Organic Chem Flashcards
What is the word for Carbon’s ability to link itself in chains and rings?
Catenation
What does it mean to be saturated?
A compound that contains only single bonds
What does unsaturated mean?
A compound that contains double or triple bonds
What does aliphatic mean?
A compound that doesn’t contain a benzene ring
What is an arena?
A compound that contains a benzene ring and therefore is unsaturated
What type of reactions do alkanes not engage in?
Addition reactions because they are saturated
By what do consecutive members of a homologous series differ?
CH2
What is the trend in boiling point down a homologous series?
As more CH2 groups are added the boiling point increases due to more instantaneous induced dipoles and therefore more London dispersion forces
What type of correlation would describe the trend in boiling point down a homologous group?
An exponential correlation: the increase in boiling point is steeper at the beginning of the homologous series because the proportion of the new CH2 to the rest of chain is larger when the chain is smaller
What increases down a homologous series?
Boiling point, density, viscosity
What is a real life application of boiling point trends in homologous series?
In the oil industry, smaller hydrocarbons boil off first at lower temperatures allowing them to be separated by mass
What are the three ways to write the formula of an organic compound?
Empirical: simplest whole number ratio of atoms present in molecule
Molecular: the actual number of atoms in a molecule (tells you molar mass)
Structural: shows exact number and how atoms are arranged
What are the three types of structural formulas and what do they show?
Full structural formula: shows the atoms graphically and the bonds present
Condensed structural formula: writes out the atoms in a non-ambiguous way to show how they are arranged
Stereo chemical formula: attempts to show how bonds and atoms are located in space
What are the steps for identifying the name of an organic molecule
1: identify the longest chain (stem)
2: identify any functional groups (suffix)
3: Identify side chains or substituents (prefix)
What substituent groups can be only side chains and which one can be either a functional group (suffix) or a side chain (prefix)?
Alkyls and halogens can only be prefixes and amines can be either one depending on whether there already is a suffix
Define structural isomer
Molecules that have the same molecular formula but different structural formulas
Do structural isomers have same or different physical properties? What about chemical?
Isomers have both different chemical and physical properties
How many isomers does C4H10 have?
2
How many structural isomers does C5H12 have?
3
How many structural isomers does C6H14 have?
5
What are common structural isomers for alkenes and alkynes?
Similar straight chain molecules with the double or triple bond in different places
Define primary carbon
A carbon that is attached to a functional group, two hydrogen atoms, and an alkyl group
Define secondary carbon
A carbon bonded to a functional group, one H, and two alkyl groups
Define terciara carbon
A carbon bonded to one functional group and three alkyl groups
Define primary nitrogen
A N bonded to an alkyl group and two H atoms
Define secondary nitrogen
A nitrogen bonded to two alkyl groups and one H
Define tertiary nitrogen
A nitrogen bonded to three alkyl groups
Benzene is unsaturated meaning it contains double bonds, but it doesn’t undergo addition reactions. Why?
The six delocalized electrons in benzene give it stabilization energy. If it were to undergo an addition reaction it’s stabilization energy would be thrown off
Describe the bond lengths in benzene
It used to be thought that the carbons in benzene were held together by alternating single and double bonds (Kekule). But it is now known that because of the delocalized electrons all the C-C bond lengths are somewhere between a single and double bond in length
Which model of benzene is more stable (the Kekule model or the current model) and by how much?
The current model of benzene which proposed the idea of stabilization energy is more stable than the alternating single double bond model by 152 kJ per mol
Compare the boiling points of carbon chains with more versus fewer branches
The more branches the weaker the intermolecular forces (because less contact) and therefore the lower the boiling point
True or false: the bonds present in alkanes are very strong
True; alkanes only react in the presence of a source of strong energy
What are two useful physical properties of alkanes?
Because the C-C and C-H bonds are so strong they are not very reactive and are therefore stable meaning they are safe to transport and store.
Because the C-C and C-H bonds aren’t polar, they won’t react with most reactants
What are the two types of reactions that alkanes undergo?
Combustion and substitution
Are combustions of alkanes extremely exo or endothermic?
Extremely exothermic
What is the product of the complete combustion of an alkane?
Carbon dioxide
What are the products of the incomplete combustion of alkanes?
Carbon monoxide and carbon
How does the C:H ratio in unsaturated molecules affect the smokiness of the combustion of hydrocarbons?
As the ratio of C:H increases there is more smokiness due to unburned carbon
What makes carbon monoxide toxic?
It will bond with the hemoglobin in blood and instead of transporting oxygen to tissue in the body, CO will be transported causing carbon monoxide poisoning
What are consequences of unburned carbon being released into the air?
It has negative consequences on people’s respiratory system and can cause smog and global dimming
What is the term for the type of substitution reaction that alkanes undergo?
Halogenation and nucleophilic
Which class of hydrocarbons requires UV light to undergo halogenation?
Alkanes
What are the three stages involved in halogenation of alkanes?
Initiation, propagation, and termination
Describe the initiation phase of the halogenation of alkanes
UV light breaks Cl2 into two free radical Cl atoms
What term is used to describe the initiation phase of halogenation of alkanes?
Photochemical homolytic fission
What are the propagation reactions in the halogenation of alkanes?
Cl•+CH4–>CH3•+HCl
CH3•+Cl2–>CH3Cl+Cl•
CH3Cl+Cl•->CH2Cl•+HCl
CH2Cl•+Cl2->CH2Cl2+Cl•
What defines a termination reaction?
It removes the free radicals from the mixture by reacting them together and pairing up their electrons
What are the termination reactions for the halogenation of methane with chlorine?
Cl•+Cl•->Cl2
CH3•+CH3•->C2H6
CH3•+Cl•->CH3Cl
What is one method to distinguish between alkanes and halogens?
React alkanes and alkenes with bromine water in the dark. Only the alkenes can undergo halogenation in the dark so the water with the alkene will change from brown to colorless and the alkane solution won’t change
Why are alkenes more reactive than alkanes?
The double bond is the site of reactivity
What are the four types of addition reactions that alkenes can undergo?
Addition of hydrogen
Addition of halogens
Addition of halogen halides
Addition of water
What are the product, catalyst, and applications of the hydrogenation of alkenes?
Product: produces a saturated alkane
Catalyst: nickel
Application: margarine industry uses this to make butter solid at room temperature (alkanes are more saturated than alkenes and therefore have higher melting points)
What are the product and physical change associated with halogenation of alkenes?
Product: a dihalogeno compound (with the two halogens bonded to the C atoms that uses to have the double bond)
Physical change: loss of color for the halogen
What is the trend in the reactivity if halogen halides?
The decreasing strength of the covalent bond down group 17 means lower down is more reactive:
HI-> HBr-> HCl (with HI most reactive)
What is the product of addition of halogen halides to alkenes?
A halogenoalkane
What are the product and catalyst for the hydration of alkenes?
Product: alcohol
Catalyst: sulfuric acid
Explain the role of the catalyst in the hydration of alkenes
In the intermediate step the sulfuric acid breaks into H+ and HSO4- and added to the carbon atoms where the double bond used to be. Then in a process called hydrolysis an OH- replaces the HSO4- and the alcohol is produced
Which alkene addition reactions take place in room temperature?
Halogenation and addition of halogen halides
Which addition reaction requires heat and steam?
Hydration
Why are alcohols so soluble in water?
The OH functional group is polar
What is the trend in energy released upon the combustion of alcohols as you go down the homologous series?
The higher the mass the more energy released because more carbon dioxide molecules are produced
What happens when alcohols are combusted in a limited supply of oxygen?
Carbon monoxide and carbon are produced
How do the combustion and oxidation of alcohols differ?
Combustion completely breaks apart the alcohol molecule and produces carbon dioxide and water.
Oxidation of alcohols only removes the OH functional group and leaves the c chain intact
What oxidizing agent is commonly used in the oxidation of alcohols?
Acidified potassium dichromate
What color is acidified potassium dichromate before and after it has been reduced?
Orange before then green
Describe the oxidation of primary alcohols.
Oxidation of primary alcohols takes place in a two-step process in which the alcohol is first turned into an aldehyde and then a carboxylic acid under prolonged conditions.
What process can be used to stop the oxidation of a primary alcohol after it has been turned into an aldehyde and remove it from the mixture?
Distillation
How does distillation work?
Because aldehydes have lower boiling points than alcohols or carboxylic acids, they are easily separated by boiling point.
What process is used to produce a carboxylic acid out of a primary alcohol?
reflux
What are the conditions for oxidation of alcohol?
the presence of acidified potassium dichromate, heat, and either distillation or reflux.
What is produced by the oxidation of secondary alcohols?
a ketone and water
What happens during the condensation of alcohols?
An alcohol reacts with a carboxylic acid to produce an ester in the presence of a sulfuric acid catalyst
What distinguishes the ester product from the alcohol and carboxylic acid reactants in a condensation reaction?
ester have lower boiling points, a strong smell, and are not polar, so they are insoluble and therefore form a layer on the surface of the mixture.
How are halogenoalkanes similar to and different from alkanes?
Both are saturated so they can only undergo substitution reactions, but halogenoalkanes have a polar bod, which makes them more reactive.
What is responsible for the reactivity of halogenoalkanes (be more specific than the polarity of the bond)?
The carbon bonded to the halogen is slightly electron deficient due to the stronger electronegativity of the halogen. This makes the carbon attract nucleophiles (which are electron rich)
What type of reactions typically results from the attraction between nucleophiles and the electron deficient portions of halogenoalkanes?
nucleophilic substitution
What is a good application of nucleophilic substitution reactions?
They can be used to turn halogenoalkanes into different types of organic molecules and therefore can be used as the intermediate step in reactions.
Pair the following words together:
electrophilic, nucleophilic, halogenoalkanes, benzene
Benzene goes with electrophilic because benzene’s electron rich ring attracts electron-dificient electrophiles in what is called electrophilic substitution.
Halogenoalkanes go with nucleophilic because nucleophiles (electron-dense) seek the electron deficient carbon bonded to the halogen in halogenoalkanes which results in nucleophilic substitution reactions.
