The Physical and Chemical Properties of Alcohols and Phenols Group of Organic Compounds

Document Type:Research Paper

Subject Area:Chemistry

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The study of a whole organic compound would be impossible if each substance could be separately studied as an entity from other substances. That is to imply, its study could be even more difficult than one might currently perceive it. Fortunately, the whole aspect of organic chemistry can be organized into one concept of the functional group (Vollhardt et al. pg. In this context, the chemistry of alcohols and phenols family of compounds is comprehensively covered based on some commonly known properties. There are wide varieties of chemical reactions that alcohols do undergo, and the same time, they can be prepared in different ways, hence being rendered to occupy a vital position in the field of organic chemistry. This context begins with the basic overview of the nomenclature of phenols and alcohols. The physical and chemical properties of these compounds are reviewed, and coverage of the methods of how lower series of phenols and alcohols can be obtained on a commercial scale. A detailed coverage of properties of these compounds follows with a particular emphasis on the laboratory test methods like the Lucas test, iron chloride test, oxidation and their solubility in water. Introduction Phenols and alcohols are groups of organic compounds having at least one group of hydroxyl (OH) that is attached to an aryl carbon or a saturated carbon atom (Zhu et al. pg. The commonly encountered group of alcohol that is even present in alcoholic beverages is ethanol (also referred to as grain alcohol or ethyl alcohol). However, in its pure form, or solution that is highly concentrated, many people have not realized that this state of ethyl alcohol is poisonous.

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In the laboratory, most of these containers are normally labelled as “96% absolute ethanol”. Hence the acquisition and disposal of these particular reagents are frequently monitored by regulatory authorities since they are considered harmful to human consumption. Alcohol that is denatured contains ethanol at very high concertation levels and added poisonous substances like methanol which is another class of alcohol. The thirdly commonly alcohol that is encountered is isopropyl alcohol (2-propanol or rubbing alcohol). This class of alcohol also happens to be toxic. It possesses the ability to kill germs and temporary lubricating properties. Isopropyl possesses less of hazard properties because it is absorbed through the skin as compared to methanol. H2 (g) + CO (g) - CH3OH (l) Ethyl alcohol constitutes the second alcohol member commonly known as ethanol. This class of alcohol is also called grain alcohol because it can be obtained through fermentation of sugar grains.

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Alternatively, it can be obtained through petroleum refining where H2O is added to ethene. Generally, the system of naming alcohols follow a pattern f R-OH to even higher series of alcohol molecules like the Propanol, n- butanol, n-hexanol, and among others depending on the carbon chain (Silverstein et al. pg. Purpose: Determination of the alcohol class through their reaction Five drops of different solutions of alcohols (1-butanol, 1-Hexanol, 2-propanol, 2-methylcyclohexanol, 2-methyl-2propanol, unknown alcohol solution) and a phenol solution were carefully placed on separate test tubes and labelled. ml of Lucas reagent was separately added to each of the seven test tubes containing different solutions of alcohol. The shaking of each test tubes was done then the observations were recorded. In the case where there no physical change, immersing of the test tubes in a water bath at 60oC for fifteen minutes was done.

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Iron chloride test Four drops of 1-butanol, 1-Hexanol, 2-propanol, 2-methylcyclohexanol, 2-methyl-2propanol, and a phenol solution added in separate labelled test tubes that were clean and dried. The steps above were repeated for 1-Hexanol, 2-propanol, 2-methylcyclohexanol, 2-methyl-2propanol, and a phenol solution. Results Solubility Compound Solubility in water 1-butanol Colourless, no separate layers 1-Hexanol Colourless, no separate layers 2-propanol Colourless, no separate layers 2-methylcyclohexanol Partially soluble, thin top layer 2-methyl-2propanol Colourless, no separate layers phenol Colourless, no separate layers Unknown Colourless, no separate layers Lucas test and iron III chloride Compound Iron III chloride test colour Time with Lucas test and observation 1-butanol Light yellow colour No reaction after ten minutes 1o 1-Hexanol Yellow colour No reaction after ten minutes 1o 2-propanol Yellow colour Reaction after five minutes 2o 2-methylcyclohexanol Yellow colour Reaction after five minutes 2o 2-methyl-2propanol Pale yellow Immediate reaction 3o phenol Purple Reaction after five minutes 2o Unknown Yellow colour No reaction after ten minutes 1o 0xidation Compound Classification (primary, secondary and tertiary ) Colour with potassium dichromate 1-butanol Primary brown 1-Hexanol Primary Brown spots 2-propanol Secondary Dark purple 2-methylcyclohexanol Secondary brown 2-methyl-2propanol Tertiary Dark purple phenol Secondary Purplish brown Unknown N/A N/A Discussion Solubility As seen in the results, alcohols dissolve in water.

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The reason behind their solubility in water is the presence of the OH functional group which has the capability of forming hydrogen bonds in water molecules. The class of alcohols having smaller carbon chains dissolve in water faster than the ones with longer carbon chain. The hydrocarbons of higher carbon chain have molecules that are closely packed hence more energy is needed for breaking the hydrogen bonds with the hydroxyl group. pg 145). Oxidation Depending on the reaction conditions, 1o alcohols can be oxidized to either carboxylic acids or aldehydes. The 2o alcohols are normally oxidized to becoming ketones. There is no reaction for the case of 3o alcohols since they are not oxidized to in presence of acidified potassium or sodium dichromate solution (Boccardi et al. pg 190). Based on the experiment, phenols can be identified through iron III chloride test due to their capability to form an intense violet colour, unlike the alcohols which do not depict any reaction with particular tests.

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List of Bibliography Vollhardt, K. Peter C. and Neil E. Schore. Non-thermal gas-phase pulsed corona discharge for lignin modification. Chemical Engineering and Processing-Process Intensification 126 (2018): 141-149. Boccardi, Giovanni, and Paul Harmon. Oxidative susceptibility testing. Pharmaceutical Stress Testing.

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