Introduction to Organic Chemistry

Carbon: The key to organic

1. What are the purposes for studying organic chemistry? (Just information, not test material)

1. Organic chemistry involves a problem solving method that most of you have not seen before

2. Solving Organic Chemistry problems is a challenge that can be interesting

3. At the beginning of the Chemistry I course, if you are asked where the electrons are in an atom, you correctly say atomic orbitals. At the beginning of the Chemistry II course if I ask you how to brominate an alkane, you say use bromine and light. Did you have to memorize these two facts? No, you became familiar with these facts by using them and understanding their context. You can NOT memorize your way through this course.

2. How did it originate?

a. In the earlier period of development of chemistry, chemists tried their best to synthesize organic compounds in the laboratory. But all their efforts proved to be futile. Their failures led them to believe that organic compounds could be prepared only by and within living beings and that they could never be synthesized in the laboratory like inorganic compounds.

3. What did scientist really believe about organic chemistry and what/who changed their minds?

a. Jöns Jacob Berzelius, a physician by trade, first coined the term "organic chemistry" in 1807 for the study of compounds derived from biological sources. Up through the early 19th century, naturalists and scientists observed critical differences between compounds that were derived from living things and those that were not. Chemists of the period noted that there seemed to be an essential yet inexplicable difference between the properties of the two different types of compounds. The vital force theory (sometimes called "vitalism") was therefore proposed (and widely accepted) as a way to explain these differences. Vitalism proposed that there was something called a "vital force" which existed within organic material but did not exist in any inorganic materials.

4. What did Friedrich Wöhler have to do with discrediting the “vital force” theory?

1. He was widely regarded as a pioneer in organic chemistry as a result of his synthesizing of the biological compound urea (a component of urine in many animals) utilizing what is now called "the Wöhler synthesis."

2. in 1828 he heated an aqueous solution of two inorganic compounds, ammonium chloride and silver cyanate, and produced “urea”.

NH4Cl + AgNCO NH2CONH2 + AgClheat

Ammonium chloride Silver

cyanateurea

Silver chloride

Urea was a compound that mammals produced to get rid of excess nitrogen. Urea is secreted in their urine. Friedrich Wohler created it using inorganic (non-living) salts. Everyone was surprised, but chemists then knew that it was possible to create chemicals found in the body using chemicals from the ground or air (non-living sources). So now organic compounds were not defined as only those compounds from organisms, but compounds based on carbon.

2. Hermann Kolbe, 1845, worked with Wohler, and converted carbon disulfide (CS2) to acetic acid (CH3COOH)

a pioneer in the development of structural formulas for organic compounds.

Introduced the term “synthesis” by discovering many synthesis methods of organic molecules from inorganic components.

discovered a method of electrolysis of salts of fatty acids known as the Kolbe electrolysis.These experiments opened the floodgates for synthetically produced compounds.

• This was the final proof to discredit the vitalism theory where organic compounds have some 'spark' and could only be created from other organic compounds. The Kolbe synthesis reaction is a method of making salicylic acid, the main component of aspirin.

How do the inorganic vs. organic compounds compare (number wise)?

Five million organic compounds to 2-3 hundred thousand inorganic compounds.

What is the modern definition of organic chemistry?Those compounds containing carbon

The exceptions to the rule: carbonates, cyanides, carbon dioxide, and carbon monoxide. (These are exceptions because they don’t contain both carbon and hydrogen)

What is there about carbon that permits the formation of so many compounds?

1. In addition to binding to hydrogen, carbon can also bind to other carbon atoms

ethane

2. An organic molecule (hydrocarbon) is formed when carbon bonds to hydrogen.  The simplest hydrocarbon consists of 4 hydrogen atoms bonded to a carbon atom (called methane): Also “CHNOPS” and the halogens

3. the uniqueness of carbon comes from the fact that it can bind to itself.  Carbon atoms can form long chains:

4. branched chains:

hexane

isooctane

5. rings:

cyclohexane

ORGANIC VS. INORGANIC1. Few elements (CHNOPS) 1. many elements

2. Complex structures (long chains) 2. simple structures3. Insoluble in HOH 3. most soluble in HOH4. Low m.p/b.p 4. high m.p/b.p

