Alcohols Identification: Different Types, Oxidation & Lucas Test, FAQs

Any organic substance with one, two, or more hydroxyl groups (-OH), which are connected to the carbon atom, is referred to as alcohol (alkyl group or hydrocarbon chain).

Alcohol in which an alkyl group has been substituted for one hydrogen atom is referred to as a derivative of water. The alkyl group is represented by R in inorganic compounds. There are numerous methods by that alcohol can be created.

Alcohols make up a sizable component of the majority of frequently occurring chemical substances. These substances can be used to create sweeteners and fragrances, but they can also act as catalysts to produce other related compounds and others can be found in a variety of organic molecules.

Different Types Of Alcohols

Whether alcohol contains hydroxyl groups determines how different it is from another alcohol. Based on where the hydroxyl group is located, alcohols have different characteristics in terms of their physical and chemical makeup.

Three categories of alcohol exist. Primary, secondary, and tertiary alcohols are the three categories of alcohol.

Depending on where the carbon atom is connected to the hydroxyl group, an alkyl group is categorised. Numerous alcohols are described as being colourless liquids or even solids when they are at room temperature. The molecular weight of an alcohol determines how soluble it is in water; the higher the molecular weight, the less soluble the alcohol is in water, and the higher the density, boiling point, vapour pressure, and viscosity of the alcohol.

Primary Alcohols: Alcohols that only have one alkyl group with a carbon atom connected to the hydroxyl group are referred to as primary alcohols (OH). These major alcohols include ethanol, methanol (propanol), and others. An alkyl chain's intricacy has no bearing on whether it is categorised as primary or secondary. Any alcohol must have exactly one bond between a -OH group and an alkyl group in order to be considered a primary.

Second Alcohol: In secondary alcohol, the hydroxyl group is only joined by one hydrogen atom (-OH). Anywhere in the carbon cycle could experience this.

Tertiary Alcohol: A tertiary alcohol has an attached hydroxyl group to a carbon atom but no hydrogen atoms. This typically means that the branch and the hydroxyl group are both bonded to the same carbon atom.

Alcohols Oxidation To Aldehydes And Ketones

• Alcohols are a class of substances that have one, two, or more hydroxyl (-OH) groups bonded to the single alkane bond. These substances all have the generic formula ROH. They play a crucial role in organic chemistry since they can be altered or transformed into other chemicals, including aldehydes and ketones, among others. There are two distinct sorts of alcohol reactions. These reactions have the ability to break the R-O bond or even the O-H bond.

• The oxidation process transforms the alcohols into aldehydes and ketones. One of the most significant reactions in the study of organic chemistry is this one.

• One of the crucial chemical reactions in the field of synthetic organic chemistry is the oxidation of alcohols to aldehydes and ketones. These reactions take place in the presence of catalysts, and the best oxidants necessary for these conversions act as the catalyst for this kind of reaction. In this case, the catalyst is high valent ruthenium. Understanding the influences and mechanisms of the oxidation reactions is crucial, as is having thorough knowledge of both.

• The synthesis of numerous synthetic intermediates in organic chemistry depends on the catalytic conversion of primary alcohols into aldehydes and secondary alcohols into ketones.

Oxidation Test

In the oxidation test, sodium dichromate is used to oxidise the alcohols (Na2Cr2O7). Depending on whether the alcohol is primary, secondary, or tertiary, the rate of oxidation changes. Based on how quickly they oxidise, alcohols are categorised as follows:

Oxidation Of Primary Alcohol : Aldehydes, which can then be transformed into carboxylic acids, are easily formed from primary alcohol.

Oxidation Of Secondary Alcohol : Ketone can be made easily from secondary alcohol, but further oxidation is not possible.

Oxidation Of Tertiary Alcohol: Tertiary alcohol does not oxidise when sodium dichromate is included in the mixture.

Lucas Test

Primary, secondary, and tertiary alcohols' reactivity to hydrogen chloride are evaluated using the Lucas test. In the Lucas test, the alcohol is prepared using Lucas reagent (concentrated HCl and ZnCl2). Turbidity results from the substituted alcohol's halides being immiscible in the Lucas reagent. Along with the time it took to reach turbidity, the following findings are noted:

• When it comes to primary alcohols, turbidity doesn't develop at room temperature. But when heated, an oily film develops.

• Using a secondary alcohol results in the formation of an oily layer in 5–6 minutes. As a result, turbidity doesn't appear right away after the reaction.

• Due to the ease with which halides can develop in tertiary alcohol, turbidity is produced right away.

• Chromium trioxide is employed as a potent oxidising agent in the Jones test when sulfuric acid is present. In the presence of the Jones reagent, a primary alcohol is transformed into an aldehyde, and then into a carboxylic acid, whereas a secondary alcohol is oxidised to a ketone.

• Tertiary alcohols do not react with chromium, hence an orange solution results instead of a precipitate.