85235-39-8

Upstream product

• 67-56-1 methanol 
• 58091-14-8 N-(L)-valine methyl ester 
• 72-18-4 L-valine 
• 6306-52-1 L-valine methylester hydrochloride 
• 79-22-1 methyl chloroformate 

Downstream Products

• 98877-79-3 ((S)-1-Formyl-2-methyl-propyl)-carbamic acid methyl ester 

Relevant academic research and scientific papers

Polymers from amino acids: Development of dual ester-urethane melt condensation approach and mechanistic aspects

A new dual ester-urethane melt condensation methodology for biological monomers-amino acids was developed to synthesize new classes of thermoplastic polymers under eco-friendly and solvent-free polymerization approach. Naturally abundant l-amino acids were converted into dual functional ester-urethane monomers by tailor-made synthetic approach. Direct polycondensation of these amino acid monomers with commercial diols under melt condition produced high molecular weight poly(ester-urethane)s. The occurrence of the dual ester-urethane process and the structure of the new poly(ester-urethane)s were confirmed by 1H and 13C NMR. The new dual ester-urethane condensation approach was demonstrated for variety of amino acids: glycine, β-alanine, l-alanine, l-leucine, l-valine, and l-phenylalanine. MALDI-TOF-MS end group analysis confirmed that the amino acid monomers were thermally stable under the melt polymerization condition. The mechanism of melt process and the kinetics of the polycondensation were studied by model reactions and it was found that the amino acid monomer was very special in the sense that their ester and urethane functionality could be selectively reacted by polymerization temperature or catalyst. The new polymers were self-organized as β-sheet in aqueous or organic solvents and their thermal properties such as glass transition temperature and crystallinity could be readily varied using different l-amino acid monomers or diols in the feed. Thus, the current investigation opens up new platform of research activates for making thermally stable and renewable engineering thermoplastics from natural resource amino acids.

Catalysts and temperature driven melt polycondensation reaction for helical poly(ester-urethane)s based on natural L-amino acids

Catalyst and temperature driven melt polycondensation reaction was developed for natural L-amino acid monomers to produce new classes of poly(ester-urethane)s. Wide ranges of catalysts from alkali, alkali earth metal, transition metal and lanthanides were developed for the condensation of amino acid monomers with diols to yield poly(ester-urethane)s. A-B Diblock and A-B-A triblock species were obtained by carefully choosing mono- or diols in model reactions. More than two dozens of transition metal and lanthanide catalysts were identified for the polycondensation to yield high molecular weight poly(ester-urethane)s. Theoretical studies revealed that the carbonyl carbon in ester possessed low electron density compared to the carbonyl carbon in urethane which driven the thermo-selective polymerization process. Optical purity of the L-amino acid residues in the melt polycondensation process was investigated using D- and L-isomers and the resultant products were analyzed by chiral-HPLC and CD spectroscopy. CD analysis revealed that the amino acid based polymers were self-assembled as β-sheet and polyproline type II secondary structures. Electron and atomic force microscopic analysis confirmed the formation of helical nano-fibrous morphology in poly(ester-urethane)s. The newly developed melt polycondensation process is very efficient and optimized for wide range of catalysts to produce diverse polymer structures from natural L-amino acids.

Conversion of carbonimidodithioates to carbamates

Carbonimidodithioates derived from primary amines or α-amino acid esters have been converted to N-benzyloxycarbonyl derivatives under mild conditions by treatment first with sodium benzyl alcoholate and then with water. N-Benzyloxycarbonyl α-amino acids have been generated from the methyl esters by alkaline hydrolysis or from the allyl esters by Pd0-catalysed de-allylation.