Carboxylic acids double bonds

Potassium permanganate, KMnO. Oxidizes alkenes under neutral or acidic conditions to give carboxylic acid double-bond cleavage products (Sections 7.9). 

Carboxylic acids Double bond between carbon and oxygen plus hydroxyl attached to same carbon 0 X... 

Mammals cannot synthesize unsaturated fatty acids having double bonds further than 9 carbons from the carboxyl group. Thus, mammals can synthesize oleic acid and palmitoleic acid (double bonds at carbon 9), but not linoleic acid (double bons at carbons 9 and 12) or linolenic acid (double bonds at carbons 9,12, and 15). As a result, fatty acids such as linoleic acid and linolenic acid are called essential fatty acids because they must be present in the diet. Figure 18.33 shows how linoleic acid is converted to arachidonic acid, an important precursor to the prostaglandins and thromboxanes. 

Fatty acids are carboxylic acids with long hydrocarbon chains. The fatty acids most frequently found in nature are shown in Table 26.1. Because they are synthesized from acetate, a compound with two carbon atoms, most naturally occurring fatty acids contain an even number of carbon atoms and are unbranched. The mechanism for the biosynthesis of fatty acids is discussed in Section 19.21. Fatty acids can be saturated with hydrogen (and therefore have no carbon-carbon double bonds) or unsaturated (have carbon-carbon double bonds). Fatty acids with more than one double bond are called polyunsaturated fatty acids. Double bonds in naturally occurring unsaturated fatty acids are never conjugated—they are always separated by one methylene group. 

Remarkably, not only are both systems effective at carrying out this process, but the photoelectron transfer rate constants of 8.1 x 10 and 4.3 x 10 for 14 and 15, respectively, suggest that the carboxylic acid double hydrogen bond is more effective at transmitting the excited electron than the a-framework in 15. despite the fact that some dissociation might occur in solution. 

Fatty acids having double bonds close to the carboxyl end can be distinguished by using methods based on the intramolecular oxymercuration of alcohols derived from the acids. Double bonds which are 3t, 4c/t or 5dt can be identified in this way (Gunstone and Inglis, 1973). 

This is the case with NAD(P)H-dependent dehydrogenases, where enzymes find applications in several synthetic processes (comprising the reduction of aldehydes, ketones, carboxylic acids, double, and triple carbon-carbon bonds), aimed at the preparation of chiral enantiopure bioactive compounds and of building blocks for fine chemicals and pharmaceutical products. Moreover, dehydrogenase-catalyzed oxidation reactions are gaining increasing interest as an environmentally friendly alternative to chemical oxidation processes, especially in those cases where a defined selectivity (either stereo-, regio-, or chemoselectivity) is required as well [1]. 

However, the term saturated is often applied to compounds containing double or triple bonds which do not easily undergo addition reactions. Thus ethanoic acid is termed a saturated carboxylic acid and acetonitrile a saturated nitrile, whereas a Schiff base is considered to be unsaturated. 

Cyclopentene derivatives with carboxylic acid side-chains can be stereoselectively hydroxy-lated by the iodolactonization procedure (E.J. Corey, 1969, 1970). To the trisubstituted cyclopentene described on p. 210 a large iodine cation is added stereoselectively to the less hindered -side of the 9,10 double bond. Lactone formation occurs on the intermediate iod-onium ion specifically at C-9ot. Later the iodine is reductively removed with tri-n-butyltin hydride. The cyclopentane ring now bears all oxygen and carbon substituents in the right stereochemistry, and the carbon chains can be built starting from the C-8 and C-12 substit""" ... 

The intramolecular reaction oF allcenes with various O and N functional groups offers useful synthetic methods for heterocycles[13,14,166]. The reaction of unsaturated carboxylic acids affords lactones by either exo- or endo-cyclization depending on the positions of the double bond. The reaction of sodium salts of the 3-alkenoic acid 143 and 4-alkenoic acid 144 with Li2PdCl4 affords mostly five-membcrcd lactones in 30-40% yields[167]. Both 5-hexe-noic acid (145) and 4-hexenoic acid (146) are converted to five- or six-mem-bered lactones depending on the solvents and bases[168]. Conjugated 2,4-pentadienoic acid (147) is cyclized with Li2PdCl4 to give 2-pyrone (148) in water[i69]. 

Double bonds m the mam chain are signaled by the ending enow acid and their position IS designated by a numerical prefix Entries 6 and 7 are representative carboxylic acids that contain double bonds Double bond stereochemistry is specified by using either the cis-trans or the E-Z notation... 

