Module 6.2 Flashcards
(133 cards)
1
Q
What are amines
A
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 They are organic chemicals where only one or more of the hdyorgen atoms on ammonia have been replaced by alkyl chains .
2
Q
what is a primary amine
A
where one hydorgen atom has been substituted . The structurl formla can be summarises as RNH2 , where R is the alkyl chain .
3
Q
what is a secondary amine
A
two hdyorgen atom have been substituted the strucutral formula can be summarised as as RNH2 where R is the alkyl xhain .
4
Q
what a tertiary amine
A
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 .
5
Q
naming amines
A
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 .
6
Q
how to name primary amines
A
for primar amines - deermine the root by the longest hydrocarbon chain . Add any pefixes for othe group . Finally add the sufix amine .
7
Q
how to name secondary amines
A
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 .
8
Q
how to name tertiary amines
A
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 .
9
Q
what is a lewis base
A
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 .
10
Q
what is a bronsted lowlry base
A
is a proton acceptor ammonia and amines can accept protons on the nitorgen atom and therefore also bronsted lowry bases .
11
Q
amines and ammonia are both weak bases - using the bronsted lowry model show
A
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
12
Q
reactions of amines with dilue inorganic acids
A
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 .
13
Q
meaning of an alkyllammonium salt
A
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 .
14
Q
erm jus the last bit ont he page l
A
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
15
Q
however when sulfuric acid is used insead of hcl acid what is the balanced chemical equaiton i more complex
A
check page 152
16
Q
preparation of aliphatic amines (1)
A
-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 .
17
Q
preparation of aliphatic amines (2)
A
a haloalkane such as 1-chloropropane , will undergo nucleophillic substitution , in a two stage process , to form a primary amine .
18
Q
preparation of aliphatic amines (3)
A
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
19
Q
preparation of aliphatic amines (4)
A
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 .
20
Q
preparation of aliphatic amines (5)
A
further substiution would produce n-tripropylamine , a tertiary amine .
21
Q
preparation of aliphatic amines (6)
A
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 .
22
Q
when
A
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 .
23
Q
preparation of aromatic amines(1)
A
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 .
24
Q
preparation of aromatic amines (2)
A
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 .
25
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 .
26
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 .
27
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 .
28
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 .
29
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 .
-
30
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 .
31
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 .
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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
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carboxylic acid reaction with alkalis
alkalis are soluble bases so aa neutralisation reaction occurs . The reaction produces a salt and water .
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carboxylic acid reaction with carbonates
this neutralisation , reaction , produces a salt , water and carbon dioxide gas . A gas is evovled , effervescence is observed .
35
carboxylic acid reaction with alcohol
this reaction produces an ester and releases a moleucle of ater .
36
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 .
37
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)
38
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
39
what are primary amides
primary amides are when the nitrogen atom has two hdyrogen atoms and one acyl group attached .
40
what are secondary amides
the nitorgen atom has one hdyrogen atom one acyl group and one alkyl group attached
41
what are tertiary amides
the nitrogen atom has no hydrogen atoms attached
42
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 .
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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 .
44
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 .
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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 .
47
meaning of chiral
a chiral carbon has four different groups attached to it .
48
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 .
49
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 .
50
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 .
51
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 .
52
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 .
53
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 .
54
what is a repeat unit
a repeat unit is the arrangement of atoms that occur many times in a polymer .
55
what is condensation polymerisation
is the chemical reaction to form a long-chain moleucl eby elimnation of a small molecule such as water .
56
what is polymerisiation
it is the chemical reaction thhat results in the production of a very long chain moleucle with repeating units - a polmer .
57
what is addition polymeriation
where monomers have at least ie c=c , whhich breaks and joins the other monomers together . There is only one product from this type of polymerisation . Common addition polymers include polytethene made from many ethene monomers .
58
what are codensation polymerisation
where two different monomers , with different functionl groups react to form a polymer and release another small moleucle , often water , hence the name .
nylon and polyester are common condensation polymers .
59
how to classify addition polymers polymers
if you are given the formula of monomer and it contains c=c , then it must form an addition polymer
60
how to classify condensation polymers
if the monomer contains two different functional groups or more than one monomer is presnet , each with different functionla groups , then they must make a condensation polmer . Do not need to recall the structures of synthetic polyesters and polyamides or their monomers .
