WordNet

changing to a lower state (a less respected state) (同)debasement

PrepTutorEJDIC

(地位の)格下げ / (品位などの)下落

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/06/18 05:43:36」(JST)

wiki en

[Wiki en表示]

Depolymerization (or depolymerisation) is the process of converting a polymer into a monomer or a mixture of monomers.^[1] All polymers depolymerize at high temperatures, a process driven by an increase in entropy.

Ceiling temperature

The tendency of polymers to depolymerize is indicated by their ceiling temperature. At this temperature, the enthalpy of polymerization matches the entropy gained by converting a large molecule into monomers. Above the ceiling temperature, the rate of depolymerization is greater than the rate of polymerization, which inhibits the formation of the given polymer.^[2]

Ceiling Temperatures of Common Organic Polymers
Polymer	Ceiling Temperature (°C)^[3]	Monomer
polyethylene	610	CH₂=CH₂
polyisobutylene	175	CH₂=CMe₂
polyisoprene (natural rubber)	466	CH₂=C(Me)CH=CH₂
polymethylmethacrylate	198	CH₂=C(Me)CO₂Me
polystyrene	395	PhCH=CH₂
Polytetrafluoroethylene	1100	CF₂=CF₂

Applications

Depolymerization is a very common process. Digestion of food involves depolymerization of macromolecules, such as proteins. It is relevant to polymer recycling. Sometimes the depolymerization is well behaved, and clean monomers can be reclaimed. In other cases, such as polyethylene, depolymerization gives a mixture of products.

Depolymerization is also related to production of chemicals and fuels from biomass. In this case, reagents are typically required. A simple case is the hydrolysis of celluloses to glucose by the action of water. Generally this process requires an acid catalyst:

H(C₆H₁₀O₅)_nOH + (n - 1) H₂O → n C₆H₁₂O₆

References

^ Depolymerization, IUPAC Goldbook
^ Carraher Jr; Charles E (2010). "7". Introduction of Polymer Chemistry (2nd ed.). New York: CRC Press, Taylor and Francis. p. 224. ISBN 978-1-4398-0953-2.
^ Stevens, Malcolm P. (1999). "6". Polymer Chemistry an Introduction (3rd ed.). New York: Oxford University Press. pp. 193–194. ISBN 978-0-19-512444-6.

External links

This chemistry-related article is a stub. You can help Wikipedia by expanding it.

UpToDate Contents

全文を閲覧するには購読必要です。 To read the full text you will need to subscribe.

1. グリコーゲン脱分枝酵素欠損症（糖原病III型） glycogen debrancher deficiency glycogen storage disease iii
2. 静脈血栓塞栓症に対する低分子ヘパリン low molecular weight heparin for venous thromboembolic disease
3. ヘパリンおよび低分子ヘパリンの治療使用 therapeutic use of heparin and low molecular weight heparin
4. ペントサン多硫酸ナトリウム：医薬品情報 pentosan polysulfate sodium drug information
5. エノキサパリン：小児用医薬品情報 enoxaparin pediatric drug information

English Journal

New insights into the mode of action of the actin ADP-ribosylating virulence factors Salmonella enterica SpvB and Clostridium botulinum C2 toxin.

Barth H, Aktories K.SourceInstitut fur Pharmakologie und Toxikologie, Universitatsklinikum Ulm, Germany.
European journal of cell biology.Eur J Cell Biol.2011 Nov;90(11):944-50. Epub 2011 Jan 17.
The C2 toxin from Clostridium botulinum represents the prototype of the family of binary actin-ADP-ribosylating toxins. These toxins covalently transfer ADP-ribose from nicotinamide adenine dinucleotide (NAD(+)) onto arginine-177 of actin in the cytosol of eukaryotic cells resulting in depolymerizat
PMID 21247657

Determination of Noscapine's Localization and Interaction with the Tubulin-α/β Heterodimer.

Alisaraie L, Tuszynski JA.SourceDivision of Experimental Oncology, Cross Cancer Institute, University of Alberta, 11560 University Avenue, Edmonton, AB T6G 1Z2, Canada Department of Physics, University of Alberta, Edmonton, AB, Canada.
Chemical biology & drug design.Chem Biol Drug Des.2011 Oct;78(4):535-46. doi: 10.1111/j.1747-0285.2011.01189.x. Epub 2011 Sep 6.
Noscapine, the benzylisoquinoline alkaloid, 5-(4,5-Dimethoxy-3-oxo-1,3-dihydro-isobenzofuran-1-yl)-4-methoxy-6-methyl-5,6,7,8-tetrahydro-[1,3]dioxolo[4,5-g]isoquinolin-6-ium, has been extensively used as a cough-suppressing medication with low toxicity. It has been recently shown to also have anti-c
PMID 21781284

Japanese Journal

P-32 低温水熱環境下におけるリグノクレゾールの分子応答(ポスターセッション1:技術05,研究発表(ポスター発表))

野中寛,舩岡正光
バイオマス科学会議発表論文集 (6), 116-117, 2011-01-12
… Significant depolymerization started above 200℃ probably due to cleavage of the β-O-4 linkages. … On the other hands, depolymerization started from 110℃ under N_2 atmosphere, followed by a formation of new C-C linkages via uncontrollable radical coupling. …
NAID 110008463459

P-31 アルカリ環境下におけるリグノクレゾールの分子応答(ポスターセッション1:技術05,研究発表(ポスター発表))

山本亮太,野中寛,舩岡正光
バイオマス科学会議発表論文集 (6), 114-115, 2011-01-12
… Lignocresol is designed so that the β-O-4 linkages can be selectively cleaved under alkaline conditions around 140-170℃, resulting in significant depolymerization named "secondary functionality control". …
NAID 110008463458