Organic Chemistry Flashcards
(T/F) A pi bond can exist without a sigma bond
False, a pi bond cannot exist independently of a sigma bond
Which type of bond (pi or sigma) is stronger?
A sigma bond is generally stronger than a pi bond
What is the hybridization of the carbon atom in CH4? What are the bond angles?
sp3, 109.5º
What is the bond angle between sp hybridized atoms?
180º
What is the bond angel between sp2 hybridized atoms?
120º
What is the general formula of a noncyclic alkane?
The general formula of an alkane is CnH2n+2
How many other carbons are 1’, 2’, 3’, and 4’ carbons bonded to?
1, 2, 3, and 4 other carbons respectively
How does increasing molecular weight affect the boiling point and melting point of an alkane
Increased molecular weight results in increased boiling and melting points
How does increased branching affect the boiling boil of an alkane
Increased branching lowers the bowling point
What are the three steps of a halogenation reaction?
Initiation, Propagation, and Termination
What does X2 –> (hv or ^) 2X• represent?
Initiation
what does 2X2• —> X2 represent?
Termination
What does R• + X2 –> RX + X• represent?
Propagation
What does X• + R• –> XR represent?
Termination
What does X• + RH –> HX + R• represent?
Propagation
What does 2R• –> R2 represent?
Termination
What is the order of free radical stability?
3º > 2º > 1º > methyl
What type of reaction involves breaking down large alkanes into smaller ones?
Prolysis or “cracking” uses heat to break down large alkanes into smaller ones
What are the products of the complete combustion of an alkane?
The complete combustion of an alkane produces: CO2, H2O, and heat
Is a nucleophile electron rich or electron poor?
A nucleophile is electron rich
All else being equal, how does basicity affect he strength of a nucleophile?
The stronger the base, the stronger the nucleophile
How many steps are involved in an SN1 reaction? What are they?
There are two steps in an SN1 reaction.
- the molecule dissociates into a carbocation and a leaving group
- the nucleophile combines with the carbocation
What is the order of carbocation stability?
3º > 2º > 1º > methyl
Which step in an SN1 reaction is the rate determing step?
The first step, the formation of the carbocation, is the rate determing step
(T/F) The rate of an SN1 reaction is dependent on the concentration of the nucleophile
False, the rate is only dependent on the concentration of the original molecule
How can SN1 reaction rate be increased?
- Stablilize the carbocation by increasing substitution and using a highly polar solvent
- Use a better leaving group (weak base)
How does basicity affect the nature of a leaving group?
The weaker the base, the better the leaving group
How many steps are involved in an SN2 reaction?
SN2 reactions have one step
Is the rate of an SN2 reaction dependent on the concentration
The SN2 reaction rate is dependent on the concentration of both the substrate and the nucleophile
(T/F) SN1 reactions involving a chiral substrate produce an optically active mixture
False, a racemic mixture results during SN1 reactions with an optically active reactant
(T/F) SN2 reactions involving a chiral substrate result in an inverted, optically active product
True
Which type of reaction is favored (SN1 or SN2) given the folowing conditions:
- Polar protic solvent
- Polar aprotic solvent
- Methyl or 1º alkyl halide
- 3º alkyl halide
- Polar protic solvents favor SN1
- Polar aprotic favor SN2
- Methyl or 1º alkyl halides favor SN2
- 3º alkyl halides favor SN1
Which form of an alkene has a higher melting point (cis or trans)?
trans due to symmetry
Which form of an alkene has a higher boiling point (cis or trans)?
cis
How many steps are there in an E1 elimination reaction?
There are 2 steps
How many steps are there in an E2 elimination reaction?
1 step
(T/F) E1 and SN1 reactions are driven by the same factors (polar solvent, good leaving groups, highly branched chains)?
True
(T/F) In the case of E2, the least substituted double bond is usually formed preferentially
False, E2 reactions favor the formation of highly substituted double bonds
What is Markovnikov’s rule?
Protons will add to the less substituted carbon of a double bond to create a more stable carbocation intermediate
Would the electrophilic addition of Br2 to an alkene result in syn or anti addition?
The Br2 would undergo anti addition
(T/F) The reduction of an alkyne on a metal surface (Pd) results in a cis alkene
False. It results in an alkane
(T/F) The reduction of an alyne in Na and NH3 produces a trans alkene
True
Does the electrophilic addition of HBr to an alkyne follow Markovnikov’s rule?
