MANNAN CONTEXT OF THE GYMNOSPERMS 



By a. W. Schorger 



Chemist in Forest Products, Forest Products Laboratory 



A marked difference between the conifers {Gymnospermae) and 

 hardwoods (Angiospermae) occurs not only in the structure but also 

 in the chemical composition of the wood. In a previous communica- 

 tion^ it was pointed out that water soluble galactans occurred in many 

 of the conifers. The present paper has a special bearing on the 

 relative amounts of mannan present in the various species. 



So far as is known, carbohydrates yielding mannose on hydrolysis 

 have been found in only one hardwood. Fromherz- obtained mannose 

 from Populus tremula h. The lignocellulose purified by treatment 

 with acid and alkali was heated with water in an autoclave at 

 150 degrees. The aqueous solution after boiling with sulphuric acid 

 was found to contain mannose. The writer, employing hydrolysis 

 at atmospheric pressure, examined six species of hardwoods, among 

 them Populus tremuloides Michx., but in no case was mannose 

 detected. 



The presence of mannans in various woods has been shown by 

 several investigators. Tollens^ and associates found mannose in sul- 

 phite liquor, the raw material generally employed being Picea excelsa 

 Lk. The presence of mannan in the wood of about a dozen conifers 

 was shown by Bertrand* who also made several quantitative determina- 

 tions. Kimoto^ found 6.35 per cent mannan in Cryptomeria Japonica 

 Don. A study of several American species was made by Storer^ but 

 only two quantitative determinations were reported ; the mannose 

 hydrazone was identified microscopically. 



Bertrand^ considers the source of the mannose from wood as a 

 mannocellulose. This classification is not justified on account of the 

 ease of hydrolysis of the parent carbohydrate, the latter falling properly 

 into the class of hemicelluloses created by Schulze. 



The presence of mannan in woods is of technical significance. 

 According to Schwalbe® waste sulphite liquors may be considered to 

 contain sufficient fermentable sugar to give 60 liters of ethyl alcohol 

 per "tonne" (2,200 pounds) of pulp, which is equivalent to 108 pounds 

 of alcohol per ton (2,000 pounds) of dry pulp. On the basis of a 



1 Schorger and Smith, Jour. Ind. Eng. Chem., 8 (1916), 499. 



^Zeit. Physiol. Chem., 50 (1906), 237. 



"Ber. 23 (1890), 2990; Zeit. Ang. Chem. 5 (1892), 155; Ann. 267 (1892), 349. 



^Compt. Rend., 129 (1899), 1027. 



5 Bull. Coll. Agr. Tokio., 5 (1902), 254. 



6 Bull. Bussey Inst., 3 (1902), 32. 



^Compt. Rend., 129 (1899). 1025. 



sZeit.'Ang. Chem., 23 (1910), 1540. 



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