61
what are polyesters
polyesters are a class of condensation polymer mde by the chemical reaction of a dicarboxlic acid (-cooh0 and a diol 9oh0 . When the carboxyilc acid roup on oe monomer reacts with the alcohol group ont he othe rmonomer an ester link is formed between the two moeleucles .. This happens many times and produces a long chain moleucle which is called a polyester .
62
is it possible to hve a moelcule that contians both an alochol group and a carboxylic acid group .
This allow just one monomer to be used to make the polyester .
63
proper focuz on page 1620and 163 with he repeating units and monomer structures .
...
64
what are polyamides
this class of confnsation polymers is amde by the chemicl reaction of a dicarboxlic acid and a diamine . Whent he carboxylic acid group on one monomer reacts witht the amine group on the other monomer an amide link is formed between the two molecules . This happens between manym oelcules and produces a long chain moleucle called a polyamide .
64
is it possible to have a moleule that contains both an amine group and a carboxylic acid group , such as we saw whenw to be e looked at amino acid in 6.2.2
this allows just one monomer to be used to make the polyamide .
65
what is hydrolysis
hdyrolysis is a chemical reaction in which water breaks bonds . For condensation polymers hydrolysis is the reverse reaction of polymerisation - causing the polymer chian to break down into their constitutent monomers .
66
what is hydrolysis like for polyesters and polyamides
with water , it is a very slow rate of reaction . This is why condensation polymers sucha s nylon do not degrade , when it rains . However , the reaction can be achieved in acidic or basic conditions and the rate cna be increased further by heaing the reaction mixture .
67
polyesters will undergo hdyrolysis in what
acidic and basic conditions . The rate of reaction iwth basic hydrolysis is so fast that if ou dropped a small amount of sodium hydroxide solution on a polyester jumper hole would be quickly be formed .
68
wwhat happens in acid hydrolysis
when polyester is rected with a strong aqueous acid , the reaction produces a diol and a dicarboxylic acid . THe acid hydrolyisis of a polyester has a slow rate of rection .
68
what happens in alkali hydrolysis
when polyester is reacted with hot sodium hdyroxide solution , the reaction produces the diol and the salt of the dicarboxylic acid .
69
hdyrolysis of polyamides
polymides will undergo hdyrolysis in acidic and basic conditions . The rae of reaction of acid h dyrolysis is much faster than basic hydrolysis for polyamides . Acids can easily hyrolyse nyon and cause holes in clothing so you msut be careful when working with htem .
70
what happens in acid hydrolysis
when a polyamide is reacted with a strong aqueous acid , the reaction produces a diammonium sal . and a dicarboxylic acid .
71
what happens in alkali hydrolysis
when a polyamide is reacted with hot sodium hydroxide solution , the reaction produces the diamine and the salt of the dicarboxylic acid .
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learning tip allkali hydrolyiss is fast in ...
acid hydrolysis is faster in ...
alkali hydrolysis is faster in POLYESTERS .
-Acid hydrolysis is faster in POLYAMIDES .
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what is cyanide
cyanide is a nucleophiel and attracted to areas of positive charge in moleucle . Other common ncleophiles includ ehdyroxide and water
74
cyanide ion is what the
cn ion - is known as the cyanide ion . II t retains , the name cyanide in inorganic chemicals like sodium cynide NaCN . However , where the -CN , group is found in an organic hcemical i become sknown as a nitrile functionl group .
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nucleophilic subsitiuions
haloalakane have a dipole in the C-X , bond due to the significant differences in the electronegativities , between the carbon and the halogen . This means that the carbon is susceptible to the nucelophilic attack
76
haloalakane mixed with potssiumc yanide what occurs
In the labortory , the haloalakane is mixed with potaium cyanide and heaed under reflux . The solven is ehanol and his ensures that the nucleophile is the cyanide ion . Iif water is used then the hdyroxide ion tends to be the nucleophile and the crbon chain length would not increase .
77
what happpens when 1-bromopropane is heated under reflux with potassium cyanide in a solution containing ethanol .