Yes, electrophilic addition of HBr to an alkyne or an alkene follows Markovnikov’s rule
Does the free radical addition of HBr to an alkyne follow Markovnikov’s rule?
No, free radical addition of HBr to an alkyne or an alkene does not follow Markovnikov’s rule
What is an aromatic compound?
A aromatic compound is defined as any unusually stable ring system. Aromatic compounds are cyclic, conjugated polyenes that follow Hückel’s rule
What is an aliphatic compound?
An aliphatic compound is any non-aromatic compound
What is Hückel’s rule?
Hückel’s rule states that an aromatic compund has (4n+2)π electrons, where n is an nonnegative integer
What is antiaromatic compound?
An antiaromatic compound is a cyclic conjugated polyene with 4n electrons
What is the difference between a phenyl and a benzyl group?
A benzene ring acting as a substituent is call a phenyl group (-C6H5). A tolune molecule substituted at the methyl position is called a benzyl- group (-CH2C6H5)
Do electron donating groups activate or deactivate an aromatic ring?
Electron donating groups activate a ring
How do electron withdrawing groups affect the reactivity of an aromatic ring?
Electron withdrawing groups deactivate a ring
Is COOH activating/ deactivating and ortho/para or meta directing?
Deactivating / meta
Is NR2 activating/ deactivating and ortho/para or meta directing?
Activating/ ortho-para
Is NH2 activating/ deactivating and ortho/para or meta directing?
Activating / ortho-para
Is NO2 activating/ deactivating and ortho/para or meta directing?
Deactivating / meta
Are F, Cl, Br, I activating/ deactivating and ortho/para or meta directing?
Deactivating / ortho-para
Is COOR activating/ deactivating and ortho/para or meta directing?
Deactivating / meta
Is OR activating/ deactivating and ortho/para or meta directing?
Activating / ortho-para
Is SO3H activating/ deactivating and ortho/para or meta directing?
Deactivating / meta
Is OCOR activating/ deactivating and ortho/para or meta directing?
Activating / ortho-para
CH3 activating/ deactivating and ortho/para or meta directing?
Activating / ortho-para
(T/F) Activating compounds are always o-p directors?
True
(T/F) Deactivating compunds are always meta directors
False, halogens are deactivating and are o-p directing
Why do alcohols have a significantly higher boiling point than analogous alkanes?
Alcohols can hydrogen bond
(T/F) Phenols are less acidic than aliphatic alcohols
False, phenols are much more acidic than aliphatic alcohols
What are three types of reactions used to synthesize alcohols?
Addition, Substitution, and Reduction
Can a tertiary alcohol be easily oxidized?
No, tertiary alcohols cannot be oxidized without cleavage of a carbon-carbon bond
Can ethers hydrogen bond?
No, ethers do not hydrigen bond
(T/F) Straight chain ethers can be cleaved under high temperature in the presence of HBr or HI
True
How does the boiling point of an aldehyde (or ketone) compare with its analogous alkane? Alcohol?
The boiling point of an aldehyde is higher than that of the corresponding alkane but lower than that of the corresponding alcohol
How is a ketone or an aldehyde from an alcohol?
Oxidizing an alcohol will produce the corresponding ketone or aldehyde (ie by using PCC or Na2Cr2O7)
How do you produce a ketone or aldehyde from an alkene?
Ozonolysis of an alkene will produce corresponding ketons or aldehydes as cleavage products
Which protons relative to a carbonyl group are acidic?
Alpha protons relative to a carbonyl group are slightly acidic
What happens when aldehydes or ketons react with water?
Aldehydes adn ketons react with water to form gemdiols
(T/F) A reaction in which two molecules combine with the loss of a water molecule is a condensation reaction
True
What would be the product when acetaldehyde is reacted with dilute NaOH?
aldol
What is the name of the reaction when acetaldehyde is reacted with dilute NaOH?
Aldol condensation
What are the common names for the first three straight chain carboxylic acids?
The first three carboxylic acids are: formic acid, acetic acid, and propionic acid
(T/F) Alcohols have higher boling points than carboxylic acids
False, carboxylic acids have higher boiling points than corresponding alcohols
How do electron withdrawing groups (-Cl, -NO2) attached to the alpha carbon affect the acidity of the carboxylic acid?
