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Abstract

Complexes of yttrium(III) and lanthanides(III) with 4-hydroxy-3,5-dimethoxybenzoic (syringic) acid were obtained as solids with metal to ligand mole ratio of 1: 3. The compounds were characterized by elemental analysis, IR spectroscopy, X-ray diffraction patterns, solubility, and thermal studies. The complexes are sparingly soluble in water and stable at room temperature. Compounds of light lanthanides (from La to Nd) are hydrated and they crystallize in a triclinic system. When heated, they lose water molecules in one step and in the next step they decompose to oxides. Complexes of yttrium and other lanthanides are anhydrous and crystallize in a monoclinic system. They are stable up to 300°C and then decompose to oxides. As the coordination number of lanthanide ions is usually equal to 9 or 8, one can suppose that hydroxy or methoxy groups take part in the coordination of these metal ions.

investigated. During this investigation, three new lupan-type triterpenoid derivatives, globimetulin A ( 1 ), B ( 2 ) and C ( 3 ), were isolated together with friedelin ( 4 ) [ 6 ], friedelan-3-ol ( 5 ) [ 7 ], 28-hydroxyfriedelin ( 6 ) [ 8 ], 4-hydroxy-3,5-dimethoxybenzoic acid ( 7 ) [ 9 ] and (1 R ,5 S ,7 S )-7-[2-(4-hydroxyphenyl)ethyl]-2,6-dioxabicyclo [3.3.1]nonan-3-one ( 8 ) [ 10 ]. Here, we report the structural elucidation of these compounds as well as the evaluation of their antimicrobial properties against the four microorganisms Staphylococcus aureus

,5-dimethoxybenzaldehyde (k = (1.7±0.3) · 109), 4-hydroxy-3,5-dimethoxybenzoic acid (k = (1.4±0.6) · 109), 4-hydroxy-3-methoxybenzaldehyde (k = (1.1±0.2) · 109), 4-hydroxy- 3-methoxybenzoic acid (k = (1.0±0.3) · 109), 3-hydroxy-4-methoxybenzoic acid (k = (1.3±0.4) · 109). Averaged activation energies of: para-substituted phenols are EA para = 11±6 kJ mol K1; 2,6-substituted phenols EA 2,6 = 15±4 , poly-substituted phenols EA poly = 16±4 kJ mol K1. From reactivity correlations it is concluded that 4-nitrophenol, 2,6-dinitrophenol and 4-hydroxyben- zoic acid react via direct electron

, available online May 31, 2013, CCDC no. 1267/3973 Abstract C22H22N4O8S, triclinic, P1 (no. 2), a = 8.730(1) Å, b = 9.730(1) Å, c = 14.220(2) Å, = 97.970(2)°, = 92.606(2)°, = 100.195(2)°, V = 1174.3 Å3, Z = 2, Rgt(F) = 0.0477, wRref(F 2) = 0.1357, T = 296 K. Source of material 6 g (about 30 mmol) of syringic acid (4-hydroxy-3,5- dimethoxybenzoic acid) in 50 mL of acetic anhydride was stirred and refluxed at 120 °C for 2h. 900 mL of water was added to the above solution to get precipitates (5300mg) by method of pump- ing filtration. 5 g (about 20 mmol) of above dry

-block elements have not been studied. Ethylenediamine is an N-donor chelator and has been studied intensively, both structurally and spectroscopi- cally for many years [5, 6]. Therefore, we selected sy- ringic acid as primary ligand and prepared Cu(II) eth- ylenediamine complexes and examined their thermal stability in air, IR spectral characteristics and crystal Syringic acid = 4-hydroxy-3,5-dimethoxybenzoic acid. 0932–0776 / 06 / 0300–0287 $ 06.00 c© 2006 Verlag der Zeitschrift für Naturforschung, Tübingen · http://znaturforsch.com structure. In this study, we report the

-cinnamic acid pentyl ester, 3,4-dihydroxybenzoic acid butyl ester, 3,4-dihydroxybenzoic acid ethyl ester, 4-hydroxybenzoic acid ethyl ester, 4-hydroxy-3-methoxybenzoic acid, 3-hydroxy-4-methoxybenzoic acid, 4-hydroxy-3,5-dimethoxybenzoic acid ethyl ester, and 4-hydroxy-3,5-dimethoxybenzoic acid, all of which showed characteristic signals of alkoxy and methylene groups, as well as 1-isobutoxy-4-(4-isobutoxybenzyl) benzene with characteristic signals of methylene. Hence, it is speculated that alkoxy and methylene are the characteristic signals of other phenolics besides

(4-Hydroxy-3,5- dimethoxybenzoic acid) p-coumaric acid (p-Hydroxy cinnamic acid) Ferulic acid (4-hydroxy-3-methoxy cinnamic acid) Cinnamic acid (3-Phenyl-2-propenoic acid) Gentisic acid (2,5-Dihydroxy benzoic acid ) Vanillic acid (4- Hydroxy, 3 methoxy benzoic acid) ASAE ASME Andrographolide Gallic acid (3,4,5- Trihydroxy b i id) Protocatechuic acid (3,4-Dihydroxybenzoic acid) Standard Standard Standard Standard Standard Standard Standard NIL 30.07 23.68 Standard Standard 1.91 6.60 3.00 1.80 6.49 4.60 81.0 33.3 3.51 6.90 1

2, 30.27; compound 3, 47.32; compound 4, 63.15; compound 5, 55.49; compound 6, 57.91; compound 7, 59.33. 4-Hydroxyacetophenone (1): MS (EI): m/z = 136.148 (calcd. for C8H8O2: 136.148). Ð 1H NMR (400 MHz, MeOH-d4): δ = 7.87 (d, J = 8.78 Hz, H-2, H-6), 6.83 (d, J = 8.78 Hz, H-3, H-5), 2.51 (s, CH3). 3,4-Dihydroxybenzoic acid (protocatechuic acid) (2): MS (EI): m/z = 154.120 (calcd. for C7H6O4: 154.120). Ð 1H NMR (400 MHz, MeOH-d4): δ = 7.41 (brs, H-2), 6.77 (d, J = 7.8 Hz, H-5), 7.40 (d, J = 7.8 Hz, H-6). 4-Hydroxy-3,5-dimethoxybenzoic acid (syringic acid) (3): MS

studies. Material and Methods Model compounds and lignins Most monomers were obtained from commercial sources while the dimers and some monomers were synthesised by standard methods. The monomers are vanillin (1); vanillic acid (2); acetovanfllone (3); syringaldehyde (4); 4-hydroxy-3,5-dimethoxybenzoic acid (5); 4- hydroxybenzaldehyde (6); 4-hydroxybenzoic acid (7); 4-hydroxy- 3,5-dimethoxyacetophenone (8); 4-hydroxycinnamic acid (9); 3,4- dihydroxycinnarnic acid (caffei acid, (10); 4-hydroxy-3-rnethoxycin- namic acid (ferulic acid, (11); 4-hydroxy-3,4^dirnethoxycinn

in H-Z