Tthe reaction will occur , the mechanisms is a nucelophilic substitution where the cyanide takes the place of the halogen . The balanced chemical equation for the reaction is . check figure 4 , mechanism .
78
why is the figure 4 mechanism an important reaction
thi sis an important reaction as the carbon chain has gone from three carbons o four carbons , in length . A new c-c bond is formed between the original organic moleucle and cyanide , which increases the lengh of the carbon chain bby one carbon atom . The new nitrile funcitonal group can udnergo more reactions and make a variety of different chemcials .
79
nuclephilic addition with hdyorgen cyanide (1)
the carbon in a carbonyl group has a slight positive charge and this makes it susceptible to nuceophilic atack . Hydrogen cyanide can be used to egenerate the cyanide nucleophile . The cyanaide ion will be attracted to the carbon of the carbonyl group and forms a new covalent bond which extends the length of the carbon chain .
80
nuclrophilic addition with hdyrogen cyanide (2)
the pi bond of the c=o then openos and the oxygen q5om ccepts a proton and becomes a hdyroxyl group , (OH) . The resut is a hdyroxynitile organic compound .
81
nucleophilic addition with hydrogen cyanide (3)
as he c=o , is a planar bond , there is an equally likley chance that the cyanide ion will attack from either side . So a racemix micture is porduced when an asymetric ketone or ana dlehyde other than methanal is used in this reacion . 5.3.4 we had learnt baout otpical isomerims nd racmeix mictures .
82
learning trip about HCN
HCN is a highly toxic gas in normal laboratory condiions . It stops the mitochondrial enzymes working in living cells . A safer a;teratove os the laboratory is to use a cyanide salt like potassium 9KCN0 . This is a solid at room temperatire and is easier to handle . The salt must be used in an acidified solution so that both CN- and H+ ions are present .
83
what is a nitrile
a nitrile is an organic chemical with a -CN , functional group .
84
reduction of nitriles
nitriles form amines when they undergo reduction .
-One defiiniton of reduction is the ADDITION OF HYDROGEN .
-Hydrogen gas can react directly with a nitrile to form a primary aliphatic amine . Two , hdyrogen atoms are dded to tth enitorgen atom of the nitrile group .
85
catalyst needed for the reduction of nitriles
a transition metal catalust , such as the nickel is needed to lower the activation energy to enable this reaction to occur . To oincreaase the rate of reaction , the reaction mixture is heated to about 150 degrees with a nickel catalyst at raised pressure .
86
how else is the reduction of a nitrile also possible
reduction is also possible using a reducing agent such as lithium tetrahydriodoaluminate . LiAlH4 .
-In a chemical equation the reducing agent is often abbreviated to H . The general equation for this reaction is
RCN+49H) --> RCH2NH2
-Where R is a h dyrocarbon or hydorgen
87
general equation of the reduction of nitriles
the general equaiton for this reaction is
-RCN +2H2--RCH2NH2
-Where R is a hydrocarbon or hdyorgen .
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how do nitriles undergo hydrolysis
nitrilies will undergo hydrolysis to initially form an amide , and then an ammonium salt . However , this second reaction is so slow that is not significant . The rate of reaction can be increased by using a strong acid as a catalyst and heating the reaction mixture under reflux . Under acid hydrolysis , nitrilies react to form carboxylic acids .
89
how do nitriles undergo hydrolysis (2)
when ethanenitrile undergoes acid hydrolysis , ehanoic acid and an inorganic ammonium salt are formed , The balanced chemical equation is l
-CH3CN 62H20+HCL --.CH3COOH +NHCL
90
How are organic aicds such as CH3COOH formed in hdyrolysis
Ratheer than an organic ammonium salt (CH3COONH4) . This is because , the strong acid , fully ionises in solution forming hydrogen ions and chloride ions . Once he amide is formed , the bond between thenitrogen adn the crbon ions and chloride ions . Once he amide is formed , the bond between between the nitorgen and the carbon is broken , making the ethanoate ion .
91
How are organic aicds such as CH3COOH formed in hdyrolysis 92)
This then , reacts with proton from the strong acid to form the carboxyclic acid . All oranic aicds , are weak acids and onl partiall ionise in solutions . In these rections th C=N , is completely broken through a series of steps via the amide , This gives the carboxylic acid and the ammonium salt as the major products .