Electron withdrawing groups increase acidity
How do electron donating groups (-NH2, -OCH3) attached to the alpha carbon affect the acidity og a carboxylic acid?
Electron donating groups decrease acidity
What type of alcohol (1º, 2º, 3º) can be oxidized to carboxylic acid?
1º alcohols can be oxidized to carboxylic acids, however 2º and 3º alcohol cannot
What is a micelle? Is the interior hydrophobic or hydrophillic?
When placed in an aqueous solution, soap molecules arrange themselves into spherical structures called micelles. The soap molecules arrange themselves such that their polar heads face outward and their nonpolar chains face inward
Would you have to oxidize or reduce a carboxylic acid to prepare an alcohol?
Reduction of a carboxylic acid forms an alcohol
(T/F) Acid chlorides are very reactive
True
How do electron donating groups affect the acidity of benzoic acid?
Electron donating groups reduce the acidity of benzoic acid
How do electron withdrawing groups affect the acidity of benzoic acid?
Electron withdrawing groups increase the acidity benzoic acid
(T/F) Anhydrides react under the same conditions as acid chlorides
True
What is the product of the hydrolysis of an amide under acidic conditions?
The hydrolysis of an amide under acidic conditions will produce a carboxylic acid
What are the products for the hydrolysis of an ester?
The products are a carboxylic acid and an alcohol
What is saponification?
Saponification is the process whereby fats are hydrolyzed, under basic conditions, to produce soaps
What is transesterification?
C-CO-OR’ + R”OH <-> C-CO-OR” + R’OH
(T/F) A glycerol molecule attached to two carboxylic acids and one phosphoric acid is a phospholipid
True
Name: CH3CH2NH2
Ethylamine (common) or ethanamine (IUPAC)
Name: CH3CH2CH2CH2N(CH3)2
N,N-dimethylbutylamine (common) or N,N-dimethylbutanamine (IUPAC)
How many alkyl groups are in a tertiary (3º) amine?
A 3º amine has 3 alkyl groups attached to the nitrogen
What is a quaternary ammonium compound?
A 4º ammonium coupound is a ntrogen atom attacked to 4 alkyl gorups. The nitrogen is positively charded and, therefore, the compound exists as a salt
(T/F) An imine is a compound with a carbon-nitrogen double bond
True
Which types of amines can form hydrogen bonds (1º, 2º, 3º)
1º and 2º amines can form hydrogen bonds
(T/F) Axial hydrogens are parallel to the ring
False, axial hydrogen are perpendicular to the ring
(T/F) Bulky groups prefer the equatorial position over the axial group
True
what are geometric isomers?
Geometric isomers are molecules that differ with respect to the spatial relationship of substituents around a double bond
What is a chiral molecule?
A chiral molecule is a molecule that is not superimposable upon its mirror image
What are enantiomers?
Enantiomers are chiral molecules that are non-superimposable mirror images of each other
(T/F) Achiral molecules are optically active
False, achiral molecules are optically inactive
What is a dextrorotatory (+) compound?
A dextrorotatory compound rotates polarized light to the right (clockwise)
What type of chemical bond involves the sharing of electrons?
Covalent bonds involve the sharing of electrons
What type of chemical bond involves the sharing of electrons?
Covalent bonds
What type of chemical bond involves the transfer of electrons?
Ionic bonds
What orbital has a spherical shape?
”s” orbitals are spherically shaped
What orbital has a bi-lobed shape?
“p” orbitals are bi-lobed
What are the prefixes of the first 12 alkanes?
Meth, Eth, Prop, But, Pent, Hex, Hept, Oct, Non, Dec, Undec, Dodec
What are the 5 steps used to name alkanes according to IUPAC rules?
- Find the longest chain
- Number the chain so that the lowest set of numbers is obtained for the substituents
- Name and alphabetize the subst.
- Assign a number to each subst.
- Complete the name
What are the 5 steps used to name alkenes according to IUPAC rules?
- Find the longest chain containing the double bond
- Number the chain so that the double cond receives the lowest possible number
- Name and alphabetize subst.
- Specifiy the configurational isomer
- Name the compound
What is the common name for ethyne?
Ethyne is commonly known as acetylene
In the case of an”en-ol” which carbon receives the lowest number?
The carbon attached to the alcohol group is assigned the lowest number
What is a diol?
