Improved Synthesis Of 1-O-acetyl-2,3,5-tri-O-benzoyl-β-D-ribofuranose,Synthesis Of L-homoserine And Synthesis And Characterization Of Silicon Carbide Nanotubes

Medicines of nucleotide and its derivatives, L-homoserine and itsderivatives are very important in chemosynthesis of medication, and thequantity of this kind of medicines is rapidly increasing.1-O-acetyl-2, 3, 5-tri-O-benzoyl-beta-D-ribofuranose is a key mediation forsynthesizing medicines of nucleotide and its derivatives. This paper mainlyto 1-O-acetyl-2, 3, 5-tri-O-benzoyl-beta-D-Ribofuranose the synthesis ofprocess improvement study, L-homoserine preparation and silicon carbidenanotubes preparation.1. 1-O-acetyl-2, 3, 5-tri-O-benzoyl-beta-D-ribofuranose was synthesized by using D-ribose and inosine as the starting materials, respectively.Effects of the ratio of reactants, reaction time, and reaction temperature onthe yield of the product were studied in detail. The experimental resultsshowed that, the proper decrease in reaction temperature and decrease indosage of pyridine were propitious for the increase of the yield of theproduct. The structure of the product was identified by IR, ¹HNMR, MSand HPLC.1). 1-O-acetyl-2, 3, 5-tri-O-benzoyl-beta-D-ribofuranose was synthesized by using D-ribose as the starting material, through methylation, benzoylation and acetylization. The optimal reaction conditions were obtained asfollows: 5.0g (0.033 mol) D-ribose was dissolved in 20 mL(15.82g) HCl-/MeOH (pH=2), stirring the solution at 20℃for 3h; The product was dissolved in 50 mL pyridine, then 15 mL(0.129 mol, 18.18g) benzoyl chloridewas added, followed by stirring the solution at 10℃for 15h; The productwas dissolved in a mixture of 40 mL(42.00g) glacial acetic acid and 5 mL(0.083 mol, 5.41g) acetic anhydride, then 3 mL(5.52g) oil of vitriol wasadded, the solution was stirred at 10℃for 15h to get the final product. Bymeans of the above process, the total yield was summed up to 74.34ï¼….2). 1-O-acetyl-2, 3, 5-tri-O-benzoyl-beta-D-ribofuranose was Synthesized by using inosine as the starting material through benzoylation andacetylization. The optimal reaction conditions were obtained as follows: 9.0g(0.034 mol) inosine was dissolved in 40 mL(39.32g) pyridine, then 15mL(0.129 mol, 18.18g) benzoyl chloride was added, followed by stirring the solution at 10℃for 15h. The product was dissolved in a mixture of 40mL(42.00g) glacial acetic acid and 5 mL(0.083 mol, 5.41g) aceticanhydride, then 3 mL(5.52g) oil of vitriol was added, the solution wasstirred at 10℃for 17h to get the final product. By means of the aboveprocess, the total yield was summed up to 74.93ï¼…. The synthesis processwas validated by magnified production under optimized conditions, asmuch as 12 times, the total yield was summed up to 74.69ï¼…(HPLC purity:98.20ï¼…).2. L-homoserine was synthesized by using L-methionine as thestarting material. Effects of the solvent, moisture and pH value on thecrystallinity of the L-homoserine were studied in detail. The structure of theproduct was identified by IR, ¹HNMR and MS.L-homoserine was synthesized by using L-methionine as the startingmaterial. The optimal reaction conditions were obtained as follows:L-methionine reacted with methyl iodide in water, the solution was stirredat 30℃for 24 hours, the solution was concentrated in vacuo; Potassiumhydrogen carbonate was added and the in aqueous solution was refluxed for10 hours, followed by evaporating the solution in vacuo; The product wasdissolved in methanol, pH was adjusted to 5～6 with hydrochloric acid.L-homoserine was summed up to 65.3ï¼….3. Based on the preparation of carbon nanotubes by CVD, synthesis ofsilicon carbide nanotubes by CVD was proposed for the first time.Methyltrichlorosilane (MTS) was selected as the SiC gaseous source and,ferrocence and thiophene as the catalyst and the cocatalyst, respectively.The influences of pyrolysis temperature, the content of catalyst and thecocatalyst, and the mole ratio between H₂ and MTS, on the shape of thepyrolysis products were investigated, respectively. The products wereidentified by SEM, EDX. XRD and HRTEM, respectively. Novel type ofmulti-walled SiCNTs, with 30～80 nm and 15～20 nm outer and innerdiameters, respectively, were observed.