Laboratory‎ > ‎ Preparation of Ethylacetate

INTRODUCTION

        Ethyl acetate is the organic compound with the formula CH3CH2OC(O)CH3. This colorless liquid has a characteristic, not unpleasant smell like certain glues or nail polish removers, in which it is used. As the ester derived from ethanol and acetic acid, EtOAc, as it is commonly abbreviated, is manufactured on a large scale for use as a solvent.

        Ethyl acetate is a moderately polar solvent that has the advantages of being volatile, relatively non-toxic, and non-hygroscopic. It is a weak hydrogen bond acceptor, and only a weak donor. Ethyl acetate can dissolve up to 3% water and has a solubility of 8% in water at room temperature. At elevated temperature its miscibility with water is higher. It is unstable in the presence of strong aqueous bases and acids.

        Ethyl acetate is widely employed as a solvent for chemical reactions and for extractions. Similarly, is also present in nail varnishes and nail varnish removers and even for the decaffeination of coffee beans and tea leaves.

        Ethyl acetate is also present in confectionery, perfumes, and fruits because it confers a fruity smell, as do most esters.

        In this experiment we obtained ester( ethyl acetate) by reaction of acetic acid and alcohol.

MATERIALS

  • Round flask

  • Reflux condenser

  • Boiling chips

  • Steam bath

  • Acetic acid

  • H2SO4

  • Ethanol

PROCEDURE

        Firstly,30 mL of glacial acetic acid and 40 mL of 95% ethanol were placed into a 200 mL round flask.Then flask was shaked slowly.5 mL of concentrated H2SO4 was added slowly.The flask was connected to a water-cooled reflux condenser and boiling chips was added.Then the mixture was heated under reflux for 30 minutes on steam bath.Finally,the flask was cooled.

POSTLAB QUESTIONS

        1- Esters are organic compounds in which an organic group (symbolized by R’ in this article) replaces a hydrogen atom (or more than one) in an oxygen acid. An oxygen acid is an acid whose molecule has an -OH group from which the hydrogen (H) can dissociate as an H+ ion.

        The most common esters are the carboxylate esters, where the acid in question is a carboxylic acid. For example, if the acid is acetic acid, the ester is called an acetate. Esters may also be formed with inorganic acids; for example, dimethyl sulfate is an ester, and sometimes called “sulfuric acid, dimethyl ester”.                                                                                

        2- Reflux is a technique used in industrial and laboratory distillations. It is also used in chemistry to apply energy to reactions over an extended period of time.

        The term reflux is very widely used in industries that utilize large-scale distillation columns and fractionators such as petroleum refineries, petrochemical plants, chemical plant and natural gas processing plants.

DISCUSSION

Acetate is the ester that an organic group replaces a hydrogen atom in -OH group of acetic acid through reaction (typically condensation) with alcohols. Condensation is the reaction in which two molecules having -OH groups are joined with eliminating a water molecule from their -OH groups. They are produced by esterification reaction from acetic acid and the corresponding alcohol in the presence of strong acids like sulfuric acid. This reaction is reversible and acetate can be hydrolyzed back into alcohol and acetic acid in the presence of strong bases or strong acid, especially at elevated temperature.  The term acetate is also for the salt that one or more of the hydrogen atoms of acetic acid are replaced by one or more cations of the base, resulting in a compound containing the negative organic ion of CH3COO.  Lower acetate is a non-polar to weak polar aprotic solvent which have some solubility portion in water. Its miscibility with water gets higher at elevated temperature. Higher acetates have a low solubility in water and used as extraction solvents for fine chemicals particularly for certain antibiotics. Organic acetates are good solvents for a broad range of resins as they are miscible with almost all common organic liquids. Due to their powerful solvency, high volatility and mild odor, acetates are widely used as solvents for paints, coatings, adhesives, cellulose, plastics, fats, wood stains.  Additionally ether acetates series are also widely used as solvents. This surfactant-like structure provides the compatibility between water and a number of organic solvents, and the ability to couple unlike phases. The main products include ethyleneglycol monoethyl ether acetate, ethyleneglycol monobutyl ether acetate, and propyleneglycol monomethyl ether acetate. Aromatic acetates such as benzyl acetate are also useful solvent. Benzyl acetate has jasmine like odor. Isoamyl acetate has a similar smell to both banana and pear. Acetates have characteristic fruity odor. They are used as component of perfumes and flavorings. They are used as chemical intermediate to manufacture pharmaceuticals, synthetic flavorings, cleaners, and other organic compounds.Ethyl acetate is present in wines. It may be considered a contaminant at too high concentrations, as typically occurs when wine is exposed to air for a prolonged period. When present at too high concentration in wine, it is regarded as an off-flavour, also called “VA” (volatile acidity).

Bir cevap yazın