Chemistry 102 - Review Sheet for Exam #3

As a guide for studying, you should be familiar with the concepts listed below  For nomenclature review information, go to Chem102 Exam #1 Review Sheet  I don't yet have sample exams, but trying to find old ones

Supplemental Review Information:

Chapter 17: Carboxylic Acids and Esters

Nomenclature of Carboxylic Acids: The characteristic functional group of carboxylic acids is the carboxyl group Many of the simpler carboxylic acids are well known by common names In the IUPAC system, the ending -oic acid is used in the names of these compounds Aromatic acids are named as derivatives of benzoic acid.

Physical Properties of Carboxylic Acids: At room temperature, low molecular weight carboxylic acids are liquids with distinctic sharp or unpleasant odors High molecular weight, long chain acids are wax-like solids carboxylic acids are quite effective in forming dimers in which two molecules are held together by hydrogen bonds Thus, they have relatively high boiling points, and those with lower molecular weights are soluble in water.

The Acidity of Carboxylic Acids: Soluble carboxylic acids behave as weak acids; they dissociate only slightly in water to form an equilibrium mixture with the carboxylate ion The equilibrium concentrations of the carboxylic acid and the carboxylate ion depend upon pH At low pH the acid form predominates, and at pH 74 (the pH of cellular fluids) and above, the carboxylate ion predominates carboxylic acids react with bases to produce carboxylate salts and water.

Salts of Carboxylic Acids: The carboxylate salts are named by changing the -ic ending of the acid to -ate The ionic nature of the salts makes them water soluble A number of carboxylate salts are useful as food preservatives, soaps, and medicines.

Carboxylic Esters: carboxylic acids, acid chlorides, and acid anhydrides react with alcohols to produce esters Polyesters result from the reaction of dicarboxylic acids and diols Polyesters are an example of condensation polymers; these are produced when monomers react to form a polymer plus a small molecule such as water.

Nomenclature of Esters: Both common and lUPAC names for esters are formed by first naming the alkyl group of the alcohol portion followed by the name of the acid portion in which the -ic acid ending has been changed to -ate Many esters are very fragrant and represent some of nature's most pleasant odors Because of this characteristic, esters are widely used as flavoring agents.

Reactions of Esters: Esters can be converted back to carboxylic acids and alcohols under either acidic or basic conditions Hydrolysis, the reaction with water in the presence of acid, produces the carboxylic acid and alcohol Saponification occurs in the presence of a base to produce the carboxylate salt and alcohol.

Esters of Inorganic Acids: Alcohols can also form esters by reaction with inorganic acids such as phosphoric acid Phosphate esters represent some of the most important biological compounds.

Chapter 19: Amines and Amides

Classification of Amines: Amines are organic derivatives of ammonia in which one or more of the ammonia hydrogens are replaced by alkyl or aromatic groups Amines are classified as primary, secondary, or tertiary depending upon the number of groups (one, two, or three) attached to the nitrogen.

Nomenclature of Amines: Common names are given to simple amines by adding the ending -amine to the names of the alkyl groups attached to the nitrogen In lUPAC names, the -NH2 group is treated as a chain substituent and given the name amino Aromatic amines are named as derivatives of aniline.

Physical Properties of Amines: Primary and secondary amines have boiling points slightly lower than those of corresponding alcohols Tertiary amines have boiling points similar to those of alkanes Low molecular weight amines are soluble in water.

Chemical Properties of Amines: Amines are weak bases They react with water to liberate hydroxide ions, and they react with acids to form salts Amines react with acid chlorides and acid anhydrides to form amides.

Biologically Important Amines: Four neurotransmitters are acetycholine, norepinephrine, dopamine, and serotonin Epinephrine is also known as the "fight or flight" hormone The amphetamines have structures similar to that of epinephrine Alkaloids are nitrogen-containing compounds isolated from plants They exhibit a variety of physiological effects on the body Examples of alkaloids include nicotine, caffeine, quinine, atropine, morphine, and codeine.

Amide Nomenclature: Amides are named by changing the -ic acid or -oic acid ending of the carboxylic acid portion of the compound to -amide Groups attached to the nitrogen of the amide are denoted by a capital N that precedes the name of the attached group.

Physical Properties of Amides: Low molecular weight amides are soluble in water due to the formation of hydrogen bonds Unsubstituted amides have higher melting and boiling points than comparable substituted amides.

Chemical Properties of Amides: Amides undergo hydrolysis in acidic conditions to yield a carboxylic acid and an amine salt Hydrolysis under basic conditions produces a carboxylate salt and an amine.

Chapter 20, 21: Amino Acids, Proteins, Enzymes and Vitamins

The General Characteristics of Enzymes: Enzymes are highly efficient protein catalysts which are involved iii almost every biological reaction They are often quite specific in terms of the substance acted upon and the type of reaction catalyzed.

Enzyme Nomenclature and Classification: Enzymes are grouped into six major classes on the basis of the type of reaction catalyzed Common names for enzymes often end in -ase and are based on the substrate and/or the type of reaction catalyzed.

Enzyme Cofactors: Cofactors are nonprotein molecules required for an enzyme to be active Cofactors are either organic (coenzymes) or inorganic ions

Mechanism of Enzyme Action: The behavior of enzymes is explained by a theory in which the formation of an enzyme-substrate complex is assumed to occur The specificity of enzymes is explained by the lock and key theory and the induced fit theory.

Enzyme Activity: The catalytic ability of enzymes is described by turnover number and enzyme international units Experiments that measure enzyme activity are referred to as enzyme assays.

Factors Affecting Enzyme Activity: The catalytic activity of enzymes is influenced by numerous factors The most important are substrate concentration, enzyme concentration, temperature, and pH.

Enzyme Inhibition: Chemical substances called inhibitors decrease the rates of enzyme catalyzed reactions irreversible inhibitors render enzymes permanently inactive and include several very toxic substances such as the cyanide ion and heavy metal ions Reversible inhibitors are of two types: competitive and noncompetitive.

Regulation of Enzyme Activity: Three mechanisms of cellular control over enzyme activity exist One method involves the synthesis of enzyme precursors called zymogens, which are activated when needed by the cell The second mechanism relies upon the binding of small molecules (modulators), which increase or decrease enzyme activity Genetic control of enzyme synthesis, the third method, regulates the amount of enzyme available.

Medical Applications of Enzymes: Numerous enzymes have become useful as aids in diagnostic medicine The presence of specific enzymes in body fluids such as blood has been related to certain pathological conditions.