92
all aromatic compounds contain what
a six membered carbon ring with delocalised electron. As we learned in 6.1.1 , the delocalisation of electronns offers additional stability to the moleucl . So it will not undergo addition reactions like other unsaturated compounds .
93
friedel crafts
reactions allow electrrophilic subsitions to occu on an aroatic ring .
94
substiutuoin rections occur when
one or more hydrogen atoms on the aromatic ring are exchanged for another atom or groups of atoms . For arenes these ractions occur by electrophilic substituio using a catalyst usch as aluminium chloride alcl3 , or ironiii , chloride fecl3 . A subsititued aromatic ring , is porduced by forming a c-c bond .
95
when do alkylation reactions occur
alkylation reactions occur when hydrocarbon chains are added to an orgganic compound . The reagen are ana romtic compound , haloallkane and srong lewis acid catalyst .
96
benzene can react with chloromethane to make what
to make methylbenzene in the presence of fecl3 caalust . Iron III chloride can be used as friedel crafts catalyst as it is an electron pair acceptor the balanved chemical equation for this reaction is shown in this equation .
96
when do acylation reactions occur
when ACYLATION REACTIONS OCCUR WHEN -RCO is added to an organic compound , where R is a hdyrocrbon chain . The reagent are an acyl chloride and a strong Lewis acid catalysts .
96
how can the electrophilic subsitution reaction be explained
by using general mechainsm , where r is a hdyrocarbon chain . It i possible for furher substitution reactions to occur nd so a mixture of products is produces . But this mechanism focuses on just one substitution occuring .
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97
benzene can be gently heated under reflux with ethanyl chlroide in the presence of anhdyrous aluminium (III) chlroide to form phenyethanone
the balanced chemical equation for this reaction is the electrophilic subsitituion reaction can be explained using a general mechanism where r is a hdyrocarbon chain .
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distillation
is a technique used to separate misicble liquids or solution. Heating under reflux is technique used to ensure that volatile compounds are not lost from he reaction mixture .
99
recrystallisation
is a method for purifing organic compouns .
100
quickfit
it is a selection of heat-resistant glassware with connectors that can be easily fixed in a variety of arrangements .
101
distillation
the bottom of he condenser is connected to the cold water supply and the top connector to aa hose that drains water into the sink . A few anti bumping granules are added to the distillation flask o ensure smooth boiilng .
-TTo complete the distillaiton the mixture is heated . As he product is collected the temperature on the thermometer can be used to idenitfy the chemical
102
heating under reflux
heating under reflux is a technique used in organic syntheissi to ensure the volatile , compounds , are not lost from the reaction mixture . Volatile regents , to the reaction mixure rather than escaping before they can react .
103
puriiciation of an organic solid filtiriation under reduced pressure (1)
1. connect thick wall rubbeer tubing to the vacuum pump and check that thee is suction .
2.Put a Buchner funnel into the top of a filer flask . For small quantities a Hirsch , funnel can be used .
3.Connect , the tubing , from the vacuum pump to the side arm of the clamped filter flask and sart the suction .
104
purification of organic solid filtiriation under reduced pressure (2)
4. place a filter paper just big enough , to cover he holes into the top of the funnel .
5.understand disilled water or the solvent from your organic syntheiss if thi is different dampen the filter papper so that it sticks over the holes of the funnel .
6. slowly pour your reaction mixture into the centre of the funnel .
105
purifiction of organic solid under reduced pressure (3)
7.wash out the reaction vessel and the funnel with the solvent and add this to the funnel .
8. rinse the collected collected solid with more solvent and maintain suction for a minute afer aall the washings have been added .
9.turn off the suctionby removing he rubbeer ube from the idearm of the filtiriiton tasks ,
10.invert the funnel into a watch glass to collect the organic solid .
106
recrystallisation overveiw
in organic synhesis often a mixtureof different organic chemicals is porduced . Recrystallisaiton is a technique that allows an organic porduct to be purified from unreacted starting materials catalysts and unwanted side porducts .
