Ethyl ethanoate hydrolysis

In Investigation 1-A in Chapter 1, you carried out a condensation reaction to produce an ester called ethyl ethanoate. In this chapter, you learned about the reverse reaction hydrolysis. 

The Hammett equation also fails for open-chain aliphatic derivatives. For example, there is no simple linear relationship between log K for a scries of substituted ethanoic acids (RCH2C02H) and log k for the hydrolysis rates of similarly substituted ethyl ethanoates (RCH2C02C2H5). The freedom of motion available to a flexible open-chain compound permits a much wider range of variations in steric effects than for meta- and para-substituted aromatic compounds. 

The base hydrolysis of ethyl ethanoate was studied at 25 °C in a conductance apparatus. Both reactants were at an initial concentration 5.00 x 10 3mol dm 3, and the conductivity, k, was found at various times. 

This can again be illustrated by a base hydrolysis of an ester, e.g. ethyl ethanoate, CH3COOC2H5. If Ca2+ or Ba2+ salts are added to aqueous OH solution, the ion... 

The opposite process to ester formation is the formation of an acid and an alcohol from the ester by hydrolysis (i.e. the action of water) in the presence of either an alkali or acid (eg. the hydrolysis of ethyl ethanoate in Figure 7.1.13). 

In many reactions, it is possible for the products to react in such a manner that the starting materials can be re-formed. This is the case when a general ester is hydrolysed under acid conditions, e.g. the hydrolysis of ethyl ethanoate ... 

In autocatalysis, one of the products of the reaction itself acts as a catalyst. In this type of reaction the reaction rate increases with time to a maximum and finally slows down. For example, in the hydrolysis of ethyl ethanoate, the ethanoic acid produced catalyzes the reaction. 

Table 3 Rate data for the hydrolysis of ethyl ethanoate. Tabulated are values for rate constant, enthalpy change and reaction order calculated from calorimetric data...

For some reactions small samples of the reaction mixture can be removed and then analysed by performing an acid-base or redox titration (Chapter 1) with a standard solution (Figure 6.39). This will allow the amount of a particular reactant remaining to be determined. The small sample of the reaction mixture is usually added to a large volume of cold water so the reaction is stopped, or at least slowed down. It suffers from being a destructive technique. This method can be used to measure the rate of saponification (alkaline hydrolysis) of ethyl ethanoate (Chapter 1) ... 

The equilibrium constant for the acid hydrolysis of ethyl ethanoate can be found by experiment. CHjCOOCjHsd) + HjOd) CHjCOOHd) + CjHjOHd)... 

The acid-catalysed hydrolysis of ethyl ethanoate can be achieved by mixing the ester with dilute hydrochloric acid. 

The hydrolysis reaction of ethyl ethanoate in basic solution occurs in three steps. How many transition states are there How many intermediates form in this reaction ... 

How do the equilibrium constant expressions differ for the hydrolysis reaction of ethyl ethanoate (written right to left) and the esterification reaction of ethanol and ethanoic acid (written left to right) What is the equilibrium constant for the hydrolysis reaction ... 

Refluxing with an acid simply reverses the preparation of the ester from an alcohol and a carboxylic acid. The acid catalyses the reaction. The reaction is reversible and an equilibrium mixture is established. In acid hydrolysis, there are always both reactants (ester + water) and products (carboxylic acid + alcohol) present after the reaction. The equation for the acid hydrolysis of the ester ethyl ethanoate is ... 

However, when an ester is refluxed with an alkali (a soluble base), such as aqueous sodium hydroxide, it is fully hydrolysed. Unlike acid hydrolysis, this is not a reversible reaction, so all the ester present can be broken down by excess alkali. An alcohol and the sodium salt of the carboxylic acid are formed. The equation for the base hydrolysis of ethyl ethanoate is ... 

Cyclopropane derivatives can be prepared by several methods. Michael addition of the enolate of ethyl chloroacetate to ethyl acrylate generated the cyclopropane ring in 7.223 via addition to form a carbanion and internal expulsion of the chlorine moietyl Manipulation of functional groups allowed selective reduction to 7.224 and conversion to 7.225 (as a mixture of cis- and trans-isomers). Rearrangement and hydrolysis led to c/s-2-(2-amino-l-cyclopropyl)ethanoic acid, 7,226. The analogous cyclobutane derivatives were also prepared by a similar route. 

Ethano-bridged phthalate ester 56 was obtained by the DA reaction in good yield and was converted to the BCOD-fiised triester 57a, the t-butyl ester group of which was removed by treatment with TFA (Scheme 15.10) [63]. The DA reaction of tosylacetylene (5a) and 2-methoxy-l,3-cyclohexadiene proceeded smoothly to afford a diastereomeric mixture (5 1) of bicyclo[2.2.2]octenone 58 in 73% yield after hydrolysis by silica gel [64]. Diastereomeric 58 was quantitatively converted to dithiolane, which was subject to the ring expansion reaction with tellurium tetrachloride [65]. Dihydro-1,4-dithiin 59 was obtained in 74% yield. The Barton-Zard reaction of 59 with ethyl isocyanoacetate afforded pyrrole-carboxylate 60a (77% yield), which was transformed to both a-hydroxymethylpyrrole 60b and a-firee pyrrole 60c in good yields. 

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