A diol is a molecule with two hydroxyl (OH) groups
(T/F) An aldehyde has a carbonyl group somewhere in the middle of the carbon chain
False. In an aldehyde, the carbonyl group is at the end of the carbon chain
(T/F) A ketone has the carbonyl group at one end of the carbon chain
False. In a ketone, the carbonyl group is somewhere in the middle of the carbon chain
In the case of an “en-one” which carbon receives the lowest number?
The carbonyl carbon receives the lowest number
What type of compound does a -COOH group denote?
The COOH group denotes a carboxylic acid
What are the common names for the following:
- methanoic acid
- ethanoic acid
- propanoic acid
- formic acid
- acetic acid
- propionic acid
Name the functional group: RSN
Thiol
Name the functional group: R2S
Sulfide
Name the functional group: RNO2
Nitro
Name the functional group: RN3
Azide
Name the functional group: RN2+
Diazo
Name the prefix and suffix: Carboxylic acid
carboxy- / -oic acid
Name the prefix and suffix: Ester
alkoxycarbonyl- / -oate
Name the prefix and suffix: Acyl Halide
halocarbonyl- / -oyl halide
Name the prefix and suffix: Amide
amido- / -amide
Name the prefix and suffix: Nitrile
cyano- / -nitrile
Name the prefix and suffix: Aldehyde
oxo- / -al
Name the prefix and suffix: Ketone
oxo- / -one
Name the prefix and suffix: Alcohol
hydroxy- / -ol
Name the prefix and suffix: Thiol
sulfhydryl- / -thiol
Name the prefix and suffix: Amine
amino- / -amine
Name the prefix and suffix: Ether
alkoxy- / -ether
Name the prefix and suffix: Sulfide
alkylthio- / -sulfide
Name the prefix and suffix: Nitro
nitro- / ~
Name the prefix and suffix: Azide
azido- / -azide
Name the prefix and suffix: Diazo
diazo- / ~
What is a structural isomer?
Structural isomers have the same chemcial formulas, but different atomic connectivity
What is a stereoisomer?
Stereoisimers are compunds that differ only in respect to the spatial arrangement of their atoms
Order the following conformation of n-butane according to energy levels (low to high): gauche, anti, eclipsed, totally eclipsed
Anti, gauche, totally eclipsed
What are the three cyclic hexam conformers in order of energy levels (low to high)
Chair, twisted, boat
What is a levorotatory (-) compound?
A levorotatory compound rotates polarized light to the left (counterclockwise)
What is a recemic mixture?
A racemic mixture contains equal amounts of both enantiomers
How many stereoisomers are possible for a molecule with four chiral centers?
A racemic mixture contains equal amounts of both enantiomers
How many stereoisomers are possible for a molecule with four chiral centers?
24 = 16
What are diastereomers?
Diastereomers are stereoisomers that are not mirror images of each other
What types of molecules are optically active?
Chiral molecules
What is a meso compound?
A meso compound is a molecule that possess stereocenters but has a plane of symmetry. It is achiral and therefore optically inactive
(T/F) All single bonds are sigma bonds?
True
What type of bond results when two p orbitals overlap?
Two overlapping p orbitals for a pi bond
What are the components of a double bond
A double bond is composed of 1 sigma and 1 pi bond
What are the compondents of a triple bond?
A triple bond is composed of 1 sigma and 2 pi bonds
Which purification technique involves a solif turning directly into a gas?
Sublimation
What separation technique makes use of two immiscible solvents?
Extraction
What seperation technique can be used to isolate a solid from a liquid?
Filtration
(T/F) Recrystallization is a process in which impure crystals are dissolved in hot solvent and then recrystallize as pure crystals as the solvent cools
true
Which separation technique can be used to separate a mixture of particiles with different densities and masses?
Centrifugation
Which separation technique takes advantage of a solution containing two or more compunds with different boiling points?
Distillation
(T/F) Vacuum distillation can be used to seperate liquids with very high boiling points
True
Which separation technique separate compounds based upon their different affinities for a medium?
Chromatogrpahy
What is the Rf value in thin layer chromatography (TLC)
The Rf value is the distance a compound travels divided by the distance the solvent travels
Would a compound with a high Rf value be near the top or near the bottom of a TLC plate?
