东北林业大学
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2008－2009学年第一学期考试试题
考试科目：木材化学（双语）
考试时间：120分钟
试卷总分70分
题号A
B
C
D
卷面成绩
平时成绩
总分
得分
评卷教师
装
得分A. Fill in the blanks:（每空1分，总计25分，答案填在空格内）
1.
The main chemical constituents are cellulose, hemicelluloses, lignin, and extractives.
cellulose is the most abundant one. Except pectin and starch, those non-cellulose polysaccharides are called hemicellulose, which could be extracted by alkaline solution.
2.
According
the figure, A is the warty layer, B is the
inner layer (S3), C is the middle layer (S2), D is the outer layer (S
1) of the secondary wall, E is the primary
wall (P), and F is the middle lamella (ML).
订
3.
In 1897, Peter Klason studied the composition of
lignosulfonates and put forward the idea that lignin was chemically related to coniferyl alcohol. 4.
Cellulose molecules are completely linear and have a strong tendency to form intra-
and intermolecular
hydrogen bonds. Bundles of cellulose molecules are thus aggregated together in the form of microfibrils,
in which highly ordered (crystalline)
regions alternate with less ordered
(amorphous) regions. The best methods for determining crystallinity is X-ray diffraction. 5.
The unit cell of native cellulose (cellulose I) consists of four glucose residues (or two cellobiose residues). 线
6.
Lignins are polymers of phenylpropane units. One of their main coupling modes is β-O-4 . 7.
Besides cellulolytic enzyme lignin, the so-called Bj?
rkman lignin, alternatively referred to
as milled wood lignin (MWL) is the best preparation known so far, and it has been widely used for structural studies. 8.
During kraft pulping, the presence of hydrogen sulfide (HS-
) ions greatly facilitates delignification because of their strong nucleophilicity in comparison with hydroxyl(OH-) ions.
9.
The hemicelluloses are peeled much more readily than cellulose. The prerequisite for the peeling
reaction
is the presence of a reducing
end (hemiacetal)
group
in the
polysaccharide chain.
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得分1.
B. True or False:大题共
（对的打√，错的打×，答案填在题后的括号内。本
1分，总计
10分）
dissolves. The
10小题，每小题
During Kraft pulping roughly half of the wood substance degrades and
organic matter in the black liquor is composed of the degradation products of lignin and polysaccharides in addition to a minor fraction comprising extractives. (2.
√)
The lignin present in hardwoods is partly dissolved during the acid hydrolysis and hence the gravimetric
values must be corrected √)
for the \
lignin\
using UV
spectrophotometry. (3.
-Aryl ether linkages in free phenolic structures are cleaved relatively easily during the initial phase of delignification. (
√)
4.-Aryl ether linkages in nonphenolic structures are cleaved much more slowly, and the
√)
(depolymerization)
℃. （×）
of the
reaction is independent of the presence of the hydrogen sulfide ions. (5.
In addition
to the peeling reaction,
alkaline
hydrolysis
polysaccharide chains becomes important at lower temperatures of 1006.
Deacetylated xylan dissolved during delignification is partially redeposited on the fibers, especially at the end of the conventional cook.
（√）
7.The composition and structure of the hemicelluloses in the softwoods are almost the same in a characteristic way with those in the hardwoods.
（×）
hemicelluloses
are
8.In contrast to cellulose
(√)
which is a homopolysaccharide,
heteropolysaccharides. 9.
Cellulose
precursors (p-coumaryl, coniferyl, and sinapyl alcohols) are formed from
glucose by enzymic reactions involving oxidations, reductions, aminations, deaminations, decarboxylations, etc. This series of reactions is known as the shikimic acid route. 10.
More xylan can be extracted with alkali (KOH or NaOH). Addition of sodium borate to the alkali facilitates the dissolution of glucomannans. However, alkali extractions have the disadvantage of deacetylating the hemicelluloses completely. (
√)
（×）
11.
得分1.
C. Finish the reactions:答案写在答题纸上）
（本大题共
2小题，每小题
5分，总计
10分，
Peeling reaction of cellulose:
Isomerization 每步反应
2.
β-alkoxy elimination
1分
Isomerization Rearrangement
1分，文字说明
The reaction of lignin during kraft pulping:
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东北林业大学
2008－2009学年第一学期考试试题
每步反应1分，α、β醚键断裂脱除1分
得分
D. Answer the following questions25分，答案写在答题纸上）
（第1题15分，第2题10分，总计
1. See the figure, please tell what the chemical structure characteristics of cellulose are.
1.2.3.
Chain: homopolysaccharide, D-pyranoses are connected by 1,4-Configration: D-glucose
βglycosidic bonds.
Repeat parts: cellobiose, 1.03nm of length. Every glucose residue is accordingly displaced 180o with respect to its neighbors.
4.basic units: three hydroxyl groups, two of them (C2 and C3) are secondary alcohol hydroxyl groups, and one of them (C6) is primary alcohol hydroxyl group..
5.the ends: one, which has C4 free hydroxyl group, is a non-reducing group, and the other one, which has C1 free hydroxyl group, is a reducing group.
6.the middle units: except the reducing ends, all other units exist in the form of pyranose. They are stable.
7.conformation: the β-D-glucopyranose chain units are in chair conformation and the
substituents HO-2, HO-3, and CH2OH are oriented equatorially. 4、7条各2.5分，其他2.
Take 4-O-methyl-glucronic hemicellulose.
5条各2分，共acid-xylan
15分。
as an example to explain Smith degradation of
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第
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主链IO4氧化、NaBH支链IO4氧化、NaBH共10分
-
-
44
还原、水解（还原、水解（
hydrolysis / Hhydrolysis / H
++
）各1分，两步产物各）及产物各
1分；
2分；
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考试科目木材化学(双语)考试时间120分钟试卷总分70分资料
