Gilman Reagent & Organocuprates

The Organic Chemistry Tutor
11 Jul 202006:05
EducationalLearning
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TLDRThis educational video delves into the synthesis and applications of the Gilman reagent, an organocuprate, highlighting its preparation from organolithium compounds and copper iodide. It underscores the reagent's utility in converting alkyl halides to alkanes, facilitating carbon-carbon bond formation, and its stereo-specific reactions with vinyl halides, preserving the double bond configuration. The video also clarifies the reagent's limitations, such as its inability to react with aldehydes or ketones, and contrasts its behavior with Grignard reagents in reactions with Ξ±,Ξ²-unsaturated ketones, emphasizing the distinct outcomes of 1,4 addition versus reduction.

Takeaways
  • πŸ§ͺ The Gilman reagent, also known as an organocuprate, is synthesized by reacting an organolithium compound with copper iodide in THF, yielding lithium iodide as a byproduct.
  • πŸ” The typical structure of the Gilman reagent features two R groups, a copper, and a lithium atom attached.
  • πŸ›  It is particularly useful for converting alkyl halides into alkanes by replacing the halogen with an R group, facilitating carbon-carbon bond formation.
  • πŸ”„ The reagent can also replace the halogen in vinyl halides while retaining the stereospecific configuration of the double bond.
  • 🚫 SN2 reactions, which are ineffective with enol or aero halides, can be bypassed using the Gilman reagent for the same substrates.
  • 🌐 The Gilman reagent can replace the bromine in an aryl halide, such as bromobenzene, to produce toluene.
  • ❌ It does not react with aldehydes or ketones, leaving the ketone group unaffected even when the halogen is displaced.
  • πŸ”„ In the case of an Ξ±,Ξ²-unsaturated ketone, the Gilman reagent leads to a 1,4 addition product, with the R group added to the Ξ²-carbon, eliminating the conjugated double bond.
  • πŸ†š In contrast, a Grignard reagent would reduce the ketone to an alcohol and add the R group to the tertiary carbon, without affecting the double bond.
  • πŸ“š Understanding the reactivity and selectivity of the Gilman reagent is crucial for predicting the outcome of organic reactions involving halides and unsaturated compounds.
  • πŸ”¬ The script emphasizes the importance of stereochemistry in reactions involving vinyl halides and the specificity of the Gilman reagent in different substrates.
Q & A

  • What is the Gilman reagent also known as?

    -The Gilman reagent is also known as an organocuprate.

  • How is the Gilman reagent prepared?

    -The Gilman reagent is prepared by reacting an organolithium compound with copper iodide in THF, producing the reagent and lithium iodide as a side product.

  • What is the typical formula of the Gilman reagent?

    -The typical formula of the Gilman reagent consists of two R groups, a copper, and a lithium atom attached to it.

  • What is the primary use of the Gilman reagent?

    -The primary use of the Gilman reagent is to convert alkyl halides into alkanes by replacing the halogen with an R group.

  • How does the Gilman reagent facilitate the formation of carbon-carbon bonds?

    -The Gilman reagent facilitates the formation of carbon-carbon bonds by replacing the halogen in alkyl halides with an R group, thus creating new alkane products.

  • Is the Gilman reagent stereospecific in its reactions?

    -Yes, the Gilman reagent is stereospecific, meaning the configuration at the double bond is retained and does not change during the reaction.

  • Can the Gilman reagent replace halogens in vinyl halides?

    -Yes, the Gilman reagent can replace the halogen in vinyl halides, allowing for the formation of new compounds with an R group at the site of the former halogen.

  • Why are SN2 reactions not effective with enol or enol halides?

    -SN2 reactions are not effective with enol or enol halides because these substrates do not allow for the nucleophile to replace the leaving group in such reactions.

  • How does the Gilman reagent differ from other nucleophilic reagents in its reaction with enol or enol halides?

    -The Gilman reagent is unique in that it can replace the bromine in enol or enol halides, which is not possible with traditional SN2 reactions.

