1.Determination of 1,4-Dioxane in the Cape Fear River Watershed by Heated Purge-and-Trap Preconcentration and Gas Chromatography-Mass Spectrometry.
Sun M1, Lopez-Velandia C1, Knappe DR1. Environ Sci Technol. 2016 Mar 1;50(5):2246-54. doi: 10.1021/acs.est.5b05875. Epub 2016 Feb 15.
Recent U.S. Environmental Protection Agency data show that 1,4-dioxane is frequently detected in U.S. drinking water derived from both groundwater and surface water. 1,4-Dioxane is a likely human carcinogen, and an excess 10(-6) cancer risk is associated with a drinking water concentration of 0.35 μg/L. To support 1,4-dioxane occurrence investigations, source identification and exposure assessment, a rapid and sensitive analytical method capable of quantifying 1,4-dioxane over a wide concentration range in a broad spectrum of aqueous matrices was developed. The fully automated method is based on heated purge-and-trap preconcentration and gas chromatography/mass spectrometry with selected-ion storage and has a reporting limit of 0.15 μg/L. Quantification of 1,4-dioxane was accomplished by isotope dilution using mass-labeled 1,4-dioxane-d8 as internal standard. Matrix spikes yielded recoveries of 86-115% in drinking water, groundwater, surface water, and wastewater treatment plant (WWTP) effluent.
2.Crystal Structure and Antibacterial Activity of (E)-(5-ethyl-2-styryl-1,3-dioxan-5-yl) Methanol Synthesized with Nanosolid Superacid.
Yuan L, Li ZY, Zhang XY, Li WY, Zhang M, Yuan XY. J Nanosci Nanotechnol. 2015 Dec;15(12):9887-91.
A new chiral 1,3-dioxane compound was synthesized by aldol condensation reaction in this paper. The reaction of cinnamic aldehyde with 2.1 equiv. of 2,2-bis(hydroxymethyl) butanol in N,N-dimethylformamide and cyclohexane, nanosolid superacid SO4(2-)/Fe2O3 was applied as catalyst, afforded the new chiral 1,3-dioxane compound (E)-(5-ethyl-2-styryl-1,3-dioxan-5-yl) methanol. The compound was fully characterized with infrared spectra, elemental analysis, melting points, 1H NMR and X-ray diffraction. Single crystal X-ray diffraction analysis revealed that the compound crystallized in the monoclinic system, space group P2(1) with a = 5.717(2) Å, b = 11.684(4) Å, c = 10.569(4) Å, α = 90.00 degrees, β = 99.646(4) degrees, γ = 90.00 degrees, V = 696.0(4) Å3, Z = 2, Dc = 1.185 g/cm(-3), R = 0.0182, μ = 0.081 mm(-1), F(000) = 268. In addition, the antibacterial activities of the compound against Bacillus subtilis, Escherichia coli and Staphylococcus aureus have been investigated.
3.Poly(ethylene glycol)-grafted cyclic acetals based polymer networks with non-water-swellable, biodegradable and surface hydrophilic properties.
Yin R1, Zhang N2, Wu W2, Wang K3. Mater Sci Eng C Mater Biol Appl. 2016 May 1;62:137-43. doi: 10.1016/j.msec.2016.01.038. Epub 2016 Jan 18.
Cyclic acetals based biomaterial without acidic products during hydrolytic degradation is a promising candidate for tissue engineering applications; however, low hydrophilicity is still one limitation for its biomedical application. In this work, we aim to achieve non-water-swellable cyclic acetal networks with improved hydrophilicity and surface wettability by copolymerization of cyclic acetal units based monomer, 5-ethyl-5-(hydroxymethyl)-β,β-dimethyl-1, 3-dioxane-2-ethanol diacrylate (EHD) and methoxy poly(ethylene glycol) monoacrylate (mPEGA) under UV irradiation, to avoid swelling of conventional hydrogels which could limit their applicability in particular of the mechanical properties and geometry integrity. Various EHD/mPEGA networks were fabricated with different concentrations of mPEGA from 0 to 30%, and the results showed photopolymerization behavior, mechanical property and thermal stability could not be significantly affected by addition of mPEGA, while the surface hydrophilicity was dramatically improved with the increase of mPEGA and could achieve a water contact angle of 37° with 30% mPEGA concentration.
4.Crystal structure of 5-[4-(di-ethyl-amino)-benzyl-idene]-2,2-dimethyl-1,3-dioxane-4,6-dione.
Stepina E1, Stepanovs D2, Mierina I1, Jure M1. Acta Crystallogr E Crystallogr Commun. 2015 Sep 26;71(Pt 10):1242-4. doi: 10.1107/S2056989015017673. eCollection 2015.
The title compound, C17H21NO4, consists of substituted Meldrum's acid with a [4-(di-ethyl-amino)-phen-yl]methyl-idene fragment attached to the fifth position. The heterocycle assumes a distorted boat conformation. The planar part of heterocycle is almost coplanar with the benzene ring due to the presence of a long conjugated system in the mol-ecule. This leads to the formation of C-H⋯O-type intra-molecular contacts. As a result of the absence of hydrogen-bond donors in the structure, the crystal packing is controlled by van der Waals forces and weak C-H⋯O inter-actions, which associate the mol-ecules into inversion dimers.