Organic Chemistry Must Knows

relationship between pka and pH

Based on the relationship between the pKa of a compound and the pH of a solution, we can predict whether a compound will be protonated or deprotonated. If the pH is lower than the pKa, then the compound will be protonated (because there are a lot of H's in the solution). If the pH is higher than the pKa, then the compound will be deprotonated. If pH = pKa, the concentration ratio of [A-] to [HA] is 1. If your pH is higher than pKa, then [A-] must be greater than [HA]. If you lower your pH such that it is lower than pKa, then [HA] must be greater than [A-] Therefore, by increasing the pH, you are dissociating HA into H+ and A-. Which makes sense according to the Le Chatelier principle, where H+ is released to counteract the increase in pH (or the decrease in [H+])

Benzene

C6H5 (PhH)

benzoic acid

C6H5COOH

Aniline

C6H5NH2

imine

C=N to form imine from carbonyl reagents: RNH2 + H+ primary amines react with aldehydes and ketones to form imines

vinyl group

CH2=CH-

allyl group

CH2=CHCH2-

D sugar vs L sugar

D- OH is on the right L- OH is on the left If given a ring, then if the CH2OH group is pointing up, it is a D sugar. If the CH2OH group is pointing down, it is a L sugar.

To extract phenols

Extract with aqueous NaOH

pkas to know

H2O- 16 H3O+- -2 CH3COOH- 5 NH4+- 10 CH3CH3CO(ketone)-alpha H 20 Phenol- 10

HF is weaker acid than HCl, HBr, and HI

HF bond is strong; since F is small, better overlap with 1s orbital of H

Determining Basicity

Higher electron density within molecule means it is more likely to share electrons with another molecule

IR absorption--what it actually means

IR is absorbed when molecule has dipole Due to symmetry, there is no dipole, therefore, it is IR inactive

symmetry and nmr----How to determine Equivalence:

Identify a mirror plane in the molecule. If there is symmetry along the mirror plane then the protons are equivalent! Identify an axis of rotation. If the molecule looks the same upon rotation, then the protons are equivalent!

diasterotopic protons

Not all CH2 groups in chiral molecules are diastereotopic - in the chiral molecules below the CH2 is on a C2 axis of symmetry, and the protons are homotopic. In general, CH2 groups (or other similar groups like CHMe2, CHF2, etc) will be diastereotopic when part of a chiral molecules unless the CH2 group is on a C2 rotation axis.

why are amines better bases than alcohols?

O is more EN, so it holds onto electrons more tightly and doesn't donate

decanting

Pouring liquid off the top when sediment has settled to the bottom

protons in nmr

Protons and other nuclei in NMR spectra can be classified as heterotopic, diastereotopic, enantiotopic and homotopic

aldehyde

R-CHO

PI3, PCl3, PBr3, SOCl2 Phosphorous Trihalides

Reacts with alcohols (SN2 type reaction) invert and replace OH with halide Can then be used to make Grignard reagent

naming aldehydes

Replace "e" with "al" e.g. butanal butane parent chain with aldehyde on C1

naming ketones

Replace the "e" with "one" e.g. 3-hexanone hexane parent chain with ketone on C3

Features that influence basicity

Resonance: due to electron delocalization, reduces electron density Atomic Radius: Br- has larger atomic radius than F- so F- is more basic. Electronegativity: atom is greedier for electrons, less willing to share electrons with a proton e.g. F- vs. NH3 Inductive effect: other atoms within molecule can take electrons away, reducing electron density Formal Charge--negative charge will increase its electron density, making it more likely to form a bond with proton

polar protic

SN1

polar aprotic

SN2

Tetrahydrofuran

THF is a universal solvent aprotic polar solvent. However, it is not nearly as polar as water

determining frequency of bonds in ir

The frequency of a given vibration is determined by two factors: the masses of the bonded atoms and the relative stiffness of the bond. Since the bonds given are all single bonds, we can assume that all have the same stiffness, so the difference in their IR stretching frequency is determined by the masses of the bonded atoms. Light atoms vibrate at higher frequency than heavier ones (based on Hooke's law). Therefore, C-Cl, having the heaviest atoms, would occur at the lowest frequency, followed by C-O, then C-N, then C-C, and C-H.

