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5 Ways to Make Stereochemistry, Stereocenters, E/Z Isomers More Approachable

Usama Attiq
Higher Education
Teaching with Labster

Introduction: Stereochemistry

Stereochemistry is the branch of organic chemistry that deals with the 3D structures of molecules. The main focus is spatial arrangements, the disposition of molecules in space, and different isomers of the same molecules. An isomer is a chemical compound with the same molecular formula but a different arrangement of atoms in space.

The isomers are divided into two main types; constitutional isomers and stereoisomers. Constitutional isomers are those compounds that have the same molecular formula but different bonds between them. Stereoisomers are compounds with the same atoms and bonds but are arranged differently in the space. Stereoisomers are also called spatial isomers.

Stereochemistry has gained popularity in the field of chemistry. The reason behind this is that the toxicity and reactivity of molecules change by altering the stereochemistry. In our body, many reactions take place that are stereospecific. Stereospecific means that the receptor sites can accept only molecules with a specific spatial arrangement.

Several aspects of stereochemistry can be difficult for students to remember. At Labster, we complied with all the complexities of stereochemistry topics for students. Then, we provide five different ways that make this topic easier for students to learn. At the end of the topic, we will convince you why a virtual lab simulation is essential for teachers to convey tough topics like stereochemistry to the students. 

classification of isomers

Figure: An image of classification of isomers from Labster theory of stereochemistry from stereocenters to E/Z isomers. 

Why stereochemistry can be tricky to learn

There are three main reasons why stereochemistry from stereocenters to E/Z isomers is a difficult topic to understand, even for hardworking students.  

1. It feels abstract

Several subtract terms are used in stereochemistry. For instance, the molecules, isomers, reactions, and optical involvement all are abstract terms. It is difficult for students to remember the structures of different isomers from learning through textbooks. The reason is that students cannot see them with the naked eye due to the very small particle size. They need to imagine the structures when they read the topic from the textbook.

2. Too many structures of molecules

In stereochemistry, students need to learn about the difference between chiral and achiral structures. Then, there are several kinds of stereoisomers that need to be remembered. In every type, there are different kinds of molecules with different kinds of structures. So, remembering and drawing these structures can be problematic for students. It is the main reason many students avoid learning stereochemistry.

3. It’s complicated

Since chemistry is a subject full of chemical reactions, it may be difficult for students to remember these reactions. There are several organic compounds that have isomers. The structures have some similarities and at the same time some differences. Students should be able to recognize and differentiate the structures of different isomers. Learning about stereochemistry can be complicated for students. They do not like this topic due to its complexities and also find this topic time-consuming.

5 ways to make stereochemistry a more approachable topic to understand

As you know the reasons that make stereochemistry a tough topic to understand, here are five ways to make this topic simpler for students to learn.

1. Talk about the people behind that science

Louis Pasteur

Louis Pasteur was a French chemist who played an important role in the field of stereochemistry. In 1848, he discovered the recognition of molecular chirality. He observed the group of compounds that were tartrates and also examined their chemical, crystallographic, and optical properties of it. He also resolved the problem related to the nature of tartaric acid. Pasteur observed that the molecules of tartaric acid have smaller faces. When examining those tartrates in the mixture of racemic mixtures, he noticed that half of the crystals were left-handed while others were right-handed. The left-handed molecules were levorotatory and the right-handed molecules were dextrorotatory. He also noticed that tartrate molecules were non-superimposable mirror image isomers. Pasteur was the first person who explained molecular chirality and the concept of isomerism.

2. Explains the basic types of stereochemistry

In stereochemistry, students need to learn about its types. There are several types of stereochemistry. It includes:

  1. Atropisomeric

  2. Diastereomers

  3. Cis trans isomerism

  4. Enantiomers

  5. Conformational isomerism

Atropisomerism: Atropisomerism is the type of stereochemistry in which the molecules are non-superimposable on their mirror image. These molecules are formed by the hindering of one or more bonds. Atropisomers can be observed in the molecules of drugs.

