Organic chemistry Flashcards
Alkanes
Phase? Boiling point? Solubility? Density?
Reactions?
Ring strain?
Nomenclature?
Hydrocarbon (containing only carbon and hydrogen) with only single bonds. Thus they are saturated compounds.
At room temperature, 1atm:
- Alkanes of 1-4 carbons are gases
- Alkanes of 5-17 carbons are liquids
- Alkanes of 18> carbons are solids
Boiling point of alipathic (straight chain) alkanes steadily increases with increasing number of carbons. Branching leads to a dramatic increase in boiling point. Melting point increases with number of carbons too.
Since alkanes are non-polar, they are not soluble in water. They are soluble in non-polar solvents.
Least dense of all organic compounds.
Combustion - where hydrocarbon converted to carbon dioxide and water in presence of oxygen - very exothermic.
Radical substitution reactions. Initiation, propogation, termination of free radicals.
Ring strain. Occurs in cyclic compounds, angles bent beyond normal. Unstable. Chair, boat conformations.
“Ane” added to longest number of carbons
Alkenes?
Properties? Stability?
Reactions?
Markovnikoff’s rule?
Alkynes?
Hydrocarbon molecules that are unsaturated, because they have one or more double bonds.
Similar to alkanes. Trans tend to have higher melting points due to symmetry and lower boiling points due to less polarity than its corresponding cis isomer.
Greater the number of alkyl groups, the greater the stability. Because alkyls are somewhat electron donating, they stabilise the double bond. An alkene with two double bonds is called a diene.
Electrophilic addition. When electrophiles (seek electrons) add to alkenes, carbocations (carbonium ions are formed). Useful diagram on page 31. The double bonds tend to resonance stabilise carbocations (positive charge).
Markovnikoff’s rule is that the nucleophile (seeks nucleus) will be bonded to the most substituted carbon (fewest hydrogens attached).
Oxidation. Alkenes can undergo a variety of reactions in which the carbon-carbon double bond is oxidised.\
Hydrogenation. Sometimes called the process of saturation. Alkenes react with hydrogen in the presence of various metal catalysts. Addition reaction, because hydrogens bond to double bonds, saturating.
Alkynes have triple bonds
Aromatics?
Properties of benzene?
Important reaction?
They are cyclic and have their p electrons delocalised over the entire ring. Therefore they are very stable Benzene the most basic example.
Known to have ring of bonds somewhere between single and doubell bonds, thus it is represented by a circle within a hexagon.
Electrophilic aromatic substitution. Occurs with electrophilic reagents. Basically a strong, positively charged electrophile (E+) bonds with the aromatic. Things rearrange a little bit and the original (E+) substitutes for a hydrogen (H+) which is removed from the molecule.
Alkyl group?
A substituent on a carbon chain that isn’t hydrogen, it could be many things
Alcohols?
Nomenclature?
Physical properties?
Reactions? (3) (What is oxidation reduction is organic chemistry?)
An compound in which a hydroxyl group (-OH) is bound to a carbon atom of an alkyl or substituted alkyl group.
“E” of the corresponding alkane is replaced with “ol”.
Alcohols are weak acids, weaker than water. Acidity decreases with increasing number of attached carbons.
Primary, secondary and teritary alcohols.
Higher boiling points, greater solubility than comparable alkanes, alkenes, aldehydes, ketones and alkyl halides. Due to greater polarity and hydrogen bonding of the alcohol.
Dehydration (loss of water), results in an alkene. Temperature of 300-400 degrees celsius and metal oxide catalyst. Alternatively, strong acids at 100-200 degrees.
*Oxidation reduction. In organic chemsitry, oxidation is the increasing of oxygen or decreasing of hydrogen. Reduction is the opposite. Primary alcohols converted to aldehydes w/ oxidising agents. Secondary alcohols converted to ketones.
Substitution. With alcohols, the -OH group is often subsitututed by a halide (usually chlorine or bromine).
Elimination. Occurs when an atom or a group of atoms is removed from adjacent carbons, leaving a double bond. E1 and E2 types of eliimination. E1 depends on concentration of 1 compound. E2 depends on concetration of 2 compounds.
Whether something is a good leaving group depends on whether it has a strong conjugate acid.
Aldehydes? Ketones?
Nomenclature?
Carbonyl group: Resonance? Polarity? Acidity of the a-hydrogen? Keto-enol tautomerisation? Hydrogen bonds?
An aldehyde contains a terminal carbonyl group, the functional group is a carbon group bonded to a hydrogen atom and double-bonded to an oxygen atom (O=CH-) and is called the aldehyde group.
A ketone contains a carbonyl group (C=O) bonded to to other carbon atoms: R(CO)R’
“E” of aldehyde is replaced with “al” for aldehydes and “one” for ketones.
Resonance. Two resonance forms of carbonyl group, delta and complete on the O anc C.
Polarity. Polarity varies with the resonance. Nucleophiles or electrophiles may react depending.
Acidity of the a-hydrogen. a-hydrogen is attached to carbon next to the carbonyl group. a-hydrogen may be removed by a base.
Keto-enol tautomerisation. Can interconvert into an isomer called an enol.
Hydrogen bonds. O of the carbonyl forms hydrogen bonds with the hydrogens attached to the other electronegative atoms such as O’s or N’s.
Carboxylic acid?
Organic acid with a carboxyl group, which has the formula -C(=O)OH. Usually written COOH or -CO2H
Carboxylic acid derivatives?
Includes acid chlorides, anhydrides, amides and esters
Ethers?
The general structure of an ether is R-O-R’ where the R’s may be either aromatic or aliphatic (only containing hydrogen and carbon)
Amines?
Compounds that contain a basic nitrogen atom with a lone pair
*Biological molecules, what are they?
Amino acids, proteins, carbohydrates, lipids, nucleic acids
