Heimei Yuki

Anionic Copolymerization of Isoprene and 1,1-Diphenylethylene

The anionic copolymerization of styrene (M1) and 1, 1-diphenylethylene (M2) was investigated. 1, 1-Diphenylethylene, which can not homopolymerize by itself, was copolymerized with styrene by means of an anionic initiator. The copolymerization reaction seemed to proceed without termination or chain transfer, and gave a high molecular alternating copolymer under appropriate reaction conditions. The monomer reactivity ratio, r1, was obtained from the copolymer composition at the complete consumption of M1, assuming the rate constant k22=0. The monomer reactivity ratio was affected by the solvent (n-hexane, benzene, toluene, or THF), but not by the catalyst (n-BuLi, Na-dispersion, Na-naphthalene, or K-dispersion) or the reaction temperature. It was 0.4 in toluene at 30°C.

Chromatographic resolution: IX. High-performance liquid chromatographic resolution of enantiomers on optically active poly(triphenylmethyl methacrylate)

Abstract Optically active (+)-poly(triphenylmethyl methacrylate) was coated on macroporous silica gel and used as a chiral stationary phase for high-performance liquid chromatographic resolution of enantiomers. The chiral polymer resolved various compounds particularly when a polar eluent such as methanol was employed. The influences of the kind of silica gel, column temperature and eluent on the separation were investigated.

Stereospecific anionic polymerization and copolymerization of 1,1-diphenylethyl methacrylate

Abstract 1,1-Diphenylethyl methacrylate (DPEMA), which is a new methacrylic ester, was synthesized and polymerized by n-butyllithium (n-BuLi) in toluene and THF. The triad tacticity of the polymers was determined from the n.m.r. spectrum of poly(methyl methacrylate) (PMMA) which was derived from them. A highly stereoregular polymer was not formed either in toluene or in THF by n-BuLi between −78° and 30°C. In toluene, the tacticity depended very much on the polymerization temperature, and unexpectedly, the polymer obtained at −78°C was rich in syndiotacticity. The polymers obtained in THF were atactic regardless of the temperature. A highly isotactic polymer was formed with Grignard reagents. DPEMA (M 1 ) was also copolymerized with methyl methacrylate (MMA), diphenylmethyl methacrylate (DPMMA), and trityl methacrylate (TrMA) (M 2 ) in toluene and THF with n-BuLi; the tacticity of the copolymers was determined. Generally, the stereoregularity of the copolymers was lower than those of the M 2 homopolymers. In the copolymerization with MMA monomer reactivity ratios were also determined.

Anionic Polymerizations and Copolymerizations of Methacrylates-Reactivity of Monomer and Tacticity of Polymer

Abstract The anionic polymerizations and copolymerizations of methacrylates were investigated. The studies were focused on the stereoregularity of the polymers and the relative reactivity of the monomers in relation to the stereospecificity of polymerization.

Studies on the Cationic Polymerization of Styrene by Using Perdeuterated Monomer

SummaryPerdeuterated styrene was polymerized by TiCl4 and EtAlCl2 in toluene at −78°C and the resultant polymer was examined for the terminal group containg protons by using 1h NMR spectroscopy. The polymer prepared by TiCl4 was found to contain 0.64 of toluene fragments per a polymer molecule and a similar amount of CHD2-group. The ratios of kM/kP and kS/kP were estimated to be 0.0228 and 0.0035, respectively. Similar results were obtained for the polymerization initiated with EtAlCl2

Structure of methyl methacrylate oligomers formed in the polymerization with butyllithium in toluene

SummaryMethyl methacrylate was polymerized with butyllithium in toluene at -78°C. The heptane-soluble oligomers were fractionated by using a high-speed liquid chromatograph and five fractions were collected. These were found by1H-NMR and mass spectroscopy to contain the tertiary alcohol, dimer, trimer, tetramer, and pentamer of the following structures: From the results, the mechanism of polymerization was proposed.

Nuclear magnetic resonance studies of 1,1-diphenyl-n-butyllithium in mixed solvents of benzene and tetrahydrofuran

Abstract 1,1-Diphenyl-n-butyllithium (DPB−, 1,1-diphenyl-n-butyllithium-3,4-d5 (DPB-d−), and 1,1-diphenyl-n-hexyllithium (DPH−) were prepared by the reactions of 1,1-diphenylethylene with corresponding alkyllithiums in benzene and benzene-d6. The NMR spectra of these anions were measured in mixed solvents of benzene and tetrahydrofuran (THF). The chemical shifts of the aromatic and aliphatic protons showed minima at THF/DPB−=2 and those of methylene protons of THF moved to downfield rapidly up to the same ratio of THF to DPB−. These phenomena were explained by assuming the dimer formation of DPB− in benzene.

Alternating copolymerization of methyl α-phenylacrylate and methyl methacrylate by n-BuLi

Abstract The copolymerization of methyl α-phenylacrylate (MPhA) and methyl methacrylate by n-BuLi was carried out in toluene at various temperatures with an initial monomer ratio of 1:1. At −78°C the product was a homopolymer of MPhA. The copolymer obtained at −40°C was a mixture of poly(methyl α-phenylacrylate) and poly(methyl methacrylate) containing a small amount of alternating copolymer of both monomers. With further increase in the polymerization temperature the fraction of alternating copolymer increased and above 30°C all the copolymers obtained were alternate. With varying composition of feed monomers the copolymerization was carried out at 30°C and the alternating copolymer was obtained over a wide range of monomer feed ratios. In tetrahydrofuran the alternate sequence began to form at a lower temperature than in toluene, and all the copolymers obtained above 0°C were alternating ones. The mechanism of the copolymerization is discussed in some detail.

Liquid chromatographic optical resolution of 2,2′-spirobibenz[e]indan derivatives and absolute stereochemistry as determined by the c.d. exciton chirality method

2,2′-Spirobibenz[e]indan derivatives, (1) and (2), have been synthesized and optically resolved by means of liquid chromatography using a column with a chiral stationary phase of (+)-poly-(triphenylmethyl methacrylate); the absolute stereochemistry of each enantiomer was unambiguously determined by the c.d. exciton chirality method.

High-performance liquid chromatography of aromatic compounds on polychloral

Abstract Chloral was polymerized by the lithium alkoxide of cholesterol and the polymer obtained was used as a packing material for high-performance liquid chromatography. Various types of aromatic compounds were chromatographed on the polychloral he relative retention times of the solutes and their 13 C nuclear magnetic resonance chemical shifts were found. Three isomers of xylene were separated with this column at lower temperatures with a methanol—water mixture as carrier.