- Method for preparing 2-hydroxy-4-methylbenzenesulfonic acid
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The invention discloses a novel path for synthesizing 2-hydroxy-4-methylbenzenesulfonic acid. The method is characterized by comprising the steps of taking a compound in a general formula I as a raw material, generating a compound of a general formula II through sulfonation reaction, and causing the compound of the general formula II to undergo catalytic hydrogenation reaction to obtain the target product 2-hydroxy-4-methylbenzenesulfonic acid. The total yield can reach 74%. According to the process path, the raw materials are low in cost and easy to obtain, and the path is simple to operate, short in reaction time and suitable for industrial production.
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Paragraph 0017; 0018; 0019; 0029; 0030; 0031; 0035; 0036
(2017/08/28)
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- Intermediates for making HIV-protease inhibitors
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HIV protease inhibitors inhibit or block the biological activity of the HIV protease enzyme, causing the replication of the HIV virus to terminate. These compounds can be prepared by the novel methods of the present invention using the novel inventive intermediates.
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- Intermediates for making HIV-protease inhibitors
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HIV protease inhibitors inhibit or block the biological activity of the HIV protease enzyme, causing the replication of the HIV virus to terminate. These compounds can be prepared by the novel methods of the present invention using the novel inventive intermediates.
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- Synthesis of (±) curcuphenol and (±)-β-sesquiphellandrene
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Two naturally occurring compounds curcuphenol 1 and β-sesquiphellandrene 2 have been synthesised using lithium tetrachlorocuperate catalysed coupling reaction.
- Sharma,Chand, Tek
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p. 553 - 556
(2007/10/03)
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- Sulfonation and sulfation in reactions of C-methylated phenols and anisoles with sulfur trioxide. 4-Substituted phenyl hydrogen sulfates: effective reagents for transsulfonation
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The sulfation and sulfonation of the methyl- and dimethylphenols with 0.9 and 4.0 equiv. of SO3 in nitromethane at 0 deg C have been studied.On using 0.9 equiv. of SO3, the sulfonic acid product distributions are determined by the ortho- and para-directing effect of the activating hydroxy substituent.In the reactions with 4.0 equiv. of SO3, the sulfonic acid product distributions are affected by the predominant initial formation and the subsequent sulfonation of the corresponding phenyl hydrogen sulfates, of which the bulky OSO3H substituent is electronically deactivating and (mainly) para-directing.For comparison, the sulfonation of the methylanisoles, phenyl methanesulfonate and 2,3-dihydrobenzofuran was also studied.The sulfonation of 1,3-dimethoxybenzene in (2H8)dioxane at 17.0 deg C has been studied using 4-substituted phenyl hydrogen sulfates as transsulfonating agents.The transsulfonation was found to be first order with respect to the phenyl hydrogen sulfates and independent of the 1,3-dimethoxybenzene concentration.The reaction constant of the transsulfonation reaction was determined to be ρ=2.0+/-0.2.
- Goossens, Hans D.,Lambrechts, Hans J. A.,Cerfontain, Hans,Wit, Peter de
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p. 426 - 430
(2007/10/02)
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- Aromatic Sulphonation. Part 92. Sulphonation of the Three Methylphenols and the Six Dimethylphenols in Concentrated Aqueous Sulphuric Acid; and the Isomerization of Some of the Resulting Sulphonic Acids and of m-Xylene-2- and o-Xylene-3-sulphonic Acid
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The isomer distributions for the mono- and di-sulphonation of the three methylphenols in 81.6-90.0percent sulphuric acid and of the six dimethylphenols in 84.9percent sulphuric acid at 35 deg C have been determined by means of 1H n.m.r. spectroscopy.Products that would result from demethylation, disproportionation, or ipso-substitution have not been observed.The monosulphonation isomer distribution of each of the three methylphenols is independent of the sulphuric acid concentration. 2,4-Dimethylphenol in 84.9percent H2SO4 yields 19percent 5- and 79percent 6-sulphonic acid, and 2,6-dimethylphenol yields 28percent 3- and 72percent 4-sulphonic acid.With the phenols (2), (3), (5),and (7), which have positions both ortho and para to the -OH substituent available for sulphodeprotonation, the yield of ortho-substitution is relatively high, viz. 44, 45, 36, and 27percent, respectively.The mono- and di-sulphonic acids of which the sulpho group is between the -OH and an -Me group are unstable under the reaction conditions employed, with the exception of the 3,5-dimethylphenol-2-sulphonic acid.It is proposed that their isomerization proceeds by protiodesulphonation followed by resulphonation to yield the more stable sulphonic acid isomer(s).From a kinetic analysis of the calculated first-order rate coefficients for protiodesulphonation, it is concluded that the unprotonated substrate species is the entity undergoing the protiodesulphonation.
- Lambrechts, Hans J. A.,Schaasberg-Nienhuis, Zwaan R. H.,Cerfontain, Hans
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p. 669 - 676
(2007/10/02)
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- Aromatic Sulphonation. Part 91. The Sulphonation of Anisole, Phenol, Phenyl Methanesulphonate, Potassium Phenyl Sulphate, and a Series of Methyl-, Bromo-, and Chloro-substituted Anisoles and Phenols in Concentrated Aqueous Sulphuric Acid
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The (homogeneous) sulphonation of a number of aromatic ethers and alcohols, viz. anisole (1), 3-methyl- (2), 4-methyl- (3), 2-bromo- (4), 4-bromo- (5), 2-chloro- (6), and 4-chloro-anisole (7), phenol (8), 2-methyl- (9), 3-methyl- (10), 4-methyl- (11), 4-bromo- (12), 2-chloro- (13), and 4-chloro-phenol (14), phenyl methanesulphonate (15), and potassium phenyl sulphate (16) in concentrated aqueous sulphuric acid at 25.0 deg C has been studied, and rates and isomer distributions have been determined.The sulphonation is first-order in the aromatic substrate, and from the rate measurements it is concluded that the species undergoing sulphonation in the phenyl ring is an unprotonated substrate species.In the lower acid concentrations the sulphonating entity is H3SO4(1+).With increasing sulphuric acid concentration there is a gradual change-over in the sulphonating entity from H3SO4(1+) to H2S2O7.The acid concentrations of equal rate contribution by the two entities for anisole and phenol are 87 and 90 +/- 1percent, respectively.Sulphonation on the oxygen atom (i.e., sulphation) does not occur.The o/p-ratios for (1) and (8) do not vary over the studied sulphuric acid range of 75-90percent H2SO4.Partial rate factors for the 2- and 4-position of (1) and (8) are reported.The very low partial rate factors for the 4-substitution of (1) and (8) and the observed extreme suppression and compression of the reactivities of the substrates (1)-(14) are ascribed to hydrogen bonding of the substrates with the acidic solvent species present.It is tentatively suggested that the relatively high contents of sulphonation ortho to -OR with anisole (36percent) and phenol (48percent) are due to specific complexation of the substrates with the sulphonating electrophile.
- Cerfontain, Hans,Lambrechts, Hans J. A.,Schaasberg-Nienhuis, Zwaan R. H.,Coombes, Robert G.,Hadjigeorgiou, Panicos,Tucker, Geoffrey
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p. 659 - 668
(2007/10/02)
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