107
stage one of recrystallisation
the crude product is dissolved int o the minimum volume of hot solvent . HOt solvent is used as the solubility of solids is higher . If the porduct is coloured activated charcol can be heated witht he mixture to remove the colorued impurtiies .
108
stage two of recrystallisation (2)
The hot solution should hten quixkly undergo gravit filtiration using fluted filter paper . The residue of the used acivated charcoal and insoluble impurities can be diposed of .
--The hot filtrate should be allowed to cool , this reduces solubiliy ad crystals of the porduct will form . If no crystals appear to be forming , sca=ratching the sides of the conical glask , with a clean glas rod cn form nucleation site and aid crystallisaiton . Crash xooling he mixure in an ice bath can also be used to speed up this sage . Any soluble impurtieies should remain dissovled .
109
stage three of recrytsallisation
the purified organic product can be collected by vcuum filtiriation . The crystals should be washed with a small amoun tof cold solvent to remove any of the filtrate which contains dissolved impurtiies .
110
checking purity - measuring melting points
-all pure chemicals have distinct melting and boiling poins , By measuring these values and comparing them to infomation in a data book or database , the chemicals can be identified .
-By meauring the melting point of a known chemical , the purity can be determined . The pure chemical will have the exct melting point as lited ina trusted source . However , hem ore impure the product is he greater the range of the melting point will be.
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two
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two method for measuring melting point - method 1 melting point apparatus (1)
in a sealed capillar tube , puot a few grains of the organic solid . Gentl , insert the tube into the melting point machine and add an accurate thermometer with suitbale range .
114
two method for measuring melting point - method 1 melting point apparatus (2)
switch on the machine nd turn the heating dial to abou 4 . FOr lower melting point compounds do not be tempted to use a higher setting or the boost function as you are likel to miss the melting point .
115
two method for measuring melting point - method 1 melting point apparatus (3)
look through the lens and carefully watch the crystals , When they start to fall away from the ides of the capillary tube , melting has begun . Record this temperature , continue to watch until the smpe hs liquefied and onte the new temp . These two values , give your melting point range .
116
second method for measuring melting point 91) - thiele tube
in a sealed capillary tube , put a few grains of the organic solid . Using a small rubber band , attach the tube to a thermometer submerge the thermometer into the oil of the thiele tube ensuring that the rubber band is above the oil line .
-Using a microburner with a small gentle flame , heat the side arm of the thiele tube . Note the temperature range of when the organic solid starts and finishes melting .
117
what is a synthetic route
synthetic route (or synthetic pahway 0 , is a series of reactions that can be used to change a starting chemical inot a target molecule .
118
what can unsaturated containinga tleast one c=c undergo reactions with
-bromine
-hdyrogen halides
-themselves to form an addition polymer
119
what can haloalaknes undergo reactions with
-react with ammonia in ehtanol to form amines .
-can be reduced by alkaline hydrolysis to form alcohols .
120
what can carbonyls undergo reactions with
-aldehydes can be reduced to priamry alcohols or oxidises to carboxylic acids .
-ketones can be reduced to secondary alcohols .
121
carboxylic acids can undergo reactions with what
reactive metals to make a salt and hdyrogen .
metal carbonate to make a salt water and carbondioixdie .
alcohols to form esters
122
alchols can undergo reactions with
primary alcohols can be oxidised to aldehdyes .
secondary alcohols can be oxidised to ketones
tertiary alcohols cannot be oxidised
123
esters can undergo reactions with
undergo alkaline hdyrolysis to form a carboxylate and an alcohol .
undergo acid hydrolysis to form a carboxylic acid and an alcohol .
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revise figrue 2 and gifure 3
...
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designing syntehtic routes part one
-Compare the starting material and the target product . Focus on the changes that have happened to the moeleucle .
a- an increase n carbon chain length by one atom means the reaction involved cyanide .
b- an increase in carbon chain length by more than one atom means a reaction involving two carbon-containing compounds .
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designing synthetic routes part two
think about the reaction sin stepts , to change he starting chemical to the target molecule . sometime it helps to foucs on the product and think backwards ; this is known as retrosynthesiss .
-wrtie down all the stages and check that they are all balanced with ebery atom accounted for .
