Picture/symbol cards Flashcards
Describe the hybridized orbital that results from:
- one s + three p’s
- one s + 2 p’s
- one s + 1 p
Recall sigma and pi bonding in organic molecules (the configuration of the hybridized/regular orbitals)
What is the general formula for straight chain alkanes?
How many hydrogen atoms are subtraced for each ring?
CnH2n+2
Add 2 H per ring
Label these common alkyl groups
Describe complete and incomplete combustion of alkanes
Summarize this exothermic reaction (ie. write it out)
Complete: Hydrocarbon converted to CO2 and H2O
Incomplete: the reaction gives other products when there is insufficient oxygen for complete combustion (eg. CO and soot/molecular C).
CnH2n+2 + excess O2 → nCO2 + (n+1)H2O
Summarize radical substitution reactions with halogens and alkanes. List the three steps and then describe how this can be inhibited
RH + X2 + uv light (hf) or heat → RX + HX
The halogen, X2may be F2, Cl2 or Br2 (I2 does not react)
- Initiation (formation of free radicals, eg. Cl·, from uv or heat)
- **Propagation **(free radicals form new free radicals)
eg. CH4 + Cl· → ·CH3 + HCl - Termination (termination reactions destroy the free radicals by coupling)
This can be inhibited by using a resonance-stabilized free radical to mop up with termination reactions
Show the two possible conformations of cyclohexane. Which one is found most in nature (99%) and why?
The chair conformation is found most often in nature because it has bond angles at 109.5º (most resembling stable tetrahedral for sp3 carbons)
In a molecule of cyclohexane, which of the hydrogens are axial and which are equatorial? What does that mean?
Equatorial: hydrogens in the same plane as the ring
Axial: Hydrogens that are perpendicular to the ring
Hydrogen atoms are maximally separated and staggered to minimize electron shell repulsion
What is the general structure of a carboxylic acid functional group?
How can a carboxylic acid be formed?
- By reacting a Grignard reagent with carbon dioxide
- By reacting an aldenyde with KMnO4
- By reacting a nitrile (N≡C-R) with aqueous acid
Carboxylic acids can undergo nucleophilic substitution reactions with many different nucleophiles. What is the product for the following nucleophiles?
- OR
- NH2
- CL from SOCl or PCl5
- OR ⇒ ester
- NH2⇒ amide
Cl ⇒ acid chloride
Summarize a typical esterification reaction with carboxylic acid
How can carboxylic acids be reduced to alcohols?
- With lithium aluminum hydride (LiAlH4) or H2/metals
- Or by converting to esters or amids first (with nucleophilic substitution) and then reducing with NaBH4 (sodium borohydride)
What is the general structure of an acid halide and how are these named?
- How are acid chlorides formed?
- How can acid chlorides be converted to alcohols? (one or two steps)
Carboxylic acid + PCl5 or SOCl2= Acid chloride
Acid chloride + NaBH4= alcohol (one step)
Acid chloride + H2/(Pd/C) = carboxylic acid
Carboxylic acid + NaBH4 = alcohol (two steps)
What is the general structure of acid anhydride? How are these named?
What is the general structure of an amide? How are these named?
How can amides be synthesized?
Reacting carboxylic acids (or other carboxylic acid derivatives) with ammonia
Describe the following reactions with amides:
- Nucleophilic substitution
- Hydrolyzation (yielding carboxylic acid and amine)
- Converted to amines
What is the general structure of an ester and how are they named?
How can esters be synthesized?
Describe nucleophilic substitution reactions with esters and hydrolysis of esters.
What type of organic compounds are fats (mono-, di- and triglycerides)?
In what type of reactions are they formed in? What is the reaction called for their hydrolization?
How are fatty acids formed?
Esters, hydrolyzed in saponification reactions (forms salts of long chain carboxylic acids, called soaps).
Fatty acids are formed from condensation of C2 units derived from acetate.
What are β-keto acids? What happens when this is heated?
Carboxylic acids with a keto group (ketone) at the beta position.
When it is heated, the carboxyl group is removed as CO2 (decarboxylation)
What are amines?
What are:
Primary amines?
Secondary amines?
Tertiary amines?
Quaternary amines?
Organic compounds with a trivalent nitrogen atom bonded to one or more carbon atom(s)
Primary amines: R-NH2
Secondary amines: R2-NH
Tertiary amines: R3N
Quaternary amines: R4-N+X-
Describe the formation of amides from amines
Primary or secondary amines react with an acid to form amides
Describe amine alkylation
Amine alkylation involves nucleophilic substitution with alkyl halides
What is the isoelectric point equation?
