Why is sulphuric acid not used during the reaction of alcohols with

H 2 ​ S O 4 ​ is an oxidizing agent. Explanation: In the presence of Sulphuric acid, KI produces HI. 2 K I + H 2 ​ S O 4 ​ → 2 K H S O 4 ​ + 2 H I Sulphuric acid is a strong oxidizing agent and it oxidises HI to produce I 2 ​ . 2 H I + H 2 ​ S O 4 ​ → I 2 ​ + S O 2 ​ + H 2 ​ O As a result, The reaction between alcohol and HI to produce alkyl halide cannot occur. ∴ H 2 ​ S O 4 ​ is not used during the reaction of alcohols with KI. Additional information: In this reaction, Non-oxidizing acids like H 3 ​ P O 4 ​ are used.

It protonates the chromic acid to form an oxonium ion, increasing positive charge at the chromium center. Using $\ce$ typically protonates the electrophile, making it more electrophilic (more electron deficient = more electrophilic), just like with acid-catalyzed esterification. In fact, you're making a chromate ester in this reaction. See the first step here in this image (and the rest is related, also):

dehydration of alcohols THE DEHYDRATION OF ALCOHOLS This page (a simple duplicate of a page in the section on alkenes!) looks at the dehydration of alcohols in the lab to make alkenes - for example, dehydrating ethanol to make ethene. Dehydration of alcohols using aluminium oxide as catalyst The dehydration of ethanol to give ethene This is a simple way of making gaseous alkenes like ethene. If ethanol vapour is passed over heated aluminium oxide powder, the ethanol is essentially cracked to give ethene and water vapour. To make a few test tubes of ethene, you can use this apparatus: It wouldn't be too difficult to imagine scaling this up by boiling some ethanol in a flask and passing the vapour over aluminium oxide heated in a long tube. Dehydration of alcohols using an acid catalyst The acid catalysts normally used are either concentrated sulphuric acid or concentrated phosphoric(V) acid, H 3PO 4. Concentrated sulphuric acid produces messy results. Not only is it an acid, but it is also a strong oxidising agent. It oxidises some of the alcohol to carbon dioxide and at the same time is reduced itself to sulphur dioxide. Both of these gases have to be removed from the alkene. It also reacts with the alcohol to produce a mass of carbon. There are other side reactions as well, but these aren't required by any current UK A level (or equivalent) syllabus. The dehydration of ethanol to give ethene Ethanol is heated with an excess of concentrated sulphuric acid at a temperature ...

10. 2 Why is sulphuric acid not used during the reaction of alcohols with KI? 10.3 Write structures of different dihalogen derivatives of propane. 10.4 Among the isomeric alkanes of molecular formula C_5H_12 , identify the one that on photochemical chlorination yields (i) A single monochloride. (ii) Three isomeric monochlorides. (iii) Four isomeric monochlorides. (iii) Four isomeric monochlorides.

Learning Objectives • Give two major types of reactions of alcohols. • Describe the result of the oxidation of a primary alcohol. • Describe the result of the oxidation of a secondary alcohol. Chemical reactions in alcohols occur mainly at the functional group, but some involve hydrogen atoms attached to the OH-bearing carbon atom or to an adjacent carbon atom. Of the three major kinds of alcohol reactions, which are summarized in Figure \(\PageIndex\): Reactions of Alcohols. Oxidation and dehydration of alcohols are considered here. A flow diagram of three possible reactions of an alcohol. The final products of the reactions are also shown at the end of the flow diagram. Dehydration As noted in Figure \(\PageIndex\), an alcohol undergoes dehydration in the presence of a catalyst to form an alkene and water. The reaction removes the OH group from the alcohol carbon atom and a hydrogen atom from an adjacent carbon atom in the same molecule: Structural formula of ethanol dehydrating under excess concentrated sulfuric acid at 180 degrees celsius. The products are ethylene and a side product of a water molecule. Under the proper conditions, it is possible for the dehydration to occur between two alcohol molecules. The entire OH group of one molecule and only the hydrogen atom of the OH group of the second molecule are removed. The two ethyl groups attached to an oxygen atom form an ether molecule. Two molecules of ethanol are dehydrated under concentrated sulfuric acid at 140 ...

H 2 SO 4 cannot be used along with KI in the conversion of an alcohol to an alkyl iodide as it oxidizes KI in the presence of sulphuric acid (H 2SO 4) to corresponding HI and then to I 2 i.e., KI produces HI, In the presence of sulphuric acid (H 2SO 4). 2KI + H 2SO 4 --> 2KHSO 4 +2HI Since H 2SO 4 is an oxidizing agent, it oxidizes HI( Produced in the reaction to I 2). 2HI + H 2SO 4 --> I 2 +SO 2 +H 2O As a result, the reaction between alcohol and HI to produce alkyl iodide cannot occur. Therefore, sulphuric acid is not used during the reaction of alcohols with KI. Instead, a non-oxidiznig acid such H 3PO 4 is used. To have three isomeric monochlorides, the isomer of the alkane of the molecular formula C5H12 should contain three different types of H-atoms The equivalent hydrogens are grouped as a, b and c. The replacement of equivalent hydrogens will give the same product. C a H 3 C b H 2 C c H 2 C b H 2 C a H 3

In the presence of sulphuric acid (H 2SO 4), KI produces HI Since is an oxidizing agent, it oxidizes HI (produced in the reaction to I 2). As a result, the reaction between alcohol and HI to produce alkyl iodide cannot occur. Therefore, sulphuric acid is not used during the reaction of alcohols with KI. Instead, a non-oxidizing acid such as H 3PO 4 is used.

KI and H 2 S O 4 In the presence of sulphuric add H 2 S O 4, K I produces H I The reaction is given below: 2 K I + H 2 S O 4 → 2 K H S O 4 + 2 H l Oxidising nature of H 2 S O 4 Since H 2 S O 4 is an oxidising agent, it oxidizes H I to l 2 . The reaction is given below: 2 H I + H 2 S O 4 → I 2 + S O 2 + 2 H 2 O Therefore, the reaction between alcohol and H l to produce alkyl iodide cannot occur. So, sulphuric acid is not used during the reaction of alcohols with K I . Instead, a non-oxidising acid such as H 3 P O 4 is used.