A new method for quick chitin isolation from the shells of crab, crayfish and shrimp is described. The main difference between the new method and the conventional method is two sodium hypochlorite (NaClO) treatments for 10 min each before the processes of demineralisation and deproteinisation. After the NaClO treatment, only 15 min is adequate for the demineralisation and 20 min for the deproteinisation processes. Newly extracted chitin from crab, crayfish and shrimp shells and commercial chitin were characterised using FT-IR, TGA, X-ray diffractometry and elemental analysis. From the results, it was observed that the chitins isolated with the new method and the commercial chitin had almost the same physicochemical properties. The advantage of the new method compared to traditional methods is the relatively rapid chitin extraction. When compared to the traditional chitin extraction method, the proposed method appears to be promising regarding its time and energy saving nature.
Thermal intramolecular Diels-Alder (IMDA) reaction of furan cored compounds has been further investigated; a series of key precursors to the IMDA reaction of furan diene (9a-c) have been prepared via facile alkylation and protection. While the cycloaddition process for (10a-c) was afforded in hot toluene, a commercial microwave (2450 MHz) was used for the synthesis of (12a-b). Treatment of fused oxy-and thio-heterotricycles (12a-b) with borontrifluoride-etherate in dichloromethane at -78°C cleaved epoxy bridge and concomitant aromatisation gave the isobenzo-furan and thiophene (13a-b) in 72-76% yields respectively.
Key indicators: single-crystal X-ray study; T = 293 K; mean (C-C) = 0.004 Å; R factor = 0.043; wR factor = 0.112; data-to-parameter ratio = 16.3.In the title compound, C 13 H 18 ClNO 4 , the molecules are linked only by weak van der Waals interactions. The boat form of the six-membered ring is almost symmetric with respect to the epoxy bridge. The three five-membered rings adopt envelope conformations.
Related literatureFor related literature, see: Brickwood et al. (1999); Christoffers & Baro (2005); Cremer & Pople (1975); Koşar et al. (2007); Prajapati et al. (1993).Experimental Crystal data C 13 H 18 ClNO 4 M r = 287.73 Monoclinic, P2 1 =c a = 18.7133 (15) Å b = 8.3800 (8) Å c = 9.2123 (7) Å = 90.134 (7) V = 1444.6 (2) Å 3 Z = 4 Mo K radiation = 0.27 mm À1 T = 293 (2) K 0.50 Â 0.32 Â 0.03 mm Data collection Stoe IPDSII diffractometer Absorption correction: integration (X-RED; Stoe & Cie, 2002) T min = 0.911, T max = 0.992 11238 measured reflections 3390 independent reflections 1847 reflections with I > 2(I) R int = 0.045 Refinement R[F 2 > 2(F 2 )] = 0.043 wR(F 2 ) = 0.112 S = 0.88 3390 reflections 208 parametersH atoms treated by a mixture of independent and constrained refinement Á max = 0.16 e Å À3 Á min = À0.17 e Å À3
Chitin was isolated from the shells of Chelonibia patula (barnacle, Crustacea), which lives on blue crab epizoically, following a 10-min demineralisation process through HCl and a 20-min deproteinisation process through NaOH. Due to the low-crystalline structure, and mineral-rich and low-protein content of the shells, chitin isolation was convenient. It was observed that the shell structure of C. patula contains 3.11% chitin per its dry weight. Following characterisation of the isolated chitin by using Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray diffractometry, elemental analysis and scanning electron microscopy, it was determined that there was close similarity with the α-chitin isolated from crabs, shrimps and insects in various studies. It was observed that chitin was composed of nanofibres with a width of 10-20 nm. It was concluded that this was an economically advantageous chitin resource compared with crustaceans such as shrimp, crayfish and crab, because it is possible to isolate chitin in a significantly shorter time.
Key indicatorsSingle-crystal X-ray study T = 293 K Mean (C-C) = 0.007 Å R factor = 0.072 wR factor = 0.091 Data-to-parameter ratio = 16.9For details of how these key indicators were automatically derived from the article, see
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