Hey guys, so now let's talk about protecting groups. Roshen Reji Idiculla Dr. Dietmar Kennepohl FCIC (Professor of Chemistry, Athabasca University), Prof. Steven Farmer (Sonoma State University). If you wish to opt out, please close your SlideShare account. Three Steps Required: 1. That's exactly what we're going to do with our protecting group. SHIELDED BY Is there anything that the alkynide could do to those functional groups? The silyl ether protecting group can be removed by reaction with an aqueous acid or the fluoride ion. In this case, I'm using the word moieties just means some kind of reaction region of the molecule from a reaction that's going to happen on another part of the molecule. Scribd will begin operating the SlideShare business on December 1, 2020 In this case, this would be an SN2 reaction. So that's what I'm trying to make happen. Let's go ahead and look at this reaction. Let's look at this reagent. After completing this section, you should be able to. How can we guarantee that a reaction won’t take place at the alcohol? I know that sounds complicated, but basically what we're going to try to do is we're going to try to shield vulnerable functional groups from certain types of strong reagents. REAGENTS. Unless otherwise noted, LibreTexts content is licensed by CC BY-NC-SA 3.0. A Quick Recap on Protecting Groups. The addition of protecting groups to functional groups is termed ‘protection’ and removal of protecting group is ‘deprotection’. 1. Now customize the name of a clipboard to store your clips. By utilizing a protecting group a Grignad reagent can be formed and reacted on a halo alcohol. See our User Agreement and Privacy Policy. Join thousands of students and gain free access to 63 hours of Organic videos that follow the topics your textbook covers. Previous Section Ether Cleavage. 2) Form the Grignard Reagent. We've got an alcohol and an alkyl halide on the same molecule. You're only going to use a protecting group if you have more than one functional group on a molecule. In fact, the alkynide will almost exclusively react with the OH and it will pretty much not react at all with the alkyl halide. We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. Protecting Groups for Alcohols- Ether protection (Alcohol to ether) • 2-Methoxyethoxymethyl ether (MEM) • Selective protection is possible • Can be incorporated at relatively weak basic conditions (3° amine) but needs • relatively strong acid (TFA) to remove • Stable in basic conditions • The reagent, MEMCl, is considered carcinogenic Let me give you an example of why I might need something like this. Our reagent is an alkynide. 20 - Carboxylic Acid Derivatives: NAS, Ch. Additional Problems. Which reaction does not require a protecting group to work (which would work exactly as shown)? Actually, yes and they react through a different mechanism. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. Well, scientists determined, you know what, alcohols are messing up a lot of different reactions, so if we can figure out a way to get rid of the alcohol for a few minutes, then run the rest of the reaction and then regenerate the alcohol, that would be really helpful. 19 - Aldehydes and Ketones: Nucleophilic Addition, Ch. FUNCTIONAL Is there anything – oh, that's supposed to be erasing. If you continue browsing the site, you agree to the use of cookies on this website. … They react through an acid-base mechanism because we know that alcohols have an acidic proton and alkynides are very strong bases. Often during the synthesis of complex molecules on functional group in a molecule interferes with an intended reaction on a second functional group on the same molecule. 1) Protect the Alcohol. 15 - Analytical Techniques: IR, NMR, Mass Spect, Ch. The LibreTexts libraries are Powered by MindTouch® and are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot.