RESINA GUAIACL 105 



acid ?), which, on addition of concentrated sulphuric acid, turns 

 beautifully red. 



After the extraction of the guaiaconic acid there remains a substance 

 insoluble in ether to which the name Guaiac Beta-resin has been 

 applied. It dissolves in alcohol, acetic acid or alkalis, and is precipitated 

 by ether, benzol, chloroform or carbon bisulphide in brown flocks, the 

 composition of which appears not greatly to differ from that of guaia- 

 conic acid. 



Giiaiacic Acid, C^^H'*0', obtained in 1841 by Thierry from guaiacum 

 wood or from the resin, crystallizes in colourless needles. Hadelich was 

 not able to obtain more than one part from 20,000 of guaiacum resin. 



Hadelich's Giuiiac-yellovj, the colouring matter of guaiacum resin, 

 first observed by Pelletier, crystallizes in pale yellow quadratic octo- 

 hedra, having a bitter taste. Like the other constituents of the resin, 

 it is not a glucoside. 



The decomposition-products of guaiacum are of peculiar interest. 

 On subjecting the resin to dry distillation in an iron retort and rectify- 

 ing the distillate, Guaiacene (Giuijol of Volckel), C^ffO, passes over 

 at 118° C. as a colourless neutral liquid having a burning aromatic 

 taste. 



At 205° — 210° C, there pass over other products, Guaiacol, 

 C*H^OCH^OH, (me thy lie ether of pyrocatechin), and Kreosol 

 C*H\OH(CH"')^ Both are thickish, aromatic, colourless liquids, which 

 become green by caustic alkalis, blue by alkaline earths, and are similar 

 in their chemical relations to eugenic acid. Guaiacol has been prepared 

 synthetically by Gorup-Besanez (1868) by combining iodide of methyl, 

 CffI, with pyrocatechin, C*HXOH)^ 



After the removal by distillation of the liquids just described, there 

 sublime upon the further application of heat pearly crystals of Pyro- 

 guaiacin, C^H■"0^ an inodorous substance melting at 180° C. The 

 same compound is obtained together with guaiacol by the dry distilla- 

 tion of guaiaretic acid. Pyroguaiacin is coloured green by ferric 

 chloride, and blue by warm sulphuric acid. The similar reactions of 

 the crude resin are probably due to this substance (EQasiwetz). 



Beautiful coloured reactions are likewise exhibited by two new acids 

 which Hlasiwetz and Barth obtained (1864) in small quantity together 

 with traces of fatty volatile acids, by melting purified resin of guaiacum 

 with potassium hydrate. One of them is isomeric with pyrocatechuic 

 acid. 



Uses — Guaiacum resin is reputed diaphoretic and alterative. It is 

 frequently prescribed in cases of gout and rheumatism. 



Adulteration — The drag is sometimes imported in a very foul con- 

 dition and largely contaminated with impurities arising from a careless 

 method of collection. 



