Organic Chemistry Primer

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Reactions of Alcohols:

What are the two forms of reaction?

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Oxidation and Dehydration
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Reactions of Alcohols:

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

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

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

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2* (secondary)
ketone (R-COR)
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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?

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

result, carbonyl group (C=O)

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Reactions of Alcohols:

In an oxidation reaction, what exactly is being oxidized?

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

Can ketones be further oxidized?

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No
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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) ________.

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diamminesilver (I) complex, in basic conditions

Silver (Ag), aldehyde

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Reactions of Alcohols:

What are the two classifications of dehydration reactions?

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intra- and intermolecular
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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?

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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.

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Reactions of Alcohols:

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

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ether.
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Reactions of Alcohols:

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

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

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

small value of K(a)

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strong acid

weak acid

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

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

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

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