Organic Chemistry Primer

Reactions of Alcohols:

What are the two forms of reaction?

Oxidation and Dehydration
Reactions of Alcohols:

_____ alcohols require two oxidation steps. The first step produces a(n) ________, and the second step produces a symmetrical ________.

1* (primary)
aldehyde (R-CHO)
carboxylic acid (R-COOH)
Reactions of Alcohols:

____ alcohols only require one oxidation step, which produces a ______.

2* (secondary)
ketone (R-COR)
Reactions of Alcohols:

In the first/only step of oxidation, where is each of the two hydrogen protons removed from, respectively?

What functional group results from this removal?

one from the hydroxyl (-OH), the other from the containing carbon

result, carbonyl group (C=O)

Reactions of Alcohols:

In an oxidation reaction, what exactly is being oxidized?

usually, the metal ion of the oxidizing agent, such as the Cr (which oxidizes from 2+ to 3+) in K2Cr4O7 (potassium dichromate)
Reactions of Alcohols:

Can ketones be further oxidized?

No
Reactions of Alcohols:

After the oxidation reaction of an alcohol, what reagent is administered to the product, under what conditions, to determine the whether the product is either an aldehyde or a ketone?

The presence of a(n) ____ ion in the product indicates the formation of a(n) ________.

diamminesilver (I) complex, in basic conditions

Silver (Ag), aldehyde

Reactions of Alcohols:

What are the two classifications of dehydration reactions?

intra- and intermolecular
Reactions of Alcohols:

Intramolecular dehydration in an alkane chain containing a ___ alcohol (unless it is 2-propanol) will normally yield a major and a minor product. According to Saytev’s Rule, which would be the major product?

secondary

Saytev’s Rule– On a chain, if the hydroxyl-carrying carbon is sandwiched between two carbons, the hydrogen will be taken from the carbon with the least number of attached hydrogens, as this carbon theoretically should have a weaker hold on its bonded hydrogens.

Reactions of Alcohols:

The product of intermolecular dehydration is a(n) _____.

ether.
Reactions of Alcohols:

Intermolecular dehydration is only effective for ___ alcohols, and produces a(n) _____.

primary, ether
2-ketopropanoic acid
pyruvic acid
2-hydroxypropanoic acid
lactic acid
which acids always go by their common name?
dicarboxylic acids
ethanedioc acid
oxalic acid
propanedioc acid
mallonic acid
butanedioc acid
succinic acid
pentanedioc acid
glutaric acid
formic acid
methanoic acid
acetic acid
ethanoic acid
butyric acid
butanoic acid
2-hydroxybenzoic acid
salicylic acid
2-methylpropanoic acid
isobutyric acid
________ reactions are characteristic of ________ compounds such as _______, _____ _______, and ________ _________.
Substitution
saturated
alkanes, alkyl halides, and aromatic compounds
________ reactions are typical of compounds containing multiple bonds. For example, ethene reacts with Br2 by breaking its pi bond to add both Br atoms to its molecule. Both reactants become a product.
Addition
___________ reactions work counter to addition reactions. They create molecules such as ethene.
Elimination
In a ______________ reaction, molecules undergo a reorganization of their substituent parts.
rearrangement
Homolysis
The breaking of a bond producing two identically charged particles; each parting atom takes with it one pair electron
these particles are called “radicals”
Heterolysis
the splitting of a bond resulting in a conjugate acid (+) and a conjugate base (-)
Bronsted-Lowry definition of acids and bases
acids are the reactants which will donate a proton;
bases are the proton acceptors
Lewis acids and bases
acids (electrophiles) will accept an electron-pair from the base (nucleophiles, or electron-pair donor
assisted heterolysis
:Y + A:B -> Y:A + B:

where Y is the molecule which gives an electron pair to A, which furnishes the energy to break the bond between A and B

conjugate base
acid – H
conjugate base
base + H
diprotic acids
at what percent does the second proton react?
can donate two protons (i.e. H2SO4)
10%, due to the leveling effect of water
leveling effect of water
water equilibrates its molecules by proton transfer so that no base present is stronger than -OH
solvated ions
hydrogen-bonding around oppositely-charged ions (like NaCl) causes them break apart in water
in a reaction between HCl and NaOH, what are the spectator ions?
ions which do not take part in the reaction
Na and Cl
H3O+ + -OH —-> 2 H2O
the net reaction between all strong acids and bases
Bronsted-Lowry reactions
proton transfer reactions starting (acid and base) and ending (conj. acid and conj. base) in two reactants and products
carbocation
ion with a positively charged carbon
carboanion
ion with a negatively charged carbon
large value of K(a)

small value of K(a)

strong acid

weak acid

the concentration of water
~55.5 M
pK(a)
-log(Ka)
large pKa
weak acid, strong base
How do we compare the strengths of the conjugate acids/ conjugate bases of two compounds?
compare the effects of their reaction with water.
equilibrium control
acid-base reactions favor the formation of the weaker acid and weaker base
Carboxylic acids containing more than 5 atoms are water insoluble, unless a chemist does THIS.
Higher carb acids react with sodium hydroxide to create water soluble salts
inductive effect
if a polar substituent is attached to a nonpolar carbon chain, the inductive effect will attract electrons to the substituent. With increase in distance from the substituent, the inductive effect weakens.
hybridization
more s-character, higher Ka value, greater acidity
structure
down the periodic table, acidity increases
across row, acidity increases
(delta)H*
change in enthalpy with the standard conditions

enthalpy is associated with changed in bonding. If a high order bond becomes a low order bond, enthalpy is positive (endothermic, to break bonds).
If two weak bonds become two strong bonds, then enthalpy is negative (exothermic)

if H is negative, G will become more negative

Gibbs free energy, relationship to H and S
(delts)G = (Delta)H – T(delta) S
gibbs free energy, relationship to Keq
G = -RT ln(Keq)
entropy
changes in the relative order of a system
entropy and the relative order of a system
the more random a system, the greater the entropy
positive, negative, or zero?

entropy changes associated with:
A + B –> C
A + B –> C + D
A –> B + C

(-)S : state of disorder to a state of order
(0)S: no change in order
(+)S: Order to disorder
carboxylic acids
RCOOH
do not give up a proton unless in the presence of an alcohol, which has a pKa of 15-18
at which phase are acids the weakest?
what is solvation and how does it help?
gas phase
no solvent can contribute hydrogen bonding or ion-dipole interactions to stabilize the acid
internal structural and electronic features
for acids in the gas phase lacking solvation to stabilize their ions, this determines gaseous acid strength
effect of solvation on entropy
solvation of an acid increases order, and decreases entropy
Free energy of strong acids
strong acids have a low free energy value, and are ordered
protic solvent
a solvent that binds to its solute by hydrogen-bonding
protonated alcohol
is the conjugated acid of an alcohol
oxonium ion
protonated alcohol
methanol + HCl —>
oxonium ion and Cl
proton transfer reactions are…
… the first step in alcohols, esters, ethers, carboxylic acid, and ketone reactions
role of carbocations
they are unstable intermediates formed during reactions where a pi-bond is broken in an alkene and a sigma bond is broken in an acid ( H:A ), so that the then-alkene-now-alkane can accept the H-proton from the :A- conjugate base.

carbocations are unstable and usually undergo two interactions

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