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関: trimerization

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/12/26 16:37:46」(JST)

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In chemistry, a trimer (/ˈtraɪmər/) (tri-, "three" + -mer, "parts") is an oligomer derived from three identical precursors. An example is the procedure of production of polymers. At first, a monomer is made. By combining two monomers, a dimer is produced. With further additions, a trimer and eventually a polymer is made. Often, trimerization competes with polymerization; for example, dimethylsilanediol polymerizes to polydimethylsiloxane, even though a trimer is made:

Me₂Si(OH)₂ + (HO)₂SiMe₂ → Me₂(OH)Si-O-Si(OH)Me₂ – dimer

Me₂(OH)Si-O-Si(OH)Me₂ + (HO)₂SiMe₂ → Me₂(OH)Si-O-SiMe₂-O-Si(OH)Me₂ – trimer

Me₂(OH)Si-O-SiMe₂-O-Si(OH)Me₂ + (HO)₂SiMe₂ → Me₂(OH)Si-O-SiMe₂-O-SiMe₂-O-Si(OH)Me₂ – tetramer

et cetera, until Me₂(OH)Si-O-[SiMe₂-O-]_nSi(OH)Me₂ (n>100) – polymer

Trimers are typically cyclic. Chemical compounds that often trimerise are aliphatic isocyanates and cyanic acids.

1 Trimerisation via breaking triple bond
- 1.1 Alkyne trimerisation
- 1.2 Breaking carbon-hetero triple bonds forms symmetrical unsaturated 1,3,5-heterocycles
  - 1.2.1 Synthesis of melamine
2 -Ene trimerisation
- 2.1 Diene trimerisation
- 2.2 Breaking carbon-hetero double bonds forms symmetrical saturated 1,3,5-heterocycles
3 References

Trimerisation via breaking triple bond

Alkyne trimerisation

The trimerization cyclization reaction can be understood with this scheme.

In 1866, Marcellin Berthelot reported the first example of cyclotrimerization leading to aromatic products, the cyclization of acetylene to benzene.^[1] In the Reppe synthesis, the trimerization of acetylene gives benzene:

Breaking carbon-hetero triple bonds forms symmetrical unsaturated 1,3,5-heterocycles

Symmetrical 1,3,5-triazines are prepared by trimerization of certain nitriles such as cyanogen chloride or cyanimide.

Cyanuric chloride is prepared in two steps from hydrogen cyanide via the intermediacy of cyanogen chloride, which is trimerized at elevated temperatures over a carbon catalyst:

HCN + Cl₂ → ClCN + HCl

In 2005, approximately 200,000 tonnes were produced.^[2]

Cyanuric bromide is analogously prepared from cyclotrimerization of cyanogen bromide:

3 BrCN → (BrCN)₃

An industrial route to cyanuric acid entails the thermal decomposition of urea, with release of ammonia. The conversion commences at approximately 175 °C:^[2]

3 H₂N-CO-NH₂ → [C(O)NH]₃ + 3 NH₃

Synthesis of melamine

The endothermic synthesis of melamine can be understood in two steps. First, urea decomposes into cyanic acid and ammonia in an endothermic reaction:

(NH₂)₂CO → HOCN + NH₃

Then in the second step, cyanic acid polymerizes to form cyanuric acid which condenses with the liberated ammonia from the first step to release melamine and water.

3 HOCN → [C(O)NH]₃

[C(O)NH]₃ + 3 NH₃ → C₃H₆N₆ + 3 H₂O

This water then reacts with cyanic acid present, which helps drive the trimerization reaction, generating carbon dioxide and ammonia.

3 HOCN + 3 H₂O → 3 CO₂ + 3NH₃

In total, the second step is exothermic:

6 HCNO + 3 NH₃ → C₃H₆N₆ + 3 CO₂ + 3NH₃

but the overall process is endothermic.

-Ene trimerisation

Diene trimerisation

The 1,5,9-trans-trans-cis isomer of cyclododecatriene C₁₂H₁₈ has some industrial importance ^[3] and is obtained by cyclotrimerization of butadiene with titanium tetrachloride and an organoaluminium co-catalyst:^[4]

Catalyzing and dehydrating by sulfuric acid, trimerization of acetone via aldol condensation affords mesitylene.

Breaking carbon-hetero double bonds forms symmetrical saturated 1,3,5-heterocycles

Cyclotrimerization of formaldehyde affords 1,3,5-Trioxane:

1,3,5-Trithiane is the cyclic trimer of the otherwise unstable species thioformaldehyde. This heterocycle consists of a six-membered ring with alternating methylene bridges and thioether groups. It is prepared by treatment of formaldehyde with hydrogen sulfide.^[5]

Three molecules of acetaldehyde condense^[how?] to form “paraldehyde,” a cyclic trimer containing C-O single bonds.

