Bettelheim Flashcards
How was Taxol discovered?
Taxol was discovered during a survey of indigenous plants sponsored by the National Cancer Institute with the goal of discovering new chemicals for fighting cancer.
What is the goal of combinatorial chemistry?
The goal of combinatorial chemistry is to synthesize large numbers of closely related compounds in one reaction mixture
Silicon is immediately below carbon in Group 4A of the Periodic Table. Predict the C-Si-C bond angles in tetramethylsilane, (CH3)4Si
109.5°
Is cis-trans isomerism possible in alkanes?
no
What generalizations can you make about the densities of alkanes relative to the density of water?
Alkanes are less dense than water. Those that are liquid at room temperature and float on water.
Suppose that you have samples of hexane and octane. Could you tell the difference by looking at them? What color would they be? How could you tell which is which?
Both hexane and octane are colorless liquids, and you cannot tell the difference between them by looking at them. One way to tell which compound is which is to determine their boiling points. Hexane has the lower molecular weight, the smaller molecules, and the lower boiling point (69°C). Octane has the higher molecular weight, the larger molecules, and the higher boiling point (126°C).
How are the boiling points of hydrocarbons during petroleum refining related to their molecular weight?
The greater the molecular weight, the higher the boiling point.
What are HFCs and HCFCs? How does their use in refrigeration systems avoid the environmental problems associated with the use of Freons?
They are hydrofluorocarbons and hydrochlorofluorocarbons, respectively. These compounds are much more chemically reactive in the lower atmosphere than the Freons and are destroyed before they reach the stratosphere.
What is one function of ethylene as a plant growth regulator?
Ethylene is a natural ripening agent for fruits.
What different functions are performed by the rods and cones in the eye?
Rods are primarily responsible for peripheral and black-and-white vision. Cones are responsible for color vision.
cis-3-Hexene and trans-3-hexene are different compounds and have different physical and chemical properties. Yet, when treated with H2 O/H2 SO4 , each gives the same alcohol. What is this alcohol, and how do you account for the fact that each alkene gives the same one?
The alcohol is 3-hexanol. Each alkene gives the same 2° carbocation intermediate and the same alcohol.
How does vitamin E function as an antioxidant?
Vitamin E participates in one or the other of the chain propagation steps and forms a stable radical, which breaks the cycle of propagation steps.
From what parts of its common name are the letters DDT derived?
The abbreviation DDT is derived from
DichloroDiphenylTrichloroethane.
Would you expect DDT to be soluble or insoluble in water? Explain.
Insoluble in water. It is entirely a hydrophobic molecule.
What are the differences in structure between Allura Red and Sunset Yellow?
One of the aromatic rings in Allura Red has a CH3 group and an OCH3 group. These groups are not present in Sunset Yellow.
From what types of plants is capsaicin isolated?
Capsicum
How many cis-trans isomers are possible for capsaicin?
Two cis-trans isomers are possible for capsaicin.
Di-tert-butyl-4-methylphenol (BHT, Section 13.4C) is an antioxidant added to processed foods to “retard spoilage.” How does BHT accomplish this goal?
BHT participates in one of the chain propagation steps of autoxidation, forms a stable radical, and thus terminates autoxidation.
Compare the acidity of alcohols and phenols, which are both classes of organic compounds that contain an 3 OH group.
Phenols are weak acids, with pKa values approximately equal to 10. Alcohols, which are considerably weaker acids, have about the same acidity as water.
When was nitroglycerin discovered? Is this substance a solid, a liquid, or a gas?
Nitroglycerin was discovered in 1847. It is a pale yellow, oily liquid
The legal definition of being under the influence of alcohol is based on blood alcohol content. What is the relationship between breath alcohol content and blood alcohol content?
The relationship is that 2100 mL of breath contains the same amount of ethanol as 1.00 mL of blood.
Which of the following objects are chiral (assume that there is no label or other identifying mark)?
(a) Pair of scissors
(b) Tennis ball
(c) Paper Clip
(d) Beaker
(e) The swirl created in water as it drains out of a sink or bathtub
(a) chiral (b) achiral (c) achiral (d) achiral (e) chiral
2-Butene exists as a pair of cis-trans isomers. Is cis-2-butene chiral? Is trans-2- butene chiral? Explain.
Neither cis-2-butene nor trans-2-butene is chiral. Each is superposable on its mirror image.
Compare the basicities of amines with those of alcohols.
Nitrogen is less electronegative than oxygen and, therefore, more willing to donate its unshared pair of electrons to H1 in an acid–base reaction to form a salt. Therefore, amines are stronger bases than alcohols.
What structural feature is common to all benzodiazepines?
The common structural feature is a benzene ring fused to a seven-membered ring containing two nitrogen atoms. This parent structural feature is named benzodiazepine.
Give two reasons why amine-containing drugs are most commonly administered as their salts.
Their salts are more soluble in water and in body fluids, and are more stable (less reactive) toward oxidation by atmospheric oxygen.
Arrange these three compounds in order of decreasing ability to form intermolecular hydrogen bonds: CH3OH, CH3SH, (CH3)2NH.
In order of decreasing ability to form intermolecular hydrogen bonds, they are CH3OH > (CH3)2NH > CH3SH. An O-H bond is more polar than an N-H bond, which is in turn, more polar than an S-H bond.
Arrange these compounds in order of increasing boiling point: CH3CH2CH2CH3, CH3CH2CH2OH, CH3CH2CH2NH2.
Butane, the least polar molecule, has the lowest boiling point; 1-propanol, the most polar molecule, has the highest boiling point.
