1 Mi2
I < , F. PATTERSON AND HAROLD HIBBERT
lowered by increase ill tlic tliclcctric cimkiiit of the medium. 2 . The benziniidazoles stutlirtl arc very rcwtive. The reactivity is apparently clue to thc hen-
VOl. 65
ziiiiitl:tzole pmpiiig, Iwing little affected by the alkyl F;roups attached to the carbon atom bearing the chlorine. I ~ I X I ~ WMARCH ED 16, 1943
PIIII,AI)IA.
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~ C U ~ I ' K l l 3 ~ T l FROM ON T l l l l 1)IVISION OF I N D U S I K I A I . ANI) Clil.l.L1l.OSl C I I E M I S l R Y ,
MCGILLUNIVBRSITY J
Studies on Lignin and Related Compounds. LXXII. The Ultraviolet Absorption Spectra of Compounds Related to Lignin BY
K. F.
PATTERSON .INI)
The use of ultraviolet absorption spectroscopy for the examination of lignins arid related compounds is by no means a new approach to the study of lignin structure. Herzog and Hillmer' were the first investigators iii this field. From the absorption spectra of a large number of lignins and simple coml~oundsthey concluded that lignin is derived from units corisisting of partly or wholly etherified di- or trihydroxy phenols haviiig side chains of about three carboil atoms coiitaining neither carbonyl nor unsaturated linkages in conjugation with the benzene ring. They also noted ;I consistent difference in the position of the'absorption maxima for lignins isolated from hardwoods and softwoods. Hiigglund arid Klingstedt? and. Stamm, Semb and Harris:' have also reported a difference between the curves of hardwood and softwood lignins, the latter workers placing the absorption maximum a t 2740-27(i0 A. for hardwoods and a t 2800-2S70 8. for softwoods. Other absorption curves for lignins, reported by Goslawski and M a r c h l e w ~ k i ,include ~ those of methanol, ethanol, isobutylcarbinol and alkali lignins in ethanol and alkali solution. Maxima range from 2793 to 2835 8. and the different curves have the same general shape in spite of the different extraction methods used. Gladingb has recently determined the absorption spectra of spruce "native" lignin, lignir~sisolated by the use of phenol, glycol, thiophenol, alkali, etc., and various lignin derivatives, all of which show the same characteristic absorption band a t approximately 2800 A. 'This author also reports the absorptiori curves for benzalacetophenone, pipero( 1 ) Herzogand Iiillmrr, %. ~ / ~ J ~ Chcvt., I ~ L . 168, 117 ( 1 9 2 7 ) . ( 2 ) Huyglunrl a m ! K l i n y . t r d l . . Y : w , i ~ k . &,,I ~ ' I J .41, , 182 ( l ! l ? ! l ) : %. physrk ( . h . - v . , 111, ?!I>I l!l:$l). I:() Stirmm. Senit) and Harria. J , I'hys. C h r t n . , 96,1.574 ( 1 ! ) : 3 2 ) . (4) Coslaw,ki and klarchlewski, Bull. inlevn. o r d l P r e r c \ t c n ~ t r i t c i e . , l l ~ l ~ l wl'oppg r~. '1'1orlr .I , 1 1 3 , Sqt I . :I; '1!1411 "1111 .A#,,, Kr.: Hl
