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Haloalkane or alkyl halides are the compounds which have the general formula "RX" where R is an alkyl or substituted alkyl group and X is a halogen (F, Cl, Br, I). Haloalkanes have been known for centuries. Chloroethane was produced in the 15th century. The systematic synthesis of such compounds developed in the 19th century in step with the ...
Darzens halogenation is the chemical synthesis of alkyl halides from alcohols via the treatment upon reflux of a large excess of thionyl chloride or thionyl bromide (SOX 2) in the presence of a small amount of a nitrogen base, such as a tertiary amine or pyridine or its corresponding hydrochloride or hydrobromide salt.
Primary alkyl halides react with aqueous NaOH or KOH to give alcohols in nucleophilic aliphatic substitution. Secondary and especially tertiary alkyl halides will give the elimination (alkene) product instead. Grignard reagents react with carbonyl groups to give secondary and tertiary alcohols.
Hydroalkoxylation is a chemical reaction that combines alcohols with alkenes or alkynes. The process affords ethers. The reaction converts alkenes to dialkyl or aryl-alkyl ethers: R'OH + RCH=CH 2 → R'OCH(R)-CH 3. Similarly, alkynes are converted to vinyl ethers: R'OH + RC≡CH → R'OC(R)=CH 2. As shown, the reaction follows the Markovnikov rule.
Industrially, most alkylations are typically conducted using alcohols, not alkyl halides. Alcohols are less expensive than alkyl halides and their alkylation does not produce salts, the disposal of which can be problematic. Key to the alkylation of alcohols is the use of catalysts that render the hydroxyl group a good leaving group.
In organic chemistry, the Wurtz reaction, named after Charles Adolphe Wurtz, is a coupling reaction in which two alkyl halides are treated with sodium metal to form a higher alkane. 2 R−X + 2 Na → R−R + 2 NaX. The reaction is of little value except for intramolecular versions, such as 1,6-dibromohexane + 2 Na → cyclohexane + 2 NaBr.
Hydroboration produces organoborane compounds that react with a variety of reagents to produce useful compounds, such as alcohols, amines, or alkyl halides. The most widely known reaction of the organoboranes is oxidation to produce alcohols from alkenes.
Deprotonation of the alcohol, forming chloroform, yields an alkoxide 5. The nucleophilic displacement of the chloride by the alkoxide yields intermediate 7. With primary and secondary alcohols, the halide reacts in a S N 2 process forming the alkyl halide 8 and triphenylphosphine oxide. Tertiary alcohols form the products 6 and 7 via a S N 1 ...