Measurement of Hydrogenation Difference Spectrum

The principles and methodology relevant to the UV spectrophotometric determination of lignin and lignin model compounds have been discussed by Goldschmid 1954, Browning 1967b, and by Lin in Chapter 5.1. 

The concentration of ethylenic groups in lignin is more commonly expressed as the number per phenylpropane (C9) unit, per 100 phenylpropane units, or per methoxyl group. For softwood lignin the number per phenylpropane unit equals approximately the number per methoxyl group. With respect to the procedure outlined above, the following calculations apply  

Unit weight of spruce milled wood lignin = 185 (Marton 1971) 

Note 1. The carbonyl groups also may be reduced with sodium borohydride using the procedure described by Marton and Adler (1961). 

Note 2. The case for the use of freshly prepared catalyst has been discussed by Adler and Marton (1961). 

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