Fischer Esterification Sample

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An ester was synthesized during an organic reaction and identified by IR spectrometry and boiling point. Acetic acid was added to 4-methyl-2-pentanol. which was catalyzed by sulphuric acid. This produced the coveted ester and H2O. After the ester was isolated a percent output of 55. 1 % was calculated from the 0. 872 g of ester recovered. This quantitative mistake was most likely due to merchandise acquiring stuck in the setup. The boiling point of the ester was 143° C. merely one grade off from the theoretical boiling point of the ester 1. 3-dimethylbutyl. 144 ° C. The values of the major extremums on the IR spectrum besides corresponded to the theoretical values of the ester 1. 3-dimethylbutyl. Therefore. it was concluded that this was the ester formed and the experiment was a success. because even though there was mistake. this was merely in the sum of the ester. non in its individuality. Introduction

Fischer Esterification is the simplest agencies of synthesising an ester and requires the reaction of a carboxylic acid and an intoxicant. The general reaction of Fischer esterification is. CH3CO2H + ROH – CH3CO2R + H2O ( reaction 1 )

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An intoxicant ( ROH in reaction 1 ) is a functional group incorporating a H. O bond. Carboxyl acids ( CH3CO2H in reaction 1 ) are characterized by a C. O dual bond. with one intoxicant group and an alkyl or aromatic side concatenation. Esters ( CH3CO2R in reaction 1 ) are identified by a C. O dual bond and an O alkyl or aromatic group. Carboxylic esters frequently have pleasant olfactory properties and are used in nutrients and drinks to make spirits miming fruit. Depending on the ester synthesized odors such as banana. Ananas comosus. or orange can be obtained. Reaction one is a dual supplanting reaction. The carboxylic acid donates its H atom to the to the intoxicant group. which accounts for H2O as a merchandise. The ester is formed by the carboxylic acid deriving the alkyl side concatenation of the intoxicant. A contact action is added to the reaction in order to speed up the procedure. The contact action used in reaction 1 is sulphuric acid. H2SO4. The reaction besides occurs in reflux. intending it is boiled at a high temperature. besides speed uping the procedure.

The reaction of a carboxylic acid and an intoxicant. like in reaction 1. is in equilibrium. A reaction in equilibrium means the net alteration of the merchandises and reactants is zero. The equilibrium is dynamic because the reaction is still happening but the sum of reactants and merchandises is no longer altering. In order to make more ester. the reaction must be shifted to the right. the product’s side. The reaction can be shifted to the right most easy by adding more reactants. specifically an surplus of the carboxylic acid. The reaction will set to the right because of added reactant by making more merchandises. i. e. more ester. Sing that the reaction has an surplus of the carboxylic acid. the intoxicant will be the modification reactant. The sum of ester yielded will depend upon the sum of intoxicant in the reaction. The intoxicant being used in this specific Fischer esterification is 4-methyl-2-pentanol.

The specific reaction is. CH3CO2H + CH3CH ( CH3 ) CH2CH ( OH ) CH3-CH3CO2 ( CH2 ) 3CH + H2O ( reaction 2 ) Sulfuric acid is used as a contact action in reaction 2. similar to reaction 1. The reaction occurs by the carboxylic acid donating a proton in the signifier of H to the intoxicant. The O of the carboxylic acid is now able to bond with the alkyl group of the intoxicant making the ester. The reaction will happen in reflux. intending it will be boiled at a high temperature for a important sum of clip. Reflux gives the ability to insulate the ester from the other constituents of the reaction and therefore purifies the ester. The H2O is removed from the ester with the assistance of Na hydrogen carbonate. The add-on of Na hydrogen carbonate. which is soluble in H2O. will divide the aqueous bed from the organic bed and the aqueous can so be removed with a pipet. If necessary the extractor can besides be used to further divide the two beds. A concluding agency of drying the ester merchandise is the add-on of farinaceous Na sulphate.

