Nitration of Chitin Monomer: From Glucosamine to Energetic Compound

The nitration of chitin monomer in a mixture of nitric acid and acetic anhydride was conducted and a highly nitrated (3R,4R,6R)-3-acetamido-6-((nitrooxy)methyl)tetrahydro-2H-pyran-2,4,5-triyl trinitrate (1) was obtained. Its structure was fully characterized using infrared spectroscopy, NMR spectroscopy, elemental analysis, and X-ray diffraction. Compound 1 possesses good density (ρ: 1.721 g·cm−3) and has comparable detonation performance (Vd: 7717 m·s−1; P: 25.6 GPa) to that of nitrocellulose (NC: Vd: 7456 m·s−1; P: 23 GPa; Isp = 239 s) and microcrystalline nitrocellulose (MCNC; Vd: 7683 m·s−1; P: 25 GPa; Isp = 250 s). However, Compound 1 has much lower impact sensitivity (IS: 15 J) than the regular nitrocellulose (NC; IS: 3.2 J) and MCNC (IS: 2.8 J). Compound 1 was calculated to exhibit a good specific impulse (Isp: 240 s), which is comparable with NC (Isp: 239 s) and MCNC (Isp: 250 s). By replacing the nitrocellulose with Compound 1 in typical propellants JA2, M30, and M9, the specific impulse was improved by up to 4 s. These promising properties indicate that Compound 1 has a significant potential as an energetic component in solid propellants.

Cassava starch-chitosan-sorghum micro-fibrillated cellulose biocomposite wrapping film to prevent COVID-19 outspread

To prevent virus spreading, the corpse or the coffin of COVID-19 patients need to be wrapped in plastic. Low-density polyethylene (LDPE), a crude oil-based wrapping plastic, is difficult to decompose in nature after use. In this study, biocomposite wrapping film was developed from cassava starch and chitosan, with the addition of sorghum Micro-Fibrillated Cellulose (MFC) by levels of 1%, 2%, 3%, 4% and 5%. Cassava starch (raw starch) was modified by acetic anhydride to produce acetylated cassava starch (acetylated starch) which is less hydrophilic thus enhance the compounding ability with LDPE. The sorghum MFC was obtained from sorghum fibers after following processes: soda pulping, bleaching and fibrillation with a super grinder. The addition of 1% sorghum MFC into raw starch-chitosan increased the tensile strength and modulus of elasticity by 33% and 17%, respectively. On the other hand, the addition of 2% sorghum MFC into acetylated starch-chitosan increased the elongation by 38%. Wrapping film needs to have good elongation ability so that it can be stretched during application. Based on elongation characteristic, acetylated cassava starch-chitosan with addition of 2% sorghum MFC can be developed to be a candidate for biocomposite wrapping film to prevent COVID-19 outspread.

Reactions of 4-hydroxycoumarin with heterocyclic aldehydes

Reactions of 4-hydroxycoumarin 1 with heterocyclic aldehydes 2-4 led to bis-4-hydroxycoumarin derivatives 5-7 under microwave irradiation as well as under the classical heating. The subsequent reactions of products 5-7 are described. 4,4’-Epoxydicoumarins 8, 9 were prepared by the reaction of 5-7 in acetic acid / p-toluenesulfonic acid medium. Compound 10 was prepared by the reaction of 5 in acetic anhydride in the presence sodium acetate. Dioxocine-1,15-dione 11 was prepared by the reaction of 6 with dichloromethane in sodium hydroxide-toluene.

Superacid ZrO2–SiO2–SnO2 Mixed Oxide: Synthesis and Study

Superacid ternary ZrO2 SiO2 SnO2 oxide has been synthesized by the sol-gel method with a different atomic ratio Zr:Si:Sn. The highest strength of acid sites has been observed in the ranges of 20 ≤ Zr4+ ≤ 29, 60 ≤ Si4+ ≤ 67, 11 ≤ Sn4+ ≤ 20 at.%. According to the XPS spectra and 119Sn, 29Si MAS NMR spectra of ZrO2 SiO2 SnO2 a partial shift of electron density from zirconium to silicon ions was observed resulting in the formation of superacid Lewis sites. It was shown that superacid Zr29Si60Sn11 mixed oxide efficiently catalyzes acylation of toluene with acetic anhydride at 423 K in a flow reactor with 45% conversion of anhydride at 100% selectivity towards p-methylacetophenone.

Synthesis of fused dihydrobenzo [4,5]imidazo[1,2-a]pyrmido[5,4-e]pyrmidin-3(4H)-amine derivatives

Some of fused dihydrobenzo [4,5]imidazo [1,2-a] pyrmido [5,4-e] pyrmidin-3(4H)-amine derivatives were synthesized, theses derivatives derived from 4-amino-2-(4-chloro or bromophenyl) -1,2-dihydropyrimido[1,2-a] benzimidazole-3-carbonitrile (4,5), which prepared by reaction 1H-benzimidazol-2-amine (1) and p-chlorobenzaldehyde or p-bromobenzaldehyde (2) and malononitrile (3). These derivatives prepared by reaction compound (4,5) with with triethylorthoformate in presence acetic anhydride to give the products (6,7), then the products was reacted with aliphatic amines (hydrazine, methyl amine, ethyl amine, propyl amine and isobutyl amine) to give pyrmidin rings (8-17) respectively. All these derivatives characterization by FT-IR , HNMR spectra and physical properties.