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Determining the identity of an organic unknown

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Introduction

Assessed practical Debbie Siobhan Warner November 2002 Determining the identity of an organic unknown When supplied with a organic unknown there are many ways of determining its identity and it is important to use as much information as can be gained to work out the identity of an unknown as many are very similar in physical properties, chemical properties and/or chemical make up. In this experiment I will be using a flow chart to identify the functional group that the unknowns contain, and once I have suggested this I will then use spectra given to me to determine what the identity of the organic unknown is. I have been told that the organic unknown, will one of the following functional groups: Alcohol's Probably the most common of these functional groups is the "-OH" group, which is known as the hydroxyl group. It is NOT the hydroxide ion, OH1-, as it does not have a charge. The dash in front of the OH stands for a single covalent bond, which is what will be formed between the oxygen and a carbon atom. An aliphatic hydrocarbon that has one hydroxyl group attached to a carbon is called an alcohol. ...read more.

Middle

Ants inject formic acid into their victim whem they bite them. The next in line is, of course, ethanoic acid, CH3COOH. Notice the ending, -oic, to the IUPAC name, and -ic, to the common name. There are some very important organic acids, and one of the most important is ascorbic acid, better known as Vitamin C. The generic formula is R-(COOH)x Why are these compounds acids? Well, they must be able to produce at least one hydrogen ion when they are put into solution, since that is the general definition for an acid. Even though these organic acids may contain quite a few hydrogen atoms in the molecule, only select hydrogens are able to be "ionized" or turned into hydrogen ions. These "select" hydrogens are those in the carboxyl group (-COOH) The presence of one or more of these groups, therefore, causes the compound to belong to the organic acids. Ester An ester results when there is an oxygen atom between two carbons in the chain. The simplest is dimethyl ester, which has the same molecular formula as ethanol. The way the formula is written to show the ester, rather than the alcohol, is CH3OCH3. There are two other esters of interest, ethylmethyl ester and diethyl ester. ...read more.

Conclusion

This is because not only does its physical properties fit those described in text books it also has the right structural formula to fit with the spectropic data provided. benzaldehyde benzaldehyde or benzenecarbonal , C6H5CHO, colourless liquid aldehyde with a characteristic almond odour. It boils at 180�C, is soluble in ethanol, but is insoluble in water. It is formed by partial oxidation of benzyl alcohol, and on oxidation forms benzoic acid. It is called oil of bitter almond, since it is formed when amygdalin, a glucoside present in the kernels of bitter almonds and in apricot pits, is hydrolysed, e.g., by crushing the kernels or pits and boiling them in water; glucose and hydrogen cyanide (a poisonous gas) are also formed. It is also prepared by oxidation of toluene or benzyl chloride or by treating benzal chloride with an alkali, e.g., sodium hydroxide. Benzaldehyde is used in the preparation of certain aniline dyes and of other products, including perfumes and flavourings. Evaluation Overall I feel this experiment went very well as I was able to determine both the functional group present and then with the aid of specropic data the exact compound. I carried out the experiment safely following all guideline set in my method. The only test that could have been performed more accurately was the test for an alderhyde that did not produce a silver mirror. ...read more.

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