Orgo C 2 Esters and Stereochemistry Theory 2nd P

These flashcards cover key concepts, definitions, and chemical principles related to esters and stereochemistry, organized for effective study and review.

What are esters?

Derivatives of carboxylic acids where –OH is replaced by –OR.

How are esters formed?

By reacting a carboxylic acid with an alcohol and removing water (condensation).

What is the ester functional group?

–COOR.

What is the physical state of low-carbon esters?

Low-carbon esters (<12 carbons) are liquids.

What is the physical state of high-carbon esters?

High-carbon esters (12+) are waxy solids.

How do low-molecular weight esters smell?

They smell fruity and pleasant.

How does the solubility of esters vary?

Insoluble in water; soluble in alcohol, ether, and chloroform.

What is the density of esters compared to water?

Esters are less dense than water.

How do boiling and melting points of esters compare to alcohols and carboxylic acids?

Lower than alcohols and carboxylic acids of similar mass.

What is the general naming rule for esters?

Alcohol → alkyl name; acid → replace –oic with –oate.

Provide an example of ester naming.

Methanol + ethanoic acid → methyl ethanoate.

What term is used for naming substituted esters?

Use the term alkoxycarbonyl for esters attached to carboxylic acids.

How are cyclic esters named?

Use alkyl carboxylate.

What are lactones?

Cyclic esters formed when hydroxy acids internally esterify.

What is the physical appearance of low mass esters?

Colorless liquids.

What is the physical appearance of higher mass esters?

Thick, waxy solids.

Why are esters less polar than acids/alcohols?

No –OH group → weaker intermolecular forces.

What reaction type forms esters?

Condensation (loss of water).

What is one way to hydrolyze esters under acidic conditions?

Ester + water → acid + alcohol.

What is saponification in the context of ester hydrolysis?

Basic hydrolysis leading to carboxylate + alcohol.

What industrial use do esters have in fragrances?

Esters create fruity and floral scents.

What industrial applications do esters have as solvents?

Used in paints, coatings, and cleaning.

Where are ester linkages commonly found in fibers?

Many fibers (like polyesters).

What are some general applications of esters?

Fragrances, medications, soaps, beauty products, solvents, fibers.

What is stereochemistry?

The study of the 3-D arrangement of atoms in molecules.

What are isomers?

Same formula, different structures/properties.

What are the two main types of isomers?

Structural isomers and stereoisomers.

What is stereoisomerism?

Same bonding sequence, different spatial arrangement.

What is chirality?

A molecule/object that has non-superimposable mirror images.

Why is chirality important in biology?

Most biological molecules are chiral.

What is a chiral carbon?

A carbon bonded to four different groups.

How is a chiral center marked?

With an asterisk (*).

What are enantiomers?

Mirror-image stereoisomers that are not superimposable.

How do enantiomers typically compare in properties?

Same physical properties except optical rotation and biological activity.

What is conformational isomerism?

Isomers created by rotation around single bonds.

What is the skew (staggered) conformation?

Lowest energy; bonds far apart.

What is the eclipsed conformation?

Highest energy; bonds overlap closely.

What are configurational isomers?

Isomers that require bond breaking to interconvert.

What are the two major configurational types?

Geometric and optical isomers.

What are geometric isomers?

Isomers that have restricted rotation and occur in pairs.

What is optical isomerism?

Isomers that rotate plane-polarized light.

What is optical activity?

Rotation of polarized light to the right or left.

What does dextrorotatory mean?

Right-rotating.

What does levorotatory mean?

Left-rotating.

What device measures optical activity?

Polarimeter.

What types of optical isomers exist?

Enantiomers and diastereomers.

What are diastereomers?

Not mirror images; different physical/chemical properties; separable.

What are epimers?

Diastereomers that differ at one chiral carbon.

What are anomers?

Stereoisomers differing at the anomeric carbon formed after ring closure.

What are meso compounds?

Molecules with chiral centers but internal symmetry → optically inactive.