The Carbonyl group. Flashcards
1
Q
What is the Carbonyl group ?
A
Consists of a carbon double bond oxygen.
2
Q
What is the functional group of an aldehyde ?
A
Carbonyl carbon has at least on hydrogen bonded to it. RCHO
3
Q
What is the functional group of a ketone ?
A
The Carbonyl carbon has 2 organic groups bonded to it . Can be either alkyl or aryl groups just not hydrogen. RRCO
4
Q
What is an alkyl group ?
A
Based on a saturated hydrocarbon group.
5
Q
What is an aryl group?
A
Based on an aromatic system.
6
Q
Why can’t carbonyl compounds H-bond to themselves ?
A
No Hydrogen bonded directly to sufficiently electronegative atom .
7
Q
Why do long chain carbonyls not dissolve in water .
A
Since the long chain means the V.D.W forces predominate over the H-Bonds so it becomes energetically favourable to be insoluble and not form weaker VDW forces with Water that originally had stronger H-Bonds.
8
Q
What part of aldehydes /ketones has a large effect on their physical properties .
A
The polar carbon double bond oxygen.
9
Q
What does the carbon double bond oxygen mean for the reactivity of aldehydes and ketones.
A
The carbon is partially positive so attacks nucleophilic reagents. The double bond leads to unsaturation so addition reactions become possible. Despite the high bond enthalpy on the carbon double bond oxygen this is where reactions occur.
10
Q
What does the carbon double bond oxygen mean for the solubility of carbonyl s ?
A
Shorter chain aldehydes and ketones can H-bond to water making them soluble in water.
11
Q
Compare boiling points of Aldehydes and ketones with similar MR alkanes and carboxylic acids .
A
Permanent dipole - Dipole forces means they have higher BP than alkanes with only VDW but less than carboxyic acids that can H-Bond .
12
Q
How does the C=C and the C=O differ in terms of their reactions.
A
C=O is stronger as does not undergo addition reactions as easily as the C=C. C=C will not be reduced by the Hydride ion like the carbonyl group is since the centre of high electron density will repel the hydride ion.
13
Q
What oxidising agent is used for the oxidation of alcoholes and aldehydes .
A
Acidified potassium dichromate solution. K2Cr207 Acidified with dilute sulphuric acid.
14
Q
Which colour change is observed when potassium dichromate is used as an oxidising agent.
A
The orange Cr207 2- ions are Reduced to green Chronium 3+ ions.
15
Q
What decides weather you heat using reflux or distillation When oxidant a carbonyl group compound.
A
If a product is required that needs lesser oxidation (multiple possible products)for example an aldehyde you distill to get the right one. If only one possible product just overkill in reflux conditions.
16
Q
Give a common Reducing agent and state the nucleophile that is generated.
A
Sodium Borohydride- NaBH4 , this produces the hydride Ion nucleophile that is :H- .
17
Q
What is an aldehyde reduced to.
A
A primary alcohol .
18
Q
What is a ketone reduced to ?
A
A secondary alcohol
19
Q
What is used to represent the reducing agent When Aldehyde / ketones are reduced to their respective alcohols.
A
2[H] Remember it’s 2 Hs for reduction.
20
Q
When NaBH4 acts as a reducing agent what must it be ?
A
It must be aqeous to produce the Hydride ion.
21
Q
Name the and outline the mechanism for the reduction of aldehydes/ketones.
A
Mechanism is nucleophilic addition. It follows:
22
Q
In the nucleophilic addition mechanism for the reduction. of aldehydes and jerked describe the two stages and where the things come from.
A
The partially positive carbonyl carbon is attacked by the hydride ion that is generated from the NaBH4 , the :O- is then attacked by a H+ ion that comes from the solvent.
23
Q
Give the general equation you would give in an exam for the reduction of a ketone into a secondary alcohol.
A
RCOR +2[H] goes into RCH(OH)R Where the two H atoms have been added. One to the O and one to the carbonyl carbon.
24
Q
Write a general equation for the reduction of a ketone into an alcohol.in both displayed and structural.
A
Displayed: Structural: RCOR’ + 2[H] into RCH(OH)R’
25
Name and outline a mechanism for the reduction of propanone.
To do
26
What is similar about the reaction of KCN with an aldehyde and the reduction of an aldehyde using NaBH4
They are both nucleophilic addition reactions.
27
What reagents are used in practice for the addition of cyanide ions to an aldehyde or ketone.
KCN (note potassium is also interchangeable) followed by the addition of HCl.
28
For the nucleophilic addition reaction involving cyanide ions what in the overall aquarium is added , what product is always formed.
HCN is added overall -from the KCN followed by dilute HCl. A 2-hydroxynitrile is always formed.
29
When a 2-hydroxynitrile is formed from a carbonyl what is the change in functional group.
The C=O becomes a NC-C-OH Nitrile and alcohol group replace carbonyl.
30
What is characteristic of the C=O in the infra red spectrum.
Strong absorption peak around 1700cm
31
How is Benedicts solution different and possibly advantageous to Tollens ?