Determining acidity vs basicity

The more positively-charged the compound = the more acidic. The more negatively-charged the compound = the more basic. Resonance increases the stability of charges, therefore a resonance-stabilized conjugate base will be a stronger acid. Electron Withdrawing groups increase acidity Electron Donating groups decrease acidity S-orbitals tend to be more electronegative, so the more "s-character" an atom has, the stronger the acid. acidity increases with electronegativity and size bigger size=charge is spread out increasing electronegativity= electron withdrawing= more positive

elimination reaction

The removal of a molecule from a saturated molecule to make an unsaturated molecule

bond strength and acid strength

Less bond strength(bigger the atom size and lower the EN), more acid strength because it holds onto the proton due to electronegativity e.g. HF has high EN and small atom size, so the bond strength would be high and the acid strength would be low HI has weaker bond strength because I is bigger and I is less EN, so it holds onto electrons less readily

endo rule

The stereochemical preference for electron-poor substituents on the dienophile to assume endo positions in a bicyclic Diels-Alder product.

oxymercuration-demercuration reaction

Markovnikov--attach oh to most subbed c

enantiotopic protons

When substitution of two H atoms by Z forms enantiomers, the two H atoms are equivalent and give a single NMR signal

addition reaction

a chemical reaction in which two or more substances combine to form a new compound

allene

a compound with two adjacent double bonds

fatty acid

a long hydrocarbon chain with a carboxyl group on one end

naming acid halides

"e" to "oyl halide" e.g. 4-methylpentanoyl iodide pentane parent chain with methyl on C4 and iodide on acid halide

aromaticity rules

*Cyclic *Conjugated *Planar *Huckel's Rule (4n+2) =2,6,10,14,18,22 etc. anti aromatic if doesn't fulfill Huckel's Rule non aromatic if doesn't fulfill first 3 there should not be sp3 carbons

dextrorotary

+

levorotary

-

aliphatic amines

- Alkyl groups are generally EDG - the more alkyl groups -> the higher the pKa/the more basic (to a point)

pka vs pH

- Bronsted theory o There is a tug of war of proton between a compound and its environment o pKa is a property of the compound and pH is the concentration of the protons in the environment o if pH > pKa (bigger pH means lower concentration of H+), environment will pull H+ from the molecule and ionization state is conjugated base form A-. A- ionization state makes the molecule more polar and more water soluble but less able to cross membranes because of reduced hydrophobicity compared to HA unionized form. o If pH < pKa (more H+ in the environment) so the molecule will grab H+ and be in HA form. Polarity and water solubility decrease in the unionized form but their ability to partition through the membrane increases. given pka= 2.3 means that at pH=2.3, we lose 50% of the hydrogens

Nucleophilicity is determined by 4 major factors:

- Charge: Increases with increasing electron density (more negative charge) - Electronegativity: Decreases as electronegativity increases(from left to right) because these atoms are less likely to share electron density (therefore, will be less basic) - Steric Hindrance: Bulkier molecule = less nucleophilic - Solvent: Protic solvents can hinder nucleophilicity by protonating the nucleophile or through hydrogen bonding.

acetyl

-COCH3

double bond

1 pi bond

Basicity vs. Nucleophilicity

1) If it's sterically hindered, it is more basic than nucleophilic...nucleophiles must have very little steric hindrance...Primary nucleophiles are most common...secondary atoms can act as bases OR nucleophiles or both...tertiary atoms ONLY act as bases 2) Reactivity (low stability) favors basicity over nucleophilicity (e.g. NH2- vs RO-) 3) If an atom has a full negative charge, it will almost ALWAYS act as a base 4) Highly electronegative atoms make good bases, but not good electrophiles, bc they want the electrons all to itself (bases are able to abstract protons and create highly polar bonds)....c basicity is thermodynamic concept, nucleophilic is kinetic concept

Factors affecting the frequency of infrared peaks

1. Resonance, bond strength, symmetry and conjugation The triple bonds are stronger than the double bonds followed by single bonds between the same two atoms and hence vibrational frequency is in the order of triple>double>single. The presence of greater degree of conjugation, the frequency is relatively lesser. Not all covalent bonds display bands in the IR spectrum. Only polar bonds do so. These are referred to as IR active. The intensity of the bands depends on the magnitude of the dipole moment associated with the bond in question: • Strongly polar bonds such as carbonyl groups (C=O) produce strong bands. • Medium polarity bonds and asymmetric bonds produce medium bands. • Weakly polar bond and symmetric bonds produce weak or non observable bands. e.g. triple bonds

naming esters

1. The alkyl group attached to the ester oxygen gets listed first with the suffix "yl". The parent chain then follows. 2. The parent chain starts at the carbonyl carbon and is counted moving away from the ester oxygen. Parent chain's suffix is replaced with "oate". e.g. ethyl pentanoate ethyl substituent on ester O pentane parent chain starting from carbonyl c of ester compound

naming carboxylic acid

1. We number the parent chain in the direction that gives the highest priority (lowest number) to the carboxylic acid group. 2. We replace "e" with "oic acid" e.g. butanoic acid butane parent chain with carboxylic acid on C1 use "dioic acid" if there are two carboxylic acids

meso compounds

2 chiral centers plane of symmetry--achiral no enantiomer!!!! therefore, in a polarimeter, meso compounds don't rotate polarized light---optically inactive Stereocenters on one half of the molecule will turn plane-polarized light one way, and the stereocenters on the other half of the molecule will turn plane-polarized light in the opposite direction, resulting in non-rotated light. Thus, meso compounds cannot be assigned with either dextrorotatory (+) or levorotatory (-) designations

triple bond

2 pi bonds

carbocation stability

3*>2*>1*>methyl tertiary carbocations are more stable than benzylic or allylic carbocations, contrary to stability of radicals

gauche conformation

A conformation in which the two largest groups are 60 apart when viewed in a Newman projection

substitution reaction

A reaction in which an atom or group of atoms is replaced with a different atom or group of atoms.

addition elimination reaction

A reaction in which two molecules combine with the release of a small molecule, often water. This type of reaction is also known as condensation.

carboxylic acid derivative reactivity

Amides (A) are the least reactive, followed by slightly more reactive esters (D and E), then anhydrides (C) and finally, the most reactive are the acid halides (B).

tautomer

An isomer that differs from another by the placement of a proton and a double bond e.g. keto enol keto form is more stable because C=O double bond is more stable

SN2 reaction

Back side attack. Inverted stereochemistry (R)--> (S) primary> secondary> tert carbon one step best in polar aprotic ( resonance structures have - and + charge... so remove + group from Nuc.. leaving Nuc: - ... therefore Nuc more reactive. BUT + part of solvent can't react with anionic Nuc because of steric hinderence

carboxylic acid and H bonding

carboxylic acid has greatest amount of hydrogen bonding ability most likely to dissolve in water to the greatest extent

Zwitterions at intermediate pH

carboxylic acids become deprotonated at neutral pH, forming zwitterions--two charges neutralize each other; molecule that has both positive and negative charge; pH is above pKa of carboxylic acid so it is deprotonated, but pH is below pKa of amine group so, protonated

acidity and atomic size

acidity increases as atomic size increases because size causes the negative charge to spread out

ortho/para director

activators AND halogens(even though halogen is a deactivator) activators are any electron donating groups O->-NR2>-NH2>-OH>-OR>-R weak activators but activators nonetheless: methyl, phenyl have lone pair of e- or an e- density that pushes into benzene

