Strecker Synthesis
TLDRThe video script delves into the Ster synthesis, an alternative method for synthesizing amino acids. It begins with the initial step involving the reaction of an aldehyde with ammonia and potassium cyanide, leading to the formation of an intermediate molecule. The process continues with the addition of hydrochloric acid to form an amine, followed by further reactions involving potassium cyanide to transform the molecule. The sequence concludes with acid hydrolysis, resulting in the production of a primary amino acid with a specific R group, depending on the starting aldehyde. The Ster synthesis, alongside other methods like the Strecker synthesis and Gabriel synthesis, offers a valuable approach to amino acid synthesis, highlighting the versatility in creating these essential biological molecules.
Takeaways
- 🧪 The Strecker synthesis is a method for synthesizing amino acids, which is being discussed in the lecture.
- 🔬 The process begins with an aldehyde containing an R group, mixed with ammonia and potassium cyanide to form an intermediate molecule.
- ➡️ A nucleophilic addition occurs where ammonia adds to the carbonyl carbon, followed by a deprotonation and protonation step to form an intermediate.
- 🔁 The addition of hydrochloric acid aids in the formation of the amine by converting the hydroxide to a water molecule, a better leaving group.
- 🔄 Potassium cyanide is used again to transform the molecule, leading to a tetrahedral intermediate with a cyanide group.
- 🌊 Acid hydrolysis is then carried out by adding hydronium in the presence of water, which leads to the formation of the primary amino acid.
- 📜 The general reaction mechanism of the Strecker synthesis is quite lengthy, involving several steps to achieve the final amino acid structure.
- 🔑 The key steps include nucleophilic addition, deprotonation, protonation, and the formation of a carbon-nitrogen double bond.
- ⏩ The process involves the removal of the cyanide group and its replacement with a carbonyl group to form the carboxylic acid of the amino acid.
- 📉 An intramolecular elimination step occurs, which helps in the transformation of the intermediate to the final amino acid structure.
- 🏁 The final product of the Strecker synthesis is an alpha primary amino acid with amine, R group, and carboxylic acid functionalities.
- 📚 The Strecker synthesis, along with the other methods mentioned (halogenation of alpha halo acids and Gabriel synthesis), provides a means to form amino acid molecules in the lab.
Q & A
What are the two methods discussed before the Ster synthesis for synthesizing amino acids?
-The two methods discussed before the Ster synthesis are the Amination of alpha-keto acids and the Gabriel synthesis, also known as the Gabriel-Noda synthesis.
What is the initial reactant in the Ster synthesis?
-The initial reactant in the Ster synthesis is an aldehyde containing an R group.
What are the key reagents used in the first step of the Ster synthesis?
-The key reagents used in the first step of the Ster synthesis are ammonia and potassium cyanide.
What occurs in the second and third steps of the Ster synthesis?
-In the second and third steps, a deprotonation and a protonation step take place, involving the ammonium group and a base, typically ammonia.
How does the addition of hydrochloric acid in the Ster synthesis help in forming the amine?
-The addition of hydrochloric acid helps in forming the amine by protonating the oxygen of the hydroxide group, turning it into a better leaving group (water molecule), which facilitates the formation of the amine.
What is the role of cyanide in the Ster synthesis?
-Cyanide acts as a nucleophile, attacking the carbonyl carbon and displacing the pi bond, which helps in forming a tetrahedral intermediate crucial for the synthesis of the amino acid.
What is the purpose of the acid hydrolysis step in the Ster synthesis?
-The purpose of the acid hydrolysis step is to transform the cyanide group into the final primary amino acid by a series of protonation, nucleophilic attack, and elimination reactions.
How does the Ster synthesis differ from the Amination of alpha-keto acids and Gabriel synthesis?
-While all three methods synthesize amino acids, the Ster synthesis specifically involves the use of aldehydes, ammonia, and potassium cyanide, and includes a unique series of steps that lead to the formation of an alpha primary amino acid with a specific R group.
What is the final product of the Ster synthesis?
-The final product of the Ster synthesis is an alpha primary amino acid, which has an amine group on the alpha position, a hydrocarbon R group or side chain, and a carboxylic acid group.
What is the significance of the R group in the Ster synthesis?
