CHEM 115 Final Exam Flashcards

Enantiomers

Stereoisomers that are nonsuperposable mirror images

Diastereomers

Stereoisomers that are not mirror images

Chiral

An object that is not superposable on its mirror image

Achiral

An object that lacks chirality; an object that is superposable on its mirror image

Superposable

In the context of molecular structure, to lay one structure on another and find that all like parts coincide

Nonsuperposable

In the context of molecular structure, to lay one structure on another and find that all like parts do not coincide

Stereocenter

A tetrahedral carbon atom that has four different groups bonded to it

R,S system

A set of rules for specifying the configuration about a stereocenter

R

Used in the R,S system to show that when the lowest-priority group is away from you, the order of priority in groups on a stereocenter is clockwise

S

Used in the R,S system to show that when the lowest-priority group is away from you, the order of priority of groups on a stereocenter is counterclockwise

Amine

A functional group in which a nitrogen atom is bonded to one, two, or three carbon groups: RNH2, R2NH, or R3N

Aliphatic amine

An amine in which nitrogen is bonded only alkyl groups or hydrogens

Aromatic amine

An amine in which nitrogen is bonded to one or more aromatic rings

Heterocyclic amine

An amine in which nitrogen is one of the atoms of a ring

Heterocyclic aliphatic amine

A heterocyclic amine in which nitrogen is bonded only to alkyl groups

Heterocyclic aromatic amine

An amine in which nitrogen is one of the atoms of an aromatic ring

Physical properties of amines

Have very sharp and penetrating odors, polar compounds (1° and 2° can form hydrogen bonds, 3° cannot), higher BP than alkanes of comparable MW but lower BP than alcohols of comparable MW, more water soluble than hydrocarbons of comparable MW, weak bases (strength: aliphatic > ammonia > aromatic)

Reaction of amines

Amines, whether soluble or insoluble in water, react quantitatively with strong acids to form water-soluble salts

Aldehyde

A compound containing a carbonyl group bonded to a hydrogen; a -CHO group

Ketone

A compound containing a carbonyl group bonded to two carbons

Physical properties of aldehydes and ketones

Polar molecules, weak IMFs (no hydrogen bonding), lower BPs than alcohols and carboxylic acids, ones of low MW are more soluble in water than nonpolar compounds of comparable weight (as hydrocarbon portion of molecule increases in size, they become less soluble in water)

Oxidation of aldehydes

Aldehydes are oxidized to carboxylic acids by a variety of oxidizing agents (ex: potassium dichromate)

Oxidation of ketones

Ketones resist oxidation by most oxidizing agents

Tollens’ reagent

Specific for the oxidation of aldehydes, used in silver-mirror test to differentiate aldehydes from ketones

Reduction of aldehydes and ketones

The carbonyl group of an aldehyde or ketone is reduced to a -C(H)OH group (alcohol) by hydrogen in the presence of a transition metal catalyst

Addition of alcohols to aldehydes or ketones

The addition of a molecule of alcohol to the carbonyl group of an aldehyde or ketone forms a hemiacetal (hemiacetals can react further react with alcohols in an acid-catalyzed reaction to form acetals and water)

Hemiacetal

A molecule containing a carbon bonded to one -OH group and one -OR group

Acetal

A molecule containing two -OR groups bonded to the same carbon

Carboxylic acid

A compound containing a -COOH (carboxyl) group

Physical properties of carboxylic acids

Has three polar covalent bonds; significantly higher BPs than other organic compounds of comparable MW; more soluble in water than alcohols, ethers, aldehydes, and ketones of comparable MW; weak acids (pKa 4.0-5.0)

Reaction of carboxylic acids with bases

All carboxylic acids react with NaOH, KOH, and other strong bases to form water-soluble salts (also form water-soluble salts with ammonia and amines)

Fischer esterification

The process of forming an ester by refluxing a carboxylic acid and an alcohol in the presence of an acid catalyst, commonly sulfuric acid

Decarboxylation

The process that leads to loss of CO2 from a carboxyl (-COOH) group

Fatty acids

Long chain carboxylic acids derived from animal fats, vegetable oils, or phospholipids of biological membranes; have polar head groups and nonpolar tails

