What is the difference between synthesis and retrosynthesis?

The main difference between synthesis and retrosynthesis is that synthesis is the process of combining simple reactions to form an organic compound. But, retrosynthesis is the process of working backwards from the target organic compound to develop a suitable synthetic pathway, starting from a simple precursor molecule. In addition, synthesis is a chemical process carried out in a test tube, while retrosynthesis is a type of planing on paper.  

Synthesis and retrosynthesis are two important processes in organic chemistry that enable a particular organic compound to be built up from simple precursor molecules through a series of chemical reactions.  

Key areas covered  

1. What is synthesis - definition, process, meaning 2. What is retrosynthesis - definition, process, meaning 3. What are the similarities between synthesis and retrosynthesis - overview of the similarities 4. What is the difference between synthesis and retrosynthesis - comparison of Main differences

key terms  

Chemical reactions, organic compounds, retrosynthesis, synthetic intermediates, synthesis, synthon

Difference Between Synthesis and Retrosynthesis - Comparative Summary

What is synthesis  

Synthesis is the process of chemically building an organic compound through a series of reactions. In general, organic compounds are complexes that contain mainly covalent bonds . The most important essential feature of the synthesis is also that it starts from simple precursors , which leads to the formation of the target organic compound. The precursor molecules can either be natural or commercially available. In addition, there are two approaches to the total synthesis of an organic compound. They are linear synthesis and convergent synthesis.

Difference Between Synthesis and Retrosynthesis

Figure 1: Alprostadil synthesis

In general, in linear synthesis, several steps of chemical reactions are carried out one after the other. Therefore, it is only sufficient for the synthesis of simple kinds of organic compounds. However, convergent synthesis involves the individual production of several “pieces” or important intermediate stages, which are then combined to form the desired product. Therefore, it is preferred for the synthesis of more complex organic compounds. Here, synthetic intermediate refers to any chemical compound that is synthesized at the end of each step. In addition, every chemical reaction is responsible for modifying the starting compound.  

What is retrosynthesis?  

Retrosynthesis is the breakdown of the target organic compound, which is complex into its simple precursors. However, this is done on paper, not chemically. The main importance of retrosynthesis is that it helps to identify the synthetic route of the target organic compound. Although this is some kind of paperwork, retrosynthesis is the reverse process of synthesis. Hence, it starts with the complex target compound and goes back to its simple ancestors. It is important that the retrosynthesis enables the comparison of several synthetic routes of a certain target compound in a logical as well as in a simple way. Basically , a synthon refers to a   Fragment of a compound that supports the formation of a synthesis derived from this target molecule. Synthetic equivalents also refer to the corresponding commercially available form of a synthon .

Key difference - synthesis vs. retrosynthesis

Figure 2: Retrosynthetic analysis of phenylacetic acid

In addition, there are several strategies of retrosynthesis. They include functional group strategies, stereochemical strategies, structure targeting strategies, transform-based strategies, and topological strategies. Of these, functional group strategies manipulate functional groups of the organic compound, thereby reducing its chemical complexity. In the meantime, stereochemical strategies remove the chirality of the target in order to simplify it. Structure targeting strategies, however, direct the synthesis towards a desirable intermediate, which greatly narrows the focus of the analysis. On the other hand, transformation-based strategies reduce the molecular complexity of the target organic compound by introducing transformations. But topological strategies identify key substructures by separating one or more key bindings.  

Similarities Between Synthesis and Retrosynthesis   

  • Synthesis and retrosynthesis are two processes involved in building a particular organic compound.   
  • Both use simple precursor molecules to synthesize a complex organic compound through a series of chemical reactions in organic chemistry .   
  • The precursor either commercially available or natural molecules may be.   
  • The structure of organic compounds is important for industrial purposes, especially in the pharmaceutical industry.  

Difference Between Synthesis and Retrosynthesis  

definition  

Synthesis is a special branch of chemical synthesis   and deals with the deliberate construction of organic compounds, but retrosynthesis refers to a technique of finding a suitable synthetic route when planning organic synthesis .   

meaning  

Synthesis is the process of combining simple reactions to form an organic compound, but retrosynthesis is the process of working backwards from the target organic compound to develop a suitable synthetic route from a simple precursor molecule.  

direction  

Synthesis is the forward process, starting with the precursors and ending with the target organic compound, but retrosynthesis is the reverse process, starting with the target organic compound and back to its relevant precursors.  

Type of process  

Synthesis is a chemical process carried out in a test tube, while retrosynthesis is a type of planing on paper.  

meaning  

Synthesis is important for the chemical makeup of an organic compound, while retrosynthesis is important for planning the synthesis of that particular organic compound from its precursors.  

Types  

The two synthetic approaches are linear and convergent synthesis, while retrosynthesis strategies include functional group strategies, stereochemical strategies, structure targeting strategies, transformation strategies, and topological strategies.  

diploma  

Synthesis is a chemical process in which organic molecules are built up through a series of chemical reactions. Generally it starts with simple precursor molecules and ends with the target organic compound, which is usually a complex. In contrast, however, retrosynthesis is the reverse process of synthesis and participates in the deconstruction of the target organic compound in order to find out its simple precursor molecules. However, it is a kind of paperwork that helps figure out a synthetic route for the target organic compound. Hence, the main difference between synthesis and retrosynthesis is in the direction and nature of the process.  

References:

1. "Organic synthesis and reactions to form carbon-carbon bonds" Organic synthesis and reactions to form carbon-carbon bonds , available here .2. “A Simple Approach to Retrosynthesis in Organic Chemistry.” Retrosynthesis Tutorial for Organic Chemistry, Available here.

Image courtesy:

1. “Alprostadil synthesis” by Nuklear - Own work ( CC BY-SA 4.0 ) via Commons Wikimedia 2. “Retrosynthetic analysis of phenylacetic acid” ( Public Domain ) via Commons Wikimedia

About the author: Lakna

Lakna, a graduate in molecular biology and biochemistry, is a molecular biologist and has a broad and strong interest in discovering things related to nature