  • Does the Gilman reagent react with aldehydes or ketones?

    -No, the Gilman reagent does not react with aldehydes or ketones; it specifically targets halogens for replacement with an R group.

  • What happens when an alpha, beta-unsaturated ketone is mixed with a Gilman reagent?

    -When an alpha, beta-unsaturated ketone is mixed with a Gilman reagent, a 1,4 addition product is formed, with the R group added to the beta carbon, and the ketone remains unaffected.

  • How does the reaction differ when using a Grignard reagent instead of a Gilman reagent on an alpha, beta-unsaturated ketone?

    -When using a Grignard reagent, the ketone is reduced into an alcohol, and the R group is added at the tertiary carbon, with the double bond remaining unaffected.

Outlines
00:00
πŸ§ͺ Gilman Reagent Preparation and Applications

This paragraph introduces the Gilman reagent, also known as an organocuprate, and its preparation method. It involves the reaction of an organolithium compound with copper iodide in THF, resulting in the Gilman reagent and lithium iodide as a byproduct. The reagent is characterized by having two R groups, a copper, and a lithium atom. It is highlighted for its utility in converting alkyl halides into alkanes, exemplified by the replacement of a bromine group with a methyl group. The paragraph also discusses the reagent's ability to form carbon-carbon bonds and its stereo-specificity in reactions with vinyl halides, where the configuration at the double bond is retained.

05:00
πŸ” Gilman Reagent's Selectivity and Reactions with Unsaturated Compounds

The second paragraph delves into the selectivity of the Gilman reagent, noting its inability to react with aldehydes or ketones, as demonstrated by an example where a ketone group remains unaffected while a bromine leaving group is displaced. The paragraph also contrasts the Gilman reagent with a Grignard reagent, showing that while the Gilman reagent adds to an alpha-beta unsaturated ketone resulting in a 1,4 addition (conjugate addition) and the disappearance of the double bond, the Grignard reagent would reduce the ketone to an alcohol and add to the tertiary carbon without affecting the double bond. This comparison underscores the unique reactivity and selectivity of the Gilman reagent in organic synthesis.

