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VSAT 2022

What is Swarts Reaction?

Last updated date: 22nd Jan 2023
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The Swarts reaction is commonly used to produce alkyl fluorides from alkyl chlorides or alkyl bromides. This is accomplished by heating alkyl chloride/bromide in the presence of heavy metal fluoride (silver fluoride or mercurous fluoride for example). The reaction will proceed if sodium fluoride or potassium fluoride are used, but the yield will be greatly reduced. In 1892, Frederic Jean Edmond Swarts was the first to report this phenomenon. The swarts reaction is also known as swarts fluorination. Chlorine is most commonly replaced by fluorine in organic compounds via Swarts fluorination in the presence of antimony salts, where its oxidation state is +5.


Swarts Reaction Mechanism

The mechanism of the Swarts reaction is simple: the metal fluorine link is broken, and a new carbon-fluorine bond is formed. The metal has made a connection with the displaced chlorine or bromine atoms. Swarts reagent is a mixture of antimony trifluoride and chlorine. Swarts' law states that the fluoride produced after fluorination has a lower boiling point than the comparable chloride.


Fluorinated hydrocarbons can be formed by combining chlorinated hydrocarbons with metallic fluorides. As a result, Swarts fluorination can be used to completely replace chlorine or bromine in alkyl chlorides/bromides with fluorine. The formation of Freons is dependent on a variant of the reaction. Anhydrous hydrogen fluoride is fluorinated in the presence of antimony salts (in catalytic quantities) in this variation, with antimony having oxidation levels of +3 and +5.


What is the Reagent used in Swarts Reaction?

In the presence of Sb salts with an oxidation state of +5, antimony trifluoride is commonly used to replace chlorines with fluorines. Thus, Swarts reagent is an antimony trifluoride and chlorine mixture.


Important Questions

1. Compare the rate of reaction between 1-chloropropane and 3-chloro-prop-1-ene.

Ans: Swarts reaction is a SN2 reaction in which the nucleophile is the F- ion. The carbon atom attached to the chlorinated carbon in 1-chloropropane is SP3 hybridised whereas the double bonded carbon attached to the chlorinated carbon in 3-chloro-prop-1-ene is SP2 hybridised.


The positive charge on chlorinated carbon decreases due to the +I effect of SP3 hybridised carbon. As a result, nucleophilic attack is hindered. Because the pi bond overlaps with the p-orbital of chlorinated carbon after breaking the C-Cl bond in 3-chloro-prop-1-ene, the transition state is more stable or has less transition energy. As a result, the Swarts reaction rate of 1-chloropropane is lower than that of 3-chloro-prop-1-ene.


2. Which solvent is used in Swarts reaction?

Ans: Acetone is the solvent used. Acetone is miscible with water and is an important organic solvent in industry, the home, and the laboratory. In 2010, approximately 6.7 million tonnes were produced worldwide, primarily for use as a solvent and the production of methyl methacrylate (and, from there, PMMA) and bisphenol A. In organic chemistry, it is a common building block. Acetone is commonly used in household products such as nail polish remover and paint thinner. It is exempt from volatile organic compound (VOC) regulations in the United States.


Key Features

  • The synthesis of alkyl halides is linked to the Swarts reactions. These reactions describe the exchange of halides between organic compounds (or organic and inorganic compounds) to produce new alkyl halides.

  • Swarts reagent is an antimony trifluoride and chlorine mixture.

Multiple Choice Questions

1. COF2 boiling point is

(a) 84.6 degree celsius

(b) 89.6 degree celsius

(c) 99.6 degree celsius

(d) 100 degree celsius

Answer: (a)


2. Which one is the Swartz reaction from the following?

(a) ${{C}{H}_{3}{Br}{+}{Na}{I}} \to {{C}{H}_{3}{I}{+}{Na}{CL}}$

(b) ${{C}{H}_{3}{Br}{+}{Na}{l}} \to {{C}{H}_{3}{l}{+}{Na}{Br}}$

(c) ${{C}{H}_{3}{Br} {+} {Ag}{F}} \to{{C}{H}_{3}{F}{+}{Ag}{Br}}$

(d) ${{2}{C}{H}_{3}{Cl} {+} {2}{Na}} \to {{C}{H}_{3}{.}{C}{H}_{3}{+}{2}{Na}{Cl}}$

Answer: (c)

Competitive Exams after 12th Science

FAQs on Swarts Reaction

1. What are the differences between Finkelstein and Swarts reaction?

Both the Finkelstein reaction and the Swarts reaction are involved in the production of alkyl halides. The exchange of halides between organic compounds (or organic and inorganic compounds) to prepare new alkyl halides is described in these reactions. The main difference between the Finkelstein and Swarts reactions is that the Finkelstein reaction produces alkyl iodide whereas the Swarts reaction produces alkyl fluoride. The reactants for the Finkelstein reaction can be primary halides, secondary halides, allyl halides, and benzyl halides, but not tertiary reactions, vinyl, or aryl halides. Swarts reaction reactants include alkyl chloride or alkyl bromide, as well as a fluorinating agent such as antimony fluoride.

2. Is Swartz reaction SN1 or SN2?

It is a SN2 reaction because one halogen atom replaces another halogen atom in this reaction. The SN2 reaction is a common type of reaction mechanism in organic chemistry. One bond is broken and one bond is formed synchronously, in one step, in this mechanism. SN2 is a type of nucleophilic substitution reaction mechanism, with the name referring to the mechanism's Hughes-Ingold symbol. Because two reacting species are involved in the slow (rate-determining) step, the term substitution nucleophilic (bi-molecular) or SN2 is used; the other major type is SN1. Many more specialised mechanisms exist to describe substitution reactions.

3. What is SN1 reaction?

The SN1 reaction is an organic chemistry substitution reaction named after the Hughes-Ingold symbol of the mechanism. The letter "SN" stands for "nucleophilic substitution," and the number "1" indicates that the rate-determining step is unimolecular. As a result, the rate equation is frequently depicted as having first-order dependence on the substrate and zero-order dependence on the nucleophile. This relationship holds true when the amount of nucleophile is significantly greater than the amount of intermediate. Instead, steady-state kinetics may be used to more accurately describe the rate equation. The reaction involves a carbocation intermediate and is commonly seen in reactions of secondary or tertiary alkyl halides under strongly basic conditions or secondary or tertiary alcohols under strongly acidic conditions.

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