Acetates ethyl aceto

It follows therefore that ethyl malonate can be used (just as ethyl aceto- acetate) to prepare any mono or di-substituted acetic acid the limitations are identical, namely the substituents must necessarily be alkyl groups (or aryl-alkyl groups such as CjHjCHj), and tri-substituted acetic acids cannot be prepared. Ethyl malonate undergoes no reaction equivalent to the ketonic hydrolysis of ethyl acetoacetate, and the concentration of the alkali used for the hydrolysis is therefore not important. 

The aldol reaction is a carbonyl condensation that occurs between two aldehyde or ketone molecules. Aldol reactions are reversible, leading first to a /3-hydroxy aldehyde or ketone and then to an cr,/6-unsaturated product. Mixed aldol condensations between two different aldehydes or ketones generally give a mixture of all four possible products. A mixed reaction can be successful, however, if one of the two partners is an unusually good donor (ethyl aceto-acetate, for instance) or if it can act only as an acceptor (formaldehyde and benzaldehyde, for instance). Intramolecular aldol condensations of 1,4- and 1,5-diketones are also successful and provide a good way to make five-and six-inembered rings. 

The addition of active methylene compounds (ethyl malonate, ethyl aceto-acetate, ethyl plienylacetate, nitromethane, acrylonitrile, etc.) to the ap-double bond of a conjugated unsaturated ketone, ester or nitrile in the presence of a basic cataljst (s ium ethoxide, piperidine, diethylamiue, etc.) is known as the Michael reaction or Michael addition. The reaction may be illustrated by the addition of ethyl malonate to ethyl fumarate in the presence of sodium ethoxide hydrolysis and decarboxylation of the addendum (ethyl propane-1 1 2 3-tetracarboxylate) yields tricarballylic acid ... 

When the second component is an a,/i-unsaturated aldehyde, somewhat different results are reported. Thus crotonaldehyde reacts with ethyl aceto-acetate to give 4/f-pyran 65,86 whereas 3-substituted crotonaldehydes with 1,3-cyclohexadiones afford 67 to 80% of the corresponding 2//-pyrans 66. ° The reaction with 1,3-pentanedione proceeded also in the second way,110 but the former cyclization with ethyl benzoylacetate gave no pyran.8 If asymmetrically substituted 1,3-cyclohexadienone components are used, the formation of mixtures of isomeric 2//-pyrans may be expected, as shown in Eq. (2)."°... 

There have been some further examples of the use of the Conrad-Limpach reaction on substituted 5-aminoquinolines for the synthesis of 4-hydroxy-1,7-phenanthrolines, although the products (see Section IV,F,1) should properly be designated as phenanthrolinones.169 Hot diphenyl ether is often employed as the medium for ring closure.170 Ethyl trifluoro-acetoacetate has been used successfully in place of ethyl aceto-acetate, and this variation has allowed entry to 2-trifluoromethyl-substituted 1,7-phenanthrolines.96 Extensions of the Conrad-Limpach type of synthesis starting with m-phenylenediamine (20) and utilizing diethyl ethoxymethylene malonate or ethyl ethoxalylacetate, reagents frequently used in quinoline syntheses, have afforded, after hydrolysis,... 

Figure 18-6 Proton nmr spectrum of ethyl 3-oxobutanoate (ethyl aceto-acetate) at 60 MHz calibrations are relative to tetramethylsilane at 0.00 ppm. Peaks marked a, b, and c are assigned, respectively, to the OH, alkenyl, and methyl protons of the enol form, whereas peaks d and e are assigned to the a-CH2 and methyl protons, respectively, of the ketoform. The quartet of lines at 4.2 ppm and the triplet at 1.3 ppm result from the ethyl groups of both keto and enol forms.

Reaction XLIV. (b) Condensation of Alkyl and Aryl Halogen Compounds with the Sodio- and other Metallo-derivatives of Ethyl Aceto-acetate and its Homolognes. (A., 186, 214 201, 143 213, 143.)—Like malonic ester, acetoacetic ester contains two 1 3-carbonyl groups with a methylene group in position 2. It is only to be expected then that it yields with metallic sodium or sodium alcoholate sodio-derivatives from which mono- and di-, alkyl and aryl homologues can be obtained by treatment with a suitable halide, including halogen esters. Acetoacetic acid... 

By reacting 2-amino-3,4,5,6-tetrahydropyridine (118) with ethyl aceto-acetate or ethyl benzoyl acetate in pyridine, Wamhofif and Lichtenthaler178 obtained 1 4 equilibrium mixtures of the tautomers 119 and 120. 

The behaviour of sodium ethyl aceto-acetate towards chloracetic ester and chloroformic ester respectively, indicates that the compound exhibits dynamic isomerism because in the first reaction it behaves as though sodium were directly united to carbon, and in the second reaction as though the sodium were united to oxygen ... 

This ion reacts as a base with ethyl aceto-acetate to regenerate another enolate ion, so only a catalytic amount of base is needed for the reaction. 

Methyl isoxazolone is obtained by reaction between ethyl aceto acetate and nitrous acid... 

An alternative route is the reaction between ethyl aceto acetate with an amidine or with guanidine sulfate (or hydrochloride)... 

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