Semi-structural formulae
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In organic chemistry a simple molecular formula is not always enough to identify the compound. Structural and semistructural formulae are needed to identify a compound. Semi -structural formulae are also known as condensed structural formulae. The use of semi-structural formulae is best suited to non-cyclic carbon compounds. Semistructural formulae are always written from left to right one carbon at a time. Lets see how the condensed structural formula of pentane is written. When a compound is represented using its condensed structural formula format, each carbon atom and the hydrogen atoms attached to it are listed as a molecular formula.
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Still further compression of the formula can be made by placing repeating groups in parentheses and using a subscript to show the number of repeating groups, as shown on the right. |
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Branched groups are shown in brackets following the carbon atom to which they are bonded to. The condensed structural formula on the right shows that in 3-methylpentane, there is a branched, methyl group, attached to the third carbon atom of the pentane chain. What do you think the condensed structural formula of 3-ethylpentane is? What is the condensed structural formula for 2,2,4-Trimethylpentane is? What is the name of the compound given by the condensed structural formula What is the condensed structural formula of 3-ethyl-2-methylheptane? What is the condensed structural formula of 2-aminobutane? |