Agric.Biol.Chem.,54(4).957-963.1990

Curie-point Pyrolysis of Cellulose in the Presenceof Potassium Malate
Kazuo IZAWA, Masao MATSUKURA and Yoshiaki ISHIZUTobacco Science Research Laboratory. Japan Tobacco Inc.,
6-2. Umgaoka.Midori-ku,Yokohama 227.Japan
Received September 25, 1989
Finely powdered cellulose was pyrolysed in a Curie-point pyrolyser, which was directly attached toa gas chromatograph and mass spectrometer (CPP-GC/MS), at 358℃ for 5sec in He (gas) without
any additives. The Pyrolysis products were levoglucosenone as the main component, 2-furaldehyde.
l,4:3.6dianhydro-β-D-glucopyranose and 5-hydroxymethyl-2-furaldehyde. However. CPP-GC/MSof cellulose in the presence of potassium malate (5 % as potassium) gave 2-furanmethanol as the main
component, and a number of low molecular compounds were formed; e.g., lactones, ketones and furans.
A possible new reaction path for cellulose to 2-furanmethanol via D-xy1ulose is presented.

It has been reported that the amount of CO
evolved was reduced by about 20% (w/w)
when cigarettes were burnt in the presence ofpotassium malate.1) In order to elucidate theeffect of adding potassium malate, a pyrolytic
study on cellulose was done.
Since the thermal decomposition temperatrue of cellulose is about 350℃, an investgation of the conversion of pyrolytic compounds from cellulose was carried out at thistemperature. A possible new pathway to theformation of 2-furanmethanol will be prescented .
Materials and Methods
sample. Powdered crystalline cellulose (avicel: Asilhi
Chemical Industry Co.. Ltd.) was used as the cellulose
sample. Finely powdered potassium malate (Kanto ChemicalCo.. Ltd.) was used after having been dried at
80℃ for 1hr. Levoglucosenone was Prepared by the method
described by Onishi et al.2)
3-Dcoxy-2-xylosulose
and 3-dcoxy-2-glucosulose were obtained from D-Xylose andD-glucose by the method described by Kato.3) The otherchemicals were of reagent grade and were used without
further purification.
Instruments A Curie-point .Pyrolyser (Nippon
Analytical Industry Co.. Ltd.: JHP-3) was directly com-binedwith a gas Chromatograph and mass spectrometer(Hewlett Packard 5890 GC and 5970 MS). A fused silica

column（0.25mmi.d.×30m）was uscd with surfacc−
bonded polyethylene glycol 20M （ DB−WAX from J＆ W
Scientific ） .Typical conditions for the CPP-GC ／ MSmeasurements were as follows ： Sample weight ． 0.2 −0.5mg：Pyrolysis temperature，358℃；heating period．5sec；
atmo-Sphere．He；flow rate of carrier gas、1.0ml/min；injection temperature．210℃；temperature program，thecolumn oven temperature was held at50 ℃ for 5min．thenraised to 200℃ at a rate of 2℃／min、and finally held
isothermally at 200℃ for 30min：El melhod、electron energy．
70eV．

Trimethysilyl derivatives and their analysis. After theCurie-Point Pyrolysis was complete the non-volatile condensate on the quartz sample holder and the pyrolytic
residue of cellulose with potassium malate in the pyrofoil
were each extracted to a glass vial with 30μl of Pyridine．
Thirty μl of N.0−bis−TMS・trifluoroacetamide（BSTFA）
was added in the former case. and 50μl of BSTFA wasadded in the latter case. The vial was finally allowed tostand for 40 min at 80 ℃ so that the Trimethysilyl(TMS)
derivatives could be obtained. Oneμl of the solution wasinjection into the GC/MS the column oven temperature
being held at 50℃ for 10 min then raised to 210℃ ata rate of 2 ℃/min and finally held isothermally at 210 ℃
for 20min .The GC/MS conditions were the same as thosealready described except that a fused silica capillarycolumn (0.25mm id x I2. 5m) was coated with dimethyl
silicone (Hewlett Packard) and the mass spectrometer was
run 10min after injecting the sample in order to avoid
contamination of the ion source.

