Flashcards
what is the net charge of a basic amino acid @ physiological pH?
+
What type of bond joins amino acids?
peptide
Define amphoteric
basic/acidic
what type of spectroscopy is useful for identifying functional groups?
IR
Do symmetrical stretches exhibit an IR absorption signal?
No
(T/F) NMR spectroscopy can be used to identify distinct H protons in a molecule
True
what separation technique makes use of two immiscible solvents?
extraction
What separation technique can be used to isolate a solid from a liquid?
diltration
(T/F) Re-crystallization is a process in which impure crystals are dissolved in hot solvent and then recrystallize as pure crystals as the solvent cools.
True
(T/F) An imine is a compound with a carbon-nitrogen double bond.
True
Which types of amines can form hydrogen bonds (1,2,3)
1 & 2 amines can form hydrogen bonds.
(T/F) Anhydrides react under the same conditions as acid chlorides.
True
(T/F) Acid chlorides are very reactives.
True
How do electron donating groups affect the acidity of benzoic acid?
reduce the acidity
How do electron withdrawling groups affect the acidity of benzoic acid?
increase the acidity
what is a micelle?
is the interior hydrophobic or hydrophilic?
soap molecules. polar head non-polar inside.
would you have to oxidize or reduce a carboxylic acid to prepare an alcohol?
reduce
what happens when aldehydes or ketones react with water?
form gemdiols
(T/F) Activating compounds are always o-p directors.
True
(T/F) Deactivating compounds are always meta directors.
False,
halogens are o-p directing
Do electron donating groups activate or deactivate an aromatic group?
EDG activate a group
How do electron withdrawing groups affect the reactivity of an aromatic ring?
EWG deactivate a group
what is an aromatic compound?
unusually stable ring system.
aromatic compounds are cyclic, conjugates polyenes that follow huckels rule
what is an aliphatic compound?
non-aromatic compund
what is huckels rule?
(4n+2)π
what is an antiaromatic compound?
cyclic conjugated polyene with 4n electrons
Does the electrophilic addition of HBr to an alkyne follow markovnikov’s rule?
yes
Does free radical addition of HBr to an alkyne follow markovnikov’s rule?
No
(T/F) E1 and SN1 reactions are driven by the same factors (polar solvent, good leaving groups, highly branched chains, etc)
True
Which type of elimination reaction uses a carboncation intermediate?
E1 reactions use a carboncation intermediate.
(T/F) In the case of E2, the least substituted double bond is usually formed preferentially.
False.
E2 reaction favor the information of highly substituted double bond.
which type of reaction is favored (SN1 or SN2) given the following conditions?
Polar protic solvent
SN1
which type of reaction is favored (SN1 or SN2) given the following conditions?
Polar aprotic solvent
SN2
which type of reaction is favored (SN1 or SN2) given the following conditions?
Methyl or 1 alkyl halide
SN2
which type of reaction is favored (SN1 or SN2) given the following conditions?
3 Alkyl halide
SN1
what are the three steps of a halogenation reaction?
Initiation, propagation and termination
(T/F) All single bonds are sigma bonds.
True
what type of bonds results when two p orbitals overlap?
Pi bonds
What are the components of a double bond?
1 sigma and pi bond.
What are the components of a triple bond?
1 sigma and 2 pi bonds.
what types of molecules are optically active?
chiral molecules
what is a meso compound?
molecule that posseses stereocenters but has a plane of symmetry
what is a levoratory (-) compound?
rotates polarized light to the left (counterclockwise)
what is a racemic mixture?
contains equal amounts of both enantiomers
how many stereoisomers are possible for a molecule with four chiral centers?
2^4=16
what are diastereomers?
stereoisomers that are not mirror images of each other.
order the following conformations of n-butane according to energy levels (low to high): gauche, anti, eclipsed, totallu eclipsed.
anti
gauche
eclipsed
totally eclipsed
what are the two primary classifications (regarding tertiary structure) of protein?
Fibrous and globular proteins
Define quaternary structure.
only exists in proteins with more than one polypeptide subunit. It refers to the way the subunits arrange themselves.
what is a conjugated protein?
protein that derives part of its function from a prosthetic group.
what happens when a protein denatures?
what can cause a protein to denature?
looses its 3D shape. Changes in temp, pH, and solute concentration can make a protein denature.
define the primary structure of a protein.
primary structure refers to the sequence of amino acids
define secondary structure
refers to hydrogen bond interactions within the protein.
what are the two most common types of secondary structure?
alpha-helix and beta-pleated sheet
define tertiary structure
3D folding of a protein
(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 non-polar amino acids usually found in a protein and why?
Non-polar amino acids are usually found in the interior of a protein becuase they are hydrophobic.
where are polar amino acids usually found in a protein?
Polar amino acids are usually found on the exterior of a protein
what is the net charge of an acidic amino acid at physiological pH?
The net charge of an acidic amino acid at physiological pH is negative.
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?
The amino acid will have a net positive charge and, therefore,move towards the cathode.
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 3?
the amino acid will have a net negative charge and , therefore, move towards the anode
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 4?
the amino acid is at its isoelectric point and will not move.
(T/F) The alpha carbon is chiral in all amino acids.
False.
Glycine’s alpha carbon has 2 hydrogen and is therefore not chiral.
what is a zwitterion?
species with both a positive and negative charge
what is a mutarotation?
change of configuration about C1 that occurs when monosaccharides 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?
any monosaccharide with a hemiacetal ring
(T/F) When converting a fisher projection to a haworth (ring) projection, groups on the ring side of fischer projection will be pointing upward.
False.
Groups on the right side of a fischer projection end up pointing downward in Haworth projection.
what monosaccharides make up a molecule of maltose?