Isoelectric piont = pl = (pKa1 + pKa2)/2
Above the isoelectric point (basic conditions), the amino acids will have a net negative charge. Below the isoelectric point (acidic conditions), the amino acids will have a net positive charge.
How can you determine the number of optical isomers for carbohydrates?
You need to know the number of asymmetric carbons, normally 4 for hexose and 3 for pentoses (these are designated as n).
optical isomers = 2n
What is the most commonly occurring stereoisomer conformation of aldose carbohydrates?
Most have the D-configuration (same conformation as D-glyceraldehyde). The designation D or L is only assigned to the highest numbered chiral carbon. The absolute configuration can be determined for any chiral carbon (eg. it is R for D-glyceraldehyde)
Recall the alpha-1,4 glycosidic linkage reaction mechanism.
Recal three different ways of drawing α-D-fructose (a furanose)
Recall the two anomers of D-glucose and the different ways of drawing them.
What happens when aldose sugars undergo oxidation?
Aldehydes can be oxidized to a carboxylic acid group.
Bromine water can give aldonic acid, dilute nitric acid can give aldaric acid.
Recall the general structure of a traicyl glycerol
- R groups may be same or different
- Usually long chain alkyl groups
- Hydrolysis yields three fatty acids and glycerol
- Unsaturated fatty acid chains have double/triple bonds
Give the generic structure that all steroids are derived from
What allows steroids to dissolve through plasma membranes?
Hydrophobic hydrocarbons make up most of a steroid. Polar side groups allow it to dissolve in water.
Give the general structure for phosphoric acids and phosphate esters
What type of spectra is this?
IR spectroscopy
What type of spectra is this?
Tautomerism
The equation shows the migration of hydrogen atom from an alpha carbon atom to an oxygen atom. The hybridization of the alpha carbon atom and oxygen atom changes during the process.
Draw the formula that represents a general structure of a fatty acid salt produced in the reaction shown
Rn-CO2-Na+
If the ester shown below were hydrolyzed in acidic H218O, which product would be expected to contain 18O?
A. CH3CO2H
B. CH3OH
C. Ph-CO2H
D. Ph-OH
A. CH3CO2H
The first step of the hydrolysis would be the protonation of the carboyl oxygen. The H218O would then act as a nucleophile, attaching the protonated carbonyl carbon. Cyclopentanol is the leaving group. The products are cyclopentanol and 18O labeled acetic acid.
Define a Diels-Alder reaction
An addition reaction in which a conjugated diene reacts with a compound with a double or triple bond so as to form a six-membered ring.
What is the enantiomer of this Diels-Alder product?
The enantiomer of the Diels-Alder adduct that results from the reaction shown is generated simply by reflecting the structure shown through the pane of the page (or ipad, as it may be).
The enantiomers formed because the dienophile (alkene) in the Diels-Alder reaction can attack the diene from either side.
These two molecules are examples of which of the following:
- Epimers
- Anomers
- Enantiomers
- Diastereomers
- Epimer (one stereocenter is isomerized)
- Anomer (note alpha beta designation due to anomeric carbon being isomerized)
Describe the chirality for a 1,2-substituted cyclopropane
The reaction involves the hydroboration-oxidation of a terminal alkene. This reaction gives an anti-Markovnikov addition product and does not involve a carbocation intermediate; therefore there is no molecular rearrangement.
Predict the results of this reaction according to a Markovnikov addition and an anti-Markovnikov addition.
Which of the following reactions could be used to prepare the alcohol from the alkene shown in the following equation?
Markovnikov: I and III
Anti-Markovnikov: II
I and III
The overall reaction involves the addition of H2O to styrene and gives a secondary alcohol (a Markovnikov product). Hydration and oxymercuration-demercuration procedures both give Markovnikov addition products, whereas hydroboration-oxidation procedure would give an anti-Markovnikov product (a primary alcohol in this case).
These two organomercurial alcohols are what type of stereoisomers?
Enantiomers
The structure of the stereoisomers are enantiomers because they are nonsuperposable mirror images of each other.
Why did researchers incorporate the four methyl groups at their specific locations in compound 1?
To prevent enolization adjacent to the carbonyl groups.
Because of the presence of the four methyl groups, compound 1 has no protons alpha to carbonyl groups and therefore cannot undergo enolization. This keeps the carbonyl groups from tautomerizing and simplifies their chemistry.