Infrared IR spectroscopy is quite useful in identifying carboxylic acid derivatives The, carbonyl stretching vibration is very strong and its position is sensitive to the nature of IKT the carbonyl group In general electron donation from the substituent decreases the double bond character of the bond between carbon and oxygen and decreases the stretch mg frequency Two distinct absorptions are observed for the symmetric and antisym metric stretching vibrations of the anhydride function... 

Prostaglandins arise from unsaturated C20 carboxylic acids such as arachidonic acid (see Table 26 1) Mammals cannot biosynthesize arachidonic acid directly They obtain Imoleic acid (Table 26 1) from vegetable oils m their diet and extend the car bon chain of Imoleic acid from 18 to 20 carbons while introducing two more double bonds Lmoleic acid is said to be an essential fatty acid, forming part of the dietary requirement of mammals Animals fed on diets that are deficient m Imoleic acid grow poorly and suffer a number of other disorders some of which are reversed on feed mg them vegetable oils rich m Imoleic acid and other polyunsaturated fatty acids One function of these substances is to provide the raw materials for prostaglandin biosynthesis... 

Step 1 In the first stage of the reaction the carboxylic acid adds to one of the double bonds of DCCI to give an O acylisourea... 

Critical micelle concentration (Section 19 5) Concentration above which substances such as salts of fatty acids aggre gate to form micelles in aqueous solution Crown ether (Section 16 4) A cyclic polyether that via lon-dipole attractive forces forms stable complexes with metal 10ns Such complexes along with their accompany mg anion are soluble in nonpolar solvents C terminus (Section 27 7) The amino acid at the end of a pep tide or protein chain that has its carboxyl group intact—that IS in which the carboxyl group is not part of a peptide bond Cumulated diene (Section 10 5) Diene of the type C=C=C in which a single carbon atom participates in double bonds with two others... 

Fats and oils (Section 26 2) Tnesters of glycerol Fats are solids at room temperature oils are liquids Fatty acid (Section 26 2) Carboxylic acids obtained by hydro lysis of fats and oils Fatty acids typically have unbranched chains and contain an even number of carbon atoms in the range of 12-20 carbons They may include one or more double bonds... 

Zaitsevs rule (Section 5 10) When two or more alkenes are capable of being formed by an elimination reaction the one with the more highly substituted double bond (the more sta ble alkene) is the major product Zwitterion (Section 27 3) The form in which neutral amino acids actually exist The ammo group is in its protonated form and the carboxyl group is present as a carboxylate... 

When side chains of two or more different kinds are attached to a cyclic component, only the senior side chain is named by the conjunctive method. The remaining side chains are named as prefixes. Likewise, when there is a choice of cyclic component, the senior is chosen. Benzene derivatives may be named by the conjunctive method only when two or more identical side chains are present. Trivial names for oxo carboxylic acids may be used for the acyclic component. If the cyclic and acyclic components are joined by a double bond, the locants of this bond are placed as superscripts to a Greek capital delta that is inserted between the two names. The locant for the cyclic component precedes that for the acyclic component, e.g., indene-A - -acetic acid. 

Polarography is used extensively for the analysis of metal ions and inorganic anions, such as lOg and NOg. Organic compounds containing easily reducible or oxidizable functional groups also can be studied polarographically. Functional groups that have been used include carbonyls, carboxylic acids, and carbon-carbon double bonds. 

The presence of the unsaturated substituent along this polyester backbone gives this polymer crosslinking possibilities through a secondary reaction of the double bond. These polymers are used in paints, varnishes, and lacquers, where the ultimate cross-linked product results from the oxidation of the double bond as the coating cures. A cross-linked polyester could also result from reaction (5.J) without the unsaturated carboxylic acid, but the latter would produce a gel in which the entire reaction mass solidified and is not as well suited to coatings applications as the polymer that crosslinks upon drying. ... 

Maleic and fiimaric acids have physical properties that differ due to the cis and trans configurations about the double bond. Aqueous dissociation constants and solubiUties of the two acids show variations attributable to geometric isomer effects. X-ray diffraction results for maleic acid (16) reveal an intramolecular hydrogen bond that accounts for both the ease of removal of the first carboxyl proton and the smaller dissociation constant for maleic acid compared to fumaric acid. Maleic acid isomerizes to fumaric acid with a derived heat of isomerization of —22.7 kJ/mol (—5.43 kcal/mol) (10). The activation energy for the conversion of maleic to fumaric acid is 66.1 kJ/mol (15.8 kcal/mol) (24). 

The chemical reactivity of sorbic acid is determined by the conjugated double bonds and the carboxyl group. 

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