5. Combustible 5. not combustible

6. doesn’t conduct electric 6. conducts electric current

current7. Consists of molecules 7. forms ions in solution

8. Slow reaction rates 8. fast reaction rates

9. Side reactions 9. no side reactions

10. High product yield 10. low product yield

10 Carbon Facts—The chemical basis of life

•Carbon is the basis for organic chemistry, as it occurs in all living organisms. •Carbon is a nonmetal that can bond with itself and many other chemical elements, forming nearly ten million compounds. •Elemental carbon can take the form of one of the hardest substances (diamond) or one of the softest (graphite). •Carbon is made in the interiors of stars, though it was not produced in the Big Bang. •Carbon compounds have limitless uses. In its elemental form, diamond is a gemstone and used for drilling/cutting; graphite is used in pencils, as a lubricant, and to protect against rust; while charcoal is used to remove toxins, tastes, and odors. The isotope Carbon-14 is used in radiocarbon dating. •Carbon has the highest melting/sublimation point of the elements. The melting point of diamond is ~3550°C, with the sublimation point of carbon around 3800°C. •Pure carbon exists free in nature and has been known since prehistoric time. •The origin of the name 'carbon' comes from the Latin word carbo, for charcoal. The German and French words for charcoal are similar. •Pure carbon is considered non-toxic, although inhalation of fine particles, such as soot, can damage lung tissue. •Carbon is the fourth most abundant element in the universe (hydrogen, helium, and oxygen are found in higher amounts, by mass).

Structure of the carbon atom:Atomic number is 6, mass is 12

Most common isotope: 6 protons, 6 neutrons, Electron configuration

Valence electrons

Simplest molecule is methane (CH4)

Other names for methane are: swamp gas or marsh gas; very flammable

Lewis Dot structure of methaneThe molecular shape of methane

•Hydrogen and the halogens bond once. (can form single bonds only)•The family oxygen is in bonds twice. (can form single and double bonds; explain)•The family nitrogen is in bonds three times. (can form triple bonds)•The family carbon is in bonds four times. (can bond single, double, and triple bonds)

The bonding capabilities of our organic elements

Structures of organic compounds:Molecular formula —shows which atoms, and how many of each, are present in a molecule. C2H6OCondensed formula – shows the atoms present and the bonds that connect to each other in a condensed format. ( CH3CH3 )

Expanded structure—shows all atoms and their bonds. examples

Review of the atom:

a. Atomic number

b. orbital

c. Hund’s rule

d. Octet rule, valence electrons

e. Ionic and covalent bonding

f. Lewis structures

g. Nonbonding electrons

h. Draw these: C2H6, C4H10O,CH3Br, C3H8, C2H7N,C3H8O,C2H5F, C6H14, CH3PO

Nonpolar molecules are hydrophobic (means "water fearing"). They do not dissolve in water.

Nonpolar molecules are hydrophobic

Polar and ionic molecules are hydrophilic.

Nonpolar molecules are hydrophobic. Polar and ionic molecules are hydrophilic.

Portions of large molecules may be hydrophobic and other portions of the same molecule may be hydrophilic.

POLAR AND NONPOLAR MOLECULES

What is the reason for the many possible arrangements of the carbon atom?

Isomerism!! The carbon atoms can bond in more than one arrangement, giving rise to different compounds with different structures and properties.Have identical molecular formulas but different

arrangements of atomsStructural isomers have the same molecular formula but the atoms bond in different patterns

Example: C2H6O

•functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules.

Functional Groups:

Combination of atoms that differentiates molecules of organic compounds of one class from those in another.

The 10 Functional GroupsTerm/Definition

•Alkane consists of only carbon to carbon single bonds•Alkene consists of at least one carbon to carbon double bond•Alkyne consists of at least one carbon to carbon triple bond•Alcohol contains an -OH group•Aldehyde contains a terminal O=C-H group•Ketone contains an internal C=O group•Carboxylic acid contains a terminal O=C-OH group•Ether contains an internal O-O group•Ester contains an internal O=C-O- group•Amine contains a terminal NH2 group

Priorities of the groups: Keep rest of semester.

Subordinate groups: Nitro < halides < alkoxy

Functional groups: (from least to greatest in priorities) alkanes < alkynes <alkenes < amines < phenols < alcohol <ketones < aldehydes < nitriles < amide <acid halide < carboxylic esters <carboxylic anhydrides < carboxylic acids (TOP DOG).