The effect of disallowing enolization far outweighs any inductive effect the methyl groups might have on the electron density of the ring.
What will the product be if this molecule is treated with
- H2/Pd/C
- LiAlH4
The basic reagent indicated in Step 1 was pyridine. What was its primary function in the preparatino of compound 3? What type of reaction is this?
To abstract a proton from the diacid, converting it into a nucleophile.
The reaction is a double aldol addition accompanied by decarboxylation. One of the two addition/decarboxylations is shown below; the second occurs in an identical manner. In order for the initial adition to occur, an alpha-proton must be abstracted from malonic acid, converting it to a nucleophile. This is the function of the pyridine.
This molecule is (-)-β-elemene
What does (+)-β-elemene look like?
The dextrorotatory (+)-β-elemene is an enantiomer in which all stereocenters are inverted from the original compound
What type of reaction is this?
A nucleophilic acyl substitution.
This is a substitution reaction (not an addition reaction), as a tetrahedral intermediate loses X3C:- but retains the hydroxyl group while regenerating the carbonyl function.
Which of the following pairs of compounds would be considered resonance structures?
II only.
Resonance structures can be interconverted simply by moving electron pairs, but not atoms. In I, hydrogen has been moved (not resonance, rather tautomerization). The compounds in III are identical.
The reaction of the compound shown with phenylhdrazine yields a phenylhydrazone. The first step in the formation of the phenylhydrazone derivative involves what type of reaction?
Hydrolysis
Phenylhydrazones are common derivatives of carbonyl compounds, traditionally syntehsized as part of a systematic identification of an unknown compound. As with all reactions of carbonyls with nucleophiles, the first step of the reaction is the addition of the phenylhydrazine nitrogen to the carbonyl carbon as shown.
It is the terminal nitrogen of phenylhydrazine, which is not conjugated to the phenyl ring and is therefore more nucleophilic, which attacks the carbonyl carbon.
The mechanism of hydrazone formation is analagous to that of imine formation and the first step is an addition.
The compound formed by replacing the oxygen atom between the two carbonyl groups in acetic anhydride with an -NG group is classified as an ___?
Imide:
An organic compound containing the group —CONHCO—, related to ammonia by replacement of two hydrogen atoms by acyl groups.
This equation can be reversed by:
A. Heating only
B. Acidication only
C. Heating, followed by acidication
D. Acidication followed by heating
Acidication followd by heating
What is the first step in the mechanism of this reaction?
Attack at a carbonyl carbon atom by the lone pair of electrons on the nitrogen atom of the amino group. The initial step in the mechanism shown involves nucleophilic attack by the lone electron pair on the nitrogen atom in RNH2 on a carbonyl carbon atom in the substrate (acetic anhydride) as shown.
What is a quick and easy way to determine which one of these is a meso compound? Also, which one is it?
A is the meso compound. This can quickly be determined by looking at the substituents on each chiral carbon.
B cannot be a meso compound as it only has 1 chiral carbon. C and D cannot be meso as they have different substituents on each chiral carbon, and therefore cannot possibly be superimposable.
What will dilute potassium permanganate (KMnO4) do to this poor ethylene in cold conditions?
KMnO4 is a strong oxidizing agent! It will add oxygen to reactants.
In cold, dilute conditions, it simply adds oxygen to the molecule. But under abrasive conditions it can cleave the double bond of ethylene to make CO2 and H2O
1-bromopentane was treated with potassium hydroxide in ethanol to yield both 1-pentene (12% yield) and ethyl pentyl ether (88% yield).
Which of the following assumptions can be made about the mechanism since ethyl pentyl ether was the major product (shown).
The reaction proceeded by nucleophilic substitution via the SN2 mechanism.
Ethoxide (-OCH2CH3) simply attacks the δ+ carbon-1, kicking out -Br in the process to make ethyl pentyl ether. This is SN2, and more favourible than the E2 reaction that must occur for OH- to remove a proton from C-2 and create a secondary carbanion intermediate that becomes 1-pentene.
Draw the E1 mechanism that results from reacting the base shown with ethanol
(the arrow is a hint)
What is the reaction in step 1?
Condensation/dehydration substitution reaction between lone pair on amino acid and the carbonyl carbon.
Is step 3 hydrolysis or oxidation?
Hydrolysis. There is oxidation happening, but this term does not completely describe the reaction, which involves putting O in the alpha keto acid and 2 H’s in the amine.
Recall the structure of an acetal
