88 INFRA-RED ABSORPTION SPECTRA. 



Commercial ether contains from 3 to 4 per cent of water. An exam- 

 ination with the large spectrometer showed only a slight depression at 

 2.9 ju., so that the presence of water is not the cause of the band at 2.95 /j.. 



Thymoi,. CioHuO. (Fig. 100.) 

 This compound comes from the oil of thyme, fre- 

 ^ quently investigated. It melts at 44°, and hence could 



HC'^ ^N:-CH3 ^^ examined in its liquid condition. It was investi- 

 HC X-OH g^ted with its isomer, carvacrol, on account of the 

 C-C3H7 OH-group it contains, as well as the question of effect 

 of structure. 

 The spectrum as a whole is marked for great transparency at 4.5 /x 

 and a large opaque region from 6 /i, to 9 /*, followed by greater trans- 

 parency. The bands are unusually sharp. Those belonging with ben- 

 zene have entirely disappeared. The 2.92 /x band lies close to that of 

 water at 2.95 /i,, while the 3.43 (x. band is found in compounds containing 

 CHg-groups. The region from 6/1, to y fi was found to contain four 

 bands when examined with the large apparatus. For a solid film the 

 small spectrometer failed to resolve the band at 3.0 fi, because of the 

 greater opacity of the film. 



Carvacrol. doHn. (Fig. loi.) 

 Carvacrol is isomeric with thymol, and is a liquid. It begins to 

 show the effect of structure at 7.44 /x, beyond which point the bands are 

 entirely rearranged. The 2.92 /x and 3.43 fi bands are in common with 

 thymol, as are also the bands at 12.3 /* and 13.55^1. This compound 

 was dried with fused sodium hydrate, also by exposing it to PoOg for 

 several days, but no change could be detected in intensity nor in the 

 position of the absorbing bands. 



As a whole the spectrum of carvacrol is marked for several regions 

 of great transparency and of great opacity, like thymol, while the group 

 itself behaves more like the alcohols than the acids. This is to be 

 noticed especially at 2.93 /x, where the fatty acids show no band, while 

 the very marked band of the acids, at 5.85 /a, is absent in this group of 

 compounds. 



EuGENOL. CioHiiOs. (Fig. 102.) 



Eugenol is derived from the oil of cloves, some- 



^C^Ha-CH-CHs times investigated.^ No bands of eugenol are in 



I I common with benzene. It is also more opaque. 



^C-^^ ^C-OCHj There are no bands in common with safrol, to 



which it is related, but there are several which 



differ but slightly in the position of their maxima. The sharpening of 



^Donath, loc. cit. 