Cyclooctatetraene

adopts a puckered tub-shaped conformation. Why? Because if it remained flat, it would become anti-aromatic as a result of having a non-Hückel number of pi electrons (8)! Because anti-aromatic systems are so unstable, this compound puckers and sacrifices the p orbital overlap so that it won't have to endure the instability associated with being anti-aromatic. NONAROMATIC, not anti

enamine

alkene+NR2 to form enamine from carbonyl reagents: R2NH + H+ secondary amines react to form enamines

flipping chair conformation of cyclohexane

all axial positions become equatorial, and all equatorial positions become axial. all up substituents remain up, and vice versa

degrees of unsaturation

allows you to identify molecules/ draw possible isomers given a molecular formula double bond- 1 degree of unsaturation ring- 1 degree of unsaturation triple bond- 2 degrees of unsaturation determining degrees of unsaturation compare given with nearest alkane (CnH2n+2) Take the difference of H's and divide by 2 If halogen is present, count as H eg. C10H10Cl2 given: C10H12 nearest: C10H22 degrees of unsaturation: 5 If N is present, subtract 1 H for every N present

radical stability

allylic/benzylic>3*>2*>1*>methyl

alpha vs. beta anomers

alpha is pointing down, beta is pointing up

amide vs amine

amide-- carbonyl with NH2 group amine--contain N with lp primary amine---RNH2 secondary amine---R2NH tertiary amine---R3N

ammonia vs ammonium

ammonia: NH3 ammonium: NH4+

oxo

an "=O" group bonded to the corresponding numbered carbon. e.g. 2-oxooctanedioic acid

anti vs syn

anti---most bulky molecule are farthest away from each other

amines

are bases

meso compound's enantiomers

aren't different...their enantiomers are identical molecules because they are superimposable

Trends in acidity on periodic table

as you go down and to the right, it becomes more acidic size matters....as size increases, so does acidity

Wavenumber and IR

as you increase wavenumber you increase in energy

Base Strength Trends

base strength increases as you go up and to the left ch3>nh2>oh>f>cl>br>I

use of sodium bicarbonate (NaHCO3) aka baking soda in extraction

basic reagent that deprotonates acid

grignards/lithiates and epoxides

basic reagents, therefore, they attack least hindered side of epoxide...

least basic NH3<NH2<NH most basic

basicity increases with negative charge resonance stabilized amines are less basic due to delocalization of electrons e.g. aniline is less basic than cyclohexylamine

benzyl vs phenyl

benzyl: C6H5CH2 phenyl: C6H5 (Ph)

As branching goes up (for london disperson forces)

boiling point goes down

As formula weight goes up,

boiling point goes up

branching, bp, heat of combustion

branching lowers bp bc less surface area more branched, lower heat of combustion (more stable)

m/z

mass to charge ratio

Melting point and purity

melting point can determine compound's purity broad range=not pure

meso vs enantiomer RS naming system

meso is RS/SR enantiomer is RR/SS

carboanion stability

methyl > 1* > 2* > 3* (opposite of carbocation stability)

mutarotation vs epimerization

mutarotation: change in the position of the group attached to the anomeric carbon (e.g. alpha vs beta glucose) epimerization: change in stereochem in one chiral center

cyclodecapentaene

non aromatic because nonplanar!!!

