James Matthew Jocson*, Gianvittorio Lanta, Chiqui Ann Llamado, Jeron Manaig College of Science Department of Biology University of Santo Tomas, Manila, Philippines
Five oxygen-bearing organic compounds were given namely Methanol, 2-propanol, tert - butanol, formalin, and acetone. Different tests were done to each sample to differentiate their characteristics. These test were Dichromate test, Tollens Test, DNPH test, Iodoform Test, and Lucas Test. This was conducted to classify the samples from being a primary alcohol, a secondary alcohol, a tertiary alcohol, aldehyde, or a ketone. Introduction
In analyzing the oxygen bearing organic compounds, there are several tests that may be performed to distinguish among the different classes of alcohols, aldehydes, and ketones. All these tests exploit differences in the type and degree of reactivity of each of the functional groups. Several different oxidizing agents may be used to cause theoxidation of molecules. Potassium permanganate (KMnO4) or potassium dichromate (K2Cr2O7) or even atmospheric oxygen (O2) are oxidizing agents.
An aldehyde is an organic compound containing a formyl group. This functional group, with the structure R-CHO, consists of a carbonyl center (a carbon double bonded to oxygen) bonded to hydrogen and an R group, which is any generic alkyl or side chain. The group without R is called the aldehyde group or formyl group. Aldehydes differ from ketones in that the carbonyl is placed at the end of a carbon skeleton rather than between two carbon atoms. Aldehydes are common in organic chemistry. Many fragrances are aldehydes. A ketone is an organic compound with the structure RC(=O)R', where R and R' can be a variety of carbon-containing substituents. It features a carbonyl group (C=O) bonded to two other carbon atoms. Methanol is a chemical with the formula CH3OH (often abbreviated MeOH). It is the simplest alcohol, and is a light, volatile, colorless, flammable liquid with a distinctive odor very similar to, but slightly sweeter than, ethanol (drinking alcohol). Isopropyl alcohol (propan-2-ol, 2-propanol) is a common name for a chemical compound with the molecular formula C3H8O. It is a colorless, flammable chemical compound with a strong odor. It is the simplest example of a secondary alcohol, where the alcohol carbon is attached to two other carbons sometimes shown as (CH3)2CHOH. It is a structural isomer of propanol. Tert-Butanol, or 2-methyl-2-propanol, is the simplest tertiary alcohol. It is one of the four isomers of butanol. tert-Butanol is a clear liquid (or a colorless solid, depending on the ambient temperature) with a camphor-like odor. It is very soluble in water and miscible with ethanol and diethyl ether. It is unique among the isomers of butanol because it tends to be a solid at room temperature, with a melting point slightly above 25 °C. IODOFORM TEST (for methyl carbonyl compounds) – This test is mainly used to identify methyl ketones. The iodoform regent iodinates the methyl group which they cleaves in the basic solution. One should confirm the presence of a carbonyl group in the unknown before this test is done as misleading results could occur with other compounds. For example, acetaldehyde and alcohols that have a methyl group bonded to the C-OH group can also give a positive test since such an alcohol can be oxidized to a methyl ketone by the iodoform reagent. LUCAS TEST (to distinguish primary, secondary and tertiary alcohols of six carbons or less) – A solution of zinc chloride in aqueous hydrochloric acid can be used to distinguish primary, secondary and tertiary alcohols. The unknown compound must be soluble in the reagent in order for the test to be valid. When a tertiary alcohol is added dropwise to the reagent, an immediate second layer or a liquid alkyl chloride is formed. Secondary alcohols form a second layer of the insoluble alkyl chloride in three to 5...