If you dissolve CH3CH2CH2OH and CH3CH2CH2NH in the same container of water and lower the pH of the solution to 2.0 by adding HCl, would anything happen to the structures of these compounds?
Write the formula of the species present in solution at pH 2.0.
The alcohol will be unchanged. The amine will react with HCl to form a salt
CH3CH2CH2NH3+ Cl-
What is the difference in structure between an aldehyde and a ketone?
The carbonyl carbon of an aldehyde is bonded to at least one hydrogen. The carbonyl carbon of a ketone is bonded to two carbon groups
Is it possible for the carbon atom of a carbonyl group to be a stereocenter? Explain.
No. To be a carbon stereocenter, the carbon atom must have four different groups bonded to it. The carbon atom of a carbonyl group has only three groups bonded to it.
In each pair of compounds, select the one with the higher boiling point.
(a) Acetaldehyde or ethanol
(b) Acetone or 3-pentanone
(c) Butanal or butane
(d) Butanone or 2-butanol
(a) ethanol
(b) 3-pentanone
(c) butanal
(d) 2-butanol
What is the characteristic structural feature of a hemiacetal? Of an acetal?
The characteristic structural feature of a hemiacetal is a tetrahedral carbon atom bonded to one OH group and one OR group, where R may be either an alkyl group or aryl group. The characteristic structural feature of an acetal is a tetrahedral carbonyl group bonded to two OR groups.
What is the compound in willow bark that is responsible for its ability to relieve pain? How is this compound related to salicylic acid?
The compound is salicin. Removal of the glucose unit and oxidation of the primary alcohol to a carboxyl group gives salicylic acid.
Why do Lactomer stitches dissolve within 2 to 3 weeks following surgery?
Lactomer stitches dissolve when the ester groups in the polymer chains are hydrolyzed until only glycolic and lactic acids remain. These small molecules are metabolized and excreted by existing biochemical pathways.
Name the three most abundant hexoses in the biological world. Which are aldohexoses, and which are ketohexoses?
The three most abundant hexoses in the biological world are D-glucose, D-galactose, and D-fructose. The first two are aldohexoses. The third is a 2-ketohexose.
What is an amino sugar? Name the three amino sugars most commonly found in nature.
In an amino sugar, one or more OH groups are replaced by NH2 groups. The three most abundant amino sugars in the biological world are D-glucosamine, D-galactosamine, and N-acetyl-D-glucosamine
Define the terms glycoside and glycosidic bond.
A glycoside is a cyclic acetal of a monosaccharide. A glycosidic bond is the bond from the anomeric carbon to the OR group of the glycoside
What is the difference in structure between oligosaccharides and polysaccharides?
Oligosaccharide - 6-10 monosaccharides
Polysaccharide - >10 monosaccharides
Starch can be separated into two principal polysaccharides, amylose and amylopectin. What is the major difference in structure between the two?
The difference lies in the degree of chain branching. Amylose is composed of unbranched chains, whereas amylopectin is a branched network with the branches started by β-1,6-glycosidic bonds
Why is cellulose insoluble in water?
Cellulose fibers are insoluble in water because the strength of hydrogen bonding of a cellulose molecule in the fiber with surface water molecules is not sufficient to overcome the intermolecular forces that hold it in the fiber
Hyaluronic acid acts as a lubricant in the synovial fluid of joints. In rheumatoid arthritis, inflammation breaks hyaluronic acid down to smaller molecules. Under these conditions, what happens to the lubricating power of the synovial fluid?
Its lubricating power decreases.
Why does congenital galactosemia appear only in infants? Why can galactosemia be relieved by feeding an affected infant a formula containing sucrose as the only carbohydrate?
With maturation, children develop an enzyme capable of metabolizing galactose. Thus they are able to tolerate galactose as they mature.
When L-ascorbic acid participates in a redox reaction, it is converted to L-dehydroascorbic acid. In this reaction, is L-ascorbic acid oxidized or reduced? Is L-ascorbic acid a biological oxidizing agent or a biological reducing agent?
L-Ascorbic acid is oxidized (there is loss of two hydrogen atoms) when it is converted to L-dehydroascorbic acid. L-Ascorbic acid is a biological reducing agent.
Why can’t a person with type A blood donate to a person with type B blood?
Mixing types A and B blood will result in coagulation.
Oleic acid has a melting point of 16°C. If you converted the cis double bond into a trans double bond, what would happen to the melting point? Explain.
The melting point would increase. The trans double bonds would fit more in the packing of the long hydrophobic tails, creating more order and therefore more interaction between chains. This would require more energy to disrupt, and hence a higher melting point.
Which has the higher melting point: (a) a triglyceride containing only lauric acid and glycerol or (b) a triglyceride containing only stearic acid and glycerol?
(b), because its molecular weight is higher
Predict the order of the melting points of triglycerides containing fatty acids, as follows:
(a) Palmitic, palmitic, stearic
(b) Oleic, stearic, palmitic
(c) Oleic, linoleic, oleic
Melting points in ascending order.
c < b < a
Rank the following in order of increasing solubility in water (assuming that all are made with the same fatty acids): (a) triglycerides, (b) diglycerides, and (c) monoglycerides. Explain your answer.
The more long-chain groups, the lower the solubility; lowest (a); then (b); highest (c).
How do the unsaturated fatty acids of the complex lipids contribute to the fluidity of a membrane?
The presence of cis double bonds in fatty acids produces greater fluidity because they cannot pack together as
closely as saturated fatty acids.
