Without Carboxylic Acid Additives

Reaction conditions for C-H activation of thiophenes can be divided into three groups 1) Heck (Jeffery) conditions/ although these are used infrequently 2) with carboxylic acid additives 3) without carboxylic acid additives. The last two types of conditions have been used in polar and aprotic solvents and may be carried out with a phosphine ligand. 

Activation of the carboxylic acid can easily be accomplished by the classical thionyl chloride method.To generate acid chlorides under mild conditions without the evolution of gaseous HCl the reaction is carried out in SOCl2/DMF or started with the dicyclohexylammonium salt of the carboxylic acid. Addition of DMF accelerates the reaction. An imide chloride is considered to be the reactive species (Scheme 2). Other methods include activation with cyanuric chloride or triphenylphosphine/ tetrachloromethane. ... 

Polar (dimethylacetamide (DMAC), DMF, NMP, THF) and nonpolar (toluene) solvents are suitable for these reactions and should be selected according to the polymer solubility. DMAc is not a suitable solvent for polymerization and always gives brown soluble material. Addition of carboxylic acid may be beneficial in nonpolar solvents owing to the high polarity of the C-H bond transition states. However, C-H bond activations have been accomplished in toluene and xylenes without carboxylic acids. ... 

The two-component waterborne urethanes are similar in nature to the one-component waterborne urethanes. In fact, many one-component PUD s may benefit from the addition of a crosslinker. The two-component urethanes may have higher levels of carboxylic acid salt stabilizer built into the backbone than is actually needed to stabilize the urethane in water. As a result, if these two-component urethane dispersions were to be used as one-component adhesives by themselves (without crosslinker), they would show very poor moisture resistance. When these two-component urethane dispersions are used in conjunction with the crosslinkers listed in Fig. 8, the crosslinkers will react with the carboxylic pendant groups built into the urethane, as previously shown in the one-component waterborne urethane section. This accomplishes two tasks at the same time (1) when the crosslinker reacts with the carboxylic acid salt, it eliminates much of the hydrophilicity associated with urethane dispersion, and (2) it crosslinks the dispersion, which imparts solvent and moisture resistance to the urethane adhesive (see phase V in Fig. 5). As a result of crosslinking, the physical properties may be modified. For example, the results may be an increase in tensile properties and a decrease in elongation. Depending upon the level of crosslinking, the dispersion may lose the ability to be repositionable. (Many of the one-component PUD s may... 

The formulated mechanism is supported by the finding that no halogen from the phosphorus trihalide is transferred to the a-carbon of the carboxylic acid. For instance, the reaction of a carboxylic acid with phosphorus tribromide and chlorine yields exclusively an a-chlorinated carboxylic acid. In addition, carboxylic acid derivatives that enolize easily—e.g. acyl halides and anhydrides—do react without a catalyst present. 

A low-molecular-weight condensation product of hydroxyacetic acid with itself or compounds containing other hydroxy acid, carboxylic acid, or hydroxy-carboxylic acid moieties has been suggested as a fluid loss additive [164]. Production methods of the polymer have been described. The reaction products are ground to 0.1 to 1500 p particle size. The condensation product can be used as a fluid loss material in a hydraulic fracturing process in which the fracturing fluid comprises a hydrolyzable, aqueous gel. The hydroxyacetic acid condensation product hydrolyzes at formation conditions to provide hydroxyacetic acid, which breaks the aqueous gel autocatalytically and eventually provides the restored formation permeability without the need for the separate addition of a gel breaker [315-317,329]. 

The isolation of 73 was then fully optimized. Upon completion of the etherification reaction, the insoluble trichloroacetamide 68 was filtered, leaving a 17 1 mixture of 18 and 19 as a DCE/heptane solution, together with starting material 10. The solvent was switched to MeOH and the esters were saponified with KOH. The carboxylic acid was isolated after neutralization and the addition of NEt3 which gave the highly crystalline triethylamine solvate 73 as a 40 1 mixture of diastere-omers. Recrystallization from MTBE/heptane gave a 109 1 diastereomeric mixture of 73 in 54% overall yield from 10. This final process was successfully implemented in the pilot plant without incident. 

Aside from alkoxycarbonylations, hydroxycarbonylations in the presence of water to yield allenic carboxylic acids [15] (93, Y = OH) and aminocarbonylations in the presence of amines to give the analogous amides [139] (93, Y = NRR ) have also been carried out, respectively (Scheme 7.13). These products of structure 102 can also be obtained if using the propargylamines 101 with R1 = Ph or R3 Z H as starting materials (Scheme 7.15) [140]. Additionally, hydroxycarbonylations, also termed carboxyla-tions, are successful without palladium catalysis by reaction of propargyl halides and carbon monoxide in the presence of nickel(II) cyanide under phase-transfer conditions [141, 142]. 

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