Grinding carboxyl

Grinding thiadiazolamines 101 with an equivalent of coumarin-3-carboxylic acid chloride 100 under solvent-free conditions in a mortar gave the corresponding amides 102 in 76-90% yields, or when heated in a microwave oven for 5-18min in 87-93% yields (Equation 29) <2006PS183>. 

Bobka (144) studied the adsorption of diphenylguanidine on graphite wear dust. As was shown by Rivin (85), diphenylguanidine adsorption is equivalent to NaHCOj neutralization in the determination of carboxyl groups. With increasing grinding time, surface area and diphenylguanidine adsorption increased parallel to each other. 

Fig. 1 Carboxylic acid heterodimer formed by solution and solid-state grinding cocrystallisation approaches[21]...

The simplest technique may be coprecipitation. In this method, a reagent is added to the stock solution that is destabilized and precipitated. Better mixing at a microscopic level is then achieved without mechanical grinding and mixing. Insoluble carboxylates such as citrates, oxalates and carbonates or hydroxides are the most suitable reagents. 

An additional useful test for aromatic carboxylic acids is to distil the acid or its sodium salt with soda-lime. Heat 0.5 g of the add or its sodium salt with 0.5 g of soda-lime in an ignition tube to make certain that there is no danger of explosion. Then grind together 0.5 g of the acid with 3 g of soda-lime, place the mixture in a Pyrex test tube and cover it with an equal bulk of soda-lime. Fit a wide delivery tube dipping into an empty test tube. Clamp the tube near the mouth. Heat the soda-lime first and then the mixture gradually to a dull-red heat. Examine the product this may consist of aromatic hydrocarbons or derivatives, e.g. phenol from salicylic acid, anisole from anisic acid, toluene from toluic acid, etc. 

Turning to assays using sensors that require more than a simple cut in the sample, Bergann et al. [37] paid considerable attention to sample preparation in attempts to measure lactate in meat with a sensor (not thick film) based on reaction of hydrogen peroxide with a platinum electrode or on the reaction of ferrocene carboxylate with the active site of lactate oxidase. Sample preparation entailed extraction into buffer following grinding. In some cases, ground samples were left to allow the lactate to diffuse into the buffer solution. This was quite effective but slow (up to 90 min). Ultimately, the quality of the assay was dependent on the method of sample preparation. 

As part of a more extensive study of cocrystals formed by isonicotinamide with carboxylic acids, 1 1 products containing the dicarboxylic fumaric or succinic acids [59]. In the structures of these particular cocrystals, the typical discrete dimeric synthon was not observed, but instead effectively infinite assemblies of one-dimensional chains were found instead. In a subsequent work, cocrystals of isonicotinamide containing mixed fumaric/succinic acids were prepared using both solid-state grinding and solution crystallization [60]. A full physical characterization of the products demonstrated that the products consisted of a single cocrystal phase, and were not simple physical mixtures of two cocrystal components. Such solid solutions were proposed as yet another method whereby one might obtain even finer control over the physical properties of cocrystal systems proposed as drug substances. 

A nice example of grinding-induced crystal engineering is the formation of a hydrogen bonded cocrystal between ferrocene dicarboxylic acid and 1,4-diazabicyclo [2.2.2] octane (DABCO). The ferrocene dicarboxylic acid exists in the solid as a hydrogen bonded dimer based on two repeats of the carboxylic acid dimer synthon (solid A). Grinding with DABCO (solid B) gives rise to a new solid, C, in which the carboxylic acid dimers have been broken and replaced by an acid-amine synthon, Figure 8.25.30... 

Aluminum powder Aluminum alkyls Grinding Heating Carboxylic acid chlorides Ethers Tertiary amines Tertiary phosphines Metal chlorides... 

Grinding reduces the raw salt to a size of < ca. 1 to 2 mm, depending upon the composition. Fines and dust interfere with this process. Conditioning entails the addition of organic compounds, mostly carboxylic acids, in quantities of 50 to 200 g/t raw salt. The salt is then dried e.g. by passing hot air over it. The (triboelectrical) charging takes place in so-called fluidized bed salt warmers in which the various salt components become oppositely charged. The residence time of the salt in this unit is less than one minute. 

Tamtd . [BASF AG] Nsq thalene sulfonates carboxylates dispersants for pigments, dyestuffs, carbon black grinding sabiliza, solubilizer tanning agent fcH leadin . 

A facile one-pot procedure for the s)mthesis of symmetric carboxylic acid anhydrides utilizes tosyl chloride (0.5-0.6 equiv) in K2CO3 media under solvent-free conditions. The desired anhydrides are formed by grinding the reaction mixture for 15 5 min in a mortar. The products were isolated by stirring the reaction mixture with CH2CI2 or CHCI3 followed by filtration and concentration. ... 

The most important metal-containing heat stabilizers in PVC can also be identified through IR-spectroscopy (see Section 8.2). Characteristic absorption bands for the salts of carboxylic acids are the bands of the ionized carboxy group in the region from 1590 to 1490 cm and from 1410 to 1370 cm Since the exact position of the absorption bands depends mainly on the metal counterions of the carboxy group, the IR-spectra provide a first identification of these metals. Tin stabilizers also show characteristic bands in these regions of the IR-spectrum. To determine the spectra, one uses pressed pellets made by finely grinding the sample material with potassium bromide. The identification of the metal becomes even more certain if an FT-IR (Fourier Transform/Infrared) instrument is available. With such an instrument, it is possible to subtract the spectrum of an additive-free... 

Addition of amines to acetylene carboxylates 246 in ball mill was studied by Stolle and Thorwirth (Scheme 3.65) [44]. Employing solvent-free protocol in planetary ball mill in conjunction with quartz sand as inert grinding auxiliary, a number of enamines 247 were prepared in high yield (Table 3.33). No further catalysts or additives was required to accomplish reaction within 5 min. Obtained E/Z ratios vary with amine applied in the case of dicarboxylates, mainly the E-isomers have been identified. In contrast, reactions with propiolates and anilines yielded favorably the Z-isomer, whereas secondary alkyl amines furnished the E-isomer preferably. Simple stirring of DMAD and aniline in flask afforded only 80% conversion and chemoselectivity was lower (E/Zratio of 87 13) in comparison to ball milling. A common method for synthesis is the reaction in solvent, for which was found to have a strong influence on the E/Z ratio of the product, while this influence is not present in solvent-free milling. 

Complex formation only by grinding a mixture in a mortar was examined for a variety of combinations of the surfactant and aromatic compounds. The CTAB, MTAB, LTAB and DTAB surfactants were selected along with hydrophilic aromatic compounds containing hydroxyl, carboxyl and imino groups, and hydrophobic aromatic compounds such as acridine, anthracene, biphenyl and phenanthrene. Table 4.2 shows the results of the complex formation, in which the letters A, B and C mean that the complex was formed completely, partly and hardly, respectively. (The asterisk indicates that the single crystals have been analysed by X-rays). It is clear that ... 

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