orgo chemistry misc

gauche (as opposed to anti, eclipsed)

2 methyl group sixty degrees apart

naming bicyclic compounds

http://www.masterorganicchemistry.com/2014/08/14/bridged-bicyclic-rings-and-how-to-name-them/ number starting from ring to longest part of ring brackets include segmented parts # number of rings bicylco[ 3 2 1 ] hexane example, only count carbon once fused ring get same treatment [3, 3, 0] spiro will show up as [2,2]

geometric isomers

isomers (an obselete term that should be replaced by cis-trans isomers) are configurational isomers that differ in the spatial position around a bond with restricted rotation (e.g. a double bond) or across a ring system: • E-2-butene and Z-2-butene

Nitrile Reduction

no NaBH4

sec, iso, di tri

not part of alphabetical naming

alkenes with acids

only acids give rearrangements

HBR and alkene

rearrangments possible stereoisomers possible markovnikov

rings strain

sp3 has 109.5 but 3 ring, 4 ring and 5 ring can't match that cyclohexane has no ring strain

The least stable antiperiplanar conformation that leads to the formation of the minor product

stable conformation when relating to alkenes

conjugation lowers

stretching frequency for IR

longest chain will contain

the greatest number of substituents.

tie breaker

tie breaker is alphabetical order giving the bromo substituent the number 1 location in this molecule.

recrystallization

use slow cooling to ensure impurities are not trapped again long crystals indicate high degree of purity, formed by slow cooling

separatory funnel

used for extraction

axial equatorial

Keq tells which conformation will happen at equilibrium

recrystillization

Recrystallization is a method of purifying a solid. There are two types of impurities: those more soluble in a given solvent than the main component and those less soluble. solvent dissolves the organic compound when hot. does not dissolve the organic compound when cold. dissolves small amounts of likely impurities.

enantiomers

are optical isomers that are non-superimposable mirror images. Enantiomers have identical chemical and physical properties in an achiral environme

diastereomers

can be defined as any stereoisomers that is not an enantiomers have different chemical and physical properties (melting range, solubility, etc.)

sn1

can have stereoisomers

naming complex subsituents

complex substituent the carbon attached to the parent chain is given the number 1 and then the substituent is numbered starting there to give the longest continuous chain which is 3

racemic 100% optical purity

0% optical purity 100% of one enantiomer Meso compounds are optically inactive

Which isomer is dominant and what is the optical purity of a mixture, of (R)- and (S)-2-bromobutane, whose specific rotation was found to be -9.2o? (-23.1 degrees given as R)

Answer: The negative sign tells indicates that the R enantiomer is the dominant one. Optical purity, % = 100 [a]mixture / [a]pure sample = 100 (-9.2) / -23.1o = 40% this indicates a 40% excess of R over S! Question: What is the percent composition of the mixture? Answer: The 60% leftover, which is optically inactive, must be equal amounts of both (R)- and (S)-bromobutane. The excess 40% is all R so there is a total of 70% (R) and 30% (S). 60% is inactive so equal amounts of R and S divide by two and add to R to find actual amount

optical purity is as the "enantiomeric excess + - signs

Dextrorotary designated as (+), clockwise rotation (to the right) Levorotary designated as (-), anti-clockwise rotation (to the left) ee % = 100 * ( [ R ] - [ S ] ) / ( [ R ] + [ S ] )

dont assume H is weakest for R or S

H might not be present

alkenes syn addition

H2/pd mcpba hydroboronation

major contributor

Satisfy the octet rule. maximal covalent bonds Minimize charge separation. Put negative charge on the more electronegative atom.

gabriel synthesis

Sn2 preferred

Simple Distillation

The simple distillation process works best for liquids with very different boiling points. hit lowest boiling point water in and water out just used to cool condenser

IR radiation

The stronger the bond, the more energy will be required to excite the stretching vibration. This is seen in organic compounds where stretches for triple bonds such a occur at higher frequencies than stretches for double bonds (C=C, C=N, C=O), which are in turn at higher frequencies than single bonds (C-C, C-N, C-H, O-H, or N-H). The heavier an atom, the lower the frequencies for vibrations that involve that atom.

acid-base extraction

Use weaker bases for stronger acids to form aqueous layer (pour out)

Fractional Distillation

When the boiling points of the two liquids in the mixture are close, generally a difference of less than 40 degrees Celsius (104 degrees Fahrenheit), fractional distillation is more efficient. Fractional distillation has fractionating column is placed between the boiling flask and the condenser. These beads improve the separation between the liquids being distilled. The reason that fractional distillation gives better separation between the liquids is because the glass beads in the fractionating column provide "theoretical plates" on which the refluxing liquid can condense, re-evaporate, and condense again, essentially distilling the compound over and over.

conformational isomers

conformational isomerism is a form of stereoisomerism in which the isomers can be interconverted exclusively by rotations about formally single bonds Conformational isomers are thus distinct from the other classes of stereoisomers (i. e. configurational isomers) where interconversion necessarily involves breaking and reforming of chemical bonds They cannot normally be separated and possess identical physical and chemical properties.

cis and trans alkenes

contribute to stereoisomers cis-trans isomers are diastereomers (non-superimposable non-mirror images).

elimnation

favors most stable product (except in e2 when hydrogen needs to be antiperiplanar )

naming ketones, amines, alcohols

find longest chain; C1 doesn't begin at ketone, amines, unless at end (impossible for ketone) start at closest functional group with highest priority that has longest chain

cyclohexane energy profile

for substituents lowest is equatorial

br2 and alkenes

forms bromonium ion anti addition markovnikov all others that form this type of ion are anti some are not markovnikov though

structural isomers

have same formula also called constitutional isomers but different connectivity

stereoisomers

have the same functional groups and connectivities, they differ only in the arrangement of atoms and bonds in space.