関: ROMP

WordNet

sound loudly and sonorously; "the bells rang" (同)peal
a toroidal shape; "a ring of ships in the harbor"; "a halo of smoke" (同)halo, annulus, doughnut, anchor ring
jewelry consisting of a circlet of precious metal (often set with jewels) worn on the finger; "she had rings on every finger"; "he noted that she wore a wedding band" (同)band
a characteristic sound; "it has the ring of sincerity"
a platform usually marked off by ropes in which contestants box or wrestle
the sound of a bell ringing; "the distinctive ring of the church bell"; "the ringing of the telephone"; "the tintinnabulation that so voluminously swells from the ringing and the dinging of the bells"--E. A. Poe (同)ringing, tintinnabulation
attach a ring to the foot of, in order to identify; "ring birds"; "band the geese to observe their migratory patterns" (同)band
make (bells) ring, often for the purposes of musical edification; "Ring the bells"; "My uncle rings every Sunday at the local church" (同)knell
first or beginning; "the memorable opening bars of Beethovens Fifth"; "the plays opening scene"
opportunity especially for employment or promotion; "there is an opening in the sales department"
a recognized sequence of moves at the beginning of a game of chess; "he memorized all the important chess openings" (同)chess opening
a vacant or unobstructed space that is man-made; "they left a small opening for the cat at the bottom of the door"
becoming open or being made open; "the opening of his arms was the sign I was waiting for"
the act of opening something; "the ray of light revealed his cautious opening of the door"
an open or empty space in or between things; "there was a small opening between the trees"; "the explosion made a gap in the wall" (同)gap
the first performance (as of a theatrical production); "the opening received good critical reviews" (同)opening_night, curtain raising
a ceremony accompanying the start of some enterprise
the initial part of the introduction; "the opening established the basic theme"
wearing a wedding ring; lawfully married; "a ringed wife"- Tennyson
having colored rings around the body
gymnastic apparatus consisting of a pair of heavy metal circles (usually covered with leather) suspended by ropes; used for gymnastic exercises; "the rings require a strong upper body"
a chemical process that combines several monomers to form a polymer or polymeric compound (同)polymerisation

PrepTutorEJDIC

『指輪』 / 『輪』,環;輪形,円形 / (円形の)サーカス演技場,公演場,競技場;(ボクシング・レスリングの)リング / 《複数形で》(体操の)つり輪 / (不法な目的で結託した)(…の)徒党,一味《+『of』+『名』》 / (原子の)環 / …を円形に取り囲む,円で囲む《+『about』(『around』,《英》『round』)+『名,』+『名』+『about』(『around』,《英》『round』)+『名』》 / 〈動物〉‘に'鼻輪(首輪,足輪)をはめる / (遊びで)…‘に'輪を投げる / 環状に動く,輪を描く
〈鐘・ベルなどが〉『鳴る』 / 《『ring』+『形』〈補〉》(…のように)聞こえる / (…を)ベルを鳴らして求める《+『for』+『名』》 / 〈音声・楽器などが〉鳴り響く;〈場所が〉(音などで)満ちる《+『with』+『名』》 / 耳鳴りがする / 〈鐘・ベルなど〉‘を'『鳴らす』 / 〈人〉‘を'(鐘などを)『鳴らして呼ぶ』;…‘を'鐘を鳴らして知らせる / 《英》…‘に'電話をかける《+『up』+『名』,+『名』+『up』》 / 《単数形で》(鐘・ベルなどの)『鳴る音,響き』《+『of』+『名』》 / 鐘(ベルなど)を鳴らすこと;ベル(など)が鳴ること / 《単数形で》(…の)固有の響き,調子,感じ《+『of』+『名』》 / 《話》電話をかけること
〈C〉(森・垣根・壁などの)空いている所;空き地;すき間,穴 / 〈C〉(物語・会議などの)始め,出だし,冒頭(beginning) / 〈C〉(…の地位の)空き,就職口《+『for』(『at, in』)+『名』》(vacant) / 〈C〉(劇などの)初演 / 〈U〉(…が)開くこと,あくこと《+『of』+『名』》 / 〈C〉(…の)よい機会,好機《+『for』+『名』》 / 初めの,開始の
輪にある;環状の / 指輪をはめた

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2016/02/07 04:56:29」(JST)

wiki en

Ring-opening metathesis polymerization (ROMP) is a type of olefin metathesis chain-growth polymerization that produces industrially important products. The driving force of the reaction is relief of ring strain in cyclic olefins (e.g. norbornene or cyclopentene) and a wide variety of catalysts have been discovered. Research has shown that the addition of substituents to the monomer and the choice of solvent can alter the molecular weight of the polymer produced.

