Organic synthesis is the process of creating organic compounds from scratch. It’s a vital part of chemistry that’s used in labs and industries. If you’ve ever wondered how the theories of organic chemistry are applied in real life, organic synthesis is a great example. It’s all about using what you’ve learned to find solutions to problems. In this series, we’ll connect the dots between the different principles you’ve learned in organic chemistry. You’ll gain a deeper understanding of how functional groups work together and how to create organic compounds from scratch. So let’s dive in and explore the world of organic synthesis!

Importance of organic synthesis

As chemistry students, you might be wondering why organic synthesis is so important. After all, most organic compounds come from living things, right? While that’s true, there are many complex organic compounds that are important but not found in nature. Take aspirin, for example. It comes from willow bark, but extracting it is inefficient and costly. That’s where organic synthesis comes in. Scientists have developed ways to create aspirin in the lab from compounds like salicylic acid. This allows for high-yield, low-cost production of important compounds like drugs and pesticides. So, the key importance of organic synthesis is to produce these compounds efficiently and cost-effectively.

‍

Organic synthesis flow chart

Before we discuss the organic synthesis flowchart, let’s cover a few key terms relating to organic synthesis.

The molecule to be synthesised in organic synthesis is called the target compound. The target compound is usually derived from a ‘scaffold’, known as the starting material. As you can see from the aspirin example above, aspirin is the target compound whereas salicylic acid is the starting material.

Organic synthesis of the target compound, therefore, involves figuring out steps to convert the starting molecule to the target compound. To achieve this, functional groups of both the target group and starting molecule are identified. Once that is done, you then figure out the steps to convert the functional group of the starting molecule to that of the target molecule. You can use the flowchart detailed below to help you identify the relevant steps.

‍

Organic synthesis can happen in one step or many steps. The goal is to keep the number of steps as small as possible to maximize the product yield. When deciding on the appropriate reaction step(s), consider the reagents and conditions required. This includes whether the reagent is oxidizing, reducing, or dehydrating, and whether heat or a catalyst is required. Scientists also consider cost, safety, waste production, and yield when deciding on the best reaction steps.

Another strategy for deciding how to produce a certain compound is to start from the final compound and work backward to determine the necessary steps from more common, cheaper, and safer starting materials. This process is called retrosynthesis. It’s a helpful tool for figuring out the best synthesis pathway for a target molecule.

Organic synthesis examples

The two organic synthesis examples covered in the AQA syllabus include the synthesis of propanoic acid from 1-bromopropane and propylamine from ethene. Please refer to Synthetic Routes for a detailed breakdown and explanation of each synthetic step.

Mapping the synthesis of propanoic acid from 1-bromopropane

Below is a diagram showing how the synthesis of propanoic acid from 1-bromopropane is mapped.

‍

These are the steps to follow when mapping a synthetic route:

From the functional group interconversion flowchart above, list out the possible molecules that can be made from the starting molecule and the molecules that can be converted into the target molecule. Identify any common intermediates between the starting material and the target. In this case, propan-1-ol is the intermediate. List out the reaction steps. In the case of the synthesis of propanoic acid from 1-bromopropane, it entails a two-step reaction that is as follows:

1-bromopropane → propan-1-ol → propanoic acid

Mapping the synthesis of propylamine from ethene

Likewise, below is a diagram showing how the synthesis of propylamine from ethene is mapped.

‍

The synthesis of propylamine from ethene is slightly more complex. The steps relating to its mapping are listed as follows:

From the functional group interconversion flowchart above, list out the possible molecules that can be made from the starting molecule and the molecules that can be converted into the target molecule. Identify any common intermediates between the starting material and the target. In this case, there is no common intermediate. As such, you need to determine whether any molecules that can be made from the starting molecule can be converted into one of the molecules that is derived from the target molecule. For the above case, a haloalkane can be converted into propanenitrile.List out the reaction steps. In the case of the synthesis of propylamine from ethene, it entails a three-step reaction that is as follows:

ethene → haloalkane → propanenitrile → propylamine

The development of the olefin metathesis method was an innovation in the field of organic synthesis. This method comprises a diverse set of reactions in forming and rearranging double bonds so that the side groups linked by them can be exchanged between two molecules. This method involves metal catalysts. The researchers who discovered it; Dr. Yves Chauvin, Professor Robert H. Grubbs, and Professor Richard R. Schrock, were granted the Nobel Prize for chemistry in 2005.

Organic synthesis involves making organic compounds from scratch in labs or industries. Its main goal is to produce these compounds in a cost-effective and efficient way. To achieve this, scientists need to carefully plan the steps needed to transform the starting material into the target compound. This involves identifying the intermediate compounds that can be formed along the way and choosing the appropriate reagents and conditions for each reaction. The synthesis route can be mapped out from either the starting material or the target compound using a strategy called retrosynthesis. Ultimately, organic synthesis plays a critical role in producing a wide range of products, from drugs and plastics to food additives and fragrances.

Organic Synthesis

What is organic synthesis in chemistry?

Organic synthesis simply means making organic compounds from scratch in laboratories or industries.

What is organic synthesis used for?

In organic synthesis we apply the principles of organic chemistry so we can produce organic compounds effectively.For example, aspirin comes from the bark of the willow tree. However, extracting aspirin from willow bark is time consuming and wasteful so scientists have developed steps to synthesise aspirin from laboratory compounds like salicylic acid. This way we can produce more aspirin at a lower cost.

Why is organic synthesis important?

The key importance of organic synthesis is to produce organic compounds (for example drugs and pesticides) efficiently.

How do you synthesise organic compounds?

Organic synthesis of the target compound involves figuring out steps to convert the starting molecule to the target compound. To achieve this, functional groups of both the target group and starting molecule are identified. Once that is done, you then figure out the steps to convert the functional group of the starting molecule to that of the target molecule.

‍