Methyl methacrylate butyllithium

Syntheses. Isotactic poly(methyl methacrylate) was synthesized by the method of Tsuruta et al. (9 ). Under a nitrogen atmosphere, a quantity of 6 mL (0.056 mole) of methyl methacrylate (MMA) dried over 4A molecular sieve was dissolved in 24 mL of similarly dried toluene. To the glass vial containing the reaction was added 0.65 mL of 1.6 M n-butyllithium, and the reaction was kept at -78°C in a dry ice/isopropanol bath. The polymerization was halted 24 hr later with the addition of hydrochloric acid and methanol (methanol/water 4.1 by volume). The polymer was dried in vacuo at 50°C, redissolved in methylene chloride, precipitated by being poured into water-containing methanol, and dried in vacuo at 50°C. Tacticlty and composition were verified with % NMR. Yield 47%. 

Braun et al. [258] used a combination of tert-butyllithium (t-BuLi) and tetramefhy-lethylenediamine to create initiator sites at the surface of carbon black for the LASIP of styrene. Schomaker et al. [259] first immobilized a methyl methacrylate derivative on colloidal silica and after activation by a Grignard reagent polymerized MMA. 

Another result of great importance—the conformational asymmetric polymerization of triphenylmethyl methacrylate realized in Osaka (223, 364, 365)— has already been discussed in Sect. IV-C. The polymerization was carried out in the presence of the complex butyllithium-sparteine or butyllithium-6-ben-zylsparteine. The use of benzylsparteine as cocatalyst leads to a completely soluble low molecular weight polymer with optical activity [a]o around 340° its structure was ascertained by conversion into (optically inactive) isotactic poly(methyl methacrylate). To the best of my knowledge this is the first example of an asymmetric synthesis in which the chirality of the product derives finom hindered rotation around carbon-carbon single bonds. 

The need for solvation in anionic polymerization manifests itself in some instances by other deviations from the normal reaction rate expressions. Thus the butyllithium polymerization of methyl methacrylate in toluene at — 60°C shows a second-order dependence of Rp on monomer concentration [L Abbe and Smets, 1967]. In the nonpolar toulene, monomer is involved in solvating the propagating species [Busson and Van Beylen, 1978]. When polymerization is carried out in the mixed solvent dioxane-toluene (a more polar solvent than toluene), the normal first-order dependence of Rp on [M] is observed. The lithium diethylamide, LiN(C2H5)2, polymerization of styrene at 25°C in THF-benzene similarly shows an increased order of dependence of Rp on [M] as the amount of tetrahydrofuran is decreased [Hurley and Tait, 1976]. 

Polymerization of the bulky monomer chloral yields an optically active product when one uses a chiral initiator, e.g., lithium salts of methyl (+)- or (—)-mandelate or (R)- or (S)-octanoate [Corley et al., 1988 Jaycox and Vogl, 1990 Qin et al., 1995 Vogl, 2000], The chiral initiator forces propagation to proceed to form an excess of one of the two enantiomeric helices. The same driving force has been observed in the polymerization of triphenyl-methyl methacrylate at —78°C in toluene by initiating polymerization with a chiral complex formed from an achiral initiator such as n-butyllithium and an optically active amine such as (+)-l-(2-pyrrolidinylmethyl)pyrrolidine [Isobe et al., 2001b Nakano and Okamoto, 2000 Nakano et al., 2001]. Such polymerizations that proceed in an unsymmetrical manner to form an excess of one enantiomer are referred to as asymmetric polymerizations [Hatada et al., 2002]. Asymmetric polymerization has also been observed in the radical... 

Studies on the Anionic Polymerization of Methyl Methacrylate Initiated with Butyllithium in Toluene by Using Perdeuterated Monomer... 

In Fig. 13 are shown typical spectra for 15% solutions of two methyl methacrylate polymers in chloroform. The polymers were prepared with (a) benzoyl peroxide in toluene at 100° and (b) n-butyllithium at — 62°. The large peak at the left is that of the chloroform solvent. The ester methyl group appears at 6.40r in both spectra, and is not affected by the chain conformation. There are three cc-methyl peaks, at 8.78t, 8.95 t, and 9.09r, whose relative heights vary greatly with the method of polymer preparation. Polymers prepared with n-butyllithium show a very prominent peak at 8.78r, the others being much smaller. Polymers prepared with benzoyl peroxide initiator show the same three peaks, but now the peak at 9.09r is the most prominent. 