Maltose is composed of two molecules of glucose.
does cellulose contain B-1,4 glycosidic bonds or alpha-1,4 glycosidic bonds?
Cellulose contains B-1,4 glycosidic bonds.
Do starch and glycogen contain Beta-1,4 glycogen contain B-1,4 glycosidic bonds or alpha-1,4 glycosidic bonds?
Starch and glycogen contain alpha-1,4 glycosidic bonds.
(T/F) Monosaccharides undergo many of the same reaction as alcohols.
True
What is the general formula for calculating the max number of possible stereoisomers of a molecule?
The general formula is 2^n when n= number of chiral center.
A pyranose has how many members in its ring?
A pyranose has a six-member ring.
A furanose has how many members in its ring?
A furanose has a five-member ring.
What is the general formula for a carbohydrate?
Cn(H2O)m
What type of spectroscopy is ideal for the study of conjugated olefins?
UV-vis
What type of spectroscopy can determine the molecular weight of compound?
Mass spectroscopy
How many different NMR peaks (doublets, triplets, etc) would appear if the molecule being analyzed were:
Ethane
1 singlet
How many different NMR peaks 9doublets, triplets, etc) would appear if the molecule being analyzed were:
Propane
1 septet
1 triplet
How many different NMR peaks 9doublets, triplets, etc) would appear if the molecule being analyzed were:
1,3-dicholoropropane
1 quintet
1 triplet
How many different types of equivalent protons are there is 1-bromo-2-chloropropane?
3 diff types
SDS-polyacrylamide gel electrophoresis separates proteins based on what factor?
masses
(T/F) Agarose gel electrophoresis is used to separate fragments of nucleic acid.
true
what is the Rf value in thin layer chromatography (TLC)?
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?
top
Which separation technique uses an electric field?
electrophoresis
(T/F) Vacuum distillation can be used to separate liquids with very high boiling points.
True
which separation technique separates compounds based upon their different affinities for a medium?
Chromatography
which purification technique involves a solid turning directly into a gas?
Sublimation
Which separation technique can be used to separate a mixture of particles with different densities and masses?
Centrifugation
Which separation technique takes advantage of a solution containing two or more compounds with different boiling points?
Distillation
How many alkyl group are in a tertiary (3) amine?
A 3 amine has 3 alkyl groups attached to the nitrogen.
What is a quaternary ammonium compound?
A quaternary ammonium compound is a nitrogen atom attached to 4 alkyl groups. The nitrogen is positively-charged and, therefore, the compound exist as a salt.
What are the products for the hydrolysis of an ester?
carboxylic acid & an alcohol
(T/F) A glycerol molecule attached to two carboxylic acids and one phosphoric acid is a phospholipid.
True
What is saponification?
fats are hydrolyzed, under basic conditions, to produce soaps.
what is the product of hydrolysis of an amide under acidic conditions?
The hydrolysis of an amide under acidic conditions will produce a carboxylic acid.
Which type of alcohol (1,2,3) can be oxidized to a carboxylic acid?
1 alcohols can be oxidized to carboxylic acids, however 2 & 3 alcohols cannot.
How do electrons withdrawing groups (-Cl, NO2) attached to the alpha carbon affect the acidity of a carboxylic acid?
Electron withdrawing group increase acidity.
How do electron donating groups (-NH2, -OCH3) attached to the alpha carbon affect the acidity of a carboxylic acid?
Electron donating groups decrease acidity.
Would you have to oxidize or reduce an aldehyde to create a carboxylic acid?
Oxidation of an aldehyde creates a carboxylic acid.
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 hydrogen bond.
what are three types of reactions used to synthesize alcohols?
Three general types of rxns used to prepare alcohols are : addition, substitution & reduction.
Why do alcohols have a significantly higher boiling point than analogous alkanes?
hydrogen bond
(T/F) Phenols are less acidic aliphatic alcohols.
false.
phenols more acidic than aliphatic alcohols.
what is the difference between a phenyl and a benzyl group?
a benzene ring acting as a substituent is called a phenyl group. A toluene molecule substituted at the methyl position is called a benzyl group.
(T/F) The reduction of an alkyne on a metal surface (Pd) results in a cis alkane.
False.
It results in alkane
(T/F) The reduction of an alkyne in Na and NH3 produces a trans alkene.
True
Which form of an alkene has a higher melting point (cis or trans?
The trans form of an alkene has a higher melting point due to its symmetry
Which form of an alkene has a higher boiling point (cis or trans?
The cis form of an alkene has a higher boiling point due to its polarity
How many steps are there in an E1 elimination reaction?
2 steps
How many steps are there in an E2 elimination reaction?
1 steps
How many steps are involved in an SN2 reaction?
1 step
Is the rate of an SN2 reaction dependent on the concentration of the substrate, of the nucleophile, or both?
the SN2 reaction rate is dependent on the concentration of both the substrate and the nuc
(T/F) SN1 reactions involving a chiral substrate produce an optically active mixture.
false.
a recemic mix results during SN1 rxn with an optically active reactant
(T/F) SN2 reactions involving a chiral substrate result in an inverted, optically active product.
true
Which step in an SN1 reaction is the rate determining step?
The first, the formation of the carbocation, is the rate determination 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?
1- Stabilize the carboncation by increasing substitution and using a highly polar solvent.
2- 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.
All else being equal, how does basicity affect the strength of a nucleaophile?
The stronger the base, the stronger the nucleophile
How many steps are involved in an SN1 reaction? what are they?
2 steps:
1st- molecule dissociates into a carboncation and a LG.
2nd- the nucleophile combines with the carboncation.
