PH1125 - Organic Functional Groups Flashcards
what is an organic compound?
- any chemical compound that contains carbon
what are carbon containing compounds that are not organic? (2)
- carbonates; -CO3-
- cyanide; -CN
what is an imine?
- a compound with a nitrogen atom double bonded to a carbon atom
what is an azide?
- a compound with -N3
what is a functional group?
- specific substituents or moieties within molecules that are responsible for the characteristic chemical reactions and physical properties of those molecules
what is the polarity and reactivity of alkanes? (4)
- mostly chemically unreactive
- non-polar
- not soluble in water; hydrophobic
- lipophilic
what kind of isomers can compounds with double bonds exist as?
E Z isomers
describe the reactivity of alkenes (2)
- reactivity due to their electron rich nature
- the pi electrons above and below the plane of the C=C double bond are more weakly held than sigma electrons and are therefore more chemically reactive
what is regioselectivity?
- the preference for one orientation over another in the arrangement of a reaction product
why do tertiary carbons have the lowest energy and the highest stability?
- they are stabilised by electron density from all three neighboring carbon atoms
what is markovnikov’s rule? (2)
- in reactions of HX to alkenes the H bonds to the carbon with more hydrogens (fewer substituents)
- the X bonds to the carbon with more substituents (fewer hydrogens)
what are the pharmaceutical considerations for alkenes as drugs? (4)
- poor water solubility
- reactive (prone to oxidation) therefore possibility of shorter shelf-life
- important in medicinal chemistry for the ability to exist as E/Z isomers
- different isomers have different biological properties
how are alkenes reduced to alkanes? (2)
- hydrogen
- palladium catalyst
what is the product when alkenes are oxidised with potassium permanganate? (2)
- cis-1,2-diols
- the permanganate adds across the double bond to form an unstable intermediate that reacts with water to generate the diol
what is the alternative oxidising agent to make trans-1,2-diols? (2)
- peroxides
- the peroxyacid converts the alkene into an epoxide that reacts with water on the opposite side of the ring
what does the reaction of ozone and alkenes make? (2)
- involves breaking the double bond
- alkenes are converted into carbonyl compounds
what are the two principle methods for synthesizing alkenes? (2)
- alcohol dehydration
- wittig reaction
what is an alkyne functional group?
- carbon-carbon triple bond
what is the hybridization present in alkynes and shape?
- sp hybridized carbon atoms
- linear geometry; 180
what are the physiochemical properties of alkynes? (4)
- rigid, non-rotatable, linear geometry where E/Z isomers are not possible
- lipophilic (non-polar) therefore with poor water solubility
- rich in pi electrons and therefore chemically reactive
- rare in nature but useful in pharmaceuticals
how are alkynes reduced to alkanes? (3)
- hydrogen
- palladium catalyst
- alkyne -> alkene -> alkane
what does the term ‘poisoning’ refer to?
- reduced reactivity
what is cis-hydrogenation?
- both H atoms add to the same side of the double bond
how are alkynes reduced to E-alkenes? (2)
- sodium
- in liquid ammonia
what do terminal alkynes have?
- C≡C-H terminal H atoms which is slightly acidid
what is the relationship between pKa and acidity?
- larger the pKa value the weaker the acid
what are the physicochemical properties of haloalkanes? (3)
- generally chemically reactive
- very useful in organic chemistry but limited use in pharmaceutics
- lipophilic therefore poor water solubility
what is a nucleophile?
- electron rich species than seeks an electron poor site (electron pair donor)
as you go down the halogens in haloalkanes (fluorine to chlorine etc) does polarity increase or decrease?
- polarity decreases
what is the shape and hybridisation of alcohols? (2)
- 109.5 tetrahedral
- sp3 hybridisation
what makes alcohols good nucleophiles?
- lone pairs on the O
why are alcohols soluble in water? (2)
- they are polar as oxygen is electronegative and creates a permanent dipole
- this means it can form hydrogen bonds with water
what is an alkoxide?
- conjugate base of an alcohol (salt formed from alcohols and strong bases)
why cant alkoxides be used in drug molecules?
- they are too reactive and react readily with water to return to the parent alcohol
how are alcohols converted to alkenes (and what kind of reaction is it)? (2)
- in the presence of strong acids
- water is removed and it is a dehydration reaction
how are primary alcohols converted to aldehydes? (2)
- oxidisation
- manganese diodide is a mild oxidising agent
what is an example of a strong oxidising agent?
- sodium/potassium dichromate (Na2Cr2O7 / K2Cr2O7)
what is an alpha hydrogen? (2)
- hydrogen connected to the alpha carbon
- the alpha carbon is the carbon connected to the function group
why can’t tertiary alcohols be oxidised?
- they do not contain an alpha hydrogen
what is the ether functional group?
- R-O-R
are ethers polar?
- they are non-polar
how are ethers synthesized? (2)
- primary alcohols are converted to ethers by acid-catalyzed dehydration reactions
- alkoxides and alkyl halides
