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Between aldehyde and alkyl halide, which is more reactive?
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Matthew Arslan
Between aldehyde and alkyl halide, which is more reactive?
Thanks on A2A.
The question is tricky, as most time alkyl halides are seen as chemical species undergoing base-promoted eliminations or nucleophilic substitutions. Mostly, due to the distribution of the electron density, meaning alkyl group has lower electron density than the halogen and thus it is prone to nucleophilic attack, not to an electrophilic attack.
That's it, if the focus of the reaction is set on the carbon center in the alkyl halide.
However, the halogen atom has its own reactivity. Halogen atoms in alkyl halides are very weak nucleophiles -this explains why most time they behave as a nucleofuge or leaving group in SN1 or SN2 reactions-. On being such weak nucleophiles, it’s not easy to find an electrophile strong enough to undergo reaction with them. But there are some species, anyway.
Much work made by Oláh György (George Andrew Olah, Nobel Prize 1994 on carbocation chemistry, died on March 8th, almost one month ago) implicitly was made with very strong electrophiles, capable of taking of halogen atoms in alkyl halides, with the generation of carbenium ions (ions where there is a formal positive charge on a trivalent carbon atom). Such electrophiles include very strong non-organic chemical species: antimonium pentafluoride, SbF5, and sometimes boron trifluoride, BF3.
Most time, the substrates for these substances are the alkyl fluorides. I think I read about R-OH (alcohols) undergoing the reaction, but never alkyl bromides or alkyl iodides.
Be aware! It’s not the reactivity on the carbon atom, as it is an electrophile, but on the halogen atom, as it is a weak nucleophile.
The question is tricky, as most time alkyl halides are seen as chemical species undergoing base-promoted eliminations or nucleophilic substitutions. Mostly, due to the distribution of the electron density, meaning alkyl group has lower electron density than the halogen and thus it is prone to nucleophilic attack, not to an electrophilic attack.
That's it, if the focus of the reaction is set on the carbon center in the alkyl halide.
However, the halogen atom has its own reactivity. Halogen atoms in alkyl halides are very weak nucleophiles -this explains why most time they behave as a nucleofuge or leaving group in SN1 or SN2 reactions-. On being such weak nucleophiles, it’s not easy to find an electrophile strong enough to undergo reaction with them. But there are some species, anyway.
Much work made by Oláh György (George Andrew Olah, Nobel Prize 1994 on carbocation chemistry, died on March 8th, almost one month ago) implicitly was made with very strong electrophiles, capable of taking of halogen atoms in alkyl halides, with the generation of carbenium ions (ions where there is a formal positive charge on a trivalent carbon atom). Such electrophiles include very strong non-organic chemical species: antimonium pentafluoride, SbF5, and sometimes boron trifluoride, BF3.
Most time, the substrates for these substances are the alkyl fluorides. I think I read about R-OH (alcohols) undergoing the reaction, but never alkyl bromides or alkyl iodides.
Be aware! It’s not the reactivity on the carbon atom, as it is an electrophile, but on the halogen atom, as it is a weak nucleophile.
Halogen containing organic compounds are relatively rare in terrestrial plants and animals. The thyroid hormones T3 and T4are exceptions; as is fluoroacetate, the toxic agent in the South African shrub Dichapetalum cymosum, known as "gifblaar". However, the halogen rich environment of the ocean has produced many interesting natural products incorporating large amounts of halogen. Some examples are shown below. The ocean is the largest known source for atmospheric methyl bromide and methyl iodide. Furthermore, the ocean is also estimated to supply 10-20% of atmospheric methyl chloride, with other significant contributions coming from biomass burning, salt marshes and wood-rotting fungi. Many subsequent chemical and biological processes produce poly-halogenated methanes.
Halogen containing organic compounds are relatively rare in terrestrial plants and animals. The thyroid hormones T3 and T4are exceptions; as is fluoroacetate, the toxic agent in the South African shrub Dichapetalum cymosum, known as "gifblaar". However, the halogen rich environment of the ocean has produced many interesting natural products incorporating large amounts of halogen. Some examples are shown below. The ocean is the largest known source for atmospheric methyl bromide and methyl iodide. Furthermore, the ocean is also estimated to supply 10-20% of atmospheric methyl chloride, with other significant contributions coming from biomass burning, salt marshes and wood-rotting fungi. Many subsequent chemical and biological processes produce poly-halogenated methanes.
