CARBONYL COMPOUNDS: ALDEHYDES AND KETONES
Four samples were placed on separate test tubes namely acetone, acetaldehyde, benzaldehyde, and cyclohexane and six tests were conducted on each of the samples in order to determine the solubility and their reactions to each of the tests. Acetone would only be negative in Tollen’s and Jone’s test; acetaldehyde would be positive in all the tests; benzaldehyde would be positive only to 2,4-DNP test, Tollen’s and Jone’s test; and cyclohexane would only be positive to 2,4-DNP test. II. Introduction
Aldehydes and ketones are organic compounds which incorporate a carbonyl functional group, C=O. The carbon atom of this group has two remaining bonds that may be occupied by hydrogen or alkyl or aryl substituents. If at least one of these substituents is hydrogen, the compound is an aldehyde. If neither is hydrogen, the compound is a ketone. The IUPAC system of nomenclature assigns a characteristic suffix to these classes, al to aldehydes and one to ketones. For example, H2C=O is methanal, more commonly called formaldehyde. Since an aldehyde carbonyl group must always lie at the end of a carbon chain, it is by default position #1, and therefore defines the numbering direction. A ketone carbonyl function may be located anywhere within a chain or ring, and its position is given by a locator number. Chain numbering normally starts from the end nearest the carbonyl group. In cyclic ketones the carbonyl group is assigned position #1, and this number is not cited in the name, unless more than one carbonyl group is present. If you are uncertain about the IUPAC rules for nomenclature you should review them now. Examples of IUPAC names are provided (in blue) in the following diagram. Common names are in red and derived names in black. In common names carbon atoms near the carbonyl group are often designated by Greek letters. The atom adjacent to the function is alpha, the next removed is beta and so on. Since ketones...
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