Home > Chemistry, Organic chemistry > Chemistry 51A Lecture 15 Notes 11/12/09

Chemistry 51A Lecture 15 Notes 11/12/09

Overview

Today is a 51 minute lecture on chiral compound properties.

Details

Optical isomers show optical activity or rotate plane polarized light.  Polarized sunglasses demonstrate this property.  Single enatiamers are generally optically active.

How to determine the optical purity?  Find the angle to which the plane polarized light rotates about.

a = [a] c l

observed rotation = [specific rotation] concentration (grams/mL) path length (dm)

This is much like Beer’s Law.  A = a l c = absorbtivity length concentration

Optical rotation varies with temperature

a = ([a]^t) length wavelength.

Temperature affects conformation – chair, boat, etc.  Sodium lamps are yellow lamps with a line at 589 nm called the d line.  This is most often used.

Racemic compounds have an equal mixture of enatimers.  These are also referred to as racemates.

Crystals on a bottle of wine are one enatiamer.

Acid Catalyzed Alkene Hydration

2-butene (g) + H20(l) (+H30+ an acid)= 2-butanol

2-butanol is chiral with a tetrahedral asymmetric carbon.  Both enantimomers will be obtained in equal proportion.  The OH coming to the front and to the rear.

Enzymes come in a single handed form or enantiomers.  Using chiral compounds to synthesize other chiral compounds.

Carbone or R-carbone.  This molecule is not superimposable on its mirror image, thus it has a chiral center.  R-carbone has the odor of spearmint.  S -carbone has the odor of caraway.

Shake right hands, get one fit.  Shake 1 left hand with a right hand, get another fit.  Chirality is very important for drugs.

Thalidomide was sold as a racemate to prevent morning sickness.  Invert all stereocenters to get the enantimer.  The R form is effective, the S form is a teratogen, causing birth defects.

Resolution is the name for separating racemic mixes.  Many drugs are resolved into single enatiamers.

Percentage of Optical Purity = alpha sample/alpha o

Enatimters have specific rotation.

(2R, 3R)-tartaric acid   a = 12.4 degrees, mp = 172 C

(2S, 3S) – tartaric acid a=-12.4, mp =  172  C

Racemic tartaric acid a = 0, 206 C

Meso tartaric acid has no handedness and is a chiral, a = 0, mp = 147

A:mmonia tartarate will seperate into two different crystals.

A 75:25 mixture of enatimers has a 50% optical purity and contains a 50% enantoeric excess.    a = 46.3

Review

Aging: oxygen, UV light, water, heat

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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