Abstraction: The aim of this experiment is to expeditiously execute a fischer esterification of 1-Hexanol to organize H2O and hexyl ethanoate. and to corroborate the esterification with a atomic magnetic resonance ( NMR ) spectrometry. It was found that 0. 3963 grams hexyl ethanoate was formed with a percent output of 33. 2 % . The merchandise was confirmed utilizing NMR. IR. and boiling point verification.
Backround:
A Fischer Esterification is the formation of an ester and H2O from intoxicant and an acid. More specifically it is a nucleophillic acyl permutation reaction carried out under acidic conditions. Carboxyl acids entirely are non reactive plenty to be attacked by impersonal intoxicants. but they can be made much more reactive in the presence of a strong acid. such as sulphuric acid or hydrochloric acid. The mineral acid protonates the carbonyl group O atom and gives the carboxylic acid a positive charge. Now positively charged. the carboxylic acid is much more reactive toward a nucleophillic onslaught by the intoxicant.
NMR ( Nuclear Magnetic Resonance ) spectrometry is a technique used to find the existent 3-D image of a molecule. This spectroscopy uses atoms that have atomic magnetic minutes such as isotope-1 Hydrogen and isotope-13 Carbon atoms. The karyon of NMR-active atoms have one of two atomic spin provinces. either ( +1/2 or -1/2 ) . These atoms when placed in a magnetic field are either whirling with the +1/2 magnetic field or against it ( -1/2 spin ) . A little bulk of the karyon are aligned with the magnetic field. because this spin orientation constitutes a somewhat lower energy spin province. If radio frequence moving ridges of the appropriate energy are supplied. karyons aligned with this field can absorb this radiation and change by reversal their spin and now oppose the applied magnetic field. The frequence of radiation needed to bring on spin transition is a direct map with the strength of the magnetic field. This sum of energy that is needed to bring on the alteration in spin must hold a frequence that matches its angular precessional frequence. This is called a resonance status and this is what is diagrammatically interpreted on a NMR printout.
Objective and Materials:
The stuffs for this experiment is listed on page 59-64 ( Organic Chemistry research lab Manual. Haden/McNeil. 2003-04 )
Procedure:
The process for this experiment is listed on page 59-64
( Organic Chemistry research lab Manual. Haden/McNeil. 2003-04 )
Datas:
All information is in research lab notebook
Calculations:
The followers is a computation for theoretical output of gms of a 1:1 mole ratio:
Output ( g ) = ( get downing stuff ( g ) ) * ( molecular weight of get downing stuff ( mol/g ) ) *
( 1 mol merchandise / 1 mol of reactant ) * ( molecular weight of merchandise ( g/mol )
The followers is a sample computation for output of methyl stearate from methyl oleate:
1. 195g C6OH14 = ( 0. 8466g C6OH14 * 1 mol C6OH14 ) * ( 1mol C8O2H16 ) *
1mol C6OH14 1 mol C6OH14
( 297. 48g C8O2H16 )
1 mol C8O2H16
The followers is a computation to happen percent recovery:
% recovery = weight of the pure sample * 100
Weight of theoretical merchandise
The followers is a sample computation for output of hexyl ethanoate:
33. 2 % recovery = 0. 39631 ( g ) / 1. 195 ( g ) * 100
Consequences:
The followers is a chart of boiling points. per centum outputs. and merchandise weight:
SubstanceBoiling Point ( C ) Text Boiling Point ( K ) % Yield ( g ) Weight ( g )
Hexyl acetate464833. 20. 39631
-Note that the merchandise smelt like vanilla and bananas
-NMR printout is interpreted and attached to the dorsum of study.
-IR printout is interpreted and attached to the dorsum of study.
Discussion:
The aim of this experiment was to expeditiously execute a fischer esterification of 1-Hexanol to organize H2O and hexyl ethanoate. and to corroborate the esterification with a atomic magnetic resonance ( NMR ) spectrometry. It was found that 0. 3963 grams hexyl ethanoate was formed with a percent output of 33. 2 % . The merchandise was confirmed utilizing NMR. IR. and boiling point verification 46 grades Celcius.
The mechanism for this specific reaction is as follows:
First the protonation of a carbonyl O activates the carboxylic acid toward nucleophillic onslaught by intoxicant. giving a tetrahedral intermediate. Transportation of a proton from one O atom to another outputs a 2nd tetrahedral intermediate and converts the OH group into a good departure group. Loss of a proton and ejection of H2O regenerates the acerb accelerator and gives the ester merchandise.
This reaction is a nucleophillic acyl-substitution carried out under acidic conditions of sulphuric acid. The intoxicant used was 1-Hexanol which limits the ester to a side hexyl concatenation.
A figure of mistakes could hold occurred in this experiment which caused it excessively fail. First. if non adequate sulphuric acid was used. protonation of the carbonyl group on the carboxylic acid would be hard to obtain. This in bend would take to a low per centum output of the concluding ester merchandise. Second. if the temperature was excessively high in heating the mixture. reflux would non happen. That is to state the dissolver would non boil and so recondense in the reflux capacitor. This would do more the ethyl ethanoate to boil out as it forms. Third. if the get downing stuff or finished merchandise were spilled when being weighed the per centum output would be wrong.
To acquire better consequences in this experiment would merely be to make as many tests as it takes until the consequences show a higher percent output. By making this one could take down the mistake per centum and see what the existent sum of Hexyl acetate that can be produced if one was hiting for high output.
