Isopentyl acetate preparation

Calculation of the theoretical yield and percentage yield can be illustrated using hypothetical data for the isopentyl acetate preparation ... 

Isopentyl Acetate Preparation Using a Monomode Microwave Apparatus... 

Natural fruit aromas are mixtures of certain organic compounds and esters. Synthetic aromas prepared in laboratories are simple mixtures of these same esters and organic compounds. They are used in perfumes, foods and drinks to give taste and pleasant smells. Ethyl acetate, for example, is a colorless liquid with an apple flavour it is known as apple ester and is used in perfumery as a fruit essence. Propyl acetate has the smell of pears, isopentyl acetate that of bananas and ethyl butyrate smells of pineapples. All are colorless liquids. Higher molar mass esters are odorless. 

The isoamylacetate(lAA)(also known at isopentyl acetate) stock solutionis prepared by adding 1 ml of pure lAA to 800 ml of odor-free water in a 1 liter jar, closing the lid, and shaking for 30 seconds. A new solution shall be prepared at least weekly. 

In this experiment you will prepare an ester, isopentyl acetate. This ester is often referred to as banana oil because it has the familiar odor of this fruit. 

Isopentyl acetate is prepared by the direct esterification of acetic acid with isopentyl alcohol. Because the equilibrium does not favor the formation of the ester, it must be shifted to the right, in favor of the product, by using an excess of one of the starting materials. Acetic acid is used in excess because it is less expensive than isopentyl alcohol and more easily removed from the reaction mixture. 

In this experiment, we prepare an ester from acetic acid and a C-4 or a C-5 alcohol. This experiment is a conventional-scale preparation, but it is similar to the microscale preparation of isopentyl acetate, which is described in Experiment 14. However, for the experiment, either your instructor will assign, or you will pick, one of the following C-4 or C-5 alcohols to react with acetic acid ... 

For experiments in which a compound is synthesized from other reagents, that is, preparative experiments, it is essential to know the main reaction. To perform sfoichiomefric calculations, you should balance the equation for the main reaction. Therefore, before you begin the experiment, your notebook should contain the balanced equation for the pertinent reaction. Using the preparation of isopentyl acetate, or banana oil, as an example, you should write the following ... 

The ratio here is the stoichiometric ratio of product to limiting reagent. In preparing isopentyl acetate, that ratio is 1 1. One mole of isopentyl alcohol, under ideal circumstances, should yield 1 mole of isopentyl acetate. 

The first of these pathways, known as Fischer esterification, is the method used for the preparation of efhyl laurate in Experiment [8A] and of isopentyl acetate in Experiment [8B]. A modem variation of the Fischer esterification is used in Experiment [8C].The development of this esterification reaction represents just one of a number of major discoveries in organic chemistry by Emil Fischer. 

Concentrated sulfuric acid is used as a catalyst for the esterification of acetic acid in the preparation of isopentyl acetate. Why is the sulfuric acid needed if another acid, acetic acid, is already present ... 

A hypothetical biosynthetic sequence has been proposed for the 3-alkyl-2,6-dimethylpyrazines (482) from various species of Odontomachus ants, as shown in Scheme 65. The acyloin (507), prepared by condensation of the pyruvate with active acetate, or the derived dione (508) may condense with the amide (509) of alanine, ultimately giving the 3-alkyl-2,6-dimethylpyrazines (482) (141). A separate biogenesis is envisaged for the 3-alkyl-2,5-dimethylpyrazines (481) such as 3-isopentyl-2,5-dimethyl (20h) and 2,5-dimethyl-3-styrylpyrazines (20j,... 

The most frequently used method for the preparation of 1,2,4,5-tetrazines 2 is the oxidation of dihvdro-1,2,4,5-tetrazines 1 with nitrous acid, iron(III) chloride, nitric acid, or other oxidizing agents, such as chlorine or bromine, hydrogen peroxide, isopentyl nitrite or lead(IV) acetate. 

When benzoin phenylhydrazone is heated for 2 hours in glacial acetic acid, a 77% yield of benzil is obtained,611 the phenylhydrazine formed acting as dehydrogenating agent on the secondary hydroxyl group. Oximes can be cleaved in a very mild reaction by nitrous acid or isopentyl nitrite in the cold, these methods being especially indicated for isolation of sensitive aldehydes for instance, Mannich and Budde prepared succindialdehyde as follows 612... 

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