Acid chlorides reactions

Acid Chloride Reaction. In situations where the reactants are sensitive to high temperature or the polymer degrades before the melt poiat is reached, the acid chloride route is often used to produce the polyamide (47). The basic reaction ia the presence of a base, B , is as follows ... 

The sulfonyl chloride group is the cure site for CSM and determines the rate and state of cure along with the compound recipe. It is less stable than the Cl groups and therefore often determines the ceiling temperature for processing. The optimum level of sulfonyl chloride to provide a balance of cured properties and processibiUty is about 2 mol % or 1—1.5 wt % sulfur at 35% Cl. It also undergoes normal acid chloride reactions with amines, alcohols, etc, to make useful derivatives (17). 

Claisen ester condensation, 6, 279 Thiazolecarboxylic acid chlorides reactions, 6, 279-280 Thiazolecarboxylic acid hydrazides synthesis, 6, 280 Thiazolecarboxylic acids acidity, 6, 279 decarboxylation, 6, 279 reactions, S, 92 6, 274 Thiazole-2-carboxylic acids decarboxylation, S, 92 Thiazole-4-carboxylic acids stability, S, 92 Thiazole-5-carboxylic acids decarboxylation, S, 92 Thiazole-4,5-dicarboxylic acid, 2-amino-diethyl ester reduction, 6, 279 Thiazole-4,5-dicarboxylic acids diethyl ester saponification, 6, 279 Thiazolediones diazo coupling, 5, 59 Thiazoles, 6, 235-331 ab initio calculations, 6, 236 acidity, S, 49 acylation, 6, 256 alkylation, S, 58, 73 6, 253, 256 analytical uses, 6, 328 antifogging agents... 

Acid chloride Reaction conditions % yield of aldehyde... 

Reactions with anhydrides and acid chlorides are more rapid and can occur in an essentially nonreversible fashion. But, anhydrides and acid chlorides are considered high-energy reactants since they often involve additional energy-requiring steps in their production, and are thus less suitable for large-scale production of materials. The activity energies for direct esterification and transesterification are on the order of 30 kcal/mol (120 kJ/mol) while the activation energies for anhydride and acid chloride reaction with alcohols are on the order of 15-20 kcal/mol (60-80 kJ/mol). 

The presence of the propionamide fragment in the stmcture of the anti-inflammatory agent broperamole (125-1) is reminiscent of the heterocycle-based NSAID propionic acids. The activity of this agent may trace back to the acid that would result on hydrolysis of the amide. Tetrazoles are virtually always prepared by reaction of a nitrile with hydrazoic acid or, more commonly, sodium azide in the presence of acid in a reaction very analogous to a 1,3-dipolar cycloaddition. A more recent (and safer) version of the reaction noted later (see losartan, 77-4) uses tributyltin azide. In the case at hand, reaction of the anion of mefa-bromobenzonitrile (125-1) with sodium azide and an acid affords the tetrazole (125-2). Condensation of the anion from that intermediate with ethyl acrylate leads to the product from Michael addition saponiflcation gives the corresponding carboxylic acid (125-3). This is then converted to the acid chloride reaction with piperidine affords broperamole (125-4) [136]. 

Yet another piperidine-based antipsychotic agent replaces the butyrophenone or diarylpropyl function found in earlier compounds by a benzopyrimidine group. The synthesis starts by the conversion of the carboxylic acid in piperidine (22-1) to its acid chloride. Reaction with 1,3-difluorobenzene (22-2) in the presence of aluminum chloride affords the acylated product (22-3). Reaction with hydroxylamine leads to the corresponding oxime (22-4). Treatment of that derivative with a base... 

Esterification of aromatic carboxylic acids with phenols, however, cannot be accomplished by a direct esterification procedure and resort must be made to the greater reactivity exhibited by the acid chlorides. Reaction is usually carried out in dilute aqueous alkali (Schotten-Baumann conditions, Section 6.6.2, pp. 916 and 1248). The preparation of 2-naphthyl benzoate is a typical example of this procedure (Expt 6.166). 

Harringtonine (107) has been synthesized 170) by the method shown in Scheme 59. Claisen condensation between 283 and ethyl oxalate in the presence of NaH gave 284 which, when heated under reflux with aqueous HC1, was converted to a mixture from which the oxide (285) was isolated. Without purification, 285 was treated with HCl/MeOH to yield 286, saponification of which yielded the unsaturated acid as its sodium salt 287. After conversion to the acid chloride, reaction with cephalotaxine yielded 288. 

IX-I Acid chlorides reaction of a carboxylic acid + PCIj, PCI5 or SOCIj... 

If one were to choose more reactive monomers, it would be possible to carry out polycondensations at considerably lower temperatures in solution. For example, consider the reaction of a diamine and a diacid to make a polyamide (nylon), a polymerization that requires relatively high temperatures (see Equation 9). A much faster reaction would occur between the diamine and a corresponding diacid chloride (see Equation 10). Both reactions would produce the same polymer, although the reaction conditions would be much different, and the byproduct HC1 from the acid chloride reaction would have to be carefully trapped. One technique for performing a polymerization such as that in Equation 10 is to dissolve the monomers in different, immiscible solvents, forcing the polymerization to occur only at the interface of the two solvents, a process called interfacial polymerization. Because of the high reactivity of an acid chloride, these reactions can be carried out at very low temperatures. This polymerization can be carried out rather dramatically in a beaker and is known as the nylon rope trick (see Section 4). 

The energy levels of the starting materials, the transition state, and the intermediate are all lower in the anhydride reaction than in the acid chloride reaction. So which goes faster We know the answer—acid chlorides are more reactive than anhydrides towards nucleophiles. The reason is that the stability of the starting materials is determined by the interaction between the carbonyl group and the substituent attached directly to it. This is a big effect as we know from infrared spectroscopy. 

In this case, from the standpoint of the acid chloride, reaction is acid-catalyzed nucleophilic acyl substitution, of the kind discussed in Sec. 20.4, with the aromatic ring acting as the nucleophile. 

Selective acylation was also possible with four equivalents of an arylsulphonyl chloride or an aroyl chloride furnishing 76c " and 76d, in yields up to about 50%, while the regioselective acylation fails with aliphatic acid chlorides. Reaction with benzyloxycarbonyl chloride (EtsN, MeCN, RT), however, allowed the partial protection of four hydroxy groups to yield 76e. Compounds 76c-76e (interesting as building blocks for various self-assembled structures ) may be used for further derivatizations. 

Carboxylic acids react with thionyl chloride to form acid chlorides. Reaction with alcohols gives esters, and with amines, amides are formed. 

Acid chlorides are prepared by standard methods and undergo the usual acid chloride reactions. They have found important applications as substrates in the syntheses of ketones by transition metal-catalyzed coupling reactions with organometallics (Section 6.02.5.5.14). Acid chlorides (424) are also good substrates for the preparation of ketones (425) using organomanganese(II) iodide, especially for the preparation of alkyl pyrimidinyl ketones <86ACS(B)764>. 

Phosphorus trichloride (PC13), b.p. 74.5°, is used particularly for preparation of volatile carboxylic acid chlorides (reaction b). Usually about 1.1 moles of the carboxylic acid is allowed to react with 0.5 mole of PC13 at room temperature or with slight warming until evolution of HC1 ceases and then the acid chloride is distilled off see, for instance, the preparation of acetyl chloride from glacial acetic acid and PCl3.33b The carboxylic acid chloride can also be taken up in a solvent (benzene, light petroleum, or CS2) at the end of the reaction and used directly for further reactions ... 

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