- Nitration of substituted phenols by different efficient heterogeneous systems
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Nitration of substituted phenols were carried out by the mixture of sodium nitrite and wet SiO2 (50% w/w) in the presence of four different efficient heterogeneous systems: 1) oxalic acid dihydrate (I), 2) sodium hydrogen sulphate (II), 3) aluminum hydrogen sulphate (III) and 4) silica sulphuric acid (IV) in CH2Cl2 at room temperature and high yields. Optimum conditions for theses systems and the regioselectivities of the reactions are reported.
- Habibi, Davood,Zolfigol, Mohammad Ali,Shiri, Morteza,Sedaghat, Abdolmajid
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- Alkyl-substituted benzoxazinorifamycin derivative, process for preparing the same and antibacterial agent containing the same
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A novel rifamycin derivative having the formula (I): STR1 wherein X1 is an alkyl group with 1 to 6 carbon atoms or a cycloalkyl group with 3 to 8 carbon atoms; X2 is a hydrogen atom or an alkyl group with 1 to 4 carbon atoms; R1 is hydrogen atom or acetyl group; A is a group represented by the formula: STR2 wherein R2 is an alkyl group with 1 to 4 carbon atoms or an alkoxyalkyl group with 2 to 6 carbon atoms and R3 is an alkyl group with 1 to 6 carbon atoms or an alkoxyalkyl group with 2 to 6 carbon atoms, or a group represented by the formula STR3 wherein STR4 is a 3 to 9 membered cyclic amino group with 2 to 8 carbon atoms, R4 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, or salts thereof, a process for preparing the same and antibacterial agents containing the same as an effective ingredient. The rifamycin derivative of the present invention having the formula (I) shows a strong antibacterial activity against the Gram-positive bacteria and the acid-fast bacteria.
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- FORMATION OF DIENONES ON THE REACTION OF CRESOLS, XYLENOLS, AND 2-NAPHTHOL WITH NITROGEN DIOXIDE: OBSERVATION OF KETO TAUTOMERS OF NITROPHENOLS
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Reaction of o- and p-cresol, the xylenols, and 2-naphthol with nitrogen dioxide gives nitrocyclohexadienones and nitrophenols.Secondary nitrodienones, the keto tautomers of the nitrophenols, have been observed in several cases and are intermediates in the formation of the nitrophenols.
- Fischer, Alfred,Mathivanan, N.
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p. 1869 - 1872
(2007/10/02)
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- ipso Nitration. XXIV. Nitration of 2-methylphenols. Formation and rearrangement of 6-methyl-6-nitrocyclohexa-2,4-dienones
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Nitration of o-cresol and some mono-, di-, and trimethyl derivatives in acetic anhydride at -60 deg C gives 6-methyl-6-nitrocyclohexa-2,4-dienones.The dienones are more labile than the isomeric 4-methyl-4-nitrocyclohexa-2,5-dienones and, if the 2-position of the dienone is not blocked, undergo regiospecific rearrangement to 6-nitro-o-cresols. 2,3,6-Trimethyl- and 2,3,5,6-tetramethylphenol also give a 2,5-dienone with nitro attached to a secondary carbon.
- Cross, Gordon G.,Fischer, Alfred,Henderson, George N.,Smyth, Trevor A.
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p. 1446 - 1451
(2007/10/02)
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- IPSO NITRATION: NITRATION OF 2-ALKYLPHENOLS IN ACETIC ANHYDRIDE. FORMATION OF 6-ALKYL-6-NITROCYCLOHEXA-2,4-DIENONES
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Low temperature nitration of 2-alkylphenols in acetic anhydride gives 6-alkyl-6-nitrocyclohexa-2,4-dienones.The dienones undergo a regiospecific rearrangement to give o-nitrophenols
- Fischer, Alfred,Henderson, George N.
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p. 4661 - 4662
(2007/10/02)
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