Related Experiment Video
Updated: Jun 12, 2025
12:27
Synthesis of Hypervalent Iodonium Alkynyl Triflates for the Application of Generating Cyanocarbenes
Published on: September 8, 2013
10.8K
Synthesis and Stabilization of Highly Reactive Haloacetylium Ions
Sebastian Steiner1, Christoph Jessen1, Alexander Nitzer1
1Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377 Munich, Germany.
The Journal of Organic Chemistry
|September 23, 2024
Summary
Reactions of haloacetyl fluorides with Lewis acids AsF5 and SbF5 yielded O-coordinated adducts or haloacetylium ions. These ions are stabilized in solids by intermolecular contacts and anion interactions.
Area of Science:
- Inorganic Chemistry
- Supramolecular Chemistry
- Computational Chemistry
Background:
- Haloacetyl fluorides are versatile precursors in synthetic chemistry.
- Strong Lewis acids like arsenic pentafluoride (AsF5) and antimony pentafluoride (SbF5) are potent electrophiles.
- Understanding the reactivity of acyl halides with Lewis acids is crucial for synthesizing novel ionic compounds.
Purpose of the Study:
- To investigate the reactions of haloacetyl fluorides with AsF5 and SbF5.
- To characterize the resulting O-coordinated adducts and haloacetylium ions.
- To elucidate the stabilization mechanisms of haloacetylium ions in the solid state.
Main Methods:
- Reactions were conducted in the aprotic solvent SO2ClF.
- Products were isolated as solids and characterized by low-temperature vibrational spectroscopy.
- Single-crystal X-ray diffraction was used to determine the crystal structures of specific compounds.
- Quantum chemical calculations (BP/def2SVPP) were employed to assess fluoride ion affinities.
Main Results:
- O-coordinated adducts and haloacetylium ions were successfully isolated depending on stoichiometry.
- [CClH2CO][Sb2F11] and [CH2FCO][Sb2F11] were characterized crystallographically, space group P21.
- Quantum chemical calculations supported the observed reactivity patterns.
- Solid-state stabilization of haloacetylium ions involves C…F contacts and anion interactions.
Conclusions:
- The study demonstrates controlled synthesis of O-coordinated adducts and haloacetylium ions.
- Structural analysis reveals key intermolecular and intramolecular stabilization factors for haloacetylium ions.
- Computational data provides insights into the electronic basis of reactivity and stability.
Related Concept Videos
01:21Acid-Catalyzed α-Halogenation of Aldehydes and Ketones
3.7K
By replacing an α-hydrogen with a halogen, acid-catalyzed α-halogenation of aldehydes or ketones yields a monohalogenated product
In the first step of the mechanism, the acid protonates the carbonyl oxygen resulting in a resonance-stabilized cation, which subsequently loses an α-hydrogen to form an enol tautomer. The C=C bond in an enol is highly nucleophilic because of the electron-donating nature of the –OH group. Consequently, the double bond attacks an electrophilic halogen to form a...
In the first step of the mechanism, the acid protonates the carbonyl oxygen resulting in a resonance-stabilized cation, which subsequently loses an α-hydrogen to form an enol tautomer. The C=C bond in an enol is highly nucleophilic because of the electron-donating nature of the –OH group. Consequently, the double bond attacks an electrophilic halogen to form a...
3.7K
01:17Reactions of α-Halocarbonyl Compounds: Nucleophilic Substitution
3.2K
Nucleophilic substitution in α-halocarbonyl compounds can be achieved via an SN2 pathway. The reaction in α-haloketones is generally carried out with less basic nucleophiles. The use of strong basic nucleophiles leads to the generation of α-haloenolate ions, which often participate in other side reactions.
3.2K
02:38Electrophilic Addition to Alkynes: Halogenation
8.2K
Introduction
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
8.2K
01:28Multiple Halogenation of Methyl Ketones: Haloform Reaction
2.0K
A method involving the transformation of methyl ketones to carboxylic acids using excess base and halogen is called the haloform reaction. It begins with the deprotonation of α hydrogen to form an enolate ion which reacts with the electrophilic halogen to give an α-halo ketone. The step continues until all the α protons are substituted to form a trihalomethyl ketone. The resulting molecule is unstable, and in the presence of a hydroxide base, it readily undergoes nucleophilic...
2.0K
01:14α-Halogenation of Carboxylic Acid Derivatives: Overview
3.3K
Unlike aldehydes and ketones, carboxylic acids do not readily participate in α halogenation reactions via enols or enolate intermediates. However, α-halogenated acids are obtained through other methods. One of the approaches is the Hell–Volhard–Zelinsky (HVZ) reaction, wherein the carboxylic acid is treated with halogen in the presence of PBr3. It involves the conversion of acid to acid halide, which exists in equilibrium with its enol form. The enol attacks the...
3.3K
01:01Acid Halides to Carboxylic Acids: Hydrolysis
2.6K
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...
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...
2.6K