Esters, carboxylic acid structure

Maleic acid, structure of, 753 Malic acid, structure of, 753 Walden inversion of, 359-360 Malonic ester, carboxylic acids from, 856-858... 

Calixarenes, which are macrocyclic compounds, are one of the best building blocks to design molecular hosts in supramolecular chemistry [158]. Synthesis of calix[4]arenes, which have been adamantylated, has been reported [105, 109]. In calix[4]arenes, adamantane or its ester/carboxylic acid derivatives were introduced as substituents (Fig. 29). The purpose of this synthesis was to learn how to employ the flexible chemistry of adamantane in order to construct different kinds of molecular hosts. The X-ray structure analysis of p-(l-adamantyl)thiacalix[4]arene [109] demonstrated that it contained four CHCI3 molecules, one of which was located inside the host molecule cavity, and the host molecule assumed the cone-like conformational shape (Fig. 30). 

ADMET depolymerizations with substituted alkenes have been done as well, thereby generating perfectly difunctional telechelic molecules. As an example, 1,4-polybutadiene has been depolymerized in an inert atmosphere with a 10-fold molar excess (based on the repeat unit) of either allyltrimethylsilane or allylchlorodimethylsilane (equation 23). In these examples, the chemistry can be driven to complete depolymerization to yield structures with either one, two, three, or four repeat units of 1,4-butadiene. The synthesis of perfectly difunctional oligomers by this chemistry offers significant opportunity, particularly for functional groups such as alcohols, esters, carboxylic acids, and amines. 

A heteroatom in a C=X bond can use its lone pair to react with a Lewis acid to give a product for which a carbocationic resonance structure can be drawn. Protonation of a carbonyl compound belongs in this category. One of the lone pairs on O coordinates to H+ to give a compound with two major resonance structures, one of which is carbocationic. The carbocationic resonance structure is not the best structure, but it tells the most about the reactivity of the ion. If the carbonyl C has heteroatoms directly attached (e.g., esters, carboxylic acids, and amides), more resonance structures can be drawn. Reactions of imines (Schiff bases) often begin by protonation of N. 

Classify the structures in Question 59 as one of the following hydrocarbon, alkene, alkyne, aromatic, alkyl halide, alcohol, ester, carboxylic acid. 

If polyaddition is induced without using basic catalysts, lower proportions of anhydride must be used, since, depending on the conditions under which the reaction takes place and the acidity of the intermediate ester carboxylic acids, some of the glycidyl groups will form ether groups according to Fig. 1 structural fragment III. 

The simple molecular connectivity indices are related to a number of other physicochemical parameters. For example, Murray et al. showed a very strong correlation between the log P values (P is the partition coefficient of a solute between water and w-octanol) of 138 simple organic molecules and their values. A correlation coefficient of 0.986 and a standard error of 0.152 was obtained. The log P values estimated ranged from -0.5 to 3.5, with the majority of compounds having values near 1.5. The xp values used were valence-corrected molecular connectivities (hence the superscript v), where the 8, values are defined as 8, = Zi - Hi, where Zy is the number of valence electrons of the atom and H, is the number of attached hydrogens. The data set studied included esters, carboxylic acids, alcohols, amines, ketones, and ethers. Although the molecules of this correlation were all quite simple in structure, being monofunctional, the correlation demonstrates that molecular connectivity indices do represent some aspects of molecular structure quite effectively. 

Label the structures in the S nithetic Transformations above according to their functional group category. Choose from alcohol (specify 1°, 2°, or 3° if indicated), amine, aldehyde, ketone, amide, ester, carboxylic acid, carboxylate, acid halide, or acid anhydride. 

Pteridine-7-carboxylic acid, 6-oxo-synthesis, 3, 310 Pteridinecarboxylic acids structure, 3, 276-277 Pteridine-4-carboxylic acids ethyl ester hydrolysis, 3, 276 Pteridine-6-carboxylic acids properties, 3, 277 reactions, 3, 304 Pteridine-7-carboxylic acids properties, 3, 277 reactions, 3, 304 Pteridine-6,7-dicarboxylic acid properties, 3, 277 Pteridine-2,4-dione, 7-hydroxy-tautomerism, 3, 271... 

The chemistry of carboxylic acids is the central theme of this chapter. The importance of carboxylic acids is magnified when we realize that they are the parent compounds of a large group of derivatives that includes acyl chlorides, acid anhydrides, esters, and amides. Those classes of compounds will be discussed in Chapter 20. Together, this chapter and the next tell the story of some of the most fundamental structural types and functional group transfonnations in organic and biological chemistry. 

