Inese Mierina

Zwitterionic and free forms of arylmethyl Meldrum's acids

C-Alkyl (including C-arylmethyl) derivatives of Meldrums acids are attractive building blocks in organic synthesis, mainly due to the unusually high acidity of the resulting compounds. Three examples, namely 5-[4-(diethylamino)benzyl]-2,2-dimethyl-1,3-dioxane-4,6-dione, C17H23NO4, (I), 2,2-dimethyl-5-(2,4,6-trimethoxybenzyl)-1,3-dioxane-4,6-dione, C16H20O7, (II), and 5-(4-hydroxy-3,5-dimethoxybenzyl)-2,2-dimethyl-1,3-dioxane-4,6-dione, C15H18O7, (III), have been synthesized, characterized by NMR and IR spectroscopy, and studied by single-crystal X-ray structure analysis. The nature of the different substituents resulted in remarkable differences in both the molecular conformations and the crystal packing arrangements. The presence of a substituent with a basic centre in compound (I) leads to the formation of an inner salt accompanied by drastic changes in the conformation of the 1,3-dioxane-4,6-dione fragment. By virtue of strong N-H···O hydrogen bonds, the residues are assembled into infinite chains with the graph-set descriptor C(10). Compound (II) contains methoxy groups in both the ortho- and para-positions of the arylmethyl fragment. Because of the absence of classical hydrogen-bond donors in this structure, the crystal packing is controlled by van der Waals forces and weak C-H···O interactions. Compound (III) contains methoxy groups in both meta-positions and a hydroxy group in the para-position. Supramolecular tetrameric synthons which comprise hydrogen-bonded dimers associated into tetramers through π-π interactions of overlapping benzene rings were observed.

Investigation of the oil and Meal of Japanese Quince (Chaenomeles Japonica) Seeds

Abstract Various extracts of Japanese quince (Chaenomeles japonica) seeds obtained using organic solvents were studied for their polyphenol content and antiradical activity. It was established that petroleum ether, hexane, ethyl acetate, acetone, as well as toluene and chloroform extracts, in comparison to synthetic antioxidant butylated hydroxytoluene (BHT), demonstrate better (or comparable) activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH). Methods for detoxification of seeds, meals and press-cakes are proposed. Phenolic composition of different extracts (80% ethanol, 70% acetone), both acid and alkali hydrolysates of seeds, as well as seed oil methanol/water extract were analysed by means of high performance liquid chromatography (HPLC): chlorogenic acid was found for the first time in seed extract; protocatechuic acid predominated in all extracts. The content of other major phenolic acids was detected; it was found that seed oil contains syringic acid. It was determined that Japanese quince seeds contain almost ten times more α -tocopherol than barley grain. Due to the presence of α -tocopherol and phenolic compounds, seed oil and lipophilic extracts of seeds could serve as antioxidants. Abstrakt Krūmcidoniju (Chaenomeles japonica) sēklu dažādu organisko šķīdinātāju ekstraktiem noteikts kopējais polifenolu saturs un antiradikāļu aktivitāte. Petrolētera, heksāna, etilacetāta, acetona, kā arī toluola un hloroforma ekstraktu spēja inhibēt 2,2-difenil- 1-pikrilhidrazilu (DPPH) ir augstāka (vai salīdzināma) nekā sintētiskajam antioksidantam BHT (butilēts hidroksitoluols). Izstrādātas cianīdus saturošo krūmcidoniju sēklu, spraukumu un spiedpalieku detoksifikācijas metodes. Izmantojot augstas izšķirtspējas šķidrumhromatogrāfijas metodi (HPLC), analizēta krūmcidoniju sēklu| dažādu ekstraktu (80% etanola un 70% acetona), skābo un bāzisko hidrolizātu, kā arī eļļas metanola/ūdens ekstrakta polifenolu kompozīcija: sēklu ekstraktā pirmo reizi konstatēta hlorogēnskābe. Visos ekstraktos kā dominējošais savienojums atrasta protokatehīnskābe; noskaidrots arī citu galveno fenolskābju daudzums, un sēklu eļļā atrasta sīringskābe. Eļļā ir daudz a-tokoferola, kura saturs krūmcidoniju sēklās ir gandrīz desmit reizes lielāks nekā miežu graudos. Tā kā sēklu eļļa un lipofilie ekstrakti satur a-tokoferolu un polifenolus, ekstraktus var izmantot kā antioksidantu avotus.

Crystal structure of 3-hy­droxy-2-(4-hy­droxy-3-meth­oxy­phenyl­methyl)-5,5-di­methyl­cyclo­hex-2-enone

In the title dimedone derivative, the 4-hydroxy-3-methoxybenzyl substituent adopts a sofa conformation. In the crystal, molecules are assembled into a sheet structure parallel to the ab plane via O—H⋯O hydrogen bonds.

Crystal structure of 3-(4-hydroxy-3-methoxyphenyl)-N-phenylpropanamide, C16H17NO3

Abstract C16H17NO3, orthorhombic, P212121 (no. 19), a = 7.9882 (2) Å, b = 11.4053 (3) Å, c = 16.2381 (5) Å, V = 1479.42 (7) Å3, Z = 4, Rgt(F) = 0.0480, wRref(F2) = 0.0991, T = 173 K.

Crystal structure of 3-(4-hy-droxy-phen-yl)-2-[(E)-2-phenyl-ethen-yl]quinazolin-4(3H)-one.

The title compound consists of a substituted 2-[(E)-2-arylethenyl]-3-arylquinazolin-4(3H)-one skeleton. The substituents at the ethylene fragment are located in trans positions. In the crystal, molecules are connected via O—H⋯O hydrogen bonds forming a 21 helix propagating along the a-axis direction.

Crystal structure of 5-[4-(di-ethyl-amino)-benzyl-idene]-2,2-dimethyl-1,3-dioxane-4,6-dione.

The title compound, 5-[4-(diethylamino)phenylmethylidene]-2,2-dimethyl-1,3-dioxane-4,6-dione, have been synthesized and its crystal structure determined. Due to the absence of hydrogen-bond donors in the structure, the crystal packing is controlled by van der Waals forces and weak C—H⋯O interactions, which associate the molecules in dimers.