Diastereomers: When two isomers do not act as mirror images of each other, it is called diastereomers. These compounds have different physical properties and also chemical reactivity. In isomers, the diastereomers are more optically active, and they are not enantiomers.

Cis trans isomerism: Cis trans isomerism is the type of stereoisomers with the same atoms. These atoms can join in the same manner, but they have different configurations. Cis trans isomers can be seen in the cases of alkenes.

Enantiomers: These isomers can give one pair of optical isomers, but the structure of enantiomers is not superimposable in mirror images. These are stable and isolable compounds that can exist in discrete pairs. The two enantiomers possess the same properties, but their interaction in a polarized light can be changed. Additionally, enantiomers are those isomers that are mirror images of each other.

Conformational isomerism is the type of stereoisomers in which the isomers can only be converted with the help of formally single-bond rotations. Conformational isomerism is observed in the alkanes due to the presence of a single bond.

Stereochemistry virtual lab 2

Figure: An image of prioritization from Labster virtual laboratory of stereochemistry from stereocenters to E/Z isomers

3. Properties of cis/trans isomers

Cis/trans isomers are stereoisomers with different spatial arrangement of molecules in the 3D space. The word “cis” and “trans” originated from Latin words. The meaning “cis” is “this side of” while the word “trans” means “that side of”. Sometimes, the physical properties of cis/trans isomers change from each other. The reason is that these molecules have different dipole moments due to the difference in the spatial arrangements of the molecules of the isomers. The properties that differentiate the molecules of the cis/trans isomers from each other are the following:

  • The molecules in the cis/trans isomers have differences in boiling points. For instance, the cis isomer of pent-2-ene has 37 degrees Celsius of boiling point while the trans isomer has 36 degrees Celsius of boiling point. The main reason for the difference in the boiling point of pent-2-ene is the low bond polarity.

  • The oleic acid and elaidic acid are cis/trans isomers of each other. The oleic acid has a melting point of 43 degrees Celsius and is solid at room temperature. Elaidic acid has a melting point of 13.5 degrees Celsius and is liquid at room temperature.  

  • The bonds of 1,2-dichloroethylene are polar in nature. This is the reason that the cis/trans molecules of 1,2-dichloroethylene have a difference in temperature. The cis molecule has a temperature of 60.3 degrees Celsius while the trans molecule has a temperature of 47.5 degrees Celsius. 

cis trans isomers

Figure: An image of cis/trans isomers from Labster theory of stereochemistry. 

4. Seeing is believing

Color diagrams play an effective role to understand difficult topics like stereochemistry. Visual learning can help to develop visual thinking in students. Learners can understand the topic more effectively when they see color images related to the topic. The diverse colors make stereochemistry easier and simpler for students to remember. In stereochemistry, students need to learn structures, their isomers, and the bonds between atoms. These can be easier to learn through color diagrams.

The color images presented below show the isomers of Limonene. Limonene has two enantiomers which are R-Limonene and S-Limonene. These two enantiomers have specific smells and flavors. Chiral and achiral are two main terms used in stereochemistry. The chiral is the non-superimposable mirror while achiral molecules are the superimposable mirror images of each other. Limonene is a chiral molecule. 

Stereochemistry virtual lab

Figure: An image shows the 3D structures of isomers of Limonene from the Labster virtual laboratory of stereochemistry from stereocenters to E/Z isomers.  

5. Use of virtual laboratory simulation

The virtual lab simulation is an effective method to explain tough topics like stereochemistry. It is helpful for teachers to convey the topic to their students. At Labster, we provide advanced 3D simulations that have gamification elements like storytelling and the scoring system.

Labster stereochemistry from stereocenters to E/Z isomers simulation explains the identification of stereogenic centers in the chiral molecules, differentiation of chiral molecules from achiral molecules, differentiation between cis/trans and E/Z isomers, and Cahn Ingold Prelog priority rule.

Stereochemistry: from stereocenters to E/Z isomers Virtual Lab GIF

Check out Labster's stereochemistry simulation here, or get in touch to find out how you can start using virtual lab simulation with your students.

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