625-23-0Relevant academic research and scientific papers
Silanol-based surfactants: Synthetic access and properties of an innovative class of environmentally benign detergents
Hurkes, Natascha,Ehmann, Heike M. A.,List, Martina,Spirk, Stefan,Bussiek, Malte,Belaj, Ferdinand,Pietschnig, Rudolf
, p. 9330 - 9335 (2014/08/05)
Herein, environmentally friendly surfactants based on new silanols as substitutes for the isoelectronic phosphonates were explored. Surface tensions of aqueous solutions are significantly reduced, particularly with those silanols that feature a high ratio of organic moiety to silanol. Besides their use as surfactants, their potential as coating agents for hydrophilic oxide surfaces was investigated for the example of glass substrates. In the solid-state sheet structures with silanol, double layers are present, in which the sheet spacing varies with the alkyl-chain length. Soap from sand? A synthetic entry to surfactants based on stable silanols, which provide beneficial properties comparable to established detergents without sharing their eutrophicating potential, was established (see figure).
Alkane oxidation by the system 'tert-butyl hydroperoxide-[Mn 2L2O3][PF6]2 (L = 1,4,7trimethyl-1,4,7-triazacyclononane)-carboxylic acid'
Kozlov, Yuriy N.,Nizova, Galina V.,Shul'pin, Georgiy B.
, p. 119 - 126 (2008/09/20)
The kinetics of cyclohexane (CyH) oxygenation with terf-butyl hydroperoxide (TBHP) in acetonitrile at 50°C catalysed by a dinuclear manganese(IV) complex 1 containing 1,4,7-trimethyl-1,4,7-triazacyclononane and co-catalysed by oxalic acid have been studied. It has been shown that an active form of the catalyst (mixed-valent dimeric species 'MnIIIMnIV,) is generated only in the interaction between complex 1 and TBHP and oxalic acid in the presence of water. The formation of this active form is assumed to be due to the hydrolysis of the Mn - O - Mn bonds in starting compound 1 and reduction of one MnIV to MnIII. A species which induces the CyH oxidation is radical tert-BuO generated by the decomposition of a monoperoxo derivative of the active form. The constants of the equilibrium formation and the decomposition of the intermediate adduct between TBHP and 1 have been measured: k = 7.4mol-1dm3 and k = 8.4 × 10 -2s-1, respectively, at [H2O] = 1.5 mol dm -3 and [oxalic acid] = 10-2 mol dm-3. The constant ratio for reactions of the monomolecular decomposition of tert-butoxy radical (tert-BuO → CH3COCH3+ CH3) and its interaction with the CyH (terf-BuO + CyH → fert-BuOH + Cy) was calculated: 0.26 mol dm-3. One of the reasons why oxalic acid accelerates the oxidation is due to the formation of an adduct between oxalic acid and 1 (K ≈ 103 mol-1 dm3). Copyright
Hydroperoxidation of alkanes with hydrogen peroxide catalyzed by aluminium nitrate in acetonitrile
Mandelli, Dalmo,Chiacchio, Karyna C.,Kozlov, Yuriy N.,Shul'pin, Georgiy B.
scheme or table, p. 6693 - 6697 (2009/04/07)
The first example of alkane oxygenation with hydrogen peroxide catalyzed by a non-transition metal derivative (aluminium) is reported. Heating (70 °C) a solution of an alkane, RH, hydrogen peroxide (70% aqueous) and a catalytic amount of Al(NO3)3·9H2O in air for a few hours afforded the corresponding alkyl hydroperoxide, ROOH. With cyclooctane, the hydroperoxide yield attained 31% and the maximum turnover number was 150. It is proposed on the basis of measurements of the selectivity parameters for the oxidation of linear and branched alkanes and a kinetic study that the oxidation occurs with the participation of hydroxyl radicals.
Efficient tetrahydropyranylation of alcohols and detetrahydropyranylation reactions in the presence of catalytic amount of trichloroisocyanuric acid (TCCA) as a safe, cheap industrial chemical
Firouzabadi, Habib,Iranpoor, Nasser,Hazarkhani, Hassan
, p. 3623 - 3630 (2007/10/03)
Preparation and cleavage of THP ethers of different hydroxy functional groups are easily and efficiently performed in the presence of trichloroisocyanuric acid (TCCA) in the absence of solvent with high yields.
Dimethyldioxirane reactions: Rate acceleration due to intramolecular H-bonding
Murray, Robert W.,Gu, Hong
, p. 751 - 758 (2007/10/03)
Absolute rate studies were carried out on a series of C - H insertion reactions of dimethyldioxirane (1a). The substrates were chosen so that the distance between a single tertiary C - H bond and an OH group could be varied. The measured rate constants indicate that a rate acceleration occurs when the distance between the reacting C - H bond and the OH group permits intramolecular H-bonding stabilization of the transition state. A similar study in related compounds without the OH group showed no effect of chain length on the rate of the C - H insertion reaction. A related study of the epoxidation reaction of la also found an increased rate when chain length permitted intramolecular H-bonding by an OH group.
