organic chemistry Flashcards
(62 cards)
what are hydrocarbons?
organic compounds that contain only carbon and hydrogen there are aliphatics and aromatics
what bonds do alkanes have?
-they contain sigma bonds
what is the bond angle of alkanes?
109.2
what happens to cyclic alkanes if they’re flat?
they are forced out of the most favourable angles causing angular strain
what type of strain can be caused due to cycloalkanes being flat?
-torsional strain because they are forced into a more eclipsed formation
-to overcome the instability, large chains e.g cyclohexanes can pucker their shape to minimise the effects
what are the physical properties of alkanes/cycloalkanes?
-they are insoluble in aqueous solutions e.g.plasma
-they are soluble in non-aqueous media e.g lipids in the body which contain long hydrocarbon backbones
-they are rapidly passed from the bloodstream into the nervous system and brain (which contain lipids),at low cons this can=hallucinations at higher concs they can cause a loss of consciousness and in extreme cases death
how is cyclopropane used as a general anaesthetic? (chemical properties of alkanes/cycloalkanes)
-it is mixed with oxygen which allows it to be used as a general anaesthetic, the absorption of cyclopropane is reversible so its effects will wear off
what does the fractional distillation of crude oil lead to? (chemical properties of alkanes/cycloalkanes)
the fractional distillation leaves a high boiling point residue called paraffin and liquid paraffin is used as a laxative since it aids lubrication and is not absorbed in its passage through the body
what is paraffin used for in pharmaceutical products?
-used as moisture resistant base for ointments and bases, its also used for vaseline
what is the structure of alkenes/cycloalkenes structure?
-unsaturated
-sigma and pi bond, the pi electrons are held less tightly
-have a planar structure
-E/Z isomerism sometimes occurs
what are the 4 major reactions alkenes/cycloalkenes undergo?
addition, oxidation,reduction,polymerisation
why are alkenes/cycloalkenes poorly soluble in aqueous environments?
-there is no ability to form a hydrogen bond or form polar interactions
what do alkenes undergo oxidation reactions with?
-cold KMnO4
-hot KMnO4
-Ozone (O3)
what can alkenes be reduced by?
hydrogen in the presence of a Pd catalyst
what is the structure of aromatic hydrocarbons?
-they are flat, conjugated cyclic hydrocarbons
-they are only aromatic if they follow huckles rule
what is huckles rule?
”for a cyclic compound to be aromatic it must have 4n +2 pi electrons where n must be a whole number
what is a physical property of aromatic hydrocarbons?
-they are insoluble in aqueous environments and soluble in non-aqueous environments
what are the chemical properties of aromatic hydrocarbons?
-they are more stable than alkenes
-they are resistant to oxidation,reduction and addition-this is because these reactions would result in a loss of aromaticity
-they undergo substitution reactions since with them aromaticity can be maintained e.g electrophilic substitution reactions-friedel crafts acylation and alkylation
what is a biological property of aromatic compounds?
-non-functionalised aromatic hydrocarbons have very little use as drugs but substitued aromatic compounds form the basis of many drugs e.g aspirin and paracetamol.
what are spirocompounds?
-bicyclicalkanes which have two rings sharing only one carbon
how do you distinguish between spirocompunds?
-if spirocompounds have the same total number of carbons but different number of carbons in each ring, the number of carbons in each ring (excl the central carbon) is placed in square brackets with a dot between them
-the numbers always go from low to high
how do you name substituted spirocompounds?
-when there are substitutes on the ring, you first start by numbering the smaller ring next to the ring junction and go around this ring through the ring junction and then into the larger ring
-you go in the direction which put the substitutes with the lowest number in each ring
what are bridgehead compounds?
-compounds where two rings of the bicyclic compound have two carbons common
how are bridgehead compounds named?
-they are given the prefix bicyclo
-the root name is based on the total number of carbons in the bicycle
-the stereochemistry is described in brackets with three numbers describing the number of intervening carbons between the two bridgehead carbons in decreasing order e.g bicyclo[4,2,2]decane