Micelles

Spherical arrangements of molecules in aqueous solution such that their hydrophobic parts are shielded from the aqueous environment and their hydrophilic parts are on the surface of the sphere and in contact with the aqueous environment

Soap

A sodium or potassium salt of a fatty acid; prepared from a blend of tallow and palm oils (triglycerides)

Saponification

The hydrolysis of an ester in aqueous NaOH or KOH to an alcohol and the sodium or potassium salt of a carboxylic acid (triglycerides are boiled with NaOH)

Anhydride

A compound derived from another or others by the loss of the elements of water; two carbonyl groups bonded to the same oxygen

Ester

A compound in which the -OH of a carboxyl group, RCOOH, is replaced by an alkoxy (-OR) group or aryloxy (-OAr) group; carbonyl group bonded to an -OR group

Amide

Functional derivative of a carboxylic acid in which an amino group replaces the -OH of the carboxyl group; carbonyl group bonded to a nitrogen atom

Lactone

A cyclic ester

Lactam

A cyclic amide

Beta-lactam

A four-membered, aliphatic, heterocyclic amide

Hydrolysis of anhydrides

Carboxylic anhydrides react readily with water (hydrolyze) to give two carboxylic acids

Reaction of anhydrides with alcohols

Anhydrides react with alcohols and phenols to give an ester and a carboxylic acid

Hydrolysis of esters in aqueous acid

Reverse of Fischer esterification, forms carboxylic acid and alcohol

Hydrolysis of esters in aqueous base

Often called saponification, the carboxylic acid formed in the hydrolysis reacts with the hydroxide ion to form a carboxylic acid anion

Hydrolysis of amides in aqueous acid

Gives a carboxylic acid and an ammonium ion (acid-base reaction)

Hydrolysis of amides in aqueous base

Gives a carboxylic acid salt and ammonia or an amine (acid-base reaction)

Reaction of anhydrides with amines

Anhydrides react with ammonia and with 1° and 2° amines to form amides

Reaction of esters with amines

Esters react with ammonia and with 1° and 2° amines to form amides

Carbohydrate

A polyhydroxyaldehyde or polyhydroxyketone, or a substance that gives these compounds on hydrolysis

Monosaccharide

A carbohydrate that cannot be hydrolyzed to a simpler carbohydrate, have the general formula CnH2nOn (n varies from 3 to 7)

Aldose

A monosaccharide containing an aldehyde group

Ketose

A monosaccharide containing a ketone group

Fischer projection

A two-dimensional representation for showing the configuration of tetrahedral stereocenters; horizontal lines represent bonds projecting forward from the stereocenter and vertical lines represent bonds projecting to the rear

D-monosaccharide

The -OH on its penultimate carbon is on the right in a Fischer projection

L-monosaccharide

The -OH on its penultimate carbon is on the left in a Fischer projection

Anomeric carbon

The new carbon stereocenter created in forming the cyclic structure of a carbohydrate

Penultimate carbon

The last chiral carbon in the open-chain form

Glycosidic bond

The bond from the anomeric carbon to the -OR group

Alditol

A polyhydroxy compound formed when the carbonyl group of a monosaccharide is reduced to a hydroxyl group

Aldonic acid

A carboxylic acid formed when the aldehyde group of an aldose is oxidized to a carboxyl group

Sucrose

Disaccharide, table sugar obtained from the juice of sugar cane and sugar beet

Lactose

Disaccharide, the principal sugar present in milk

Maltose

Disaccharide; from malt, the juice of sprouted barley, and other cereal grains

Starch

A polymer of D-glucose, can be separated into amylose and amylopectin, primary energy storage in plants

Glycogen

The energy reserve carbohydrate for animals, a branched polysaccharide of approximately 10^6 glucose units joined by alpha-1,4- and alpha-1,6-glycosidic bonds

Cellulose

A linear polysaccharide of D-glucose units joined by beta-1,4-glycosidic bonds, provides structural support in plant cell walls, not digestible by humans and other animals

Heparin

Synthesized and stored in mast cells of various tissues (liver, lungs, gut); best known and understood of its biological functions is its anticoagulant activity

Acidic polysaccharides

A group of polysaccharides that contain carboxyl groups and/or sulfuric ester groups; play important roles in the structure and function of connective tissues