L5: Chirality and Its Effects

The way you smell certain fragrances is influenced by __________

• weather

• mood

• stereochemistry

• heat

Answer explanation

Answer: the way we perceive fragrances is affected by their molecular structure, specifically stereochemistry. Different arrangements of atoms can lead to different smells, influencing our olfactory experience.

Fun Fact: Many naturally occurring molecules in food, such as sugars, amino acids, and flavors, are chiral. For example, the sugar L-glucose is sweet, while its mirror image D-glucose is also sweet, but the body uses them differently in metabolism!

For pharmaceuticals, slight difference in ______ can make difference between targeted treatment and undesired side effects

• melting point

• spatial arrangement

• boiling point

• net dipole

Answer explanation

Answer: the effectiveness of some medicines can vary based on their stereochemistry. Different stereoisomers can interact differently with biological targets, affecting their efficacy and safety.

Fun Fact: Many scents are made up of chiral molecules. For instance, the two enantiomers of the molecule limonene smell quite different—one smells like oranges, and the other smells like pine. It’s all about how they fit into the receptors in your nose!

Food flavorings that have equal amount of mixture is named as ________

• meso

• diastereoisomers

• enantiomers

• racemic

Answer explanation

Answer: food flavorings can contain a mix of enantiomers, which are molecules that are mirror images of each other. This mixture can enhance the complexity and depth of flavors in food products.

Fun Fact: Some flavor compounds, like vanillin, are sold as racemates, which means they contain equal amounts of both enantiomers. These mixtures can taste different than the pure form of a single enantiomer, and often have a less intense flavor.

__________ can have different melting and boiling points?

• Optical active compounds

• Enantiomers

• Diastereosiomers

• Mirror image compounds

Answer explanation

Yes, diastereoisomers can have different melting and boiling points due to their distinct spatial arrangements, which affect intermolecular forces. This leads to variations in physical properties.

Fun Fact: While enantiomers have identical physical properties, diastereoisomers—stereoisomers that are not mirror images—can have distinct properties, such as different solubilities, which is useful in purifying compounds from mixtures.

The chiral nature of molecules ________on each other.

• superimposable

• non-superimposable

• have center of symmetry

• same 3D arrangement

Answer explanation

Answer: the chiral nature of molecules means that they can exist in different forms (enantiomers) which cannot superimposable on one another.

Fun Fact: Some of our daily life object are non-superimposable. For example, our hands, snails, finger print and so on.

Chiral compounds that proceeds with clockwise manner in Cahn-Ingold-Prelog assignment of a chiral center is named as _______

• sinister

• rector

• L-

• D-

Answer explanation

Answer: Chiral center that proceeds in clockwise manner in assignment of chirality during CIP rule is named as rector or R.

Fun Fact: In addition to the way molecules smell, their chirality can influence how they taste. The enantiomer of an amino acid, like L-glutamate (found in MSG), is responsible for the umami flavor that enhances the taste of food.

A molecule with two or more chirality may be chiral or non-chiral. In contrast, molecule with a chiral centre must be _____

• non-chiral

• achiral

• chiral

• same

Answer explanation

Answer: A chiral center must consists of 4 different of atoms or groups that attached to a center carbon.

Fun Fact in Daily Life: This concept is key to why molecules like aspirin work effectively in your body! The chiral center in aspirin has different atoms attached to the central carbon, giving it a specific 3D shape. This shape is what allows aspirin to interact with specific enzymes in your body, reducing pain and inflammation by blocking certain pathways. If the chiral center were different, aspirin wouldn't work the same way—just like how a left-hand glove won’t fit on your right hand!

________compounds are optically inactive even though they have chiral centers?

• Sugar

• Diastereosiomer

• Enantiomer

• Meso

Answer explanation

Answer: Meso compounds have multiple chiral centers but possess an internal plane of symmetry, making them superimposable on their mirror images. This symmetry results in optical inactivity despite the presence of chiral centers.

Fun Fact: While tartaric acid has two chiral centers, its symmetrical structure makes it optically inactive. This unique feature is what allows tartaric acid to have useful properties in food science, like stabilizing egg whites when making meringues or whipped cream, without affecting the optical behavior of the final product.

The R/S and (+)/(-) plane of polarized light has _____relationship

• direct

• no

• alternate

• linear

Answer explanation

Answer: Plane of polarized light is measured using polarimeter. While R and S configuration is determine through atoms or groups attached to center carbon. There is no relationship between these two information.

Fun Fact: vanillin, the molecule responsible for the flavor of vanilla, is optically active. When it’s manufactured, its optical rotation can be measured to ensure its purity. In medicine, optical activity is also used to identify and test the purity of drugs, making sure you're getting the right enantiomer of a drug to ensure its effectiveness and safety. It's like having a "molecular fingerprint" that can verify the quality of your vanilla ice cream or the medicine you're taking!

The _____line represent attachment coming out of the page and _____line represent attachment going back into the page.

• horizontal, vertical

• horizontal, horizontal

• vertical, horizontal

• vertical, vertical

Answer explanation

Answer: Fisher projection can also be used to represent molecules with chiral centres. Horizontal lines represent attachments coming out of the page. Vertical lines represent attachments going back into the page. Lowest priority group bonded to a chiral atom must be shown as a horizontal line.

Fun Fact in Daily Life: This simple diagram is especially useful when studying sugars and carbohydrates, which are essential in our daily diets. For instance, glucose, the sugar our bodies use for energy, is often represented using a Fischer projection in textbooks and research. By using this projection, scientists can easily understand how glucose interacts with other molecules, influencing everything from its role in energy production to its behavior in processed foods like sports drinks. Fischer projections help chemists design better food additives, medicines, and even artificial sweeteners by giving insight into the molecular shapes that impact taste and absorption!