Mindmap
Keywords
πŸ’‘Gilman Reagent
The Gilman Reagent, also known as an organocuprate, is a chemical compound that plays a central role in the video. It is prepared by reacting an organolithium compound with copper iodide in THF, resulting in a reagent with two R groups, a copper, and a lithium atom. The Gilman Reagent is crucial for converting alkyl halides into alkanes and is highlighted in the script as a versatile tool in organic chemistry for creating carbon-carbon bonds.
πŸ’‘Organolithium Compound
An organolithium compound is a key starting material for the synthesis of the Gilman Reagent. These compounds contain a lithium atom bonded to a carbon atom and are highly reactive, making them useful in organic synthesis. In the script, the organolithium compound reacts with copper iodide to form the Gilman Reagent, which is then used in various reactions throughout the video.
πŸ’‘Copper Iodide
Copper iodide is a chemical salt used in the preparation of the Gilman Reagent. It provides the copper atom necessary for the formation of the organocuprate. In the script, copper iodide reacts with an organolithium compound in THF to produce the Gilman Reagent, with lithium iodide as a byproduct.
πŸ’‘THF (Tetrahydrofuran)
Tetrahydrofuran, commonly abbreviated as THF, is a solvent used in the synthesis of the Gilman Reagent. It provides a suitable environment for the reaction between the organolithium compound and copper iodide. The script mentions THF as the medium in which the Gilman Reagent is made.
πŸ’‘Alkyl Halides
Alkyl halides are organic compounds in which an alkyl group is attached to a halogen atom. They are important in the context of the video because the Gilman Reagent is used to convert these compounds into alkanes by replacing the halogen with an R group. The script provides examples of such reactions, illustrating the reagent's utility in organic synthesis.
πŸ’‘Alkanes
Alkanes are saturated hydrocarbons containing only single bonds between carbon atoms. In the video, the Gilman Reagent is shown to be effective in converting alkyl halides into alkanes, which is a significant transformation in organic chemistry. The script demonstrates this by showing the replacement of a bromine group with a methyl group.
πŸ’‘Vanillyl Halide
A vanillal halide is a specific type of alkyl halide that contains a vanillal group attached to a halogen. The script discusses the use of the Gilman Reagent to replace the halogen in a vanillal halide, retaining the stereospecificity of the double bond, which is an important aspect of the reaction's selectivity.
πŸ’‘Stereospecificity
Stereospecificity refers to the ability of a chemical reaction to occur in such a way that the stereochemistry of the reactants is preserved in the products. In the context of the video, the Gilman Reagent's reaction with vanillal halides is stereospecific, meaning the configuration at the double bond remains unchanged after the reaction.
πŸ’‘Arenium Ion
An arenium ion is an intermediate species in certain types of aromatic substitution reactions. The script mentions that the Gilman Reagent can be used to replace a leaving group in an arenium ion, such as a bromine atom, with an R group, which is not possible with traditional SN2 reactions on vinyl or aryl halides.
πŸ’‘SN2 Reaction
An SN2 reaction, or bimolecular nucleophilic substitution, is a type of reaction where a nucleophile replaces a leaving group in a single step. The script points out that SN2 reactions are not effective with vinyl or aryl halides, which is where the Gilman Reagent's unique properties come into play.
πŸ’‘Alpha Beta Unsaturated Ketone
An alpha beta unsaturated ketone is a compound with a carbonyl group and a carbon-carbon double bond in proximity, with the double bond being separated from the carbonyl by one single bond (alpha) and one double bond (beta). The script describes a reaction where the Gilman Reagent adds to the beta carbon of such a ketone, leading to the disappearance of the conjugated double bond.
πŸ’‘Conjugate Addition
Conjugate addition is a type of reaction where a nucleophile adds to the beta carbon of an alpha beta unsaturated system. In the video, the Gilman Reagent is shown to undergo conjugate addition to an alpha beta unsaturated ketone, resulting in the formation of a new carbon-carbon bond and the elimination of the conjugated double bond.
πŸ’‘Grignard Reagent
A Grignard reagent, named after its discoverer Victor Grignard, is a type of organometallic compound used in organic synthesis. The script contrasts the behavior of the Gilman Reagent with that of a Grignard reagent, noting that while the Gilman Reagent adds to the beta carbon of an alpha beta unsaturated ketone, a Grignard reagent would reduce the ketone to an alcohol.
Highlights

Introduction to the Gilman reagent, also known as an organocuprate.

Explanation of how the Gilman reagent is made using organolithium compound and copper iodide in THF.

Lithium iodide as a side product in the creation of the Gilman reagent.

Typical formula of the Gilman reagent with two R groups, copper, and a lithium atom.

Utility of the Gilman reagent in converting alkyl halides into alkanes.

Demonstration of replacing the bromine group with a CH3 group using the Gilman reagent.

The reagent's role in facilitating carbon-carbon bond formation.

Stereospecificity of the reaction where the configuration at the double bond is retained.

Replacement of the halogen in a vinyl halide using CH3CuLi.

Incompatibility of SN2 reactions with enol or enolates halides.

Advantage of the Gilman reagent in dealing with poor leaving groups in certain substrates.

Conversion of bromobenzene to toluene using the Gilman reagent.

The Gilman reagent's lack of reactivity with aldehydes or ketones.

Predictability of the product when using the Gilman reagent by simply replacing the halogen with the R group.

1,4 addition product formation with alpha, beta-unsaturated ketones using the Gilman reagent.

Conjugated double bond disappearance after the addition reaction with the Gilman reagent.

Difference in reaction with a Grignard reagent, leading to ketone reduction and R group addition at the tertiary carbon.

Transcripts

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Related Tags
Gilman ReagentOrganocuprateChemical SynthesisAlkyl HalidesAlkanesCarbon-Carbon BondsStereospecific ReactionsOrganolithium CompoundsCopper IodideTHF