Halide Elimination
Halide Elimination - Related Videos
02:45
Alkyl Halides
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2023
Structural Properties Alkyl halides are halogen-substituted alkanes wherein one or more hydrogen atoms of an alkane is replaced by a halogen atom such as fluorine, chlorine, bromine, or iodine. The carbon atom in an alkyl halide is bonded to the halogen atom, which is sp3-hybridized and exhibits a tetrahedral shape. Unlike alkyl halides, compounds in which a halogen atom is bonded to an sp2 -hybridized carbon atom of a carbon-carbon double bond (C=C) are called vinyl halides. Whereas aryl...
01:12
Acid Halides to Esters: Alcoholysis
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2025
Alcoholysis is a nucleophilic acyl substitution reaction in which an alcohol functions as a nucleophile. Acid halides react with alcohol to produce esters. The mechanism proceeds in three steps: First, the alcohol acts as a nucleophile and attacks the acyl carbon to form a tetrahedral intermediate. Next, the carbonyl re-forms with the loss of a chloride ion. Lastly, the positively charged intermediate loses a proton to give an ester as the final product along with H3O+, making HCl an...
08:12
Low Pressure Vapor-assisted Solution Process for Tunable Band Gap Pinhole-free Methylammonium Lead Halide Perovskite Films
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Cited by 2 •
2017
Here, we present a protocol for the synthesis of CH3NH3I and CH3NH3Br precursors and the subsequent formation of pinhole-free, continuous CH3NH3PbI3-xBrx thin films for the application in high efficiency solar cells and other optoelectronic devices.
01:22
Mass Spectrometry: Alkyl Halide Fragmentation
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2025
Chlorine isotopes exist as 35Cl and 37Cl in a 3:1 ratio, while bromine isotopes exist as 79Br and 81Br in a 1:1 ratio. The mass spectrum of alkyl halides typically produces two distinct molecular ion peaks, the molecular ion peak, [M], and the molecular ion plus two, [M + 2] peak. The relative heights of these two peaks are proportional to the isotopic abundance ratios of the halide. For example, 2‐chloropropane and 1‐bromopropane display two peaks with relative peak heights in a 3:1 and 1:1...
01:01
Acid Halides to Carboxylic Acids: Hydrolysis
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2025
Hydrolysis of acid halides is a nucleophilic acyl substitution reaction in which acid halides react with water to give carboxylic acids. The reaction occurs readily and does not require acid or a base catalyst. As shown below, the mechanism involves a nucleophilic attack by water at the carbonyl carbon to form a tetrahedral intermediate. This is followed by the reformation of the carbon–oxygen π bond along with the departure of a halide ion. A final proton transfer step yields carboxylic acid...
FAQs
E2 elimination proceeds through a single concerted step: a strong base removes a hydrogen from the carbon adjacent to the one bearing the halide, while the carbon–halogen bond breaks and the alkene forms. Because these changes occur together, the substrate structure and the reacting base jointly influence which alkene and stereochemical outcome result.
E1 elimination first generates a carbocation, so conditions that stabilize this intermediate favor the pathway. The subsequent loss of a hydrogen produces the alkene. This stepwise sequence differs from E2 elimination because carbocation formation becomes a central mechanistic feature, making substrate structure and the surrounding reaction conditions especially important to the observed outcome.
Regioselectivity, the preference for forming one alkene location over another, depends on substrate structure, base, solvent, and temperature. These variables can change which adjacent hydrogen is removed and therefore which carbon–carbon double bond forms. Examining the possible alkene products helps chemists connect reaction conditions with the distribution of products.
The key distinction is the timing of bond changes. E2 elimination combines base removal of a β-hydrogen, C–X bond cleavage, and alkene formation in one concerted event. E1 elimination separates these events through carbocation formation. Comparing the pathways helps explain why different substrates and conditions can favor different mechanisms and products.
Condition selection begins with the factors identified as influential in the reaction: substrate structure, base, solvent, and temperature. Chemists consider how these variables affect the relative likelihood of E2 or E1 behavior and the alkene outcome. Adjusting the conditions provides a way to study or guide regioselectivity, stereochemistry, and mechanism.
The alkene product provides evidence about both reaction outcome and mechanism. Its position reveals regioselectivity, while its arrangement reflects stereochemical effects associated with the elimination. Comparing products under different conditions can show how substrate structure, base, solvent, and temperature influence the reaction, making product analysis useful in synthetic planning and mechanistic studies.