Synthesis of Esters from Alcohol - Essay Example

Ethanol + Propanoic acid Ethyl propionate + Water C2H5OH (aq) + C2H5CO2H (aq) C2H5CO2C2H5 (aq) + H2O (l)The esterification equilibrium is displaced towards ester formation by use of an acid or large excess of alcohol. Additionally, the esterification reaction can be displaced by the removal of water using a dehydrating agent e.g. sulphuric acid or distilling off the water. Esters can as well be prepared from alcohols with acid anhydrides and acyl halides.

The reverse reaction of esterification is called hydrolysis. Esterification cannot be catalyzed by a base but hydrolysis can be catalyzed by OH- ions (Daintith 85). Spectroscopic techniques typically involve the interaction of some form of electromagnetic energy with molecules to generate a spectrum that may be easily translated to disclose the incidence of distinctive groups and structural features. They are regularly used to authoritatively characterize the chemical, physical and specific structural attributes of an organic molecule.

They are mainly efficient when analyzing unadulterated compounds. They include Afra-Red (IR) spectroscopy- a technique for observing distinctive bending and stretching frequencies of bonds. The spectra of regular organic functional groups have characteristic Infra-Red light absorption ranges that may be used to identify functional groups in an unidentified organic compound. Additionally, the fingerprint region of an IR spectrum usually provides a distinctive pattern for an organic molecule.

This pattern can be used for identifying an organic compound by comparing it with a known sample (Fox and James 209). Nuclear Magnetic Resonance-a technique that identifies the nuclear spin flipping provoked in the radio frequency array of a molecule placed in a high magnetic field. Because 1H, as well as 13C, are magnetically vigorous nuclei. NMR spectroscopy may offer crucial structural information about organic molecules. Information acquired from H-NMR and C-NMR is corresponding. In H-NMR: the chemical shifts, integration, and multiplicity of signals afford crucial information on the type of proton, the number of protons liable for the observed signal as well as several nearest neighbors.

In C-NMR: Each distinctive carbon generates a distinct signal. The chemical shifts of these signals can be calculated with substantial accuracy (Fox and James 208).In Gas chromatography, the mixture being evaluated is passed through an exceptionally long column i.e. either covered with a liquid adsorbent or packed with solid support. An inert gas acts as a carrier to move the organic molecules through the column. In chromatography, the time required for the elution of a preferred compound is directly related to the degree of the compound’s absorption in the stationary phase.

The retention time is thus an indicator of the size and polarity of the given molecule. Chromatography can be used not only as a purification technique but also as an analytical method for characterizing mixtures as retention times are typical for individual compounds (Fox and James 208).