-The R group in the Ster synthesis determines the specific side chain of the resulting amino acid, as it remains unchanged throughout the reaction.
How many specific steps are involved in the Ster synthesis?
-There are 15 specific steps involved in the Ster synthesis.
What is the role of water in the final steps of the Ster synthesis?
-In the final steps of the Ster synthesis, a water molecule acts as a nucleophile, attacking the carbonyl carbon, leading to the formation of a double bond between carbon and oxygen, and ultimately the carboxylic acid group of the amino acid.
Outlines
🧪 Ster Synthesis: Introduction and Initial Steps
The first paragraph introduces the Ster synthesis as another method for synthesizing amino acids, following the alation of alpha acids and Gabriel synthesis. It outlines the general steps of the Ster synthesis, starting with the reaction of an aldehyde with ammonia in the presence of potassium cyanide to form an intermediate molecule. This is followed by the addition of hydrochloric acid to produce an amine, then potassium cyanide to transform the molecule further. The final steps involve acid hydrolysis to obtain the primary amino acid with its characteristic amine group on the alpha position, a variable R group, and a carboxylic acid group. The paragraph also mentions that the reaction mechanism is quite lengthy, with 15 specific steps to be discussed in detail.
🔍 Ster Synthesis: Detailed Mechanism and Acid Hydrolysis
The second paragraph delves into the specific steps of the Ster synthesis, starting with the nucleophilic attack of ammonia on the carbonyl group of the aldehyde, leading to the formation of an intermediate with charges on oxygen and nitrogen. This is followed by a series of deprotonation and protonation steps that result in the formation of a tetrahedral intermediate. The paragraph then describes the acid hydrolysis process, where hydronium protonates the nitrogen, leading to the formation of a protonated nitrogen and a triple bond between carbon and nitrogen. The mechanism continues with the removal of the cyanide group and its replacement with a carbon-oxygen double bond through a series of protonation, elimination, and nucleophilic attack steps. The final step involves the deprotonation of oxygen to form the carboxylic acid group, completing the synthesis of the amino acid. The paragraph emphasizes the Ster synthesis as a valuable method for creating amino acid molecules.
📚 Conclusion: Ster Synthesis as a Method for Amino Acid Synthesis
The third and final paragraph concludes the discussion on the Ster synthesis, reiterating its value alongside the alation of alpha acids and Gabriel synthesis as a method for forming amino acid molecules. It does not introduce new information but serves to summarize the importance and utility of the Ster synthesis in the context of amino acid synthesis.
Mindmap
Keywords
💡Aldah
💡Amine Group
💡Potassium Cyanide
💡Acid Hydrolysis
💡Nucleophile
💡Leaving Group
💡Triple Bond
💡Strecker Synthesis
💡Carboxyl Group
💡Alpha Position
💡R Group
Highlights
Introduction to the Strecker synthesis as a method for synthesizing amino acids.
General outline of the Strecker synthesis reaction mechanism discussed.
Use of an aldehyde containing an R group and ammonia in the presence of potassium cyanide to form an intermediate molecule.
Addition of hydrochloric acid to produce an amine, transforming the hydroxide to a water molecule.
Formation of a tetrahedral intermediate with a cyanide group attached to the carbon.
Acid hydrolysis steps leading to the formation of the primary amino acid.
Step-by-step nucleophilic addition of ammonia to the carbonyl group and subsequent reactions.
Role of a base, such as ammonia, in deprotonating nitrogen to form an intermediate molecule.
Use of hydrochloric acid to improve the leaving group properties of water in the reaction.
Formation of a pi bond between nitrogen and carbon, displacing the water molecule.
Cyanide acting as a nucleophile and its interaction with the protonated amine.
Transformation of the intermediate molecule through a series of protonation and deprotonation steps.
Elimination of the pi bond in an intramolecular elimination reaction.
Protonating the nitrogen group to facilitate the removal of the cyanide and formation of a carbon-oxygen double bond.
Final steps involve the deprotonation of oxygen to form the carboxylic acid group, completing the amino acid synthesis.
The R group in the final amino acid depends on the initial aldehyde used in the reaction.
Comparison of the Strecker synthesis with other methods like the Strecker and Gabriel synthesis for amino acid formation.
Transcripts
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