Mechanism

The catalysts used in the ROMP reaction include a wide variety of metals and range from a simple RuCl₃/alcohol mixture to Grubbs' catalyst^[1]^[2]

The ROMP reaction is catalyzed primarily through the formation of metal-carbene complexes as first reported by Nobel Prize winner Yves Chauvin and his colleague Jean-Louis Hérisson^[3]^[4] although a hydride mechanism has also been reported.^[1] The initiation of the carbene species occurs through numerous pathways; solvent interactions, substituent interactions, and co-catalysts all can contribute to the production of the reactive catalytic species^[1]^[5] .^[6]

The ROMP catalytic cycle requires a strained cyclic structure because the driving force of the reaction is relief of ring strain. After formation of the metal-carbene species, the carbene attacks the double bond in the ring structure forming a highly strained metallacyclobutane intermediate. The ring then opens giving the beginning of the polymer: a linear chain double bonded to the metal with a terminal double bond as well. The new carbene reacts with the double bond on the next monomer, thus propagating the reaction^[3]

Solvent effects

The choice of solvent can play a vital role in the formation of the carbene species. One example of such interactions was reported by Basset, et al. regarding RuCl₃ and the effects of various alcohols on its catalytic activity. Depending upon the alcohol used, the mechanistic pathway resulted in either a reactive ruthenium-hydride species or the formation of a ruthenium-carbene. Experimental results demonstrated that by altering the solvent, the molecular weight of the polymer produced was either increased or decreased. This observation could result in increased diversity of the catalytic system enabling the production of polymers of various strengths, as polymers with higher molecular weights are typically stronger than polymers of low molecular weights.^[1] Drastic differences in the rate of the reaction were also observed, thereby supporting the conclusion that the solvent plays a role in the formation of the ruthenium-carbene.

Hamilton, et al. report that altering the solvent in metal salt-type catalytic systems can drastically change the microenvironment of the system; these changes affect the tacticity of the polymer, the cis-trans ratio, and can increase the regularity of copolymers.^[7]

Substituent Effects

As previously stated, ROMP catalysis is dependent on ring strain. Therefore, the best substrates are bi- and tri-cyclic rings; however, these reactions can lead to numerous products.^[8]^[9] The addition of substituents to the ring system can result in more complex or more functional polymer products. Unfortunately, substituents on the ring can react deleteriously with some of the most common catalysts. The first Grubbs’ catalyst is poisoned by nitrile or amine groups.^[5] Many common molybdenum or tungsten metathetical catalysts are affected by oxygenate or nitrogenous groups. Thus alternative catalysts, such as ruthenium carbene complexes that are not affected by these functional groups are being researched.^[1]

The position of the substituent in the ring complex has a correlation to the poisoning effect on the catalyst.^[10]^[11] However, in cases where it is non-poisoning, it also plays a role in determining the reactivity of the substrate. Substituents cannot be placed on the carbon with the double bond or the reaction will not take place.^[8] Slugovc, et al. tested the effect of numerous functional groups on the ROMP reaction using the ‘Super-Grubbs’ catalyst, (H₂IMes)(PCy₃)(Cl)₂Ru=CHPh. The experimental results show that the addition of common substituents to the reaction mixture can be used to tune the molecular weight range of the polymer produced.^[5]

Depending on the catalyst, some substituents can increase the rate of reaction. Norbornene epoxides increase the rate of reaction when a ruthenium trichloride/alcohol mixture is used as the catalyst. Basset, et al. contribute this rate increase to the production of a metallooxacyclobutane complex that, upon metathetic opening, gives the active ruthenium carbene complex directly.^[1] It stands to reason that other functional groups that can react with a similar mechanistic pathway will also increase the rate of reaction.

Precision control of polymer stereo- and regiochemistry is a powerful approach for the manipulation of polymer properties. This is particularly true in the case of polyolefins where tacticity and regiochemistry can have dramatic influence on the thermal, rheological, and crystallization properties. The authors Hillmyer, Kobayashi and Pitet demonstrate the regio- and stereoselective ring-opening metathesis polymerization (ROMP) of 3-substituted cis-cyclooctenes (3RCOEs, R = methyl, ethyl, hexyl, and phenyl).^[12] Later studies by Hillmyer and Cramer demonstrated that the regioselectivity was due to the steric interactions between the substituent and the NHC-ligand, but with a significant contribution from the solvent polarity.^[13] In this study the authors also found different rate limiting step for the different ring sizes.

Industrial Applications

Ring-opening metathesis polymerization of cycloalkenes can produce many important petrochemicals; this is of particular importance in an industrial capacity because synthetic capabilities include linear polymers from inexpensive monomers or polymers with special properties, thus compensating for an additional expense. Some examples of polymers produced on an industrial level through ROMP catalysis are Vestenamer or trans-polyoctenamer which is the metathetical polymer of cyclooctene; Norsorex or polynorbornene is another important ROMP product on the market; Telene and Metton are polydicyclopentadiene products produced in a side reaction of the polymerization of norbornene.^[9]

The ROMP process is quite useful because a regular polymer with a regular amount of double bonds is formed. The resulting product can be subjected to partial or total hydrogenation or can be functionalized into more complex compounds.^[9]

References

^ ^a ^b ^c ^d ^e ^f Mutch, A.; Leconte, M.,; Lefebvre, F.; Basset, J.M. (1998). "Effect of alcohols and epoxides on the rate of ROMP of norbornene by a ruthenium trichloride catalyst". Journal of Molecular Catalysis A: Chemical 133 (1–2): 191–199. doi:10.1016/S1381-1169(98)00103-4.
^ Scholl, M.; Ding, S.; Lee, C. W.; Grubbs, R. H. (1999). "Synthesis and Activity of a New Generation of Ruthenium-Based Olefin Metathesis Catalysts Coordinated with 1,3-Dimesityl-4,5-dihydroimidazol-2-ylidene Ligands". Organic Letters 1 (6): 953–956. doi:10.1021/ol990909q.
^ ^a ^b Grubbs, R.H.; Tumas, W. (1989). "Polymer Synthesis and Organotransition Metal Chemistry". Science 243 (4893): 907–915. Bibcode:1989Sci...243..907G. doi:10.1126/science.2645643. PMID 2645643.
^ Hérisson, J.L.; Chauvin, Y. (1971). "Catalyse de transformation des oléfines par les complexes du tungstène. II. Télomérisation des oléfines cycliques en présence d'oléfines acycliques". Die Makromolekulare Chemie 141 (1): 161–176. doi:10.1002/macp.1971.021410112.
^ ^a ^b ^c Slugovc, C.; Demel, S.; Riegler, S.; Hobisch, J.; Stelzer, F. (2004). "Influence of functional groups on ring opening metathesis polymerization and polymer properties". Journal of Molecular Catalysis A: Chemical 213 (1): 107–113. doi:10.1016/j.molcata.2003.10.054.
^ Zhang, D.; Huang, J.; Qian, Y.; Chan, A.S.C. (1998). "Ring-opening metathesis polymerization of norbornene and dicylopentadiene catalyzed by Cp₂TiCl₂/RMgX". Journal of Molecular Catalysis A: Chemical 133 (1–2): 131–133. doi:10.1016/S1381-1169(98)00087-9.
^ Samak, B.A.; Amir-Ebrahimi, V; Corry, D.; Hamilton, J.G.; Rigby, S; Rooney, J.J.; Thompson, J.M. (2000). "Dramatic solvent effects on ring-opening metathesis polymerization of cycloalkenes". Journal of Molecular Catalysis A: Chemical 160 (1): 13–21. doi:10.1016/S1381-1169(00)00228-4.
^ ^a ^b Hammond, P. 10.569 Synthesis of Polymers Fall 2006 materials; Massachusetts Institute of Technology OpenCourseWare, 2006.
^ ^a ^b ^c Mol, J.C. (2004). "Industrial applications of olefin metathesis". Journal of Molecular Catalysis A: Chemical 213 (1): 39–45. doi:10.1016/j.molcata.2003.10.049.
^ Wright, D.L.; Schulte II, J.P.; Page, M.A (2000). "An Imine Addition/Ring-Closing Metathesis Approach to the Spirocyclic Core of Halichlorine and Pinnaic Acid". Organic Letters 2 (13): 1847–1850. doi:10.1021/ol005903b. PMID 10891173.
^ Alcaide, B.; Almendros, P.; Alonso, J.; Aly, M.F (2001). "A Novel Use of Grubbs' Carbene. Application to the Catalytic Deprotection of Tertiary Allylamines". Organic Letters 3 (23): 3781–3784. doi:10.1021/ol0167412. PMID 11700137.
^ Shingo Kobayashi, Louis M. Pitet, and Marc A. Hillmyer http://pubs.acs.org/doi/abs/10.1021/ja201644v
^ Martinez, Henry (2012). "Selectivity in Ring-Opening Metathesis Polymerization of Z -Cyclooctenes Catalyzed by a Second-generation Grubbs Catalyst". ACS Catalysis 2 (12): 2547–2556. doi:10.1021/cs300549u.

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