Stereospecific Anionic Polymerization of Methyl Bicyclobutane-1-carboxylate

Kitayama, Tatsuki; Kawauchi, Takehiro; Chen, Xiaoping; Padías, Anne Buyle; Hall, H. K.

doi:10.1021/ma012250l

Cited by 9 publications

(5 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thus our trial to obtain high 28 The benzylamino group in the PMMA could be removed by the treatment with H 2 /Pd-C in THF to afford a PMMA with a primary amino functionality at the chain end ( Figure 3); the characteristic signals due to benzylamino group in its ammonium salt form [Ph; 7.4, 7.6 ppm, CH 2 ; 4.2 ppm, (Figure 3b)] completely disappered in the spectrum of the product (Figure 3a). Thus, BnTMSNLi can be regarded as a lithium amide doubly protected with TMS and benzyl groups, and equivalent to TMS 2 NLi; with the latter lithium amide, the control of MMA polymerization was much difficult (see Table I, ref 26), probably due to the low nucleophilicity. 25 Other Polymerization Systems Anionic polymerization of MMA in THF is a versatile method for synthesis of PMMA with controlled molecular weight.…”

Section: Identification Of N-benzylmethacrylamidementioning

confidence: 99%

“…[16][17][18][19][20][21][22][23][24] More recently, the authors have reported that t-BuLi/bis(2,6-di-tert-butylphenoxy)ethylaluminum [EtAl(ODBP) 2 ] initiating system was effective for stereospecific living polymerization of methacrylates, 20 acrylates 25 and methyl bicyclobutane-1-carboxylate. 26 These exam-ples illustrate utility of organoaluminum compounds (Lewis acid) in the stereocontrol of anionic polymerization with organolithium initiators.…”

mentioning

confidence: 96%

See 1 more Smart Citation

Anionic Polymerization of (Meth)acrylates with Trialkylsilyl-protected Lithium N-Benzylamide

Kitaura

Kitayama

2007

Polym J

Self Cite

View full text Add to dashboard Cite

The polymerization of methacrylates with lithium N-benzyltrimethylsilylamide (BnTMSNLi) in the presence of aluminum compounds afforded syndiotactic or heterotactic polymethacrylates with narrow MWD quantitatively. The end-group analysis of these polymers revealed that benzylamino end-group was quantitatively introduced at the initiating chain-ends of the polymers. The initiator efficiency of the polymerization was slightly lower than unity (0.8-0.9), suggesting possible side reactions in the initiation process. The crude reaction mixture from methyl methacrylate (MMA) polymerization with BnTMSNLi was found to contain a small amount of N-benzylmethacrylamide, which should be formed through the 1,2-addition (carbonyl addition) of BnTMSNLi to MMA in the initiation step of the polymerization. The in situ formed silylsubstituted methacrylamide was not involved in the further polymerization process, as MALDI-TOF mass analysis of the formed polymer indicated the absence of the respective unit in the polymer chain. The methacrylamide remained intact was transformed to N-benzylmethacrylamide when the polymerization was terminated with acidified methanol. Therefore, 1,4-/ 1,2-addition selectivity in the initiation step could be estimated by NMR spectroscopic quantification of the benzylamino end-group in the polymer and N-benzylmethacrylamide in the polymerization mixture. A lithium amide with bulky triisopropylsilyl substituent, BnTIPSNLi, completely suppressed the 1,2-addition and thus the methacrylamide formation, while 15% of BnTMSNLi and 2% of BnTBSNLi, tert-butyldimethylsilyl derivative, underwent the 1,2-addition.KEY WORDS: MMA / Anionic Polymerization / End-functional Polymer / Lithium Amide / 1,2-Addition / 1,4-Addition / Methacrylamide / End-functional polymers have attracted much attention since they can be used for constructing more elaborated polymer chain architectures. 1 Living polymerization, the concept of which was first proposed by Szwarc, 2 is one of the most promising ways to introduce a specified functional group at a polymer chain-end through the reaction of the living polymers with the respective functional reagent. 3 Another means to obtain end-functional polymers is to polymerize a monomer with an initiator which comprises a functional group or its precursor group. 4 Lithium dialkylamides (R 2 NLi) such as lithium diisopropylamide (LDA) have been known as useful anionic initiators for methacrylate polymerizations. 5-9 For example, Antoun et al. reported that LDA/lithium chloride (LiCl) was an effective initiating system for anionic polymerization of methyl methacrylate (MMA) in tetrahydrofuran (THF) and generated PMMA with narrow molecular weight distribution (MWD) in high initiator efficiency (> 0:9). 6,7 The obtained polymer has the tertiary amino group at the chain end, which is less feasible for further chemical modification than primary and secondary amino groups. Kubo et al. reported that polymerization of MMA with N, N 0 -diphenylethylenediamine monolithium amide in THF afforded PMMA havin...

show abstract

Section: Identification Of N-benzylmethacrylamidementioning

confidence: 99%

mentioning

confidence: 96%

Anionic Polymerization of (Meth)acrylates with Trialkylsilyl-protected Lithium N-Benzylamide

Kitaura

Kitayama

2007

Polym J

Self Cite

View full text Add to dashboard Cite

show abstract

“…Other stereoregular polymers were also obtained in the Lewis acid‐assisted anionic polymerization of methyl bicyclobutane‐1‐carboxylate. Although methylaluminum bis‐hindered phenoxide gave approximately 75% trans enchainment, the ethylaluminum analogue gave 92% trans 12. Further study of this monomer and methyl 1‐cyclobutenecarboxylate will be reported soon.…”