Thanks on A2A.
The question is tricky, as most time alkyl halides are seen as chemical species undergoing base-promoted eliminations or nucleophilic substitutions. Mostly, due to the distribution of the electron density, meaning alkyl group has lower electron density than the halogen and thus it is prone to nucleophilic attack, not to an electrophilic attack.
That's it, if the focus of the reaction is set on the carbon center in the alkyl halide.
However, the halogen atom has its own reactivity. Halogen atoms in alkyl halides are very weak nucleophiles -this explains why most time they behave as a nucleofuge or leaving group in SN1 or SN2 reactions-. On being such weak nucleophiles, it’s not easy to find an electrophile strong enough to undergo reaction with them. But there are some species, anyway.
Much work made by Oláh György (George Andrew Olah, Nobel Prize 1994 on carbocation chemistry, died on March 8th, almost one month ago) implicitly was made with very strong electrophiles, capable of taking of halogen atoms in alkyl halides, with the generation of carbenium ions (ions where there is a formal positive charge on a trivalent carbon atom). Such electrophiles include very strong non-organic chemical species: antimonium pentafluoride, SbF5, and sometimes boron trifluoride, BF3.
Most time, the substrates for these substances are the alkyl fluorides. I think I read about R-OH (alcohols) undergoing the reaction, but never alkyl bromides or alkyl iodides.
Be aware! It’s not the reactivity on the carbon atom, as it is an electrophile, but on the halogen atom, as it is a weak nucleophile.
Thanks on A2A.
The question is tricky, as most time alkyl halides are seen as chemical species undergoing base-promoted eliminations or nucleophilic substitutions. Mostly, due to the distribution of the electron density, meaning alkyl group has lower electron density than the halogen and thus it is prone to nucleophilic attack, not to an electrophilic attack.
That's it, if the focus of the reaction is set on the carbon center in the alkyl halide.
However, the halogen atom has its own reactivity. Halogen atoms in alkyl halides are very weak nucleophiles -this explains why most time they behave as a nucleofuge or leaving group in SN1 or SN2 reactions-. On being such weak nucleophiles, it’s not easy to find an electrophile strong enough to undergo reaction with them. But there are some species, anyway.
Much work made by Oláh György (George Andrew Olah, Nobel Prize 1994 on carbocation chemistry, died on March 8th, almost one month ago) implicitly was made with very strong electrophiles, capable of taking of halogen atoms in alkyl halides, with the generation of carbenium ions (ions where there is a formal positive charge on a trivalent carbon atom). Such electrophiles include very strong non-organic chemical species: antimonium pentafluoride, SbF5, and sometimes boron trifluoride, BF3.
Most time, the substrates for these substances are the alkyl fluorides. I think I read about R-OH (alcohols) undergoing the reaction, but never alkyl bromides or alkyl iodides.
Be aware! It’s not the reactivity on the carbon atom, as it is an electrophile, but on the halogen atom, as it is a weak nucleophile.
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Alkyl Halide Occurrence
Halogen containing organic compounds are relatively rare in terrestrial plants and animals. The thyroid hormones T3 and T4are exceptions; as is fluoroacetate, the toxic agent in the South African shrub Dichapetalum cymosum, known as "gifblaar". However, the halogen rich environment of the ocean has produced many interesting natural products incorporating large amounts of halogen. Some examples are shown below.
The ocean is the largest known source for atmospheric methyl bromide and methyl iodide. Furthermore, the ocean is also estimated to supply 10-20% of atmospheric methyl chloride, with other significant contributions coming from biomass burning, salt marshes and wood-rotting fungi. Many subsequent chemical and biological processes produce poly-halogenated methanes.
Alkyl Halide Occurrence
Halogen containing organic compounds are relatively rare in terrestrial plants and animals. The thyroid hormones T3 and T4are exceptions; as is fluoroacetate, the toxic agent in the South African shrub Dichapetalum cymosum, known as "gifblaar". However, the halogen rich environment of the ocean has produced many interesting natural products incorporating large amounts of halogen. Some examples are shown below.
The ocean is the largest known source for atmospheric methyl bromide and methyl iodide. Furthermore, the ocean is also estimated to supply 10-20% of atmospheric methyl chloride, with other significant contributions coming from biomass burning, salt marshes and wood-rotting fungi. Many subsequent chemical and biological processes produce poly-halogenated methanes.
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