In the following posts, we will learn about the main reactions of alcohols. Each post is accompanied by practice problems of alcohol reactions to show the transformations and their corresponding mechanisms. The practice problems include simple one-step transformations such as the preparation of alcohols by reductions reactions of carbonyl compounds using NaBH4, LiAlH4, Pd/C, DIBAL-H and many more, as well as the oxidation of the alcohols to convert them into aldehydes, ketones and carboxylic acids depending on the reagent that is used. All the major oxidizing agents such as Na2Cr2O7/ H2SO4, H2CrO4, CrO3/ H+, KMnO4/ -OH/ H+, NaClO/AcOH. will also be discussed.
We will also discuss in detail how alcohols react in substitution and elimination reactions. This will include the reactions where alcohols are used as a substrate and also reactions where they work as the base and the nucleophile.
The Grignard Reaction used for the synthesis of alcohols and in general, the application of the Grignard Reaction in Organic Synthesis is also covered in many examples. To be used in organic synthesis, the hydroxyl group often needs to be protected in the presence of strong bases like organometallics. The protecting groups of alcohols and strategies for their use organic synthesis are also covered with a handful of practice problems.
Alcohols can be prepared from carbonyl compounds such as aldehydes, ketones, esters, acid chlorides, and even carboxylic acids by hydride reductions. These reductions are a result of a net addition of two hydrogen atoms to the C=O bond: … Read more
We have seen many times when discussing the SN2 mechanism that ethers are common products of nucleophilic substitution reactions. They are synthesized by reacting alkyl halides or other substrates with good leaving groups with alkoxides: This method of … Read more
Alcohols can be converted to alkyl halides by reacting with HX (X = Cl, Br, I) acids. The reaction works for 1°, 2°, and 3° alcohols: Let’s now understand how this happens. We have seen many times in … Read more
Remember when discussing the substitution reactions, we said that the hydroxide ion (–OH) is a poor leaving group since it is quite a strong base. Therefore, the –OH cannot be expelled by a direct nucleophilic attack in an SN2 or … Read more
Thionyl chloride (SOCl2) and phosphorus tribromide (PBr3) can be used for converting primary and secondary alcohols to alkyl chlorides and alkyl bromides respectively: Both reactions have similar mechanisms with the idea of turning the OH into a good … Read more
Dess–Martin periodinane (DMP) oxidation Alcohols can be oxidized to aldehydes, ketones, and carboxylic acids depending on their structure and the type of oxidizing agent. In general, we can classify oxidizing agents as strong and mild. Mild oxidizing reagents stop the … Read more
Pyridinium Chlorochromate (PCC) Oxidation PCC oxidation is one of the selective methods for oxidizing primary alcohols to aldehydes. Although very often the outcome of the oxidation will depend on the presence or absence of water, traditionally, the most common mild oxidizing … Read more
Swern oxidation is one of the selective methods for oxidizing primary alcohols to aldehydes. Like other mild oxidizing agents, such as pyridinium chlorochromate (PCC), pyridinium dichromate (PDC), and the Dess-Martin (DMP) oxidation, it stops the oxidation once the carbonyl group … Read more
Dehydration of alcohols using phosphorus oxychloride (POCl3) and pyridine (an amine base) in place of H2SO4 or TsOH is a good alternative for converting alcohols to alkenes when working with compounds that decompose in the presence of strong acids: … Read more
Alcohols can be oxidized into a variety of carbonyl compounds depending on the nature of the alcohol and the oxidizing agent used. Secondary alcohols can only be oxidized to ketones, while primary alcohols are oxidized to aldehydes and carboxylic acids, … Read more
