Corrosion inhibition of three α,β-unsaturated carbonyl compounds on N80 steel at high temperature and in concentrated acid medium was evaluated, and the inhibition mechanism was investigated. The results proved that...Corrosion inhibition of three α,β-unsaturated carbonyl compounds on N80 steel at high temperature and in concentrated acid medium was evaluated, and the inhibition mechanism was investigated. The results proved that both cinnamaldehyde and benzalacetone had an evident anticorrosion effect and could reduce the corrosion of steel effectively in acid medium, α,β-unsaturated carbonyl compounds with a benzene ring structure had good adsorption on steel surface. The experiments proved that polymerization of α,β-unsaturated carbonyl compounds on the steel surface at a high temperature and in concentrated acid medium resulted in a good corrosion inhibiting effect, which was attributed to the structures of α,β-unsaturated carbonyl compounds.展开更多
One-sixth of the currently known natural products containα,β-unsaturated carbonyl groups.Our previous studies reported a rare C-sulfonate metabolic pathway.Sulfonate groups were linked to theβ-carbon ofα,β-unsatu...One-sixth of the currently known natural products containα,β-unsaturated carbonyl groups.Our previous studies reported a rare C-sulfonate metabolic pathway.Sulfonate groups were linked to theβ-carbon ofα,β-unsaturated carbonyl-based natural compounds through this pathway.However,the mechanism of this type of metabolism is still not fully understood,especially whether it is formed through enzyme-mediated biotransformation or direct sulfite addition.In this work,the enzyme-mediated and non-enzymatic pathways were studied.First,the sulfite content in rat intestine was determined by LC-MS/MS.The results showed that the amount of sulfite in rat intestinal contents was from 41.5 to 383μg·g^(-1),whereas the amount of sulfite in rat feed was lower than the lower limit of quantitation(20μg·g^(-1)).Second,the reaction kinetics of sulfite-andrographolide reactions in phosphate buffer solutions(pH 6-8)was studied.The half-lives of andrographolide ranged from minutes to hours.This was suggested that the C-sulfonate reaction of andrographolide was very fast.Third,the C-sulfonate metabolites of andrographolide were both detected when andrographolide and L-cysteine-S-conjugate andrographolide were incubated with the rat small intestine contents or sulfite,indicating that the sulfite amount in rat intestine contents was high enough to react with andrographolide,which assisted a significant portion of andrographolide metabolism.Finally,the comparison of andrographolide metabolite profiles among liver homogenate(with NADPH),liver S9(with NADPH),small intestine contents homogenate(with no NADPH),and sulfite solution incubations showed that the C-sulfonate metabolites were predominantly generated in the intestinal tract by non-enzymatic pathway.In summary,sulfite can serve as a substrate for C-sulfonate metabolism,and these results identified non-enzymatically nucleophilic addition as the potential mechanism for C-sulfonate metabolism of compounds containingα,β-unsaturated carbonyl moiety.展开更多
We report a new, effective and simple method for preparing a,fl-unsaturated carbonyl compounds by reacting ketones and aromatic alcohols at 56 ℃ in the presence of CrO3 （CrO3 acts as an oxidant and also a catalyst）...We report a new, effective and simple method for preparing a,fl-unsaturated carbonyl compounds by reacting ketones and aromatic alcohols at 56 ℃ in the presence of CrO3 （CrO3 acts as an oxidant and also a catalyst） for around 10 h. The condensation reactions occurred effectively among a wide combination of ketones and alcohols. The procedure is simple and the yields can be high up to 98%. And a probable mechanism is proposed.展开更多
An efficient,inexpensive and simple method for the reduction of variousα,β-unsaturated ketones to corre-sponding saturated ketones using tosyl hydrazide as a hydrogen donor in DMF using calcium oxide powder has been...An efficient,inexpensive and simple method for the reduction of variousα,β-unsaturated ketones to corre-sponding saturated ketones using tosyl hydrazide as a hydrogen donor in DMF using calcium oxide powder has been reported.A variety of enones underwent reduction without forming undesirable side products.High chemose-lectivity,broad functional group tolerance and good yields are the noteworthy features of this protocol.展开更多
A series of condensation reactions of unmodified ketones and aromatic aldehydes to prepare α,β-unsaturated carbonyl compounds by means of Aldol reactions in Bronsted acid ionic liquids（BAILs）was explored.1-Butyl-3...A series of condensation reactions of unmodified ketones and aromatic aldehydes to prepare α,β-unsaturated carbonyl compounds by means of Aldol reactions in Bronsted acid ionic liquids（BAILs）was explored.1-Butyl-3-methylimidazolium hydrogen sulphate（BMImHSO4）acting as an effective media and catalyst in aldol reactions was compared with other BAILs,with the advantages of high conversion and selectivity.The product was easily isolated and the left ionic liquid can be readily recovered and reused at least 3 times with almost the same efficiency.The scope and limitation of the present method were explored and the possible catalytic mechanism was speculated.展开更多
A series of pyrido[2,3-d]pyrimidine derivatives were easily constructed by cyclocondensation reactions of 6-aminouracils or 6- aminothiouracil withα,β-unsaturated carbonyl compounds（aldehyde,ketone and ester） poss...A series of pyrido[2,3-d]pyrimidine derivatives were easily constructed by cyclocondensation reactions of 6-aminouracils or 6- aminothiouracil withα,β-unsaturated carbonyl compounds（aldehyde,ketone and ester） possessing a leaving group on theβposition,in H_2O under reflux conditions.展开更多
文摘Corrosion inhibition of three α,β-unsaturated carbonyl compounds on N80 steel at high temperature and in concentrated acid medium was evaluated, and the inhibition mechanism was investigated. The results proved that both cinnamaldehyde and benzalacetone had an evident anticorrosion effect and could reduce the corrosion of steel effectively in acid medium, α,β-unsaturated carbonyl compounds with a benzene ring structure had good adsorption on steel surface. The experiments proved that polymerization of α,β-unsaturated carbonyl compounds on the steel surface at a high temperature and in concentrated acid medium resulted in a good corrosion inhibiting effect, which was attributed to the structures of α,β-unsaturated carbonyl compounds.
基金supported by the National Natural Science Foundation of China(No.81873079)。
文摘One-sixth of the currently known natural products containα,β-unsaturated carbonyl groups.Our previous studies reported a rare C-sulfonate metabolic pathway.Sulfonate groups were linked to theβ-carbon ofα,β-unsaturated carbonyl-based natural compounds through this pathway.However,the mechanism of this type of metabolism is still not fully understood,especially whether it is formed through enzyme-mediated biotransformation or direct sulfite addition.In this work,the enzyme-mediated and non-enzymatic pathways were studied.First,the sulfite content in rat intestine was determined by LC-MS/MS.The results showed that the amount of sulfite in rat intestinal contents was from 41.5 to 383μg·g^(-1),whereas the amount of sulfite in rat feed was lower than the lower limit of quantitation(20μg·g^(-1)).Second,the reaction kinetics of sulfite-andrographolide reactions in phosphate buffer solutions(pH 6-8)was studied.The half-lives of andrographolide ranged from minutes to hours.This was suggested that the C-sulfonate reaction of andrographolide was very fast.Third,the C-sulfonate metabolites of andrographolide were both detected when andrographolide and L-cysteine-S-conjugate andrographolide were incubated with the rat small intestine contents or sulfite,indicating that the sulfite amount in rat intestine contents was high enough to react with andrographolide,which assisted a significant portion of andrographolide metabolism.Finally,the comparison of andrographolide metabolite profiles among liver homogenate(with NADPH),liver S9(with NADPH),small intestine contents homogenate(with no NADPH),and sulfite solution incubations showed that the C-sulfonate metabolites were predominantly generated in the intestinal tract by non-enzymatic pathway.In summary,sulfite can serve as a substrate for C-sulfonate metabolism,and these results identified non-enzymatically nucleophilic addition as the potential mechanism for C-sulfonate metabolism of compounds containingα,β-unsaturated carbonyl moiety.
基金Project supported by the National Natural Science Foundation of China （NSFC） （Nos. 50825303 and 30890140） and the Ministry of Science and Technology of China （No. 2009CB-930400）.
文摘We report a new, effective and simple method for preparing a,fl-unsaturated carbonyl compounds by reacting ketones and aromatic alcohols at 56 ℃ in the presence of CrO3 （CrO3 acts as an oxidant and also a catalyst） for around 10 h. The condensation reactions occurred effectively among a wide combination of ketones and alcohols. The procedure is simple and the yields can be high up to 98%. And a probable mechanism is proposed.
基金University Grant Commission-Basic Science Research(Order no DV-5/662/RFSMS/2012-13),New Delhi,India for financial support.
文摘An efficient,inexpensive and simple method for the reduction of variousα,β-unsaturated ketones to corre-sponding saturated ketones using tosyl hydrazide as a hydrogen donor in DMF using calcium oxide powder has been reported.A variety of enones underwent reduction without forming undesirable side products.High chemose-lectivity,broad functional group tolerance and good yields are the noteworthy features of this protocol.
基金Supported by National Natural Science Foundation of China(No.20576026)Environmental Engineering Key Subject of He-bei Province,China.
文摘A series of condensation reactions of unmodified ketones and aromatic aldehydes to prepare α,β-unsaturated carbonyl compounds by means of Aldol reactions in Bronsted acid ionic liquids（BAILs）was explored.1-Butyl-3-methylimidazolium hydrogen sulphate（BMImHSO4）acting as an effective media and catalyst in aldol reactions was compared with other BAILs,with the advantages of high conversion and selectivity.The product was easily isolated and the left ionic liquid can be readily recovered and reused at least 3 times with almost the same efficiency.The scope and limitation of the present method were explored and the possible catalytic mechanism was speculated.
文摘A series of pyrido[2,3-d]pyrimidine derivatives were easily constructed by cyclocondensation reactions of 6-aminouracils or 6- aminothiouracil withα,β-unsaturated carbonyl compounds（aldehyde,ketone and ester） possessing a leaving group on theβposition,in H_2O under reflux conditions.
