Robustic acid

Grindelia. Gum-plant (of California Dried leaves and flowering tops of Grindelia camporum Greene or of G. humilis H. A, (G. cuneifotia Auth.), Compositae. Habit. North America (California). Constit Volatile oil, over 20% resin, grindelol, saponin, tannin, robustic acid. therap cat Expectorant. 

We have already isolated several new, bioactive compounds from these robust, acid mine waste bacteria and fungi, several of which will be described later in this chapter. Over the next few years we will continue the search for bioactive metabolites from these microbes. 

Sulfonated aromatic polymers have been widely investigated [32—42] for fuel ceU use due to their enhanced physical and chemical robustness, acid and water... 

HSTIPS and tri-f-butoxysilanethiol are equally effective and robust acidic polarity-reversal catalysts since they are both remarkably stable to hydrolysis. The HSTIPS catalyst is preferred owing to the fact that it is commercially available. The reaction is conducted under inert atmosphere, at reflux in dry octane, in the presence of 5 mol % of the catalyst. It is to be noted that, when DTPB is used, 50 mol % of the initiator is necessary. 

Sulfonic acids are such strong acids that in general they can be considered greater than 99% ionized. The piC value for sulfuric acid is —2.8 as compared to the piC values of —1.92, —1.68, and —2.8 for methanesulfonic acid, ethanesulfonic acid, and benzene sulfonic acid, respectively (3). Trifluoromethanesulfonic acid [1493-13-6] has a piC of less than —2.8, making it one of the strongest acids known (4,5). Trifluoromethanesulfonic acid is also one of the most robust sulfonic acids. Heating this material to 350°C causes no thermal breakdown (6). 

The conversion of 3 to 8 is summarized in Scheme 2. The trityl group (too large and too acid sensitive for the ensuing steps) was removed from N, and both N s were protected by Cbz (benzyloxycarbonyl) groups. Protection of the tertiary OH specifically as the robust TBS (f-butyldimethylsilyl) group was found to be necessary for the sequence involving the electrophilic aromatic substitution step, 5 to 6, and the Stille coupling steps (6 + 7 —> 8). 

The design of the economizer must be robust enough to survive occasional excursions beneath the acid dewpoint and the effects of the methods used to clean the economizer periodically. This may take the form of rapping equipment to shake off deposits, sootblowing by steam or air and water washing with lances. 

Since the FeCp(C6H6)+ unit is robust towards oxidation even in concentrated sulfuric acid, oxidation of alkyl substituents upon boiling in aqueous KMn04 solution can be achieved and leads to carboxylic substituents. The mesitylene complex can be oxidized to the mono-, di-, or tri-carboxylic add depending upon the reaction conditions. In the latter case, the decomplexed trimesic acid is obtained [106, 107] Scheme XXII ... 

The transition metal catalyzed cross coupling of an organohalide with a boronic acid derivative, the Suzuki-Miyaura coupling, has become one of the most popular ways of preparing biaryls.3 The reaction is very robust and can easily be scaled to provide multigrams of material.4... 

Abstract The unique and readily tunable electronic and spatial characteristics of ferrocenes have been widely exploited in the field of asymmetric catalysis. The ferrocene moiety is not just an innocent steric element to create a three-dimensional chiral catalyst enviromnent. Instead, the Fe center can influence the catalytic process by electronic interaction with the catalytic site, if the latter is directly coimected to the sandwich core. Of increasing importance are also half sandwich complexes in which Fe is acting as a mild Lewis acid. Like ferrocene, half sandwich complexes are often relatively robust and readily accessible. This chapter highlights recent applications of ferrocene and half sandwich complexes in which the Fe center is essential for catalytic applications. 

Binary systems of ruthenium sulfide or selenide nanoparticles (RujcSy, RujcSey) are considered as the state-of-the-art ORR electrocatalysts in the class of non-Chevrel amorphous transition metal chalcogenides. Notably, in contrast to pyrite-type MS2 varieties (typically RUS2) utilized in industrial catalysis as effective cathodes for the molecular oxygen reduction in acid medium, these Ru-based cluster materials exhibit a fairly robust activity even in high methanol content environments of fuel cells. 

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