The pureness and individuality of the merchandise can be determined through the usage of odor. IR spectrometry and runing point finding. A general thought of what the ester is can be obtained by odor. Esters can hold specific odors and if the aroma can be determined. one may hold an thought of the ester was created. IR spectrometry will place the bonds of the functional groups. The ester can be considered pure if there are no extra extremums on the IR spectrum. For illustration. if a extremum matching to an intoxicant group appeared on the IR spectrum it would intend the ester is non wholly pure. Melting point can besides be used to corroborate the individuality and how pure the concluding merchandise is. Comparison of the experimental thaw point and the literature value allows for finding of how close the experimental value is to the literature value. If the experimental value is within the scope of the literature value. the merchandise can be considered pure. Procedure:

A 10 milliliter round-bottom flask was weighed both before and after about 1. 5 milliliter of the given intoxicant. 4-methyl-2-pentanol. was added. 3 milliliter of glacial acetic acid. one boiling bit. and 2-3 beads of concentrated sulphuric acid were added to the flask in that order. The reflux setup was assembled. the solution poured in. and the assembly placed in the warming mantle for about one hr. At this clip. an Iridium of the get downing stuff was taken. After the reaction mixture was cooled. about 3 milliliters of 5 % aqueous Na hydrogen carbonate was added while stirring. The reaction mixture was so transferred to a extractor tubing and shaken smartly. After the mixture settled into two beds. the lower organic aqueous bed was removed with a pipet. The reaction mixture was so centrifuged before reiterating the old measure two extra times. A microspatula full of farinaceous Na sulphate was added. The per centum output was calculated. an IR spectrum was taken. and the boiling point was calculated of the ester that formed.

A Fischer esterification was performed. intending an ester was synthesized from a reaction between a carboxylic acid and an intoxicant. The intoxicant used was 4-methyl-2pentanol and the ensuing ester was ( 1. 3-dimethylbutyl ) ethanoate. The ester was successfully formed from the reaction and therefore the aim of the lab. to synthesise an ester. was met.

The ester was formed in a reflux setup. By puting the reaction in reflux ( boiling at a high temperature ) . the reaction is speed up and the ester was formed quicker. The reaction needed to pass a certain sum of clip in reflux to to the full finish the formation of ( 1. 3-dimethylbutyl ) ethanoate. If the reaction was non in reflux long plenty there would be residuary intoxicant that would demo up in the concluding merchandise and the maximal sum of ester would non be formed. The sum of merchandise formed is determined by the sum of intoxicant used. as it is the confining reagent.

Ester and H2O are both merchandises of the esterification. In order to mensurate the theoretical output. of the ester. the H2O must be removed from the merchandise. Water is able to be removed by using the solubility of Na hydrogen carbonate. Sodium hydrogen carbonate is polar ; therefore it is soluble in H2O. The add-on of the H2O soluble Na hydrogen carbonate causes the merchandise to divide into an aqueous bed and an organic bed. The separation of the H2O from the ester allows for remotion of the H2O with a Pasteur pipet. The aqueous bed was on the underside while the organic bed was on top. intending the organic bed was less heavy than the aqueous bed.

In order to corroborate the pureness of the concluding merchandise and to corroborate that the reaction was in reflux long plenty. IR spectrums were taken of the concluding merchandise and the boiling point of the experimental merchandise was compared to literature values. IR spectrums were taken of acetic acid and 4-methyl-2pentanol. the reactants. every bit good as the merchandise. ( 1. 3-dimethylbutyl ) ethanoate. The IR spectrum of the ester confirms the pureness and individuality of the merchandise. The spectrum contains no intoxicant extremums. corroborating that the reaction was in reflux long plenty and the reaction went to completion. The spectrum has the right extremums matching to the C. O dual bond. every bit good as the extremums for the sp3 hybridized C. O bonds. The boiling point of the formed ester was found to be 143? . The literature value of the boiling point is 144? . Comparison of the literature and experimental value of the boiling point confirm the individuality of the ester and its pureness. The boiling point signifies that all the drosss of the ester were removed and the concluding merchandise was pure ( 1. 3-dimethylbutyl ) ethanoate.

The theoretical output was calculated to be 1. 584 g and the experimental output was 0. 872 g. The percent output of the merchandise was 55. 1 % . Loss of merchandise can be contributed to residuary merchandise being left in the reflux setup. trial tubing. or spatulas. In order to minimise. merchandise being left in trial tubing. the concluding merchandise was dried with Na sulphate but if non plenty was used or if non adequate clip was allowed for drying. some merchandise would be left in trial tubing. lending to lost merchandise. Mistake can besides be found in the initial or concluding weighing’s of the stuffs. The graduated tables being used can hold incompatibilities which will give inaccurate sums of the reactants or merchandises.

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