Organic Chemistry

Atomic Structure

protons and nutrons are located in the nucleus small, electrons outside of nuckeys

Aufbau principle

electrons occupy the lowest energy orbital first

Paulis exclusion principle

an orbital can hold a max of 2 electrons

hunds rule

degenerate orbitals will fill up first with one electron before doubling up

Lewis structures

for a netal the number of dots is what an atom looses to form a cation, nonmetals is unparied dots

Dipole moment

=partial charge X distance between partial charges

Ionic atom id

if the difference in electronegitivity is greater then 2.0 then its ionic

Formal charge

VE-#of NE - ½ (BE)

valence, nonbonding, bonding

structures with small formal charges are prefered

Exceptions to the octet

B and Be have less then, and some have expanded valence shellls

Bond order

total electrons/number of bonded-atom pairs

Pi bonds and sigma

sigma are stronger and formed by direct overlap, pi are formed by cross overlap

Alkanes

saturated acyclic hydrocarbons CnH2n+2

Intermolecular forces

Hydrogen bonding, dipole dipole, london disperson forces

hydrogen bonding

between an hydrogen atom to a small electronetitive atom with lone electrons, N,O, F

Dipole dipole

in polar molecules

Van der walls forces, London forces

movment of electrons in a molecule, due to movment their can be uneven distribution of electrons in temporary dipole, forces exist in all molecules,

Alkanes properties

insoluble in water, must have intermolecular forces of the same type to dissolve alkanes, increasing melting abd boiling point with chain length, branched isomers have lower boiling points then straight chains,

Sources for alkanes

often make up protective coating on leaves and fruits, they are found in crude oil and natural gas

Alkane reactions

in general they are intert, dont react with common acids bases or oxidisers, good solvents for extraction and recrystilization due to inertOxidationess,

Oxidation Reactions Alkanes

used as fuel, combustion is reaction and they are exothermic

Halogenation of Alkanes

called substutution reaction, a halogen atom is substuted for a hydrogen hallogens used Cl and Br

this is a free radical process in which heat or light is used to breal a hallogen bond forming two halllogen free radicals

Alkane Hallogenation initiation

where the free radical is formed light breaks hallogen into their molecules

Alkane hallogneation propogation

where the halide radical reacts with the hydrocarbon generating one bond and still one intermediate radical repeating based on how many hallogens

Hallogenation alkane termination

where the remaining free radicals are comsumed halide with halide or carbon carbon radical or halide carbon

cyclopropane

smallest ring structure rigid and bond angles are 60, more reactive then linear alkane as c-c are strained

cyclobutane

puckerd conformation, not flat but drawn that way, more flexible then cyclopropane but strain is high, 90 angle

cyclopentane

minimu energy conformation more flexible angles are 105

cyclohexane

most common formation is chair, highly flexable can be a free non planar conformation with a bond angle of 109.5

Conformational isomers cyclohexane

addition of a methyl group can have two conformations axial or equtorial, or their is a boat conformation

Ring flip

becuse the c-c bonds are all sigma bonds it is possible to rotate about the bonds called chair chair or flipping all axial to equtorial and vice versa

geometric isomers

molecules same formula atoms in same order but located in different places,

cis trans isomerism

cis are methyl groups on the same side of the ring plane, trans are on oppisate sides of the ring plane

substiturent must be on didfferent carbons, non identical substitients, and one must be common

alkenes and alkynes

double and triple, unsaturated and contain pi bonds

Alkene and alkyne arrangments

cumulated c=c=c conjugated c=c-c=c, c=c-=c, isolated c=c-c-c=c

alkene bonding

sp2 hybridized trigonal planar 120 locked c=c bond

E nomenclature

E double bond the higher ranked bonds are on oppisate sides priority assigned based on atomic number

z nomenclautre

Z bonds are on the same side of the double bond

Alkene addition reactions

reactivity due to pi bonds and pi electrons the pi is wekaer then the sigma so they react first.

Alkene hallogenation

react with cl or br, hallogen is usually disolved in chloraform or tetrachloride, reactions are rapid at room temp reiles on polarity of halogen bonds

Nucleophiles

a molecule or ion that donates a pair of electrons to form a new covalent bond, due to formal or partial negitive charge pi bonds or lone pairs

Halogenation 1st step

pi electrons act as nucleophile attacking the bromide ion forming cyclic bromic cation

halogenation second step

nucleophile bromide ion attackes the side of bromium ion away from bromide opening the cyclic structure

Tacticity of polymers

refers to 3d arrangment (steriochemical arangment) of substituent groups

polymer must have an asymetric c atom in the monomer

Atactic polymers

centers have random configuration leas rigid

isostatic polymers

sterioregular, all groups orentated on the same side of polymer chain, most rigid

syndotatic polymers

sterioregular all groups alternate in same pattern, packed closeley

Thermoplastic

polymers that melt or soften by heating them and harden when cooled, polymers more riged by adding cross linked polymer chains

thermoset

materials made by joined polymer chains not able to melt.

Markovnikovs rule

when unsymmetrical reagent adds to a double bond the electrophillic part adds to the carbon with the most hydrogen atoms

electrophiles

positivley charged or neutral and electron deficent

carbocation

electro deficent and has an empty p orbital, not all carbocations are stable

Inductive electron donation

the electrons in a c-c sigma bond pulled closer to the middle c to mimimize charge, creating positive change on all atoms

Hyperconjugation

orbital interaction between adjacent bonds overlaps with empty porbidals helps mimimize charge on c

Electrophillic addition

basic mecanism same for all reagents teo step reaction where electrophile is added to the pi bond creating a carbocation intermediate the nucleophile is added

Catlysts

Ni, pt, pd

Syn addition

both h atoms add to the same side of the double bond

Anti addition

both halogens are on oppisate sides of double bond

radical addition reactions

forms free radical polymers

additions to conjugated systems

synthsize cycloalkenes

chain growth polymers

retain all atoms of the monomer

condensation or step growth

produced from the reaction between functional groups with the loss of a small molecule