1. 2-(2,4-Dichloro-phen-yl)acetic acid
Jiang-Sheng Li, Qi-Xi He, Peng-Yu Li Acta Crystallogr Sect E Struct Rep Online. 2009 Dec 12;66(Pt 1):o110. doi: 10.1107/S1600536809052453.
In the title compound, C(8)H(6)Cl(2)O(2), the dihedral angle between the C-C(=O)-OH carboxyl unit and the benzene ring is 70.70 (4)°. In the crystal, mol-ecules are linked into inversion dimers by pairs of O-H⋯O hydrogen bonds. The dimers are linked into chains extending along [001] by weak C-H⋯Cl inter-actions.
2. 1-[(4-Chloro-phen-yl)(phen-yl)meth-yl]piperazine-1,4-diium bis-(trichloro-acetate)-trichloro-acetic acid (1/1)
Yanxi Song, C S Chidan Kumar, Mehmet Akkurt, S Chandraju, Hongqi Li Acta Crystallogr Sect E Struct Rep Online. 2012 Sep 1;68(Pt 9):o2695-6. doi: 10.1107/S1600536812034794. Epub 2012 Aug 11.
In the title salt adduct, C(17)H(21)ClN(2) (2+)·2C(2)Cl(3)O(2) (-)·C(2)HCl(3)O(2), the Cl atom of the dication is disordered over two positions in a 0.915 (3):0.085 (3) ratio. The Cl atoms in the trichloroacetate anions and trichloroacetic acid molecule are also disordered, with refined site-occupation factors of 0.59 (3):0.41 (3), 0.503 (12):0.417 (12) and 0.653 (12):0.347 (12). The piperazine ring adopts a chair conformation, with puckering parameters Q(T) = 0.587 (3) Å, θ = 2.6 (2) and Φ 334 (6)°. In the crystal, neighbouring mol-ecules are linked by N-H⋯O, O-H⋯O, N-H⋯Cl, C-H⋯O and C-H⋯Cl hydrogen bonds, forming a three-dimensional network.
3. Staining of proteins in gels with Coomassie G-250 without organic solvent and acetic acid
Ann-Marie Lawrence, H Uuml Seyin Besir J Vis Exp. 2009 Aug 14;(30):1350. doi: 10.3791/1350.
In classical protein staining protocols using Coomassie Brilliant Blue (CBB), solutions with high contents of toxic and flammable organic solvents (Methanol, Ethanol or 2-Propanol) and acetic acid are used for fixation, staining and destaining of proteins in a gel after SDS-PAGE. To speed up the procedure, heating the staining solution in the microwave oven for a short time is frequently used. This usually results in evaporation of toxic or hazardous Methanol, Ethanol or 2-Propanol and a strong smell of acetic acid in the lab which should be avoided due to safety considerations. In a protocol originally published in two patent applications by E.M. Wondrak (US2001046709 (A1), US6319720 (B1)), an alternative composition of the staining solution is described in which no organic solvent or acid is used. The CBB is dissolved in bidistilled water (60-80 mg of CBB G-250 per liter) and 35 mM HCl is added as the only other compound in the staining solution. The CBB staining of the gel is done after SDS-PAGE and thorough washing of the gel in bidistilled water. By heating the gel during the washing and staining steps, the process can be finished faster and no toxic or hazardous compounds are evaporating. The staining of proteins occurs already within 1 minute after heating the gel in staining solution and is fully developed after 15-30 min with a slightly blue background that is destained completely by prolonged washing of the stained gel in bidistilled water, without affecting the stained protein bands.
