Caiboxylates

ANTIBACTERIALAGENTSSYNTHETIC - NITHOFURANS] (Vol2) 2-Acetoxy-9,10-dimethoxyl,3,4,6,7,llb-hexahydro-2FIben2o[a]qumoli2in-3-caiboxylic acid diethylamide [63-12-7]... 

Caiboxylates Caiboxylate salts Caiboxylate soaps Caiboxylation... 

AMINES-LOWERALIPHATIC AMINES] (Vol 2) b-Diethylammoethylanude. See Butoxyquinoline-4-caiboxylic acid. 

Substitution of caiboxylic groups by halogen via Ag saHs (Hunsdiecker, Borodin) or Hg salts (Cnstol-Rrth)... 

KOLBE - SCHMIDT Salicylic Acid Synthesis Caiboxylation (usually ortho) of phenols. Industrial method to obtain salicylic acid derivatives... 

The preparation of esters can be classified into two main categories (1) carboxy-late activation with a good leaving group and (2) nucleophilic displacement of a caiboxylate on an alkyl halide or sulfonate. The latter approach is generally not suitable for the preparation of esters if the halide or tosylate is sterically hindered, but there has been some success with simple secondaiy halides and tosylates (ROTs, DMF, K2CO3, 69-93% yield). ... 

The most common O- and N-acylation procedures use acylating agents that are more reactive than caiboxylic acids or their esters. Carboxylic acid chlorides and anhydrides react rapidly with most unhindered hydroxy and amino groups to give esters and amides, respectively ... 

The general mechanisms are well established. The nucleophihc species undergoes addition at the earbonyl group, followed by elimination of the halide or caiboxylate... 

As long as the nucleophilic atom is the same, the more basic the nucleophile, the more reactive it is. An alkoxide ion (RO ) is more basic and more nucleophilic than a caiboxylate ion (RC02 ). 

Caiboxylic acids aie exceedingly difficult to reduce. Acetic acid, for example, is often used as a solvent in catalytic hydrogenations because it is inert under the reaction conditions. A very powerful reducing agent is requued to convert a caiboxylic acid to a pri-maiy alcohol. Lithium aluminum hydride is that reducing agent. 

Sodium borohydride is not neaiTy as potent a hydride donor as lithium aluminum hydride and does not reduce caiboxylic acids. 

Esters aie more easily reduced than caiboxylic acids. Two alcohols aie fonned from each ester molecule. The acyl group of the ester is cleaved, giving a primary alcohol. 

Electron delocalization in caiboxylate ions is nicely illustrated with the aid of electrostatic potential maps. As Figure 19.4 shows, the electrostatic potential is different for the two different oxygens of acetic acid, but is the same for the two equivalent oxygens of acetate ion. 

For many years, resonance in caiboxylate ions was emphasized when explaining the acidity of carboxylic acids. Recently, however, it has been suggested that the inductive effect of the carbonyl group may be more important. It seems clear that, even though then- relative contributions may be a matter of debate, both play major roles. 

Metal caiboxylates are ionic, and when the molecular weight isn t too high, the sodium and potassium salts of carboxylic acids are soluble in water. Carboxylic acids therefore may be extracted from ether solutions into aqueous sodium or potassium hydroxide. 

Caiboxylate groups are hydrophilic ( water-loving ) and tend to confer water solubility on species that contain them. Long hydrocarbon chains are lipophilic ( fat-loving ) and tend to associate with other hydrocarbon chains. Sodium stearate is an exfflnple of an amphiphilic substance both hydrophilic and lipophilic groups occur within the sfflne molecule. 

Detergents are designed to be effective in hard water, meaning water containing calcium salts that fonn insoluble calcium caiboxylates with soaps. These precipitates rob the soap of its cleansing power and fonn an unpleasant scum. The calcium salts of synthetic detergents such as sodium lauryl sulfate, however, are soluble and retain then- micelle-fonning ability even in hard water. 

Overall, the caiboxylation of Grignard reagents transfonns an alkyl or aryl halide to a car boxylic acid in which the car bon skeleton has been extended by one car bon atom. 

The answer to this question is critical because it tells us whether the caibon-oxygen bond of the alcohol or a caibon-oxygen of the caiboxylic acid is broken during esterification. 

The thennal decarboxylation of malonic acid derivatives is the last step in a multistep synthesis of caiboxylic acids known as the malonic ester synthesis. This synthetic method will be described in Section 21.7. 

Notice that the caiboxyl group that stays behind during the decarboxylation of malonic acid has a hydroxyl function that is not directly involved in the process. Compounds that have substituents other than hydroxyl groups at this position undergo an analogous decarboxylation. 

Two processes that are consistent with second-order kinetics both involve hydroxide ion as a nucleophile but differ in the site of nucleophilic attack. One of these processes is an Sn2 reaction in which hydroxide displaces caiboxylate from the alkyl group of the ester. 

In base the carboxylic acid is deprotonated, giving a caiboxylate ion ... 

Section 20.17 Like ester hydrolysis, fflnide hydrolysis can be achieved in either aqueous acid or aqueous base. The process is ineversible in both media. In base, the carboxylic acid is converted to the caiboxylate anion in acid, the fflnine is protonated to an ammonium ion ... 

Phenols that bear strongly electron-withdrawing substituents usually give low yields of caiboxylated products their- derived phenoxide anions are less basic, and the equilibrium constants for then- caiboxylation are smaller. 

With p fa s of approximately 10, phenols aie stronger acids than alcohols, but weaker than caiboxylic acids. They aie converted quantitatively to phenoxide anions on treatment with aqueous sodium hydroxide. 

A key biochemical reaction of amino acids is their conversion to peptides, polypeptides, and proteins. In all these substances fflnino acids aie linked together by amide bonds. The amide bond between the fflnino group of one amino acid and the caiboxyl of another is called a peptide bond. Alanylglycine is a representative dipeptide. 

By agreement, peptide structures aie written so that the ffluino group (as H3N— or H2N—) is at the left and the caiboxyl group (as CO2 or COiFl) is at the right. The... 

Step 1 The Boc-protected amino acid is anchored to the resin. Nucleophilic substitution of the benzylic chloride by the caiboxylate anion gives an ester. 

If a substituted aromatic hydrocarbon is used, the ketone gioLip then enteis the paia-position, or, if this is occupied, the oitho-position. Substituted aromatic acid chlorides may. also be used, and if the acid is dibasic and has two caiboxyl chloiide gioups, two molecules of the aromatic hydiocaibon may be. attached. If phosgene is used with two molecules of benzene, benzophenone is obtained. 

ATP is activated by coordination to magnesium ion, and nucleophilic addition of a fatty acid caiboxylate to phosphorus then yields a pentacoordinate intermediate. . ... 

T.L. Boggs et al, AIAA J 8 (2), 370-72 (1970) CA 72, 113371 (1970) Scanning electron microscopy is used to study the surface structure of solid proplnts, prepd from AP (1) and polyurethane or caiboxylated polybutadiene. Polyurethane proplnts are self-extinguish-ing at high pressure due to the flow of molten binder over I crystals. I crystals formed a thin surface melt with gas liberation in the molten phase... 

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