Carboxylic acids reacting with

Carboxylic acids react with butadiene as alkali metal carboxylates. A mixture of isomeric 1- and 3-acetoxyoctadienes (39 and 40) is formed by the reaction of acetic acid[13]. The reaction is very slow in acetic acid alone. It is accelerated by forming acetate by the addition of a base[40]. Addition of an equal amount of triethylamine achieved complete conversion at 80 C after 2 h. AcONa or AcOK also can be used as a base. Trimethylolpropane phosphite (TMPP) completely eliminates the formation of 1,3,7-octatriene, and the acetoxyocta-dienes 39 and 40 are obtained in 81% and 9% yields by using N.N.N M -tetramethyl-l,3-diaminobutane at 50 in a 2 h reaction. These two isomers undergo Pd-catalyzed allylic rearrangement with each other. 

The carboxylic acids react with ammonia and with primary amines in a similar manner ... 

Carboxylic acids react with trifluoroacetic anhydride to give mixed anhydrides that are especially useful for the acylation of hindered alcohols and phenols ... 

Carboxylic acids react with xenon difluoride to produce unstable xenon esters The esters decarboxylate to produce free radical intermediates, which undergo fluonnation or reaction with the solvent system Thus aliphatic acids decarboxylate to produce mainly fluoroalkanes or products from abstraction of hydrogen from the solvent Perfluoro acids decarboxylate in the presence of aromatic substrates to give perfluoroalkyl aromatics Aromatic and vinylic acids do not decarboxylate [91] (equation 51)... 

Aliphatic carboxylic acids react with sulfur tetrafluonde to give, in addition to 1,1,1-trifluoromethylalkanes, considerable amounts of symmetrical bis(l,l-di-fluoroalkyl)ethers. Yields of the ethers are related to the nature of the acids and to the reaction conditions. The optimum conditions for the formation of the ethers depend on their stability in highly acidic reaction medium and on the reactivity of the acids toward sulfur tetrafluonde Simple unsubstituted acids form the ethers only at low temperatures, whereas longer chain and cycloaliphatic acids give the corresponding ethers at somewhat higher temperatures Halosubstituted acids form the ethers at the relatively high reaction temperatures necessary for these reactions to proceed [203, 204, 205] (equation 101). 

Furan-2-carboxylic acid reacts with sulfur tetrafluoride at 0 °C to give 2-furoyl fluoride, but attempts at further fluorination results in resin formation [222] A second carboxylic group and/or electron withdrawing substiments, such as the nitro or tnfluoromethyl group, stabilize the furan ring Thus, turandicar-... 

Carboxylic acids such as acetic acid react with alcohols such as methanol or with methoxytrimethylsilane 13 a in the presence of trimethylchlorosilane (TCS) 14 in THF or 2-methyl-THF to give esters such as methyl acetate in 97% yield and hex-amethyldisiloxane 7. Even methyl pivalate can be readily prepared in 91% yield [111]. Reaction of a variety of carboxylic acids, for example N-benzoylglycine 329, with two equivalents of yS-trimethylsilylethanol 330 and with 14 has been shown to afford esters such as 331 in 98% yield [112, 112 a]. Likewise, silylated carboxylic acids react with silylated alcohols or thiophenols in the presence of 4-trifluoro-methylbenzoic anhydride and TiCl4/AgCl04 to furnish esters or thioesters in high yields [113, 114] (Scheme 4.43). 

Carboxylic acids can be converted to acyl chlorides and bromides by a combination of triphenylphosphine and a halogen source. Triphenylphosphine and carbon tetrachloride convert acids to the corresponding acyl chloride.100 Similarly, carboxylic acids react with the triphenyl phosphine-bromine adduct to give acyl bromides.101 Triphenviphosphine-iV-hromosuccinimide also generates acyl bromide in situ.102 All these reactions involve acyloxyphosphonium ions and are mechanistically analogous to the alcohol-to-halide conversions that are discussed in Section 3.1.2. 

Pyranopyrrolothiazoles can be prepared in a similar way to certain pyrano- and thiopyrano-pyrrolizines and pyrrolizinopyridines as discussed earlier. Thus, thiazolidine-4-carboxylic acid reacts with the aldehyde 179 to give a 2 1 mixture of 180 and 181 (Equation 16). This reaction is a 1,3-dipolar cycloaddition of the alkene to the 1,3-dipole formed from reaction of the amino acid amine with the aldehyde <1988T4953, 1990T2213>. The alkyne analogue of 179 is similarly converted into 182 (Equation 17). 

The alkali in these water pools reacts with organic matter such as algae and moss growing on the stone. The most common of these reactions is saponification (see p. 240), which causes naturally occurring esters to split, to form the respective carboxylic acid and an alcohol. Once formed, this carboxylic acid reacts with more alkaline rainwater to form a metal carboxylate, according to... 

Let s do a problem illustrating how a carboxylic acid reacts with an alcohol to form an ester. 

Like other acids, a carboxylic acid reacts with a base to produce a salt... 

As you learned earlier, a carboxylic acid reacts with an alcohol to produce an ester. Water is the second product of this reaction. A strong acid, such as H2SO4, is used to catalyze (speed up) the reaction. The reverse reaction can also occur. (See Reactions of Esters and Amides, below.)... 

Carboxylic acids react with ammonia to give ammonium salt which on further heating at high temperature give amides. For example ... 