References

^ Schetter, M. C. R. (1866). Hebd. Seances Acad. Sci. 62: 905.
^ ^a ^b Klaus Huthmacher, Dieter Most "Cyanuric Acid and Cyanuric Chloride" in Ullmann's Encyclopedia of Industrial Chemistry, 2005, Wiley-VCH, Weinheim. doi:10.1002/14356007.a08_191.
^ 1995 figures for global annual capacity 8000 ton
^ Industrial Organic Chemistry, Klaus Weissermel, Hans-Jurgen Arpe John Wiley & Sons; 3rd 1997 ISBN 3-527-28838-4
^ Bost, R. W.; Constable, E. W. "sym-Trithiane" Organic Syntheses, Collected Volume 2, p.610 (1943). http://www.orgsyn.org/orgsyn/pdfs/CV2P0610.pdf

Wikimedia Commons has media related to Trimers.

English Journal

On the reactivity of tetrakis(trifluoromethyl)cyclopentadienone towards carbon-based Lewis bases.

Holle S1, Escudero D, Inés B, Rust J, Thiel W, Alcarazo M.
Chemistry (Weinheim an der Bergstrasse, Germany).Chemistry.2015 Feb 9;21(7):2744-9. doi: 10.1002/chem.201405418. Epub 2014 Dec 11.
The reactivitiy of tetrakis(trifluoromethyl)cyclopentadienone towards different C-based Lewis bases, such as N-heterocyclic carbenes (NHC), ylides and isonitriles, are reported. While sterically not hindered carbenes were found to yield kinetic adducts by regiospecific nucleophilic attack at the pos
PMID 25504921

COL1A1 and miR-29b show lower expression levels during osteoblast differentiation of bone marrow stromal cells from Osteogenesis Imperfecta patients.

Kaneto CM1, Lima PS, Zanette DL, Prata KL, Pina Neto JM, de Paula FJ, Silva WA Jr.
BMC medical genetics.BMC Med Genet.2014 Apr 27;15:45. doi: 10.1186/1471-2350-15-45.
BACKGROUND: The majority of Osteogenesis Imperfecta (OI) cases are caused by mutations in one of the two genes, COL1A1 and COL1A2 encoding for the two chains that trimerize to form the procollagen 1 molecule. However, alterations in gene expression and microRNAs (miRNAs) are responsible for the regu
PMID 24767406

Assembling of AcrB trimer in cell membrane.

Lu W1, Chai Q, Zhong M, Yu L, Fang J, Wang T, Li H, Zhu H, Wei Y.
Journal of molecular biology.J Mol Biol.2012 Oct 12;423(1):123-34. doi: 10.1016/j.jmb.2012.06.036. Epub 2012 Jul 3.
Many membrane proteins exist and function as oligomers, but how monomers oligomerize in the cell membrane remains poorly understood. AcrB is an obligate homo-trimer. We previously found that the folding of individual subunit precedes oligomerization. Following folding, individual AcrB subunits must
PMID 22766312

Japanese Journal

Curing Reactions of Bismaleimide Resins Catalyzed by Triphenylphosphine. High Resolution Solid-State 13C NMR Study.

Shibahara Sumio,Enoki Takashi,Yamamoto Takahisa,Motoyoshiya Jiro,Hayashi Sadao
Polymer Journal 28(9), 752-757, 1996
… On the other hand, maleimides trimerize above 120°C in the presence of DABA and TPP. …
NAID 130004429790

The synthesis of isocyanurates on the trimerization of isocyanates under high pressure.

Taguchi Yoichi,Shibuya Isao,Yasumoto Masahiko,Tsuchiya Tohru,Yonemoto Katsumi
Bulletin of the Chemical Society of Japan 63(12), 3486-3489, 1990
… Aryl and normal alkyl isocyanates trimerized under high pressure to give the corresponding isocyanurates in good yields, whereas isocyanates having bulky alkyl groups such as t-butyl and cyclohexyl did not trimerize even under 800 MPa. …
NAID 130001979833

The Isocyanurates. III. The Formation of Tributyl Isocyanurates from Butyl Bromides in the Presence of 1-Butanol

Nagasawa Atsuo,Kitano Hisao,Fukui Kenichi
Bulletin of the Chemical Society of Japan 39(11), 2434-2437, 1966
… An attempt to trimerize n-butyl or s-butyl isocyanate in the presence of carbamates and dimethylthylformamide, or in the presence of carbamates and potassium cyanate, resulted in failure. …
NAID 130001963115