Module 6.2 Flashcards
What are amines
amines are a class of compounds relaed to ammonia , NH3 . They are organic chemicals where only one or more of the hdyorgen atoms on ammonia have been replaced by alkyl chains .
what is a primary amine
where one hydorgen atom has been substituted . The structurl formla can be summarises as RNH2 , where R is the alkyl chain .
what is a secondary amine
two hdyorgen atom have been substituted the strucutral formula can be summarised as as RNH2 where R is the alkyl xhain .
what a tertiary amine
all three hydorgen atoms have been substituted . The structural formula can be summarises as RRNR’R2 , wheree R,R’abdR” , can be the same or different hydrocarbon groups .
naming amines
when naming amines , the suffix is always amine . Then the alkyl chains must be determined and used to generate the root and prefix of the name .
how to name primary amines
for primar amines - deermine the root by the longest hydrocarbon chain . Add any pefixes for othe group . Finally add the sufix amine .
how to name secondary amines
determine the root by naming the two alkyl chains , add any prefixes for additional groups and write them in alphabeical order . FFinally , add the suffix amine as the alkyl groups are attached to the nitorgen atom , secondary amines are often calld N-substituted and thi is given as a prefix to the name .
how to name tertiary amines
for tertiary amines -determine the root by naming the thre alkyl chains . If there is more than one of the same groupa dd thw apropriate prefix di or tri .
what is a lewis base
a lewis base has a lone pair of electrons for donation - ammonia and amines have a lone pair of electrons on the nitrogen atoms and are making them lewis bases .
what is a bronsted lowlry base
is a proton acceptor ammonia and amines can accept protons on the nitorgen atom and therefore also bronsted lowry bases .
amines and ammonia are both weak bases - using the bronsted lowry model show
when an amine reacts with an acid it ccepts a proton . A covalent bond is formed by the nitorgena tom donating its lone apir of electron to the proton to form a dative covalen (or coordiante bond .
-see figure 5 - reaction of methylamine as a base
reactions of amines with dilue inorganic acids
HCL is a strong inorganic acid and will fully ionise in solution . When HCL (aq0 , reacts with a base , a chloride salt and water are produced . When primar amines reacts with this cid , an alkylammonium salt is made . This is formed by the proton in the acid being replaced by an alkulammonium ion .
meaning of an alkyllammonium salt
it is a compound where the hydrogen930 on an ammonium ion has been substituted by alkl chians
-other strong inorganic acids such as nitric and sufluric acids will react in a simialr way to make a sal t .
erm jus the last bit ont he page l
when nitric acid is used instead of hydrochloric acids the nitrte ion NO3- , is imply substituted fo rthe chlroide ion CL- in the balanced chemical equation
however when sulfuric acid is used insead of hcl acid what is the balanced chemical equaiton i more complex
check page 152
preparation of aliphatic amines (1)
-using a sealed tube a haloalkane ammonia and ehanol are heated together to make an amine . Reflux , cannot be used as the ammonia is volatile , it would escape out of the condenser rather than react .
preparation of aliphatic amines (2)
a haloalkane such as 1-chloropropane , will undergo nucleophillic substitution , in a two stage process , to form a primary amine .
preparation of aliphatic amines (3)
stage 1 ; the ammonia reacts with the haloalkane to make an ammonium salt .
CH3CH2CH2CL+NH3– CH3CH2CH2NH3CL
Stage 2 ; an additional ammonia molecule , reacts to form the propylamine product and ammonium , chloride salt .
CH3CH2CH2NH3CL+NH3–.ch3ch2ch2nh2+nh4cl
preparation of aliphatic amines (4)
this is a reversible , so excess ammonia will drive the reaction to the right and increase , the yield , of the desired primary amine product .
-Additional substiution of the hydrogen atoms of the nitrogen atom can occur . In this reaction , N-dipropylamine a secondary amine is made .
preparation of aliphatic amines (5)
further substiution would produce n-tripropylamine , a tertiary amine .
preparation of aliphatic amines (6)
The final stage i a quartenary ammonium sla t, where each hydorgen on the ammonium ion has been repalced with an alkyl chain .
-These further substitution reaction can occur because mines have lone pair of electors on the nitrogen atom that cn act as a nucleophile .
when
when preparing amines by t this method there is always a mixure of the product produced . As the second stage , of the mechanism , is an equillib[rium , reaction , using excess ammonia favours , the primary amine , and excess haloalkane favours , the quaternary ammonium salt .
preparation of aromatic amines(1)
nitroarenes sucha s nitorbenezene can be reduced to produce an amine . The reducing agent is in situ , by using a mixture of tin and concentrated hydrochloric acid . The reaction occurs , under reflucx at 100 degrees .
preparation of aromatic amines (2)
about half an hr a strong alkali such as sodium hydroxide is added . This undergoes a neutralisation reactionn to remove the excess hydrochloric acid and produce amine . Sepaarating the aromatic amine is a multistage process that icnldues steam distillation solven extraction and further distillaiton .
what are amino acids
amino acids are a class of compounds , with two funcional groups a cabroxylic acid -COOH and an amine group -NH2 . When both functional groups are attached to the same carbon atom , the compound is called an alpha amino acid . This group of organic chemical has the general formula RCH9NH2COOH .