Section: Polymer Stereochemistrymentioning

confidence: 88%

“…Classical anionic polymerizations of the bicyclobutane 1‐nitrile and 1‐ester monomers occurred but gave modest yields of low polymers. Recently, our collaborators in Kitayama's group at Osaka demonstrated Lewis acid‐assisted anionic polymerization of the 1‐ester to obtain highly stereoregular polymers 12. The analogy between bicyclobutane and vinyl copolymerization even extended to the use of Lewis acids to enhance the electrophilicity of the electron‐poor bicyclobutane.…”

Section: Bicyclobutanesmentioning

confidence: 99%

Bicyclobutanes and cyclobutenes: Unusual carbocyclic monomers

Hall

Padías

2003

J. Polym. Sci. A Polym. Chem.

Self Cite

View full text Add to dashboard Cite

ABSTRACT:Bicyclobutanes and cyclobutenes substituted with electron-attracting groups represent novel classes of reactive monomers. They readily undergo free-radical and anionic polymerizations to give high polymers consisting of 1,3-and 1,2-enchained cyclobutane rings, respectively.They also copolymerize readily with conventional vinyl monomers. These polymers display numerous attractive properties in comparison with their vinyl counterparts, including enhanced thermal stability, superior optical properties, and higher glass-transition temperatures. The syntheses of these monomers are reviewed, and suggestions toward future larger scale production are made.

show abstract

“…In the previous paper, 4 we reported the anionic polymerization of MBCB with tert-butyllithium (t-BuLi)/bis(2,6-di-tertbutylphenoxy)ethylaluminum [EtAl(ODBP) 2 ] in toluene at À78 C gave transtactic polymers (trans contents > 90%) in high yields. This kind of favorable effect of aluminum bisphenoxides on the anionic polymerization has been well demonstrated in stereospecific living polymerizations of methacrylates and acrylates.…”

mentioning

confidence: 99%

Structural Analyses of Methyl Bicyclobutane-1-carboxylate Oligomers Formed with tert-Butyllithium/Aluminum Bisphenoxide and Mechanistic Aspect of the Polymerization

Kawauchi

Nakamura

Kitayama

et al. 2005

Polym J

Self Cite

View full text Add to dashboard Cite

ABSTRACT:Anionic polymerization of methyl bicyclobutane-1-carboxylate (MBCB) with tert-butyllithium (t-BuLi)/bis(2,6-di-tert-butylphenoxy)ethylaluminum [EtAl(ODBP) 2 ] in toluene at À78 C gives transtactic polymers (trans contents > 90%) with high yields, but with low initiator efficiency and broad molecular weight distribution. In order to obtain information on the initiation mechanism, oligomers of MBCB were prepared with t-BuLi/EtAl-(ODBP) 2 in toluene at À78 C, and fractionated into dimer to pentamer by size exclusion chromatography. The dimer fraction was further subjected to recycling SEC and found to consist of two types of dimers of different chemical structures. 1 H NMR analyses of the dimers revealed that one type of the dimer comprises of an initiating tert-butyl (t-Bu) group and two MBCB units while the other contains one t-Bu carbonyl group within the monomeric units in addition to the initial t-Bu group. Based on the NMR spectroscopic information on the oligomers, 1 H NMR spectra of the polymer was investigated with the focus on the end-group structures, that confirms that the carbonyl addition of t-BuLi to MBCB occurred and the ketonic compound thus formed participates in the polymerization. [DOI 10.1295/polymj.37.439] KEY WORDS Transtactic 1,3-Cyclobutane Polymer / Initiation Mechanism / Stereospecific Anionic Polymerization / Chain-end Analysis / NMR spectroscopy / Carbonyl Addition / Bicyclobutanes carrying electron-withdrawing substituents at 1-and/or 3-positions are a remarkable class of reactive monomers.1 Either free radical or anionic polymerization occurs readily across thelike 1,3-bond to give high molecular weight polymers consisting of 1,3-linked cyclobutane rings in the main chain.1 Such polymers have interesting properties including high glass transition temperatures, chemical and thermal stability, superior optical clarity, and resistance to depolymerization.1,3-Disubstituted cyclobutanes exist as either cisor trans-isomers. Accordingly the stereochemistry of the polybicyclobutanes becomes of interest, particularly for its influence on physical properties. Free radical polymerization of dimethyl bicyclobutane-1,3-dicarboxylate gives 95% trans-linkages.2 Similar polymerizations of various 1-monoesters give polymers with trans/cis ratio of about 2/1. 3Anionic polymerization offers potentially better control of stereochemistry of polymers, but early attempts for methyl bicyclobutane-1-carboxylate (MBCB) with n-butyllithium as an initiator gave only low molecular weight products. In the previous paper, 4 we reported the anionic polymerization of MBCB with tert-butyllithium (t-BuLi)/bis(2,6-di-tertbutylphenoxy)ethylaluminum [EtAl(ODBP) 2 ] in toluene at À78 C gave transtactic polymers (trans contents > 90%) in high yields. This kind of favorable effect of aluminum bisphenoxides on the anionic polymerization has been well demonstrated in stereospecific living polymerizations of methacrylates and acrylates.5-14 However, the given poly(MBCB) had broad molecular weight distribution (M w =M...

show abstract

Stereospecific Anionic Polymerization of Methyl Bicyclobutane-1-carboxylate

Cited by 9 publications

References 16 publications

Anionic Polymerization of (Meth)acrylates with Trialkylsilyl-protected Lithium N-Benzylamide

Anionic Polymerization of (Meth)acrylates with Trialkylsilyl-protected Lithium N-Benzylamide

Bicyclobutanes and cyclobutenes: Unusual carbocyclic monomers

Structural Analyses of Methyl Bicyclobutane-1-carboxylate Oligomers Formed with tert-Butyllithium/Aluminum Bisphenoxide and Mechanistic Aspect of the Polymerization

Contact Info

Product

Resources

About