CONCERNING THE OCCURRENCE OF 
 FREE PENTOSES IN PLANTS 
 
 liY 
 
 L. W. VAN RYN 
 
 THESIS 
 
 FOR THE 
 
 degree: of bachelor of science 
 
 IN 
 
 CHEMICAL ENGINEERING 
 
 COLLEGE OE LIBERAL ARTS AND SCIENCES 
 
 UNIVERSITY OF ILLINOIS 
 
 1922 
 

 UNIVERSITY OF ILLINOIS 
 
 liar OR 
 
 192 i 
 
 THIS IS TO CERTIFY THAT THE THESIS PREPARED UNDER MY SUPERVISION BY 
 
 .lx*—’ EL— ‘ Yan-Rvi 
 
 ENTiTLED___£L<ini2.ejming._tJie__Qcjiuairfinc-e__Qf— Fxefi.-P^nJiojs.es.-i 1 
 
 IS APPROVED BY ME AS FULFILLING THIS PART OF THE REQUIREMENTS FOR THE 
 degree of JBa.clifiLQ.r__Qf__Sfi.i£ii£Le__irL_Ciiej 2 iiii£ — — -- 
 
 HEAD OF DEPARTMENT OF 
 

 
 
 
 
 
 
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table of contents 
 
 Page 
 
 Aclmowledgement 
 
 Introduction — — — --- 1 
 
 Experimental 5 
 
 Experimental Lata — 8 
 
 Summary 
 
 10 
 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 - 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
ACKNOWLEDGEMENT 
 
 The author wishes to thanh 
 Dr. Duane T. Englis for his many 
 
 invaluable suggestions, and for his 
 
 interest and ready willingness to 
 
 help in the work. 
 
Digitized by the Internet Archive 
 in 2015 
 
 https://archive.org/details/concerningoccureOOrynl 
 
CONCERNING- THE OCCURRENCE OE EREE PENTOSES IN PLANTS 
 
 By: 1. W. van Ryn, under the 
 
 direction of Ur. Uuane T. 
 
 Englis, Department of 
 Chemistry, University of 
 Illinois. 
 
INTRODUCTION 
 
 The sugars occurring in plants are nearly all of Ihe five 
 and six carbon atom class, pentoses and hexoses. Although 
 both are found widely in the combined state as polysaccharides 
 such as starch, cellulose, xylan and araban, only the hexoses 
 occur extensively in the free state. The presence of mono- 
 saccharide pentoses has been but recently established. If the 
 sugars are considered to be formed by a successive condensation 
 of formaldehyde it would seem reasonable to expect that pentoses 
 should also be found free. 
 
 However, there is the possibility that pentoses may be p 
 produced as waste products in a down grade process in the plant 
 since according to Armstrong 1 2 they are present as skeletal 
 and not as food products and are therefore not fermentable by 
 
 ordinary enzymes. 
 
 2 
 
 Spochfr has brought out the theory of the formation of 
 pentoses from such substances as glucuronic acid. He states 
 that in the disaccharides and poly-saccharides the CEgQH 
 group is the first to be effected and that such a reaction 
 results in a primary formation of glucuronic acid, CH:0( CHOEy^GOOH. 
 A veiy general property of saccharides of this character is the 
 splitting off of COg from the carboxyl group and so glucuronic 
 acid would form 1 - xylose. 
 
 t 
 
 1. Camagie Institute Pub. 287 - 1919 
 
 2. The Carbohydrate Economy of Cacti. 1919 
 

 
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- 2 - 
 
 Such an oxidation would permit the production of pentoses 
 from hexoses while the latter were still in certain poly sac- 
 charide forms, i.e. one in which the primary alcohol group 
 was exposed and consequently the pentose would not be liberated 
 except on hydrolysis of the stable polysaccharide and would 
 perhaps not be found abundantly in the plant sap. 
 
 Also if pentoses are derived from a direct oxidation of 
 hexoses, d - glucose would yield d -arabinose and d - galact- 
 
 ose^ould yield d - xylose. ^ 
 
 Qff // Ofr 
 
 CoH- 
 
 
 
 H- 
 
 
 
 
 
 0 
 
 H b 
 
 (■ 
 
 FT 
 
 < 
 
 d - glucose d - ar&binose 
 
 1$ is a striking fact, however, that in nature d - glucose 
 is almost always found with 1 - xylose and that d - galactose 
 is usually associated with 1 - arabinose. Also tjae pent- 
 oses sugars thus formed are of the 1 - and not of the d - 
 series. The fact and the isolation of glucuronic acid by 
 Spoch£ seems to substantiate his theory of the method of form- 
 ation. 
 
