water by filtration, sucked as dry as possible on the filter, and then crystallized from a mixture of 250 ml. of alcohol and 250 ml. of water (Note 10). The recrystallized coumarilic acid is colorless, weighs 93-100 g. (82-88%) (Note 11), and melts at 190-193°. 

The checkers found that considerable decomposition occurred when this procedure was employed, perhaps because it happened to be carried out on a warm humid day they found it preferable to remove the chloroform by distillation under reduced pressure from a water bath at this step and the succeeding ones. Because of the instability of the dibromide, it is advisable to convert it to coumarilic acid on the day it is made. 

Coumarilic acid has been prepared by treating coumarin dibromide with alcoholic potassium hydroxide and acidifying with hydrochloric acid, a method due essentially to Perkin.1... 

Coumarilic acid and derivs 3 C549 coumarilic acid azide 3 CS49 mononitrocoumarilic acid 3 C549... 

Alkaline degradation of coumarin dibromides (353) to coumarilic acids is effected in good yield by boiling aqueous ethanolic potassium or sodium hydroxide (82-88% with R1 = H).785 This reaction makes it possible to obtain Bz-substituted coumarilic acids unsubstituted in... 

If the coumarin is heated with an amine, the amide of the coumarilic acid is isolated thus, 3-halo-4-piperidinocoumarins with piperidine (X = CH2) or morpholine (X = 0) gives the corresponding compounds 359.791... 

Ring contraction of coumarins is used for the preparation of benzo[Z>]furans. Alkaline degradation of the 3-halo-, 4-halo- or 3,4-dihalo-coumarins gives the coumarilic acids (Scheme 104). The coumarilic acids are decarboxylated to the corresponding benzo[Z> ]f urans. Basic mercury(II) oxide oxidation of 4-phenylcoumarin (neoflavanoid) yields the 3-phenyl-benzo[/>]furan (71IJC1316). 

The use of bases such as piperidine or morpholine leads to the isolation of the amides of the coumarilic acids (70KGS(S2)116). Coumarins have been found to produce benzo[6]furans under electron impact (B-64MI31200). 

Coumarilic Acid or 2-Benzofurctnccirboxylic Acid [called Cumarilsaure or Cumaron-carbonsaure -... 

Coumarilic Acid Azide or Coumaril Azide (Called Cumarilsaure-azid in Ger),... 

If no acetic acid is used, benzofuran is formed in only 30-31% yield, and coumarilic acid, mp. 194-196°, is isolated in about 45% yield. 

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