[Chemistry Class Notes] Isopropyl Alcohol Pdf for Exam

What is Isopropyl Alcohol?

Isopropyl alcohol, also well-known as 2-propanol, is one of the most predominant members of the organic compound family. Isopropyl alcohol was the first commercial synthetic alcohol; it was first produced in 1920 by chemists at New Jersey’s Standard Oil Company (later Exxon Mobil), while studying petroleum by-products. It is easily synthesized by the propylene reaction with sulphuric acid, followed by hydrolysis.

IUPAC Name: Propan-2-ol

Molecular Weight: 60.1 g/mol

Synonyms

• Isopropanol

• 2-propanol

• Isopropyl alcohol

• Propan-2-ol

Isopropyl Alcohol Chemical Formula: 

Isopropyl alcohol formula can be written as C3H8O or CH3CHOHCH3 or (CH3)2CHOH

Isopropyl Alcohol Structure

It is a 1-propanol, and ethyl methyl ether structural isomer.

Isopropyl alcohol structural formula

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Properties

Physical properties of isopropyl alcohol

Isopropyl alcohol is miscible in water, chloroform, ethanol and ether

It dissolves ethyl cellulose, many oils, natural resins, polyvinyl butyral, gums and alkaloids.

Salting out

An azeotropeis formed when Isopropyl alcohol acts with water, which gives a boiling point of 80.37 ° C (176.67 ° F) and an isopropyl alcohol composition of 87.7 wt per cent (91 vol per cent).

Water-isopropyl alcohol mixtures have lower melting points.

It is slightly bitter in taste.

With decreasing temperature and freezing at −89°C (−128°F), isopropyl alcohol becomes ever more viscous.

Isopropyl alcohol is maximally absorbed in an ultraviolet – visible spectrum at 205 nm.

Chemical Properties of Isopropyl Alcohol

Isopropyl alcohol can be oxidized to acetone (equivalent ketone). This can be achieved with oxidizing agents such as chromic acid, or with isopropyl alcohol dehydrogenation over a heated copper catalyst.

                                              (CH3)2CHOH → (CH3)2CO + H2

In reduction of Meerwein-Ponndorf-Verley and other transfer hydrogenation reactions, isopropyl alcohol is often used as both solvent and hydride source. Isopropyl alcohol can be converted to 2-bromopropane using tribromide phosphorus, or dehydrated to propene by sulfuric acid heating.

Like most alcohols, isopropyl alcohol reacts to the formation of alkoxides that can be called isopropoxides with active metals such as potassium. The aluminum reaction (initiated by a mercury tracer ) is used to prepare the aluminum isopropoxide catalyst

Isopropyl Alcohol Synthesis

This is produced primarily by combining water and propene in a hydration reaction or by hydrogenating acetone. 

There are two ways for the hydration process, and both processes require distillation of the isopropyl alcohol from water and other by-products. 

Isopropyl alcohol and water form an azeotrope, and simple distillation gives an alcohol content of 87.9% by weight isopropyl alcohol and 12.1% by weight water. Pure isopropyl alcohol (anhydrous) is formed by azeotropic distillation of the wet isopropyl alcohol using either diisopropyl ether or cyclohexane as azeotropic agents.

Indirect Hydration

In this process propene is reacted to form a mixture of sulfate esters with sulfuric acid. This method can use propene that is of low quality.

These processes primarily give isopropyl alcohol rather than1-propanol, because it follows Markovnikov ‘s rule to add water or sulfuric acid to propene. The subsequent hydrolysis by steam of these esters results in isopropyl alcohol, by distillation.

Diisopropyl ether is a major by-product of this process; it is reprocessed back to the process and hydrolyzed to give the preferred product.

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Direct Hydration

In the presence of solid or supported acid catalysts, direct hydration reacts to propene and water, either in gas or liquid phase, at high pressures.This type of process usually requires propylene with higher purity (> 90 per cent) 

Isopropyl Alcohol Uses

As Solvent

A number of non-polar compounds is reduced by isopropyl alcohol. This also evaporates rapidly, leaving almost zero traces of oil compared with ethanol, and is relatively non-toxic compared with alternative solvents. It is thus widely used as a solvent and as a purifying fluid

Intermediate

Alcohol is esterified to give another solvent, the isopropyl acetate. It reacts with carbon disulfide and sodium hydroxide to provide a reagent for sodium isopropylxanthate, herbicide.

For Medical purpose:

Rubbing alcohol, hand sanitizer, and disinfectant pads typically contain a water solution of 60–70 per cent isopropyl alcohol or ethanol. Water is needed to open bacterial membrane pores which act as a gateway for isopropyl alcohol.

As an Anesthetic

While isopropyl alcohol can be used for anesthesia, this use is prohibited because of its many negative attributes or drawbacks. Isopropyl alcohol can also be used as a solvent, similar to ether

Automotive

Isopropyl alcohol is an important ingredient in fuel additives for the “gas dryer.”

Laboratory

Isopropyl alcohol is a biological preservative which provides a comparatively non – toxic alternative to formaldehyde and other synthetic preservatives. 70–99 per cent of isopropyl alcohol solutions are used to preserve specimens.