Fumio Sanda

Syntheses and functions of polymers based on amino acids

In this article, we review our studies concerning the design of novel functional polymers based on amino acids. Although an amino acid is the simplest optically active compound in the nature, its polymers, peptides, and proteins show a wide variety of functions such as electron transfer, information transfer, photo reactivity, and selective catalytic function, which cannot be imitated by synthetic compounds. It is expected to develop “artificial proteins” consisting of polymeric materials which show excellent functions, with exploring a precise molecular design based on amino acids.

Structural analysis of polyhydroxyurethane obtained by polyaddition of bifunctional five-membered cyclic carbonate and diamine based on the model reaction

This article focuses on the structural analysis of polyhydroxyurethane obtained by the reaction of 2,2-bis[p-(1,3-dioxolan-2-one-4-yl-methoxy)phenyl]]propane with a diamine based on the model reaction. The compounds obtained in the model reaction could be separated into hydroxyurethanes containing primary and secondary alcohol groups by preparative gel permeation chromatography with a recycling technique to determine the structures by 1 H NMR, 13 C NMR, distortionless enhancement by polarization transfer (DEPT) and C-H correlation spectroscopy to obtain hydroxyurethane carrying the primary alcohol structure moiety dominantly. The ratios were independent of the reaction temperature but somewhat dependent on the solvents and amines.

Polyaddition behavior of bis(five- and six-membered cyclic carbonate)s with diamine

Polyadditions of 1,2-bis[3-(1,3-dioxan-2-one-5-yl)-propylthio]ethane (B6CC) and 1,2-bis[4-(1,3-dioxolan-2-one-4-yl)-butylthio]ethane (B5CC) with 4,9-dioxadodecane-1,12-diamine were carried out. The reactivity of B6CC with the diamine was higher than that of B5CC. Additionally, B6CC gave a higher molecular weight polymer than B5CC. The reaction-rate constants of B6CC and B5CC at 30, 50, and 70 °C were evaluated as 0.70, 0.89, and 1.07 L/mol · h; and 0.03, 0.06, and 0.10 L/mol · h in N,N-dimethylacetamide (initial reagent concentration 0.5 M), respectively. The activation energies were estimated to be 9.2 and 24.9 kJ/mol in the reactions of B6CC and B5CC with the diamine, respectively.

Reactivity comparison of five- and six-membered cyclic carbonates with amines: Basic evaluation for synthesis of poly(hydroxyurethane)

The reaction of six- and five-membered cyclic carbonates, 5-(2-propenyl)-1,3-dioxan-2-one (1) and 4-(3-butenyl)-1,3-dioxolan-2-one (2) with hexylamine and benzylamine was carried out in N,N-dimethylacetamide at 30, 50, and 70 °C. The six-membered cyclic carbonate 1 proceeded quantitatively with hexylamine at 30 °C for 24 h, while the five-membered cyclic carbonate 2 converted in 34%. The reaction rate constants at 50 °C are evaluated as follows; 1.42 L/mol · h (1 with hexylamine) > 0.29 L/mol · h (1 with benzylamine) > 0.04 L/mol · h (2 with hexylamine) > 0.01 L/mol · h (2 with benzylamine). The activation energies in the reactions of 1 and 2 with hexylamine were estimated to be 10.1 and 24.6 kJ/mol, respectively. The ring-strain energy was calculated by the semi-empirical method using the PM3 Hamiltonian. The ring-strain energy of the six-membered cyclic carbonate was 2.86 kcal/mol larger than that of five-membered one.

Addition of five-membered cyclic carbonate with amine and its application to polymer synthesis

A bifunctional five-membered cyclic carbonate was synthesized from carbon dioxide and diglycidyl terephthalate, and its polyaddition with alkyl diamines were carried out in DMF at room temperature to obtain the corresponding poly(hydroxyurethane)s with Mn s in the range of 6300–13200 in good yields. The structures of the obtained polymers were confirmed by IR and NMR spectroscopy and their glass-transition and decomposition temperatures were observed at 3–29 °C and 182–277 °C, respectively.

