CHLOROFORM

Made By:

13BCH024- Shardul Karve

13BCH025-Yagnesh Khambhadiya

INTRODUCTION  Chloroform is an organic compound with formula . It is one of the four chloromethane.

The colourless, sweet smelling, dense liquid is a trihalomethane, and is considered hazardous. 

The hydrogen attached to carbon in chloroform participates in hydrogen bonding.

The total global flux of chloroform through the environment is approximately 660000 tonnes per year, and about 90% of emissions are natural in origin.

 Many kinds of seaweed produce chloroform, and fungi are believed to produce chloroform in soil,thus are the natural sources of chloroform.

Trichloromethane (Chloroform) was synthesized independently by two groups in 1831.

Liebig carried out the alkaline cleavage of chloral, whereas Soubeirain obtained the compound by the action of chlorine bleach on both ethanol and acetone.

 In 1835, Dumas prepared the substance by the alkaline cleavage of trichloroacetic acid.

 Today, Trichloromethane is prepared exclusively and on a massive scale by the chlorination of methane and monochloromethane.

PHYSICAL PROPERTIES

Chloroform has the following physical properties:

(1) It is a sweet smelling colourless liquid.

(2) It is practically insoluble in water but dissolves in organic solvents such as ether, alcohol etc.

(3) It is non-inflammable but its vapours may burn with green flame.

(4) It brings temporary unconsciousness when vapours are inhaled for sufficient time.

• Molecular Formula : CHCl3

• Molar Mass : 119.38 g/mol

• Appearance : Colorless liquid

• Density : 1.483 g/c

• Melting Point : 63.5 oC

• Boiling Point : 61.2 oC

• Molecular shape : Tetrahedral

HEALTH HAZARDS

• Toxic by inhalation or ingestion.

• Harmful, irritant and possibly carcinogenic after prolonged exposure.

• Immediate symptoms following ingestion or inhalation include excitement and nausea followed by dizziness, drowsiness, coma and convulsions.

• Delayed effects may include kidney and liver damage.

• Inhalation causes shortness of breath and dryness of the mouth and throat.

• Ingestion causes a burning sensation of the mouth and throat and stomach upset.

• Skin or eye contact may cause irritation and inflammation.

PRODUCTION

In industry, chloroform is produced by heating a mixture of chlorine and either chloromethane or methane.

At 400–500 °C, a free radical halogenation occurs, converting these precursors to progressively more chlorinated compounds:

 +  →  + HCl  +  →  + HCl  +  →  + HClChloroform undergoes further chlorination to yield carbon tetrachloride (CCl4):

 +  →  + HCl The output of this process is a mixture of the four chloromethanes (chloromethane,

dichloromethane, chloroform, and carbon tetrachloride), which can then be separated by distillation.

The above method is used in industries for the production of chloroform while other methods are also used.

Hydrolysis of Bleaching Powder. Chloroform is mainly obtained commercially by the action of bleaching powder on alcohol or on

acetone. Its technical preparation is described in Chemiker-Zeitung (1886, 10, 338), as follows.The bleaching powder acts partly as an oxidising agent and partly as a chlorinating agent, first converting the alcohol, through various intermediate stages, into chloral, CCl3CHO.

This is then decomposed by the calcium hydroxide of the bleaching powder into chloroform and calcium formate:

2CCl3CHO

+ Ca(OH)2 2CHCl3 + Ca(OCHO)2.

Chloral. Chloroform. Calcium formate.

(2) Reduction of carbon-tetrachloride The method is used for the production of chloroform on large scale by

reduction of carbon tetrachloride with iron fillings as catalyst and water.

+HCl

But, the product obtained form the method is not pure and is mainly used as a solvent.

(3) Distilling chloral hydrate Chloroform is obtained as a product by distillation of chloral hydrate

with conc. Sodium hydroxide solution.

+ NaOH

USES In the late 19th and early 20th centuries, chloroform was used as an inhaled

anesthetic during surgery. However, safer, more flexible drugs have entirely replaced it in this role. The major use of chloroform today is in the production of the freon refrigerant R-22. However, this use can be expected to decline as R-22 is replaced by refrigerants that are less liable to result in ozone depletion.

Smaller amounts of chloroform are used as a solvent in the pharmaceutical industry, and for producing dyes and pesticides.

Chloroform is often used as a tool in kidnapping, especially in books and movies.

Chloroform containing deuterium (heavy hydrogen), CDCl3, is the most common solvent used in Nuclear Magnetic Resonance (NMR) spectroscopy.

Chloroform was mainly used as a anaesthetic during ancient time when the anaesthesia was not invented.

Chloroform is also used as a reagent in many industrial reactions, for eg.-generally affects the ortho-formylation of activated aromatic rings such as phenols, producing aryl aldehydes like Reimer- Teimann reaction, Kharasch addition.

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