A compound with a high Rf value would be near the top of a TLC plate
Which separation technique uses an electric field?
Electrophoresis
SDS-polyacrylamide gel electrophoresis sepatates proteins based on what factor?
Based on their masses
(T/F) Agarose gel electrophoresis is used to separate fragments of nucleic acid
True
What type of spectroscopy is useful for identifying functional groups?
IR is useful. NMR has limited utility in this area.
Do symmetrical stretches exhibit an IR absorption signal?
No
(T/F) NMR spectroscopy can be used to identify distinct 1H protons in a molecule
True
How many different NMR peaks (doublets, triplets, etc) would appear if the molecule being analyzed were:
Ethane
Propane
1,3-dichloropropane
Ethane - 1 singlet
Propane - 1 septet (7) and 1 triplet
1,3-dichloropropane - 1 quintent and 1 triplet
How many different types of equivalent protons are there in 1-bromo-2-chloropropane?
There are three different types of equivalent protons
What type of spectroscopy is ideal for the study of conjugated olefins?
UV-vis spectroscopy is ideal
What type of spectroscopy can determine the molecular weight of a compound?
Mass spectroscopy determines the molecular weight of a compound
What is the general formula for a carbohydrate?
Cn(H2O)m
(T/F) Monosaccharides undergo many of the same reactions as alcohols
True
What is the general formula for calculating the maximum number of possible stereoisomers of a molecule?
The general formula is 2n where n = number of chiral centers
(T/F) When converting a Fischer Projection to a Haworth (ring) Projection, groups on the right side of a Fischer Projection will be pointing upward
False, groups on the right side of a Fischer Projection end up pointing downward in a Haworth Projection
What monosaccharides make up a molecule of maltose?
Maltose is composed of two molecules of glucose
Does cellulose contain ß-1,4 glycosidic bonds or a-1,4 glycosidic bonds
Cellulose contains ß-1,4 glycosidic bonds
Do starch and glycogen contain ß-1,4 glycosidic bonds of a-1,4 glycosidic bonds?
Starch and glycogen contain a-1,4 glycosidic bonds
What is mutarotation?
Mutarotation is the spontaneous change of configuration about C1 that occurs when monosaccarides are exposed to water
(T/F) Glucose is an aldohexose
True
(T/F) Fructose is an aldopentose
False, fructose is a ketohexose
What is a reducing sugar?
A reducing sugar is any monosaccharide with a hemi-acetal ring
(T/F) The alpha carbon is chiral in all amino acids
False, glycine’s alpha carbon has 2 hydrogens and is therefore not chiral
What is a zwitterion?
A zwitterion is a species with both a positive and a negative charge
Define amphoteric
An amphoteric species can act as either a base or an acid
In what direction will an amino acid with a neutral side chain move during electrophoresis at pH 4:
- If the pI of the amino acid is 7?
- If the pI of the amino acid is 3?
- If the pI of the amino acid is 4?
- The amino acid will have a net positive charge and, therefore, move toward the cathode
- The amino acid will have a net negative charge and, therefore, move towards the anode
- The amino acid is at its isoelectric point and will not move
(T/F) The buffering capacity of an amino acid is greatest at its isoelectric point
False, the buffering capacity of an amino acid is least at its isoelectric point. It is greatest at its two or more pKa’s
Where are nonpolar amino acids usually found in a protein and why?
nonpolar amino acids are usually found in the interior of a protein because they are hydrophobic
What is the net charge of a basic amino acid at physiological pH?
The net charge of a basic amno acid at physiological pH is positive
What type of bond joins amino acids?
a peptide bond joins amino acids together
Define the primary structure of a protein
Primary structure refers to the sequence of amino acids
Define secondary structure
Secondary structure refers to hydrogen bond interactions within the protein
What are the two most common types of secondary structure?
The two most common types of secondary structure are a-helix and ß-pleated sheet
What are the two primary classifications (regarding tertiary structure) of proteins?
Fibrous and globular proteins
Define quaternary structure
quarternary structure only exists in proteins with more than one polypeptide subunit. If refers to the way the subunits arrange themselves
What is a conjugated protein?
A conjugated protein is a protein that derives part of its fucntion from a prosthetic group
What happens when a protein denatures? What can cause a protein to denature?
A protein loses its three-dimensional shape when it denatures. Changes in temperature, pH, and solute concentration can cause denaturation