Results and Discussion
Pyrolysis of cellulose in the presence or absence ofpotassium malateA typical result from the CPP-GC/MS orcellulose is shown in Fig. I. The pyrolytic
products or cellulose were 2-rurilldehydc (A).
Levoglucosenone ( 1.6-anhydro-3.4-dideoxy-PD-glycero-hex-3-enopyranos-2-ulosc: a). I,4:
3.6-dianhydro-a-D-glucopyranose (C). and 5hydroxymethyl-2-furaldehyde (D). In the caseof cellulose alone. anhydro-sugar homologues
such as a and C were formed in large quantities. these being the important products fromthe Pyrolysis or cellulose.4)
The CPP-GC/MS result for cellulose in thepresence or potassium malate (as 5% potassium) is shown in Fig. 2. In this case, themain component was 2-furanmethanol. and anumber or low molecular compounds werealso found: e.g., lactones. ketones and furans It should be noted that only very small
amounts of anhydro-sugar homologous wereobserved. The presence or potassium malate
decreased the formation of anhydro-sugdr andaccelerated the formation of various lower
molecular compounds..
After the Curie-point Pyrolysis had been
Conducted, the tar left on the quartz sample
tube was collected and converted to TMS
derivatives The GC/MS chromatogram ofthese TMS derivatives is shown in Fig 3.
Levoglucosan ( 1.6-anhydro-β-D-glucopyranosc; A) and 1.6-anhydro-β- D )-glucofuranoseB) were observed in the pyrolytic tar of cellulose. but no similar compounds were observed in the pyrolytic tar produced with potassium malate. similar results were also obscrv-ed with the addition of the potassium salt oftartaric, citric, lactic, oxalic or malice acid.
These results suggest that alkaline substances such as potassium malate accelerate
the fragmentation of cellulose and contributeto the generation of 2-furanmethanol.

Elucidation of the generation mechanism for2-furanmethanol

Molton et al.5) reported the thermal degradation of cellulose with sodium carbonate.
but they did not note the formation or 2furanmethanol.
However. the addition of 0.1% by weight ofpotassium or sodium as the carbonate orhydroxide to cellulose led to furfural derivatives and low molecular weight compounds
such as acetaldehyde and acetol.6)
When Ievoglucosan. levoglucosenone, 2-furaldehyde and 5-hydroxymethyl-2-furaldehyde
were pyrolyzed in the presence or potassium

malate. 2-furanmethanol was not detected.
The Pyrolysis or D-glucose and D-fructose
produced only 2:ruraldehyde and 5-hydroxymethyl-2-furaldehyde as the major components. When potassium malate was added.
they produced many compounds including
2-furanmethanol. In the case of the pyrolysis of D-xylose alone, 2-furaldehyde was themajor product. but with potassium malate,themain product was 2-furanmethanol as shown
inFig.4.
Kato has suggested that 3-dcexy-2-xylosulose and 3-deoxy-2-glucosulose become significant decomposition intermediates. Which,in turn, would lead to the formation of furancompounds such as 2-furaldehyde and 5-hydroxymethyl-2-furaldehyde.7) The pyrolysis ofthese two intermediates with potassium malate, however. revealed that 2-fhranmethanol
was produced from 3-deoxy-2-xylosulose. but
little was formed from 3-dcexy-2-glucosulose.

When D-xylulose, an Isomeric Compound ofD-xylose. was pyrolyzed in the presence ofPotassium malate. 2-ruranmclhanol was one of
the main Compounds (Fig. 5) From Figs. 2and 4. it is Considered that cellulose and Dxylulose would be degraded via similar pyrolytic paths in the presence or potassium malale

In general, 2-furaldehyde is converted into
2-furanmethanol and 2-furancarbonic acid by
Cannizzaro’s reaction. However. in the presentcase. 2-furancarbonic acid (82.9 min retentiontime) was not found, and the present reaction
was assumed not to be a Cannizzaro case.
D-Xylose was detected in the pyrolytic residue of cellulose with potassium malate by a

TMS derivative analysis. However, D-xylulose
was not found by this method, as shown inFig. 6. which may have been due lo the factthat D-Xylulose is not Stable against theat.

Apossible
formation
2-furan-methanol

parthway

Evans et al.6) proposed that cellulose decomposes to form substituted furans with intermolecular dehydration in the presence of alkalimetal.
In the presence of potassium malate, thepyrolysis of levoglucosan、levoglucosenone、5hydroxymethyl-2-furaldehyde and 2-furaldehyde did not fprm 2-furanmethanol,but thatof D-glucose、D-fructose、D-xylose,D-xylulose
and 5-deoxy-2-xylosulose decomposed to 2furanmethanol.However,D-glucose and Dfructose are not considered to have beenprecursors of 2-furanmethanol because it was
not found in the pyrolytic residue (Fig. 6).
From these observations, the assumed reaction path for cellulose to 2-furanmethanol ispresented in Fig. 7. It is considered that cellulose would be decomposed to 1.2-endiol bydecarboxylation via dehydrated cellulose derivatives. and that 1.2-endiol would be transformed to D-xylose and/or D-xylulose byforaldose-ketose isomerization ( Lobry deBruynAlberda von Ekenstein transformation.8)
When potassium malate was added, D-xylose
could be transformed to D-xylulose. whichmakes 2-furanmethanol. Here, it has beentaken into consideration that no aldehydegroup would be necessary to from 2-furanmethanol. On the other hand, when no potassium malate was added, D-xylulose is liable
to be transformed to D-xylose, which makes 2furaldehyde.