Aliphatic

nonaromatic

optically active molecules

nonmeso molecules with chiral centers, cis-trans molecules that aren't meso, E/Z molecules that are not meso

determining melting point when there is symmetry

normally, an increase in branching would mean lower boiling point right and melting point, right? well, for melting point, it can also get complicated..... if there is symmetry in the branching, it trumps the branching effect linear versus branched —> higher melting/boiling points due to better stacking and surface area contact. highly branched vs. branched —> more sphere-like -> better stacking -> higher melting point highly branched vs. branched —>more sphere-like - -> lower surface area —> lower boiling point.

what makes a good nucleophile?

nucleophilicity is measured by rate 1. the conjugate base is always a better nucleophile (higher electron density) 2. periodic trend (nucleophilicity increases as we go to the left of the periodic table) the least electronegative, the most nucleophilic

Rf value

compound travel distance / solvent distance traveled more polar --> smaller value

azeotrope

constant boiling mixture that is made up of substances in a certain ratio that simple distillation cannot separate. can either have a boiling point higher or lower than either component eg. ethanol and water 95.63% ethanol and 4.37% water (by mass) boils at 78.2 °C. Ethanol boils at 78.4 °C, water boils at 100 °C, but the azeotrope boils at 78.2 °C, which is lower than either of its constituents.

how many atoms lie in same plane ?

count sp2 atoms and the atoms next to the sp2 atoms

network solid

covalent network high melting point, hard, non conductive (bc no sea of electrons to share like in metallic) C, SiO2

all about resonance

occurs when electrons are delocalized, not belongjng to any single atom single lewis structure cannot depict an actual specie. the actual specie is a composite or average of all the resonance contributors. when writing resonance forms, the major contributors have octets on all atoms, no charge separation, and the maximum number of covalent bonds. all contributors must have the same number of paired and unpaired electrons. resonance does not represent equilibrium, but a phenomenon that simply gives a rough approximation of a particular specie. as a general rule, the greater the number of resonance structures, the greater the delocalization of electrons and the greater the stability.

isomeric

of, relating to, or exhibiting the phenomenon exhibited by two or more chemical substances containing the same numbers of atoms of the same elements in the substances but differing in the structural arrangement of the atoms.

meta director

deactivators (not HALOGENS THOUGH) electron withdrawers/deactivators have a positive charge on substituent or a very EN atom attached to it, which pulls electrons out of benzene -NO2>-NR3+>NH3+>-SO3H>-CN>-CO2H>-CO2R>-X

naming acid anhydrides

determine length of chain on either side of bridging o list both lengths alphabetically, replacing "e" with "oic" write "anhydride" at the end of the name e.g. butanoic ethanoic anhydride

epimers

diastereomers that differ in configuration at only one chiral carbon

steam distillation

distill high boiling point substances (purify liquids that aren't volatile) can be employed on immiscible liquids distills at a temperature below bp of the lower boiling component allows for collection of temperature-sensitive aromatic compounds useful for isolation of oils, waxes, and complex fats

to convert empirical to molecular

divide molecular weight by weight of empirical formula. multiply the answer you got to each of the subscripts in your empirical formula

how polar aprotic solvent affects nucleophilicity

don't have to worry about size because don't have to worry about solvation shell main culprit is basicity F is most basic trend reversed: F->Cl->Br->I-

F- in polar protic solvent

e.g. F- in H2O solvation/hydration shell forms around F- hinders nucleophilicity of F-!!!

I- in polar protic solvent

e.g. I- in H2O not hindered as much due to its size!!!

Inductive effect

e.g. electron withdrawing groups Inductive effect increases acidity, decreases basicity because stabilizes negative charge on donating atom by alleviating burden... therefore conjugate base is more stable

what constitutes a better base?

electron donating!!!

NMR Spectroscopy

electron rich to the right because shielded by external magnetic field, therefore lower frequency e.g. sp3 vs. sp2 sp3 is more electron rich because sp2 has more s character (electronegativity withdraws electrons) electron poor (EWG) to the left, less shielding of external magnetic field by electrons, therefore higher frequency

equatorial vs axial

equatorial--larger group eg. methyl vs. Br methyl is equatorial because it has 4 atoms substituents on chair conformation prefer equatorial over axial because they are farther away from each other, increasing stability PLACE LARGER GROUP IN EQUATORIAL POSITION **When you have two groups that can either be both axial or equatorial, it is more stable when they are both equatorial

To extract amines

extract with aqueous HCl

To extract carboxylic acids (or organic acids, or acids)

extract with aqueous NaOH or NaHCO3

naming amides

first, list substituent attached to N as "N-methyl", "N-ethyl" etc. second, parent chain that starts at carbonyl chain and is counted moving away from N "e" to "amide" e.g. N-methylbutanamide

CH2O

formaldehyde

empirical formula calculation

formulas that give the most reduced whole number ratio of each atom two types of questions: 1. given molecular formula, find specific element's percent calculate total mass then, calculate the mass of the specific element and put it over the total mass and multiply by 100 2. give mass percent of each element, determine compound's formula assume 100g of total sample. treat the mass percentages as grams, and then divide each mass percent by the element's atomic mass. Then, divide by the smallest number of all of them if answers are close to whole numbers, go to the next step. if not, then multiply by 2 or 3 to change them into whole numbers

furanose vs pyranose

furanose (5 membered ring) pyranose (6 membered ring)

first four alkanes

gaseous and nonpolar at room temperature

mutarotate

general property of sugars, as well as cyclic hemiacetals The specific rotation of α-D-glucopyranose decreases from +112° to +52.5°. The specific rotation of β-D-glucopyranose increases from +19° to +52.5°. This behaviour is called mutarotation (literally, "change in rotation"). Hold on. Isn't specific rotation of a molecule supposed to remain the same? Yes - if it is indeed the same molecule! And therein lies the answer to the puzzle. For when the solutions whose specific rotations have changed to +52.5° are analyzed, they are found to no longer consist of 100% alpha (α) or 100% beta (β) anomers, but instead a ratio of alpha (α) (36%) and beta (β) (64% ) isomers.

use of dichloromethane in extraction

good solvent, considered nonpolar, immiscible with water

molecular solid

h bonding, dipole-dipole songs, london dispersion low melting point nonconductive H2, CO2

eclipsed conformation

highest energy no separation. or 120 separation. torsional strain because of repulsive forces between electron pairs in the C−H bonds of adjacent carbons

naming nitriles

parent chain is longest carbon chain that involves nitrile carbon number parent chain in direction that gives the smallest number to the nitrile carbon add nitrile to parent name e.g. pentanenitrile

when to use pipet versus buret

pipet is calibrated to deliver a specific volume of a liquid when filled to the mark and allowed to drain buret will deliver known volumes of solution, but during a titration

carboxylic acid H

pka = 5

phenol H

pka= 10

DMSO

polar aprotic solvent

IR spectroscopy

identify functional groups

-OH vs -SH which one is a better nuc

if on same row, doesn't depend on solvent. nucleophilic strength parallels base strength if on same column, depends on solvent (aprotic--nucleophilicity increases as you go up; protic---increases as you go down) in protic solvent, -SH is more nucleophilic in aprotic solvent, -OH is more nucleophilic OH is a better base regardless of what solvent is used base strength increases going up a column bc bigger molecules would delocalize negative charge

hammond postulate

in exothermic (reactants are higher energy), transition state resembles reactants in endothermic (products are higher energy), transition state resembles products

free radical reaction/halogenation

light, hV, X2 Halogen added to most substituted Remove H at most substituted C and substitute with X

terpene

lipid, may be found in oils such as peppermint, celery and ginger. contain four carbon chain with a one carbon branch called an isoprene unit ignore any double bonds, OH groups etc, they don't necc have to have it

pka

lower the pka, the more acidic

staggered conformation

lowest energy conformation

racemic mixture

rotations cancel each other out therefore no optical activity 50% R: 50% S optically inactive (will not rotate the plane of polarized light)

simple distillation

separate liquids that boil below 150 degrees C at least 25 degrees apart - separation by bp (lowest bp distills out of mixture)

