- Hydrates of Organic Compounds. XVI. Determination of the Melting Points and Hydration Numbers of the Hydrates of Tetrabutyl(or Tetraisopentyl)ammonium Alkanesulfonates
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The solid liquid phase diagrams of binary mixtures of water with tetraisopentylammonium alkanesulfonates, (n=1-8), bis(tetrabutylammonium) alkanedisulfonates, 2 (n=2-5), and with bis(tetraisopentylammonium) alkanedisulfonates, 2 (n=2-5), were examined in order to confirm the formation of hydrates.For all of the sulfonates examined the formation of hydrates has been newly confirmed.The hydrates of the tetraisopentylammonium alkanesulfonates have hydration numbers of around 37-40 and fairly high melting points (lie between 13 and 19 deg C).The typical hydrates formed by the bis(tetrabutylammonium) alkanedisulfonates have hydration numbers of around 52 and those by the bis(tetraisopentylammonium) alkanedisulfonates around 76.The former disulfonate hydrates have low melting points (between 1.0 and 10 deg C).However, the latter disulfonate hydrates have fairly high melting points (between 13 and 18 deg C).A salt with n=4 forms the most stable hydrate for both series of alkanedisulfonates.Judging from the hydration numbers and melting points, these hydrates seem to be clathrate-like.
- Nakayama, Haruo,Yamanobe, Masashi,Baba, Kei
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- Discovery, Synthesis and Evaluation of a Ketol-Acid Reductoisomerase Inhibitor
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Ketol-acid reductoisomerase (KARI), the second enzyme in the branched-chain amino acid biosynthesis pathway, is a potential drug target for bacterial infections including Mycobacterium tuberculosis. Here, we have screened the Medicines for Malaria Venture Pathogen Box against purified M. tuberculosis (Mt) KARI and identified two compounds that have Ki values below 200 nm. In Mt cell susceptibility assays one of these compounds exhibited an IC50 value of 0.8 μm. Co-crystallization of this compound, 3-((methylsulfonyl)methyl)-2H-benzo[b][1,4]oxazin-2-one (MMV553002), in complex with Staphylococcus aureus KARI, which has 56 % identity with Mt KARI, NADPH and Mg2+ yielded a structure to 1.72 ? resolution. However, only a hydrolyzed product of the inhibitor (i.e. 3-(methylsulfonyl)-2-oxopropanic acid, missing the 2-aminophenol attachment) is observed in the active site. Surprisingly, Mt cell susceptibility assays showed that the 2-aminophenol product is largely responsible for the anti-TB activity of the parent compound. Thus, 3-(methylsulfonyl)-2-oxopropanic acid was identified as a potent KARI inhibitor that could be further explored as a potential biocidal agent and we have shown 2-aminophenol, as an anti-TB drug lead, especially given it has low toxicity against human cells. The study highlights that careful analysis of broad screening assays is required to correctly interpret cell-based activity data.
- Bayaraa, Tenuun,Kurz, Julia L.,Patel, Khushboo M.,Hussein, Waleed M.,Bilyj, Jessica K.,West, Nicholas P.,Schenk, Gerhard,McGeary, Ross P.,Guddat, Luke W.
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p. 8958 - 8968
(2020/07/04)
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- Studies on Sulphochlorination of Paraffins. VIII. Studies on the Hydrolysis of Individual Alkane Sulphochlorides by Sodium Hydroxide
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The hydrolysis of individual C1-C5 alkane sulphochlorides by sodium hydroxide in dioxane/water (1:1) was kinetically studied at 25 deg C by means of stopped-flow technique, measuring the change of electric conductivity.The rate constants were influenced by steric hindrance, but in all cases were higher than the rate constant for alkaline hydrolysis of benzene sulphochloride, which cannot react according to the elimination-addition (sulphene) mechanism.The reaction enthalpy of the alkaline hydrolysis of four individual alkane sulphochlorides was determined by a simple calorimetric apparatus; the average value amounts to ΔRH = -239 kJ mol-1.
- Hampel, M.,Just, G.,Krebes, W.,Pritzkow, W.
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p. 987 - 990
(2007/10/02)
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