WHAT are proteins essential for .
they eare essential nutrients for all aniamals as they are used to make among other things , hormones , muscles and enzymes . All proteins are polymer chains , made up of amino acid monomers bonded together . In human biochem there are around 20 alpha amino acids .
structure of alpha amino
the carboxylic acid funcitonal group is a weak acid that will partially ionise in water . The nitorgen atom on the amine group has a lone pair of electronn and can act as a base . This means that aminoo acids are amphoeric 9they can acts as both an acid and a base 0 , as their carboxylic acid roup can react with base and hteir amine group can react with acids .
as yiu have learned alpha amino acids have two functional groups
-COOH , and NH2 , ATTACHED to the same carbon atom . Alpha amino acids can from zwitterions , where their two functional groups exchange a proton , and make an internal salt . The carboxylic acid donates a proton , to the amino group . As the two charges cancel each other out , the resultant moleucle has no overall charge .
WHat is the isoelectirc point
this is the point where there is no electric charge due to each zwitterion having an internal balance of chagre . By changing the pH , you alter the amino acid so that onlyo ne of its functional groups is charged .
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at the isoelectic point , what happens at low pH
This means at low pH , where there is a lot of H+ , the carboxylic acid , functional group becomes -COOH , and only the amine group is charged .
at isoelectric point , what happens at high pH
-However ,a t high Ph the miane group ebcomes -NH2 , and onlyt he cabroxylic acid group is charged .
carboxlic cid functional group reaction with metal oxides
metal oxides , are bases , so a neutralisation reaction occurs . The hdyrogen atom on the carboxlic acid group is exchanged for a metal ion to produce a metal alt , Water is also produced in the reaction
carboxylic acid reaction with alkalis
alkalis are soluble bases so aa neutralisation reaction occurs . The reaction produces a salt and water .
carboxylic acid reaction with carbonates
this neutralisation , reaction , produces a salt , water and carbon dioxide gas . A gas is evovled , effervescence is observed .
carboxylic acid reaction with alcohol
this reaction produces an ester and releases a moleucle of ater .
wht happens to the amine functional group in an amino acid
the amine functional group cna act as a base due to the lone pair of electrons ont he nitrogen atom . When an acid is added to an amino acid , the amine group accepts a proton . The result is an ammonium salt .
What are amides
An amide is a class of compound with a functional group made of an acyl group , RCO which is directly attached to an amine . (-NH2)
how re these amide compounds related to carboxylic acids and ammonia
where the hydroxyl group has been substituted for an amine group .
-they are also related to ammonia where one or more of the hydrogen atoms have been substituted for an acyl group
what are primary amides
primary amides are when the nitrogen atom has two hdyrogen atoms and one acyl group attached .
what are secondary amides
the nitorgen atom has one hdyrogen atom one acyl group and one alkyl group attached
what are tertiary amides
the nitrogen atom has no hydrogen atoms attached
what are polyamides
this is a type of condenstation polymer , a very long chain moelcule with a repeting pattern of toms . They are made from a reaction between carboxylic acid and an amine and contain a number of secondary amine groups . Can find more about polyamides in topic 6.2.5 .
how to name primary amides
when naming primary amides , the suffix is amide and the root is generated by the number of carbon atoms in the parent hdyrocarbon chain , which has the functional group . TO number prefixes the functional group is considered to be on carbon atom 1 .
naming secondary amides
when naming secondaary amides the suffix amide and the root is geenrated by the number of carbon atoms in the parent hdyrocarbon chain which has the functional group . The alkyl chain is attached to the nitrogen so it is clled an N-substitued compound .
opticl isomers
are molecles which are non-superimposable mirror images of each other . They have the same chemcial properties but ineract with polarised light differentl .
meaning of chiral
a chiral carbon has four different groups attached to it .
what are sterosiomers
stereosioemrs are a class of isomers that have a different arrangement of atoms in space . You studies E/Z isomerism , a type of geometric isomerism , these isomers re generated because of a lack of rotation of the C=C bond .
what is optical isomerism
the isomers are non -superimposable mirror image of eachother and are known as enantiomers . This means that each of the two enantiomers look like mirror images of each other , and no matter how hard you try you cnanot lay them on top of eachother .
why is enantiosomers optical isomers
this type of isomerism is called optical isomerism as each enantiomer interacts with light in a different way . Although both enantiomers , have the same chemical propeties and similar physical properties , they may have different biological propetites . One example of this is limoenen . chekc page 158 , it is a chiral hdyrocarbon that is naurally found in citrus fruits . One enantiomer smells strongly oranges with the other enantiomer smell of pine .
check page 159 f3
… a 50;50 mixture of enantiomers is called a racemic mixture or a racemae . A racemic mixture will have no effect on polarised light as the rotations of the two isomers cancel each other out .
chirality in opticl isomers
for optical isomers ot be formed in an organic compoud , there must be a carbon atom with four different groups attached . This carbon is known as the chiral center and i often shown with a * on diagrams o the moelcuel . It is also possible for inorganic atoms sucha s nitorgen to be chiral centres .
do chrials have a plane of symmetry yes or on
chiral moleucles do not have a plane of symmetry due to the asymmetric or chiral carbon . SOme molecules have more than one chiral cenre . Each will be a carbon atom with four different groups attached .