 Davis and Sawyer have given evidence of pentoses in the 
 free state. They btfsed their conclusions on the fact that a non- 
 fermenting, reducing sugar was obtained from a plant extraction 
 after a fermentation with yeast and that by running the regular 
 

 
 
 
 
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 ICobliA=Tollen T s determination a greater ppt. was obtained than 
 could be accounted for as due to hexoses alone. 
 
 Moreover, for the purpose of neutralizing any organic 
 acids that were present, they added ammonium hydroxide (sp. gr. 
 .0.88) to the alcoholic extract in a proportion of 1 $ by 
 volume. This treatment would tend to throw some doublt as to 
 the conclusion of their results. The isomerizing effect of 
 weak alkalies upon sugars is v/ell recongnized to day. Also, it 
 seemed possible that the introduction of air to lessen bumping 
 during concentration might have caused an increased oxidation 
 of the sugars and increased pentose formation. 
 
 The evidence is not conclusive because Nef has indicated th 
 that a great number of products may be formed and the nature 
 of the products depends on the temperature and concentration. 
 
 Hale has sought to verify or disprove the conclusion of 
 Davis and Sawyer by an investigation of the effect of their 
 precess of extraction with a mixture of pure hexose sugars. 
 
 As a result of his work, he concludes that although 
 considerable quantities of apparent pentoses produced from the 
 hexose sugars are indicated by both methods used by Davis and 
 Sawyer, the amount is insufficient to account for the total 
 quantities reported by them in their plant extract solutions. 
 
 Since in plant extracts, phosphates and many other mineral 
 salts may be present it seemed desirable to study ' further 
 Davis’s process of extraction in the presence of certain amounts 
 of these salts in order to determine their influence on apparent 
 

 
 
 
 
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 pentose production. 
 
 In prliminary work this writer was unable to duplicate 
 exactly some of the resits of Hale so it appeared advisable to 
 repeat his work in some detail and then proceed to the study 
 of the effect of phosphates on the process of extraction# 
 
 It has been stated by E.J. Wittzman"^ that di^sodium 
 phophate catalyzes the quantitative oxidation of glucose to 00^ 
 by hydrogen peroxide. Previous work by L0b states that in 
 a salt-free solution, hydrogen peroxide produces only a vanishing- 
 ly small amount of oxidative glycolysis and that this is 
 markedly increased by raising the hydroxyl ion concentration 
 and that the phosphate ions accellerate the glycolysis by the 
 OH ions. 
 
 l. Jour. Bio. Chem. (Wittzeman) 
 

 
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 v: 
 
 
 
EAPEBIMMTAL 
 
 Preparation of Solutions: 
 
 Twenty grams of pure sucrose was dissolved in 220 c.c 
 of distilled water, 100 c.c, of this solution was inverted with 
 invertase and made up to 220 c.c. This was called solution A. 
 The invertase was prepared according to Sherman and was 
 dialyzed to remove any sugars. Another 100 c.c. portion of the 
 original solution was diluted to 220 c.c. This was called 
 solution B. Now, by using 100 c.c of each A and B a solution 
 could be obtained which would have sucrose and invert sugar 
 in about equal proportions and a total sugar content slightly 
 less than ten grams. 
 
 Extraction Process: 
 
 Experiment I : Into 750 c.c. of boiling alcohol 50 clc. 
 
 of each A and B was measured, then 5 c.c. of ammonia (sp. gr. 
 
 0. 90) was added. This solution was refluxed on the water 
 bath in a Pyrex flask for eighteen hours. After refuxing the 
 solution was concentrated fo about 150 c.c. under diminished 
 pressure. During concentration air from a capillary tube 
 was allowed to bubble slowly through the solution to lessen 
 bumping. The 150 c.c residue was diluted with water until its 
 volume reached 500 c.c. The solution was then cleared with 
 basic lead acetate, filtered and washed to about 1000 c.c. 
 Excess lead was removed with, sodium carbonate and the precip- 
 
 1. J. Am. Ghem. Soc. 36, 1566 (1914) 
 
- 6 - 
 
 itate filtered off and washed until the volume was two liters. 
 