Chelates as intermediates in nucleophilic additions to alkoxy ketones according to Cram's rule (cyclic model)
Chen, Xiangning,Hortelano, Edwin R.,Eliel, Ernest L.,Frye, Stephen V.
, p. 1778 - 1784 (2007/10/02)
Chelates have been considered intermediates in the often highly stereoselective reactions of α-alkoxy and similarly substituted ketones for over 30 years,10 but without mechanistic evidence. It is now shown, by stop-flow ("rapid injection") NMR kinetics,15 that the specific rates of reaction of ketones C6H5COCH(OR)CH3 with Me2Mg, where R = (i-Pr)3 ("TIPS"), t-BuPh2Si, t-BuMe2Si, Et3Si, Me3Si, and Me, parallel the diastereoselectivity of the reaction; i.e., the fastest reacting compound (R = Me) is the one which gives the highest proportion of the product predicted by Cram's chelate rule. The major product of the slowest reacting compound (R = TIPS) is not in accord with Cram's chelate rule, and this compound reacts at the same specific rate as the parent, C6H5COCH2CH3. This is in accord with earlier work indicating that TIPSO does not chelate. Compounds intermediate in the series react at intermediate rates and give the two diastereomeric products in proportions which can be calculated by assuming two competing reactions (cf. Figure 2): one proceeding via the chelated transition states giving the product predicted by the chelate rule and one not involving chelation which gives the same product composition as the R = TIPS compound. Direct steric effects on carbonyl reactivity due to the remote bulky silyloxy substituents have been excluded by the study of carbon analogues bearing similar bulky groups. Thus, the kinetic effect in the above series appears to be due to steric hindrance to chelation; hence, the parallel of specific rate and stereoselectivity demonstrates that high stereoselectivity is associated with strong chelation, as postulated by Cram and Kopecky in 1959.10.
Mechanism of the Grignard Adddition Reaction. XVI. Homolytic and Concerted Mechanisms in the Reaction of α,β-Unsatureted Carbonyl Compounds with Grignard Reagents
Holm, Torkil
, p. 925 - 929 (2007/10/02)
Kinetic measurements have shown that the addition of Grignard reagents to α,β-unsaturated carbonyl compounds takes place either by a concerted mechanism or by a homolytic mechanism.Phenylmagnesium bromide, which is incapable of homolysis, reacts rapidly in a 1,4-fashion if an s-cis conformation exists between the C=C and the C=O bonds, but only 1,2-addition takes place if the conformation is s-trans.tert-Butylmagnesium bromide is unsuited to the concerted reaction, but 1,4-addition takes place via homolysis.Primary and secondary Grignard reagents, like phenyl, react rapidly in a concerted manner with s-cis substrates, but unlike phenyl, these Grignard reagents may, with s-trans substrates, produce some 1,4-adduct via the homolytic mechanism.
Mechanistics Studies on the Cobalt(II) Schiff Base Catalyzed Oxidation of Olefins by O2
Hamilton, Dorothy E.,Drago, Russell S.,Zombeck, Alan
, p. 374 - 379 (2007/10/02)
The cobalt complex cobalt(II), CoSMDPT, has been shown to catalystically oxidize olefins in the presence of dioxygen or hydrogen peroxide.When terminal olefins are oxidized, the methyl ketone and corresponding secondary alcohol are produced selectively.Internal as well as terminal olefins are oxidized.The most common pathway for the oxidation of olefins catalyzed by first-row transition metals - autoxidation - has been ruled out in this system.A Wacker-type mechanism, oxidation by peracids, and mechanisms involving the formation of peroxymetallocycles have also been ruled out.A new mechanism for O2 oxidations is proposed which involves oxidation of the primary alcohol solvent by CoSMDPT to produce the corresponding aldehyde and hydrogen peroxide.Reaction of hydrogen peroxide with CoSMDPT occurs to form a cobalt hydroperoxide, which can be viewed as a stabilized hydroperoxy radical which has spin paired with the dz2 electron of CoSMDPT.The cobalt hydroperoxide then adds to the olefin double bond, leading to formation of an alkyl hydroperoxide.Haber-Weiss decomposition of this alkyl hydroperoxide by CoSMDPT produces the observed ketone and alcohol products.Deactivation of the catalysts is due to oxidation of the ligand system of the cobalt complex as well as formation op a μ-peroxo-dicobalt complex.
