In several industrial applications, the occurence of silica in the used waters is undesirable. Many studies show the complexity and the diversity of the topic. For a better understanding of the problem encountered in water treatment, particularly in water desalination, a synthesis of the different analytical aspects of silica are presented. A diagram summing up the evolution of the different forms of silica (dissolved, polymerized and colloïdal) as well as the terminology associated to its determination is proposed. The different approaches and processes of silica removal, in aqueous electrolyte solutions, are reviewed.
B. Hamrouni, M. Dhahbi
amorphous silica, electrolyte solutions, determination, solubility, silica removal
1,3-Cycloaddition of 2-diazopropane (DAP) 1 with indenone 2 led to an expected Δ1-pyrazoline 4. The Addition of 1 with 4,6-dimethylbicyclo[3.3.1]nona-3,6-diene-2,8-dione 3 gave a mono-adduct 5 with an "inverse" regiochemical way and an "exo" stereochemistry. The photolysis of 4 and 5 gave an ethylenic derivative 6 and a gem-dimethyl cyclopropane 7 respectively.
N. Boukamcha, M.T. Martin, A. Khemiss
2-diazopropane, Δ1-pyrazolines, photochemistry, gem-dimethyl cyclopropane
Five novel monoglyceride compounds have been isolated from Ajuga pseudoiva leaves. Their structures have been established by spectroscopic procedures.
H. Ben Jannet, A. Chaari, M.T. Martin, Z. Mighri
Ajuga pseudoiva, Labiatae, isolation, monoglycerides, structure
Reaction of Isophorone 1 with arylaldehydes in alkali media leads to 3-[2-hydroxy-2-aryl]-5,5-dimethylcyclohex-2-enones 2 in good yields. These latters are epoxydized to give epoxycyclohexanone derivatives 4, or dehydrated to give semicyclic dienones 3. Compounds 3 are reduced into their corresponding alcohols 5 when compounds 3 or 5 are submitted to Diels Alder reactions, the tricyclic compounds 6 and 9 are obtained.
Y. El Barkaoui, N. Jorio, S. Fkih-Tetouani, A. El Louzi
Ergosterol peroxide and cyasterone have been isolated from the plant Ajuga iva. Their structural elucidation have been established by spectroscopic methods. We remind that ergosterol peroxide has been identified for the first time in the Ajuga genus. Seven structural analogous have been hemisynthezised from cyasterone, three of them are new. The study of the antibacterial activity of these structural analogous has allowed us to get an idea about sites taking part in this activity.
H. Ben Jannet, A. Chaarl, A. Bakhrouf, M. T. Martin, Z. Mighri
Ajuga iva, Labiatae, steroid, phytoecdysteroid, hemisynthesis, structural analogous, antibacterial activity
We have prepared a serie of 18 chiral trichloromethylalcohols in one step by the reaction of trichloroacetic acid with the corresponding aldehyde using nitrobenzene as catalyst in dimethylsulfoxyde at 20°C.We have prepared the new ketones corresponding to the alcohols listed above using barium manganate as oxidant in dichloromethane.
I. Cheraief, T. Homri, B. Ben Hassine
trichloromethyl alcohols, trichloromethyl ketones, trichloroacetic acid, nitrobenzene
The reaction of aminoazoles with γ-keto-δ-formylphosphonates 1 leads to (β-phosphocycloalcaneazolopyrimidines and pyridazines 2, 3, 4, 5 and 5'. The structure of all obtained products was determined on the basis of their IR and NMR data.
S. Touil, H. Zantour
γ-keto-δ-formylphosphonates, β-phosphocycloalcaneazolopyrimidines, β-phosphocycloalcaneazolopyridazines, RMN 1H, RMN 31P, RMN 13C
The reaction of some ethoxyalkylidenes with 2-aminopyridine have been studied. We have shown that this reaction lead to 4-oxopyrido [1, 2-a] pyrimidines or 4-iminopyrido [1, 2-a] pyrimidines. The reactionnel intermediary have been isolated in some cases.
M.T. Kaddachi, M. Ben Amor, S. Zouari, J. Cossy, P. Kahn
2-aminopyridine, ethoxyalkylidenes, 4-oxopyrido [1, 2-a] pyrimidines, 4-iminopyrido [1, 2-a] pyrimidines
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