 Another solution prepared by diluting 100 c.c. of each 
 A and E to two liters with water was used as a blank for comp- 
 arison with the refluxed solution. 
 
 Experiment II 
 
 The above experiment was then aarried out with the omission 
 of any introdpiction of air to lessen bumping as it was thought 
 possible that this might have caused an increased oxidation of 
 the sugars and an increase in pentoses. 
 
 Experiment III 
 
 This experiment was the same as Experiment I except that 
 the refluxing for eighteen hours was ommitted. 
 
 Determination of Pentoses by Distillation 
 
 After deleading with sodium carbonate 50 c.c. portions 
 of this filtrate were distilled with E01 according to the 
 regular Kobler- To liens Method of analysis and the precipitate 
 resulting from the coupling with phloroglucin was weighed. 
 
 In carring out this distillation the rate of distillation 
 was maintained as near to 30 c.c eveiy 10 minutes since accord- 
 ing to Van Hears t and Olivier' 1 ’ except in the case of 1 - arbin- 
 ose, more complete distillation of the furfural is obtained 
 ?/hen the time is short. Continued boiling with HOI tending to 
 
 1. Chem. Vocekblad 11, 918 (1914) 
 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
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 de compose the furfural. 
 
 Exp esriment IV 
 
 Ten percent ferric chloride was added to 50 c.c portions of 
 the filtered extraction III. The regular Kohler- Tollens 
 test was run on it and pentose calculated. 
 
 Experiment V 
 
 The sodium phosphate and hydrogen peroixide were added 
 according to Watze/mann, to Extract III and the pentose 
 determined. 
 
 Experiment VI 
 
 The Kobler- To liens determination was made on a half gram 
 sample of pure non-reducing Sucrose and the results compared 
 with those obtained after the additcSn of the phosphate and 
 the hydrogen peroxide to pure sucrose. 
 

 
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 EXPER IlIER TAL RESULTS 
 
 The results of the experiments explained above are 
 recorded here: 
 
 Blank: a 
 
 b 
 
 Exp. I: a 
 b 
 
 Expe II a 
 
 b 
 
 Exp. Ill a 
 
 b 
 
 APPARENT PENTOSES 
 
 Phloroglueid 
 
 — .0027 
 
 — ----- - — - .0028 
 
 — .0054 
 
 — .0052 
 
 .0054 
 
 .0052 
 
 - .0012 
 
 — . .0020 
 
 Pentose 
 
 .0080 
 
 .0081 
 
 .0107 
 
 .0105 
 
 .0107 
 
 .0105 
 
 .0065 
 
 .0072 
 
 Exp. IV a — -• - — .0048 .0101 
 
 b ----- — — .0039 .0093 
 
 Exp. V a — — — — .0090 .0141 
 
 b — .0090 .0141 
 
 Exp. VI (pure sucrose) 
 
 a -- .0068 .0120 
 
 b .0063 .0116 
 
 a' — — — — .0101 .0153 
 
 b' .0108 .0161 
 
 After the addition of the phloroglucinol care was taken 
 
 not to allow the solution to stand longer than over night 
 
 before filtering it for it was observed that after the filtrate 
 
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 had stood for some time an additional precipitate came down. 
 
 The duplication of Hales work gave results of smaller 
 magnitude than he obtained but of the same order. 
 
 The addition of the ferric chloride shows a very marked 
 increase in pentose formed. 
 
 The addition of the di- sodium phosphate and hydrogen 
 peroxide shows a very great increase in pentose formed — 
 practically double the amount formed without. 
 

 
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 SUMMABY 
 
 1, Pentoses are ):nown to be found in the 
 free state. This is evidenced by the facts 
 that after fermentation of hexoses with 
 brewers yeast a non- fermentable residue remained 
 and more phloroglucid was obtained than could 
 
 be accounted for as due to hexoses along. The 
 extraction of the hexoses involved refluxing with 
 ammonical alcohol and concentration. 
 
 2. It is shown in this paper that such an 
 extraction gives considerable quantities of 
 apparent pentoses and further that the presence 
 of certain salts produces a large increase of 
 apparent pentoses.