It is a tertiary alcohol with the hydroxyl group flanked by two identical R (= butyl) groups. The chemists who wanted to make the compound knew that an ester would react twice with the same organolithium reagent, so they made it from this unsaturated ester (known as methyl methacrylate) and butyllithium. 

Methyllithium treatment enhances the nucleophilicity of zirconacyclopentadienes <2004TL5159>. Thus, when zirconacyclopentadiene 23 (R = R = R = R = Et, Cp =Cp, M = Zr) reacts with benzaldehyde in the presence of methyllithium in an acidic medium, the product is PhOHCHC(Et)=C(Et)C(Et)=C(Et)H <2004TL9041>. A similar reaction occurs with methyl methacrylate in the presence of -butyllithium in acidic medium and the product is MeOOCCHMeCH2C(Et)=C(Et)C(Et)=C(Et)H. When the electrophile is 1-bromobutyne, MeC=CCH2C(Et)=C(Et)C(Et)=C(Et)H is obtained. This methodology is illustrated in Equation (9). 

The structure of the hydrocarbon group also affects reactions leading to the start of polymerization. Initiation by butyllithium leads to the rapid formation of a relatively large amount of lithium methoxide, whereas by the reaction of diphenylhexyllithium with methyl methacrylate only a small amount of methoxide is formed slowly in both cases, the reaction proceeds according to scheme (36) or by cyclization or termination of the active centres [170] by 1,2 addition [i. e. again in analogy to reaction (36)]... 

Several attempts at the free-radical (benzene, 1% AIBN, 100 h, 55 °C) and anionic (1 4 THF-benzene, n-butyllithium-18-crown-6 complex [16, 17], -78 °C) polymerization of IPTMSK afforded only traces (<2 %) of a viscous product. Free-radical copolymerization of IPTMSK with methyl methacrylate (MM A) (50 mol % MM A, benzene, 0.5% AIBN, 100 h, 45 °C) resulted in a low yield (<10 %) of a copolymer composed mainly of MMA units and, as indicated by the IR (Figure 1C) and NMR data, of largely decomposed IPTMSK units. The presence of IPTMSK during copolymerization with MMA significantly decreased the molecular weight of the resulting copolymer. These results suggest that IPTMSK is incapable of homopolymerization by either a free-radical or an anionic mechanism. 

A number of CSPs have been developed that are based on optically active synthetic helices formed by the asymmetric polymerization of methacrylate monomers. These polymers have been formed using either chiral monomers such as (S)-acryloylphenyl-alanine (73) and N-methylacryloyl-(S)-cyclohexylethylamine (73), or achiral monomers such as triphenyl methacrylate (74) and diphenyl-2-pyridyl-methyl methacrylate (74). In the latter case, the polymers were prepared using chiral cation catalysts including (—)-spartene-butyllithium and (+)-6-benzylsparteine-butyllithium complexes (74). The commercially available forms of these CSPs are listed in Table 3. 

Poly(methyl methacrylate) was prepared in two different ways polymer F, with initiation by benzoyl peroxide at 100polymer G, with initiation by / -butyllithium at -62°. Their nmr spectra were, with considerable simplification, as follows ... 

Acrylonitrile (H .C=CHCN), methyl methacrylate fH2C=C(CH3)C02CHs], and styrene (H2C=CHC6Hj) can all be polymerized anionically. The polystyrene used in foam coffee cups, for example, is prepared by anionic polymerization of styrene using butyllithium as catalyst. 

Difunctional Initiators The methodology for preparation of hydrocarbon-soluble dilithium initiators is generally based on the reaction of an aromatic divinyl precursor with two mol of butyllithium. Unfortunately, because of the tendency of organolithium chain ends in hydrocarbon solution to associate and form electron-deficient dimeric, tetrameric, or hexameric aggregates, most attempts to prepare dilithium initiators in hydrocarbon media have generally resulted in the formation of insoluble three-dimensionally associated species [70]. The reaction of meffl-diisoprenylbenzene with 2 mol of f-butyllithium in the presence of 1 equivalent of triethylamine in cyclohexane at -20 °C has been reported to form pure diadduct without oligomerization. Equation 7.11 [71]. This initiator in the presence of 5 vol% of diethyl ether for the butadiene block has been used to prepare well-defined poly(metliyl methacrylate)- -polybutadiene-fe -poly(methyl methacrylate). 

Hatada K, Kitayama T, Fumikawa K, Ohta K, Yuki H. Studies on the anionic polymerization of methyl methacrylate initiated with butyllithium in toluene by using perdeuterated monomer. In McGrath JE, editor. Anionic Polymerization. Kinetics, Mechanisms and Synthesis. ACS Symposium Series. Volume 166. Washington (DC) American Chemical Society 1981. p 327. 

Some abnormalities were reported in the initiations of methyl methacrylate polymerizations in toluene by butyllithium. Their nature is such that they suggest the possibility of more than one reaction taking place simultaneously. One, which must be the major one, is that of the oiganomet-allic compound reacting with the carbon-to-carbon double bond as shown above. The other, minor one, may be with the carbon-to-oxygen double bond. The major reaction produces methyl methacrylate anions. The minor reaction, however, yields butyl isopropenyl ketone with an accompanying formation of lithium methoxide ... 

Polymerizations of polar monomers, like acrylic and methacrylic esters with alkyllithium initiators, yield the greatest amount of steric control. Almost all isotactic poly(methyl methacrylate) foims at low temperatures. Addition of Lewis bases such as ethers or amines reduces the degree of isotactic placement. Depending upon the temperature, atactic or syndiotactic polymers form. Also, butyllithium in heptane yields an isotactic poly(A, A -dibutylacrylamide) at room temperature. ... 

Electron-withdrawing substituents in anionic polymerizations enhance electron density at the double bonds or stabilize the carbanions by resonance. Anionic copolymerizations in many respects behave similarly to the cationic ones. For some comonomer pairs steric effects give rise to a tendency to altemate. The reactivities of the monomers in copolymerizations and the compositions of the resultant copolymers are subject to solvent polarity and to the effects of the counterions. The two, just as in cationic polymerizations, cannot be considered independently from each other. This, again, is due to the tightness of the ion pairs and to the amount of solvation. Furthermore, only monomers that possess similar polarity can be copolymerized by an anionic mechanism. Thus, for instance, styrene derivatives copolymerize with each other. Styrene, however, is unable to add to a methyl methacrylate anion, though it copolymerizes with butadiene and isoprene. In copolymerizations initiated by w-butyllithium in toluene and in tetrahydrofuran at-78 °C, the following order of reactivity with methyl methacrylate anions was observed. In toluene the order is diphenylmethyl methacrylate > benzyl methacrylate > methyl methacrylate > ethyl methacrylate > a-methylbenzyl methacrylate > isopropyl methacrylate > t-butyl methacrylate > trityl methacrylate > a,a -dimethyl-benzyl methacrylate. In tetrahydrofuran the order changes to trityl methacrylate > benzyl methacrylate > methyl methacrylate > diphenylmethyl methacrylate > ethyl methacrylate > a-methylbenzyl methacrylate > isopropyl methacrylate > a,a -dimethylbenzyl methacrylate > t-butyl methacrylate. 

Sodium dispersions in hexane yield syndiotactic poly(methyl methacrylate). A 60-65% conversion is obtained over a 24-hour period at a reaction temperature of 20-25 C. Lithium dispersions, butyllithium, and Grignard reagents " "yield crystalline isotactic poly(r-butyl acrylate). The reactions take place in bulk and in hydrocarbon solvents. Isotactic poly(isopropyl acrylate) forms with Grignard reagents. ... 

Example 3.20 Preparation of Isotactic and Syndiotactic Poly(Methyl Methacrylate) with Butyllithium in Solution... 

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