Reactant and product structures. Because the transition state stmcture is normally different from but intermediate to those of the initial and final states, it is evident that the stmctures of the reactants and products should be known. One should, however, be aware of a possible source of misinterpretation. Suppose the products generated in the reaction of kinetic interest undergo conversion, on a time scale fast relative to the experimental manipulations, to thermodynamically more stable substances then the observed products will not be the actual products of the reaction. In this case the products are said to be under thermodynamic control rather than kinetic control. A possible example has been given in the earlier description of the reaction of hydroxide ion with ester, when it seems likely that the products are the carboxylic acid and the alkoxide ion, which, however, are transformed in accordance with the relative acidities of carboxylic acids and alcohols into the isolated products of carboxylate salt and alcohol. 

Dimethyl acetylenedicarboxylate gave first a similar adduct (2) which then added further molecules of furan yielding (3) and subsequently (4). Between 1931 and 1940 the reactions of acetylenedi-carboxylic acid and its dimethyl ester with a number of nitrogen containing heterocyclic compounds were examined, and structures were proposed for the products. Apart from an unpublished investigation of the products from pyridine and dimethyl acetylenedicar-... 

Only in the case of the pyruvic acid condensation product was it possible to isolate the corresponding ethyl ester under these conditions. This, on mild hydrolysis, reverted to 1-methyl-1,2,3,4-tetrahydro-j8-carbohne-1-carboxylic acid, identical with the starting material, which therefore had the assigned structure 26 (R = CH3) and was not the SchiflF s base 25 (R = CH3). Alkaline hydrolysis of the ester was accompanied by decarboxylation. ... 

The molecular structure has so far been determined only for 3-(pyrazol-4-yl) propargyl alcohol (98M076) and 5-trimethylsilanyl-4-trimethylsilanylethynyl-l//-pyrazole-3-carboxylic acid ethyl ester (88JOM247). 

Chemical Name (bicyclohexyl)-1-carboxylic acid 2-(diethylamino)ethyl ester hydrochloride Common Name Dicycloverin hydrochloride Structural Formula ... 

Closely related to the carboxylic acids and nitriles discussed in the previous chapter are the carboxylic acid derivatives, compounds in which an acyl group is bonded to an electronegative atom or substituent that can net as a leaving group in a substitution reaction. Many kinds of acid derivatives are known, but we ll be concerned primarily with four of the more common ones acid halides, acid anhydrides, esters, and amides. Esters and amides are common in both laboratory and biological chemistry, while acid halides and acid anhydrides are used only in the laboratory. Thioesters and acyl phosphates are encountered primarily in biological chemistry. Note the structural similarity between acid anhydrides and acy) phosphates. 

Acid-catalyzed ester hydrolysis can occur by more than one mechanism, depending on the structure of the ester. The usual pathway, however, is just the reverse of a Fischer esterification reaction (Section 21.3). The ester is first activated toward nucleophilic attack by protonation of the carboxyl oxygen atom, and nucleophilic addition of water then occurs. Transfer of a proton and elimination of alcohol yields the carboxylic acid (Figure 21.8). Because this hydrolysis reaction is the reverse of a Fischer esterification reaction, Figure 21.8 is the reverse of Figure 21.4. 

Problem 27.1 Carnauba wax, used in floor and furniture polishes, contains an ester of a C32 straight-chain alcohol with a C20 straight-chain carboxylic acid. Draw its structure. 

The relative amounts of LDL and HDL cholesterol in your bloodstream depend, at least in part, on your diet In particular, they depend on the total amount and the type of fat that you eat. Fats (triglycerides) are esters of glycerol with long-chain carboxylic acids. The general structure of a fat can be represented as... 

Gandini and Rieumont26,119 have carried out an extensive examination of the polymerizability of several vinyl esters of furan carboxylic acids and of the causes of the autoinhibition which most of them display with free-radical initiation. The compounds studied were the vinyl esters of 2-furoic, 2-furylacetic, 2-furylpropionic, 2-furylacrylic and sorbic acid. All these derivatives, showed the same strong indifference towards radical polymerization. Only when treated with large doses (10—30%) of initiator did they give small yields of oligomers. The structure of all these products was carefully studied by spectroscopic and other techniques. Invariably, it was... 

Recognize a simple haloalkane, alcohol, ether, phenol, aldehyde, ketone, carboxylic acid, amine, amide, or ester, given a molecular structure. 

Write the structural formula of an ester or an amide formed from the condensation reaction of a given carboxylic acid with... 

---