Syntheses and radical polymerizations of optically active (meth)acrylamides having amino acid moieties

Syntheses and radical polymerizations of several (meth)acrylamides having L-amino acid moieties were examined. The monomers were prepared by the reactions of L-amino acid ester hydrochlorides with (meth)acryloyl chloride in the presence of triethylamine in satisfactory yields. Radical polymerizations of the monomers were carried out in the presence of AIBN (1 mol %) in bulk and in several solvents to afford the corresponding polymers in satisfactory yield. The glass transition temperatures and specific rotations of the polymers depended on the substituents of the L-amino acid moieties. Nearly the same specific rotations were observed for the monomers and the model compounds of the polymer units, N-pivaloyl amino acid methyl esters. On the contrary, the specific rotations of the polymers shifted to the negative direction in ca. 30°. The interaction between the polymer side chains might affect the changes in the specific rotations from monomers to polymers.

Cationic ring-opening polymerization behavior of an aliphatic seven-membered cyclic carbonate, 1,3-dioxepan-2-one

Synthesis and cationic ring-opening polymerization of a seven-membered cyclic carbonate, 1,3-dioxepan-2-one (1), were examined. The cationic ring-opening polymerization of 1 proceeded without decarboxylation at 20°C to give the corresponding polycarbonate, differently from a six-membered cyclic carbonate (2), for which polymerization is generally accompanied by partial elimination of carbon dioxide. The observed polymerization rate of 1 in nitrobenzene was about 1.3 times faster than that in dichloromethane. The observed pseudo first-order polymerization rate constants of 1 and 2 at 20°C were determined to be 4.15 x 10 -4 and 4.16 x 10 -6 s -1 , respectively. The observed polymerization rate of 1 was 100 times larger than that of 2. The activation energies in the polymerization of 1 and 2 were estimated to be 6.27 and 8.52 kcal/mol, respectively.

Synthesis of cyclic trithiocarbonates from cyclic ethers and carbon disulfide catalyzed by titanium complex

Abstract This work deals with reaction of oxetane derivatives with carbon disulfide in the presence of (2-propanolato) titanatrane. It afforded six-membered cyclic trithiocarbonates in good yields. Reaction of propylene oxide with carbon disulfide also proceeded in a similar manner to give a five-membered cyclic trithiocarbonate in excellent yield.

Ring-opening polymerization of cyclic carbonates by alcohol–acid catalyst

Ring-opening reactions of 1,3-dioxepan-2-one (1) and 1,3-dioxan-2-one (2) with several alcohols were examined. The reactions proceeded without trifluoroacetic acid (TFA) in low conversions, while they proceeded smoothly with TFA to afford the ring-opened adducts and oligomers. Ring-opening polymerizations of 1 and 2 were also carried out by alcohol–acid catalysts to afford the corresponding polycarbonates (Mn = 2500−6800). The molecular weights increased with increase of the conversions of 1 and 2. The observed polymerization rates of 1 and 2 were determined as 24.4 × 10−6 and 0.8 × 10−6 s−1, respectively. Mechanistic aspects were studied by NMR spectroscopy. The methylene protons α and β to the carbonate moieties shifted to lower fields in 0.06–0.11 ppm in the 1H-NMR spectra by the addition of TFA. Downfield shifts of the carbonyl carbon signals of 1 and 2 were observed in 3.94–4.15 ppm in the 13C-NMR spectra. These results strongly suggest that the cyclic carbonates are activated by TFA.

Activated monomer cationic polymerization of 1,3‐dioxepan‐2‐one initiated by water‐hydrogen chloride

The ring-opening polymerization of 1,3-dioxepan-2-one (7CC) was carried out by water-hydrogen chloride as an initiator to obtain the corresponding polymer with the molecular weight controlled by the amount of water. A 1H NMR spectroscopic study suggests that the chain growth in this system is based on the attack of the terminal hydroxyl group to the monomer activated with hydrogen chloride.