Combinatorial chemistry, by contrast, involves the reaction of one set of compounds with a second set of compounds, each set belonging to a particular family of compounds. For example, one set of compounds might consist of primary alcohols, and the second set, of carboxylic acids. The products of the reactions between these two sets of compounds would, then, be a set of all esters (the compounds formed when carboxylic acids react with alcohols) that could be synthesized from the alcohols and acids in each group. 

Amides are the least reactive carboxylic acid derivatives, and are easily obtained from any of the other carboxylic acid derivatives. Carboxylic acids react with ammonia and 1° and 2° amines to give 1°, 2° and 3° amides. 

Many aliphatic carboxylic acids react with sulfur tetrafluoride to give, in addition to 1.1,1-trifluoroalkanes 4, dimeric products, bis(1,l-difluoroalkyl) ethers 5. Cycloaliphatic c/v-1.2-dicarboxylic acids and sterically crowded arene-l,2-dicarboxylic acids give cyclic a,a,a, a -tetra-fluoro ethers 6 as the main or sole product. 

Ames and Ribeira (75JCS(Pl)1390) described a method for the preparation of thieno[2,3-c]pyridin-7-ones (Scheme 68). The sodium salt of 3-bromothiophene-2-carboxylic acid reacts with carbanions in the presence of copper or copper(II) acetate to give condensation products (274) by displacement of bromide ion, often with simultaneous deacetylation. Cyclization of (274) provides a convenient route to thieno[2,3-c]pyridin-7-ones. Thieno[2,3-c]pyridin-4-ones and thieno[3,2-c]pyridin-7-ones have been prepared by Friedel-Crafts cyclization of AT-(2-thenyl)- and A-(3-thenyl)-glycine derivatives (81H(l6)127l). 

Another interesting derivative of benzo[c]thiophene which may be useful for preparative purposes has been described by Castro and coworkers. Strictly analogous to a synthetic sequence outlined in Section 3.17.2.1.1, 3-iodothiophene-4-carboxylic acid reacts with a copper(I) acetylide in DMF at 125 °C to give a l//-thieno[3,4-c]pyran-2-one (equation 53) (68JHC227). 

Carboxylic acids react with phosphorus trichloride, phosphorus pentachloride, or thionyl chloride with replacement of OH by Cl to form acyl chlorides, RCOC1 ... 

Carboxylic acids react with aryl isocyanates, at elevated temperatures to yield anhydrides. The anhydrides subsequently evolve carbon dioxide to yield amines at elevated temperatures (70—72). The aromatic amines are further converted into amides by reaction with excess anhydride. Ortho diacids, such as phthalic acid [88-99-3], react with aryl isocyanates to yield the corresponding N-aryl phthalimides (73). Reactions with carboxylic acids are irreversible and commercially used to prepare polyamides and polyimides, two classes of high performance polymers for high temperature applications where chemical resistance is important. Base catalysis is recommended to reduce the formation of substituted urea by-products (74). 

A second kind of polymerization process occurs when molecules with two functional groups react. We ve seen, for example, that a carboxylic acid reacts with an amine to yield an amide (Section 23.14). If a molecule with two carboxylic acid groups reacts with a molecule having two amino groups, an initial reaction joins the two molecules together, and further reactions then link more and more... 

The unexpected formation of the blue crystalline radical cation (97) from the reaction of triazinium salt (98) with tetracyanoethylene has been reported and the product identified by its EPR spectrum and by X-ray crystallography (Scheme 42).199 Carboxylic acids react with the photochemically produced excited state of N-t-a-phenynitrone (PBN) to furnish acyloxy spin adducts RCOOPBN. The reaction was assumed to proceed via ET oxidation of PBN to give the PBN radical cation followed by reaction with RCO2H.200 The mechanism of the protodiazoniation of 4-nitrobenzenediazonium fluoroborate to nitrobenzene in DMF has been studied.201 Trapping experiments were consistent with kinetic isotope effects calculated for the DMF radical cation. The effect of the coupling of radicals with different sulfur radical cations in diazadithiafulvalenes has been investigated.202... 

Protection2 and activation1 of carboxylic acids. Carboxylic acids react with 1 in the presence of a 2-chloropyridinium salt, proton sponge, and DMAP to form amides (2). These amides are stable to acids and bases but deprotection is possible with oxidative hydrolysis with ceric ammonium nitrate (CAN). If the oxidation is carried out in the presence of an amine, an amide is obtained in 70-95% yield. For this purpose, the combination of copper(II) oxide and ceric pyridinium chloride is far superior to CAN.4 No racemization was observed in the benzoylation of an a-amino ester. 

Hammett s correlation for rate constants of substituted carboxylic acids reacting with hydroxyl radical. Experimental conditions elementary hydroxyl radical rate constants (l/m sec 108), pH 9. 

Reaction pathway for carboxylic acids reacting with hydroxyl radical. 

This method is based on the fact that only esters, but not free carboxylic acids, react with hydroxylamine to form hydroxamic acids, which can be determined colorimetrically as complex with ferric chloride (8). The method—in contrast to most other procedures—measures the concentration of remaining substrate instead of products of hydrolysis. It also requires purified enzymes because of the interference of colored contaminants in the colorimetric measurements. 

Carboxylic acids react with phosphorous trichloride (PC13), phosphorous pentachloride (PC15), thionyl chloride (SOCl2), and phosphorous tribromide (PBr3) to form acyl halides. 

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