Acetic acid malonic ester synthesis

The malonic ester synthesis makes substituted derivatives of acetic acid. Malonic ester (diethyl malonate) is alkylated or acylated on the more acidic carbon that is a to both carbonyl groups, and the resulting derivative is hydrolyzed and allowed to decarboxylate. 

By performing two successive alkylation steps the malonic ester synthesis can be applied to the synthesis of a a disubstituted derivatives of acetic acid... 

The synthetic importance of the malonic ester synthesis follows from the fact that the substituted malonic ester can easily be hydrolyzed, and subsequently decarboxylates to yield a substituted acetic acid 9. This route to substituted acetic acids is an important method in organic synthesis ... 

Monoalkylated and dialkylated acetic acids can be prepared by the malonic ester synthesis, but trialkylated acetic acids (R3CCO2H) can t be prepared. Explain. 

Malonic esters have two ester groups, each of which may react as in the acetoacetic ester synthesis due to their similar structure (see the preceding section). The malonic ester synthesis provides a method for preparing a substituted acetic acid. Figure 15-14 shows the structure of one type of malonic ester. Figure 15-15 outlines the basic malonic ester synthesis. May repeat in that figure refers to the reaction with a second molecule of RX (or R X). 

MALONIC ESTER SYNTHESIS OF R-SUBSTITUTED ACETIC ACIDS,... 

Malonic Ester Synthesis of Substituted Acetic Acids... 

Fig. 13.36. Malonic ester synthesis of altylated acetic acids I preparation of alkylated malonic esters.

Fig. 13.37. Malonic ester synthesis of alkylated acetic acids II hydrolysis and decarboxylation of the all lated malonic ester.

The malonic ester synthesis is similar to the acetoacetic ester synthesis. It begins with deprotonation of diethyl malonate (pKa = 11) to produce an enolate anion that is the synthetic equivalent of the enolate anion derived from acetic acid ... 

Both acidic H atoms of a malonic ester can be replaced by alkyl groups. These dialky-lated malonic esters are formed by successively removing the acidic protons with sodium alkoxide and treatment of the enolates with an alkylating reagent. The subsequent hydrolysis and decarboxylation of these dialkylated malonic esters affords a,a-dialkylated acetic acids as another class of products accessible via the malonic ester synthesis. 

Malonic ester synthesis (makes substituted acetic acids Chapter 22)... 

The product of a malonic ester synthesis is a substituted acetic acid, with the substituent being the group used to alkylate malonic ester. In effect, the second carboxyl group is temporary, allowing the ester to be easily deprotonated and alkylated. Hydrolysis and decarboxylation remove the temporary carboxyl group, leaving the substituted acetic acid. 

Show how the malonic ester synthesis makes substituted acetic acids, and how the acetoacetic ester synthesis makes substituted acetones. Give mechanisms for these reactions. 

One of the best methods of amino acid synthesis is a combination of the Gabriel synthesis of amines (Section 19-20) with the malonic ester synthesis of carboxylic acids (Section 22-16). The conventional malonic ester synthesis involves alkylation of diethyl malonate, followed by hydrolysis and decarboxylation to give an alkylated acetic acid. 

MALONIC ESTER SYNTHESIS OF R-SUBSTITUTED ACETIC ACIDS, RCH2COOH OR R(R ) CHCOOH (R could R)... 

The malonic ester synthesis converts a primary or secondary alkyl halide into a carboxylic acid with two more carbons (a substituted acetic acid). Identify the component that originates from malonic ester (the acid component). The rest of the molecule comes from the alkyl halide, which should be primary or methyl. 

Anhydrides—Continued reduction to alcohols, 155 reduction to lactones, 535 Arenes, see Hydrocarbons, aromatic Amdt-Eistert reaction, 433, 487, 573 Aryl esters. Fries rearrangement, 344 hydrolysis, 169 preparation, 169 Aryl halides, see Halides Atyloxy acids, preparation, by aceto-acetic ester synthesis, 430 by malonic ester synthesis, 429 from atyloxy alcohols, 419 from atyloxy cyanides, 414 preparations listed in table 48, 460 Aryloxy acyl halides, preparation, 547 preparations listed in table 61, 553 Aryloxy esters, preparations listed in table 55, 516... 

From Aceto-acetic Ester.—Glutaric acid may also be made by either the aceto-acetic ester synthesis or by the malonic ester synthesis as follows,... 

A malonic ester synthesis yields an acetic acid in which one or two hydrogens have been replaced by alkyl groups. 

In planning a malonic ester synthesis, our problem is to select the proper alkyl halide or halides to do this, we have only to look at the structure of the acid we want. Isocaproic acid, for example, (CH3)2CHCH2CH2COOH, can be considered as acetic acid in which one hydrogen has been replaced by an isobutyl group. To prepare this acid by the malonic ester synthesis, we would have to use isobutyl bromide as the alkylating agent ... 

With only a few exceptions, the fatty acids are all straight-chain compounds, ranging from three to eighteen carbons except for the C3 and C5 compounds, only acids containing an even number of carbons are present in substantial amounts. As we shall see in Sec. 37.6, these even numbers are a natural result of the biosynthesis of fats the molecules are built up two carbons at a time from acetate units, in steps that closely resemble the malonic ester synthesis of the organic chemist (Sec. 26.2). 

Certain acid derivatives are capable of reactions involving intermediate carbanions. The malonic ester synthesis is used to synthesize substituted acetic acids. The reaction involves abstraction of... 

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