CHE-005-LAS-8-Rationale PDF

ACTIVITY NO.8 PROPERTIES OF ALCOHOLS AND PHENOLS RACEL TRANGIA-BACTOL, RPh, MPA, MMSc ALCOHOL An alcohol is an organic compound in which an -OH group is bonded to a saturated carbon atom. The -OH group, the functional group that is characteristic of an alcohol, is called a hydroxyl group....

ACTIVITY NO.8 PROPERTIES OF ALCOHOLS AND PHENOLS RACEL TRANGIA-BACTOL, RPh, MPA, MMSc ALCOHOL An alcohol is an organic compound in which an -OH group is bonded to a saturated carbon atom. The -OH group, the functional group that is characteristic of an alcohol, is called a hydroxyl group. – A hydroxyl group is the -OH functional group. Alcohols are classified as primary (1°), secondary (2°), or tertiary (3°) depending on the number of carbon atoms bonded to the carbon atom that bears the hydroxyl group.  PHENOL A phenol is an organic compound in which an -OH group is attached to a carbon atom that is part of an aromatic carbon ring system. The general formula for phenols is Ar–OH, where Ar represents an aryl group. An aryl group is an aromatic carbon ring system from which one hydrogen atom has been removed Immiscible Immiscible Miscible ACTIVITY QUESTIONS: 1. Provide one example for each classification of alcohols and draw the structure. 2. How do you classify alcohols as primary, secondary, or tertiary using the Lucas Reagent? Lucas reagent or Lucas test is used to distinguish low molecular weight alcohols based on the rates of reaction of alcohols. The positive indicator of the reaction is the formation of a water-insoluble alkyl chloride appeared as a cloudy mixture or a precipitate. The formation of an alkyl chloride with tertiary alcohol is very rapid, followed by the secondary alcohol that may take from 5 to 20 minutes to form visible cloudy mixture without heating. Primary alcohols do not react with Lucas reagent or it may show very little result in a very long time. 3. Why does Ferric chloride T.S. and Bromine water only react with phenolic compounds and not with alcohols, even though both contain a hydroxyl (-OH) group? Ferric chloride T.S. and bromine water selectively react with phenolic compounds due to the presence of the phenol functional group (-OH) in phenolic compounds. In phenolic compounds, the hydroxyl group is directly attached to an aromatic ring, which enhances the reactivity of the hydroxyl group compared to alcohols. On the other hand, alcohols do not typically react with ferric chloride T.S. or bromine water under normal conditions because the hydroxyl group in alcohols is not as reactive as the hydroxyl group in phenolic compounds. 4. Give 3 other examples of Phenolic compounds and draw their structures. Will they also react with Ferric chloride T.S. and Bromine Water? Explain why or why not. Phenolic compounds react with both Ferric chloride T.S. and Bromine Water, producing characteristic color changes or decolorization, respectively, due to their distinctive chemical properties. 5. What is Jones Oxidation Test or Chromic Acid Test, and how is it used to classify alcohols as primary, secondary, or tertiary? Does it react with phenolic compounds? The Jones Oxidation Test, also known as the Chromic Acid Test, is a chemical test used to classify alcohols as primary, secondary, or tertiary based on their reactivity towards chromic acid (H2CrO4) or sodium dichromate (Na2Cr2O7) in the presence of sulfuric acid (H2SO4). This test relies on the different rates of oxidation of primary, secondary, and tertiary alcohols. Regarding its reactivity with phenolic compounds, the Jones Oxidation Test is specific to alcohols and does not react with phenolic compounds. 7. What are hydration and hydrogenation/reduction reactions, and how are they used to prepare alcohols? Hydration and hydrogenation/reduction reactions are chemical processes used to prepare alcohols from different starting materials. a. Hydration reaction Hydration is a chemical reaction in which water (H2O) adds across a double bond, resulting in the formation of an alcohol. The hydration of alkenes is a common example of this reaction. In this process, the double bond of the alkene reacts with water in the presence of an acid catalyst, such as sulfuric acid (H2SO4) or phosphoric acid (H3PO4). b. Hydrogenation/Reduction reaction a chemical reaction in which hydrogen (H2) is added Alcohols may also be prepared via the hydrogenation or also known as reduction of aldehydes and ketones. In organic and biochemical reactions, reduction is recognized as the loss of oxygen or the gain of hydrogen. In the hydrogenation of aldehydes and ketones, it is the gain of hydrogen atoms that allows us to recognize that reduction has occurred. 8. What is a dehydration reaction, and why is it considered the opposite of hydration reaction in relation to alcohols? A dehydration reaction is a chemical process in which a molecule loses a water molecule or an OH group and an H atom from adjacent carbon atoms, resulting in the formation of a double bond between those carbon atoms. This reaction commonly occurs with alcohols, where a molecule of alcohol loses a hydroxyl group (-OH) and a hydrogen atom (-H) from adjacent carbon atoms, leading to the formation of an alkene.  A dehydration reaction is considered the opposite of a hydration reaction in relation to alcohols because hydration involves the addition of a water molecule to an unsaturated bond to form an alcohol, whereas dehydration involves the removal of a water molecule from an alcohol to form an unsaturated bond. In other words, hydration adds water, while dehydration removes water. 9. How can alcohols be oxidized to form aldehydes, ketones, and carboxylic acids? Alcohols may be oxidized with a variety of oxidizing agents to aldehydes, ketones, and carboxylic acids. The most commonly used oxidizing agents are solutions of basic potassium permanganate and chromic acid (H2CrO4). Oxidation of a primary alcohol produces an aldehyde, as seen in the equation below:  Oxidation of a secondary alcohol produces a ketone: Tertiary alcohols cannot be oxidized: