Home > Chemistry, Organic chemistry > Chemistry 51A Lecture 27 Notes 12/04/09

Chemistry 51A Lecture 27 Notes 12/04/09

Overview

Last lecture of the first series here.  Tomorrow, we’ll begin the next organic section.  For now, a 50 minute lecture on E1 reactions to close things out.

Details

Again, we have tert butyl bromide.  It is a tertiary alkyl halide.

(CH3)3CBr ( Heat at 55 C in EtOH/solvolysis) = (CH3)3COEt 72%SN1 + 28% CH3CCH3CH2 E1 + HBr

Reactions that make two molecules from one are especially helped by increasing temperature.  Carbocations are very unstable – its carbon with only 6 electrons around it.

A polar solvent favors ionization.  Ethanol has electrons and is a nucleophile.

E1 is a unimolecular elimination reaction.  The formation of the high energy intermediate is the rate limiting step, when the carbocation is formed.

For an E1 reaction, we go from reactants to t butyl bromide, the carbocation as the high energy intermediate, then the products.  The first step has the biggest hump and is the rate determining step.

Both SN1 and E1 form by way of a common carbocation intermediate which forms in the RDS or rate determining step.

Treat t butynol and end up with isobutylene.  Treat the reagents with H2SO4.  Sulfuric acid protonates the alcohol, making a good leaving group, H2O.

How do alkyl halides react?

3′ RX   Strong base leads to E2.  Weak bases/nucleophiles lead to E1 and SN1.

1′ RX  SN2 or sometimes E2.  Never SN1 or E1, because carbocation stability is too low.

Good nucleophiles – SN2.

Most bases – SN2.

Sulfur anions are good nucleophiles.

CH3CH2Br  + NaSCH3 = CH3CH2SCH3    SN2

CH3CH2Br  + NaOH = CH3CH2OH            SN2

2′ RX   It depends, all reactions.  Strong bases lead to E2 and some SN2.  Good nucleophiles lead to SN2 reactions.  Weak bases/polar soldvents lead to E1 reactions.

Review

Lewis acids accept electrons, lewis bases donate electrons

Brainstem: midbrain, pons, medulla oblongata

Brain: cerebrum, cerebellum, brainstem

Pineal Gland: seratonin, melatonin

Layers: dia/arachnoid/pia mater

X = fluorine, chlorine, bromine, iodine, astatine (radioactive, no stable isotopes)

Ambush – deploy, suppress, report

n1sin01 = n2sin02

SN2 = inversion of stereochemistry

Nice-Manipulative-Assertive-Aggressive-Assaultive-Murderous

L Chatlier – add reactants/products, volume, pressure, temperature

Successful Ambush: Surprise , Speed, Violence of Action

Aging: oxygen, UV light, water, heat

A = a l c

Electronegativity: NOF Cl Kr

Alkane CnH2n+2

Alkene CnH2n

Alkyne CnH2n-2

Most important cyclic molecules: Benzene C6H6/Naphthalene C10H8

Moving formations: column line wedge vee eschelon

When not moving: herring bone and coil

Transversing Terrain: traveling, traveling overwatch, bounding overwatch

breaking bonds takes energy, making bonds releases energy

Loads on average were: – fighting load: 63 lbs – approach march load: 101 lbs – emergency approach march load: 132 lbs

One well-established norm is that a soldier cannot sustain a load greater than one-third of his body weight over time.

Noble gases: He, Ne, Ar, Kr, Xe, Rd

Types of bonding: ionic >1.7, polar covalent between, non polar <0.5

PV = nRT

METT TC mission enemy troops terrain time civilians

SALUTE size activity location unit time equipment

2s 6p 10d 14f

KE electron = E photon – Ionization Energy

Tissue: epithelial, connective, nervous, muscular

Epithelial: simple/stratified/pseudostratified cuboidal/columnar/squamous

  • single covalent bond – 1 shared pair
  • double covalent bond – 2 shared pairs
  • triple covalent bond – 3 shared pairs

Bond energy: single < double < triple

Bond length: single < double < triple

pKa’s:

Alkanes (50)

CH4/CH3-

Alkene (44)

Alkyne (25

HF +3.2

HCl -7

HBr -9

HI -10

NH3 38 L

RCOOH (4-5)

HF (3.2)

NH4+ (9.26)

H2O (15.7)

ROH (17)

RSH (11)

H30+ (-1.7)

pKa = – log Ka

Spectroscopy: emission/absorption

A = e l c

IGL: point source, random motion, elastic collisions, high temp, low pressure

6 strong acids:

  • HCl
  • H2SO4
  • HNO3
  • HClO4
  • HBr
  • HI

The stronger the acid, the higher the Ka, the weaker the conjugate base.

hydrogen helium

lithium beryllium boron carbon nitrogen oxygen fluorine neon

sodium magnesium aluminum silicon phosphorus sulfur chlorine argon

potassium calcium scandium titanium vanadium chromium manganese iron cobalt nickel copper zinc gallium germanium arsenic selenium bromine krypton

rubidium strontium yttrium zirconium niobium molybdenum technicium ruthenium rhodium palladium silver cadmium indium antimony tin tellurium iodine xenon

cesium barium lutium hafnium tantalum tungsten rhenium osmium iridium platinum gold mercury thallium lead bismuth polonium astatine radon

SWAT – snipers, entry team, inner perimeter/gas people

AOR = area of responsibility

Catalysts: nickel, platinum, palladium

Markovnikov’s Rule: when an unsymmetrical alkene reacts with a hydrogen halide to give an alkyl halide, the hydrogen adds to the carbon of the alkene that has the greater number of hydrogen substituents, and the halogen to the carbon of the alkene with the fewer number of hydrogen substituents

Response to ambush: Lay down a base of fire, maneuver, indirect-fire support, and close-air support.

Plasma 4L

Interstitial Fluid 10L

Extracellular Volume 14L  Plasma + IF

Intracellular Volume 28L

Total Body Water 42L Plasma + IF + ICF

Vd = volume of distribution.  This is the hypothetical volume of fluid into which a drug is disseminated and prior to elimination.

Vd = Bioavailable Dose/Concentration in Plasma at T initial

rate of chemical reactions doubles for every 10 °C

HKBA

pH = pK + log base/acid

k = A e^{{-E_a}/{RT}}

Alkyl Halide     SN1      SN2

3′                       common     rare

2′                      sometimes   sometimes (less reactive, harsher reaction)

1′                        rare           common

Methyl Halides    never    common (good electrophiles, mild conditions)

“A steady hand, good muscle control, and calm actions may be difficult to achieve when the natural tendency is to panic”

Cheekbone to cheekbone, the widest spot on the head, on an average man was five and three-quarter inches.

Carbocation Stability

3′ > 2′ > 1′ > CH3+

Advertisements
  1. No comments yet.
  1. No trackbacks yet.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: