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Questions and Answers
What type of halide is dichloromethane classified as?
What type of halide is dichloromethane classified as?
What is the main reason why the preparation of aryl halides is challenging?
What is the main reason why the preparation of aryl halides is challenging?
Which of the following compounds is considered an aryl halide?
Which of the following compounds is considered an aryl halide?
Which of the following methods can yield vic-dibromides during alkene reactions?
Which of the following methods can yield vic-dibromides during alkene reactions?
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What is the key characteristic of the products obtained from the free radical chlorination of alkanes?
What is the key characteristic of the products obtained from the free radical chlorination of alkanes?
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What is the result of nucleophilic substitution in SN2 reactions of chiral alkyl halides?
What is the result of nucleophilic substitution in SN2 reactions of chiral alkyl halides?
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According to Markovnikov's rule, which product predominates when propene reacts with hydrogen halides?
According to Markovnikov's rule, which product predominates when propene reacts with hydrogen halides?
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How are alkyl halides generally prepared?
How are alkyl halides generally prepared?
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Which of the following statements about DDT is true?
Which of the following statements about DDT is true?
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What kind of reaction is the Finkelstein reaction?
What kind of reaction is the Finkelstein reaction?
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Which type of halide is characterized by a halogen bonded to an sp2-hybridised carbon in a carbon-carbon double bond?
Which type of halide is characterized by a halogen bonded to an sp2-hybridised carbon in a carbon-carbon double bond?
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How are geminal halides specifically defined?
How are geminal halides specifically defined?
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How many different monochloro structural isomers can be formed from the free radical monochlorination of (CH3)2CHCH2CH3?
How many different monochloro structural isomers can be formed from the free radical monochlorination of (CH3)2CHCH2CH3?
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What classification best describes a compound containing three halogen atoms?
What classification best describes a compound containing three halogen atoms?
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What occurs during the addition of bromine to an alkene in a laboratory setting?
What occurs during the addition of bromine to an alkene in a laboratory setting?
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What is the IUPAC naming convention for dihalogen derivatives of benzene?
What is the IUPAC naming convention for dihalogen derivatives of benzene?
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What is a characteristic feature of the boiling points of organohalogen compounds compared to corresponding hydrocarbons?
What is a characteristic feature of the boiling points of organohalogen compounds compared to corresponding hydrocarbons?
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Why is the separation of products from free radical halogenation of alkanes difficult?
Why is the separation of products from free radical halogenation of alkanes difficult?
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Which of the following describes an aryl halide?
Which of the following describes an aryl halide?
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In nucleophilic substitution reactions, what role does the polarity of the carbon-halogen bond play?
In nucleophilic substitution reactions, what role does the polarity of the carbon-halogen bond play?
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Which of the following best describes vicinal halides?
Which of the following best describes vicinal halides?
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In the nomenclature of alkyl halides, how are they commonly named?
In the nomenclature of alkyl halides, how are they commonly named?
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What is a characteristic feature of benzylic halides?
What is a characteristic feature of benzylic halides?
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What type of halides do the terms alkylidene or alkylene dihalides refer to?
What type of halides do the terms alkylidene or alkylene dihalides refer to?
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Study Notes
Haloalkanes and Haloarenes
- Halogenated compounds persist in the environment due to resistance to breakdown by soil bacteria.
- Replacement of hydrogen atoms in an aliphatic or aromatic hydrocarbon by halogen atoms forms alkyl halides (haloalkanes) and aryl halides (haloarenes).
- Haloalkanes have halogen atoms attached to sp³ hybridized carbon atoms in an alkyl group.
- Haloarenes have halogen atoms attached to sp² hybridized carbon atoms in an aryl group.
- Many halogen-containing organic compounds occur in nature and are clinically useful.
- These compounds are used as solvents and starting materials for various organic compounds.
- Examples include Chloramphenicol (antibiotic) and Thyroxine (hormone).
- Also used as anesthetics (e.g., halothane) and potential blood substitutes.
Classification
- Classified as mono, di, or polyhalogen compounds based on the number of halogen atoms.
- Alkyl halides (or haloalkanes) are further classified as primary, secondary, or tertiary based on the nature of the carbon atom to which the halogen atom is attached.
- Allylic halides have halogen attached to an sp³-hybridized carbon adjacent to a double bond.
- Benzylic halides have halogen attached to an sp³-hybridized carbon adjacent to an aromatic ring.
Nomenclature
- Common names for alkyl halides are based on the alkyl group followed by the halide name.
- IUPAC naming follows the prefix halo for the type of halogen, followed by the parent hydrocarbon name.
- Specific prefixes (e.g., o-, m-, p-) are used for dihalogenated benzene derivatives in common system, but in IUPAC system, numerical prefixes (1,2; 1,3; 1,4) are used.
Methods of Preparation
- Hydroxyl groups in alcohols are replaced by halogen using concentrated halogen acids, phosphorus halides, or thionyl chloride.
- Tertiary alcohols react with concentrated HCl at room temperature to yield alkyl halides.
- Primary and secondary alcohols react with HCl in the presence of ZnCl₂.
- Alcohols are treated with sodium/potassium iodide in 95% orthophosphoric acid for the synthesis of alkyl iodides.
- Alkyl chlorides are prepared by the reaction of alcohols with dry hydrogen chloride gas or a mixture of the alcohol and concentrated aqueous halogen acid.
- Alkyl halides are also prepared by free radical halogenation or addition of hydrogen halides to alkenes.
- Aryl halides are prepared by electrophilic substitution of arenes with Cl₂/Br₂ in presence of Lewis acid catalysts( Fe/ FeCl₃ )
- Amines can be converted into aryl halides by Sandmeyer's reaction.
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Description
Explore the properties and classifications of halogenated compounds, including haloalkanes and haloarenes. Learn about their environmental persistence, clinical uses, and various organic applications. This quiz covers the nature of the compounds and their significance in chemistry.