Extraction must knows

separates compounds through manipulation of acid-base properties to extract acid, use base like NaOH or NaHCO3 to extract amine, use acid such as HBr to extract phenol, use a base like NaOH

distillation

separates liquids based on boiling point(depends on imf) the process of purifying a liquid by boiling it and condensing its vapors

vacuum distillation

separates liquids that boil above 150C reduced P, lowering BP of liquids (preventing decomposition typical at high T)

fractional distillation

separates liquids that boil less than 25 degrees apart near the top of the column, vapor is composed solely of 1 component, which will condense and collect in the receiving flask AKA repeated distillation of same vapor

extraction

separatory tunnel nonpolar organic layer aqueous polar layer organic layer usually on top, unless you use chlorinated solvents like dichloromethane, then they will be the bottom layer bc denser

determining heat of hydrogenation

smallest indicates more stable alkene

dielectric constant

solvents ability to moderate the force of attraction between oppositely charged particles solvent with a high polarity like water has a high dielectric constant if a solvent has a dielectric constant over 15, we refer it to as polar.

bond length and s character

sp3 - least s character, longer bond bc less electronegativity

hyperconjugation

spreading out charge by the overlap of an empty p orbital with an adjacent sigma bond e.g. three R groups and a radical in p orbital is more stable than a radical with 2 R groups,,,,hyperconjugation is a factor in explaining why more alkyl substituents on carbocations make it more stable.

strong bases

stable(weaker) conjugate acid

strong acids

stable(weaker) conjugate base

eclipsed vs staggered

staggered is more stable bc less energy

H's next to EN atom H NMR

still in single bond land less than 5 (which are usually vinylic protons and crossing double bond territory)

torsional strain

strain caused by van der Waals repulsion which can be reduced or eliminated by rotation around single bond from eclipsing conformations/gauche staggered conformations

IMFs and physical properties

stronger IMFs, higher bp, mp, and lower its vapor pressure(less likely for gas molecules to want to escape from solution)

heterotopic protons

strutural isomer (diff connectivity)

non reducing sugar

sucrose does not have hemiacetal group== non reducing = negative Tollens linkage between fructose and glucose glucosidic linkage (acetal group)

symmetric vs asymmetric stretching why does secondary amine have two peaks to the left of 3000 in IR?

symmetric requires less energy one peak is symmetric, one peak represents asymmetric stretching

how polar protic solvent affects nucleophilicity

take into account the size of the nucleophile better nuc I->Br-<Cl-<F- least nuc

gauche interaction

the interaction between two atoms or groups that are gauche to each other ranking gauche interactions:

UV absorption

the more conjugated the molecule is, the more stable, more likely to have color, and the longer will be the UV wavelength absorption

s character and electronegativity

the more s character, the more electronegative bc s orbitals are closer to atom's nucleus and thus closer to its protons

what are the consequences of a compound being meso?

there would be one less steroisomer e.g. 2^4 would be 2^3 instead

conjugation (resonance) and hybridization

to accommodate resonance, the hybridization of an atom can change bc lone pair moves into p orbital eg. N in amide is sp2 hybridized

oxirane

to name epoxides, it would be for example 2-methyloxirane

alkene hydrogens NMR

trans--more downfield (more deshielded, higher ppm) cis---more upfield

1-3 diaxial interactions

unfavorable interactions with other axial atoms on the same side

omega 3 vs omega 6 vs omega 9

used to describe fatty acids with double bonds count from farthest carbon away from carboxylic acid toward double bond

less s character means... sp3 vs. sp2 vs. sp

weaker, longer bond bc more s character means more electronegative (more sigma overlap from s orbital) sp3...uses all 3 p orbitals sp2..uses 2 of 3 sp...uses only 1 of the 3

ketene

when one end of an allele is replaced with an oxygen

relationship between vapor pressure and boiling point

increase in vp, decrease in bp

what happens when you increase percentage of c triple bonded to g?

increase mp and stability of DNA sample

ionic solid

ionic bonding high melting point brittle, hard NaCl, MgO