Home > Chemistry, Organic chemistry > Chemistry 51A Lecture 17 Notes 11/13/09

Chemistry 51A Lecture 17 Notes 11/13/09

Overview

Today is a 48 minute lecture on energetics.

Details

CH3CH2-I + CN- = CH3CH2CN (propane nitrile) + I-

Cyano comes in and literally pushes out the iodo group.  Electrons from the cyano attack the carbon and electrons are pushed onto iodine.  This reaction occurs in one step.

Ph3CBr + CN- = Ph3CCN + Br-

This reaction proceeds by several steps.  Tribromomethane breaks up.

Ph3CBr = Ph3C+ + Br-

This carbocation forms because of resonance stabilization and that tertiary carbocations are particularly stable, much more than primary carbocations.

Ph3C+ + CN- = Ph3CCN

Electrons flow from the cyano group to the carbon.

Energy diagrams show Energy versus Time as the reaction proceeds; for an exothermic reaction, the reaction goes downhill.  An endothermic reaction goes uphill.  A reaction goes from reactants, to higher energy intermediate or transition state, down to products, releasing energy as bonds are formed.  Sometimes enthalpy or entropy is considered as the y axis.

dE formation = Energy reactants – Energy products

Substitution/addition reactions on a primary halide occurs in one step.  Similar reaction in tertiary halide occur in two steps; this is due to the carbocation and steric hindrance.  Secondary halides are even more complicated.  When you perform a reaction, you get a variety of products.

The rate determining step has a higher energy barrier; thus it is the slowest step.  Carbocations are higher in energies then most other things.  Reactions with equilibrium occurring on the right tend to be downhill.

Reverse reactions occur along exactly the same reaction path/diagram.

Rates of reactions also have an organic flavor.

rate = k [reactants involved in the rate determining step]

rate = k [CH3CH2I] [CN-]

rate = k [Ph3CCH3]  (doubling the CN- concentration here does nothing…)

Rate of reaction is affected by temperature.  Higher temperature, more energy, more molecules overcome the energy barrier of the rate determining step, faster rate, bigger k.

Review

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

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