organic chemistry

Question 1

what are hydrocarbons?

Answer 1

organic compounds that contain only carbon and hydrogen there are aliphatics and aromatics

Question 2

what bonds do alkanes have?

Answer 2

-they contain sigma bonds

Question 3

what is the bond angle of alkanes?

Answer 3

109.2

Question 4

what happens to cyclic alkanes if they’re flat?

Answer 4

they are forced out of the most favourable angles causing angular strain

Question 5

what type of strain can be caused due to cycloalkanes being flat?

Answer 5

-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

Question 6

what are the physical properties of alkanes/cycloalkanes?

Answer 6

-they are insoluble in aqueous solutions e.g.plasma
-they are insoluble 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

Question 7

how is cyclopropane used as a general anaesthetic? (chemical properties of alkanes/cycloalkanes)

Answer 7

-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

Question 8

what does the fractional distillation of crude oil lead to? (chemical properties of alkanes/cycloalkanes)

Answer 8

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

Question 9

what is paraffin used for in pharmaceutical products?

Answer 9

-used as moisture resistant base for ointments and bases, its also used for vaseline

Question 10

what is the structure of alkenes/cycloalkenes structure?

Answer 10

-unsaturated
-sigma and pi bond, the pi electrons are held less tightly
-have a planar structure
-E/Z isomerism sometimes occurs

Question 11

what are the 4 major reactions alkenes/cycloalkenes undergo?

Answer 11

addition, oxidation,reduction,polymerisation

Question 12

why are alkenes/cycloalkenes poorly soluble in aqueous environments?

Answer 12

-there is no ability to form a hydrogen bond or form polar interactions

Question 13

what do alkenes undergo oxidation reactions with?

Answer 13

-cold KMnO4
-hot KMnO4
-Ozone (O3)

Question 14

what can alkenes be reduced by?

Answer 14

hydrogen in the presence of a Pd catalyst

Question 15

what is the structure of aromatic hydrocarbons?

Answer 15

-they are flat, conjugated cyclic hydrocarbons
-they are only aromatic if they follow huckles rule

Question 16

what is huckles rule?

Answer 16

”for a cyclic compound to be aromatic it must have 4n +2 pi electrons where n must be a whole number

Question 17

what is a physical property of aromatic hydrocarbons?

Answer 17

-they are insoluble in aqueous environments and soluble in non-aqueous environments

Question 18

what are the chemical properties of aromatic hydrocarbons?

Answer 18

-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

Question 19

what is a biological property of aromatic compounds?

Answer 19

-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.