It is more convenient since doesn’t need to be prepared by mixing. It contains Cu 2+ Ions like Fehllings but has a different complexing agent.
32
What is observed as a positive result for an aldehyde reacted with Tollens.
A silver mirror deposit on the inside of the test tube.
33
What must the test tube be for Tollens reagent to work.
Must be spotlessly clean.
34
Give the general equation when oxidising an aldehyde into carboxylic acid In structural formula.
RCHO +[O] goes into RCOOH Only one oxygen.
35
What Ions are reduced in Fehlings and what is the observed colour change?
Blue Cu 2+ ions are reduced to Cu 1+ Ions forming the brick red precipitate Cu2O.
36
What is Fehlings solution actually made up of.
Mixture of 2 solutions. Fehlings A and Fehlings B. A=Cu2+ ions and B contains an alkali and complexing agent.
37
Give the overall ionic equation for ethanal being heated with Fehlings.
CH3CHO+2Cu2+ +2H2O goes into Cu2O +4H+ + CH3COOH
38
What conditions should both Fehlings and Tollens tests be done under?
Gently heat both.
39
How is Tollens reagent formed hence what can it be named.
By mixing ammonia with silver Nitrate. The actual reagent is called amonious silver nitrate.
40
What is the active substance (not the reagent itself) in Tollens reagent (ammonious silver nitrate) .
The active substance in Tollens is the complex: [Ag(NH3)2]+
41
Draw a diagram to show how a nucleophile would attack attack a carbonyl group.
To do
42
Give the general equation that shows the oxidation of an aldehyde to a carboxylic acid.
RCOOH+ [O] goes into RCOOH.
43
Give an overall ionic equation for the reaction of ethanal with Tollens reagent.
CH3CHO+ 2Ag2+(Ion) goes into CH3COOH + 2Ag + 2H+
44
Give an equation to show how, in Tollens, the complex is reduced to silver to form the silver mirror observation.
Complex add electron goes into silver element and 2NH3.
45
Explain the stages that are involved in the synthesis of 2-Hydroxypropanoic acid.
1) Standard nucleophilic addition using :CN - ( cyanide nucleophile) 2) The Nitrile group is converted into a carboxylic avid group by the addition of water acidified with dilute HCL. stage 2 is called hydrolysis
46
Name the 2 stages of producing 2-hydroxypropanoic acid (lactic acid )
Stage 1 mechanism= nucleophilic addition of CN Stage 2 mechanism = hydrolysis Water acidified with dilute HCl
47
Give the equation for the first stage of the synthesis of lactic acid .
Hydrogen cyanide is added across the double bond of ethanal in a nucleophilic addition reaction: CH3CHO +HCN goes into CH3CH(OH)CN Forming 2-hydroxypropanenitrile
48
How do you name a 2-hydroxynitrile
With the CN included as carbon 1 in the main chain. Keep the “e “
49
Why is KCN follower by dilute HCl used instead of just HCN which gets added in the overall equation anyways?
HCN is a toxic gas that is difficult to contain and prevent it escaping in the lab. CN nucleophile. Prevents respiration in cells.
50
Write in displayed and structural formula the reaction between ethanal and KCN
CH3CHO+ HCN into CH3CH(OH)CN
51
Why is the the nucleophilic addition of cyanide ions important in organic synthesis.
Since it increases the length of the main carbon chain by 1 .
52
What can be done with 2-hydroxynitriles that makes them useful in organic synthesis ?
The OH and CN groups are reactive so can be converted into other functional groups as in stage 2 of lactic acid synthesis.
53
Give the overall balanced equation for the stage 2 hydrolosis to make synthesise lactic acid.
CH3CH(OH)CN+HCl +2H20 goes into CH3CH(OH)COOH + NH4CL
54
At which point during the synthesis of lactic acid does the molecule become chiral ?
After the nucleophilic addition to ethanal the molocule has 4 different groups.
55
What group gets replaced for COOH during hydrolysis to form lactic acidosis ?
The CN group is replaced but the OH group will remain.
56
What is the bi product of hydrolysis to form lactic acid ?
1 mole of NH4Cl
57
Why does the reaction between an aldehyde or asymmetric. Ketone produce two enantiomers and hence a racemic mixture when CN is added during nucleophilic addition.
There is an equal probability of the cyanide nucleophile attacking above or below the planar carbonyl group.
58
Draw out the two possible enantiomers that could arise from nucleophilic addition of Ethanal with cyanide.
Two mirror images drawn with CN and CH3 swapped over.
59
How do you name a carboxylic acid with the carboxyl group at both ends.
It is called a dioic acid where you keep the “e” in. Name to total number of carbons.
60
Why is no numbering needed for a carboxylic acid ?
Because the carboxyl group is always on the end chain.
61
How do you number carbons in a carboxylic acid?
With the carboxyl carbon being carbon number 1 .
62
Explain what the relative acidity of of carboxylic acids is dependent on.
An equilibrium is established between carboxylic acid going into carboxylate ion and H+ , the acidity is dependent on the degree of dissociation which in turn is dependent on the stability of the carboxylate ion.
63
Explain in terms of Carbon and Oxygen how the carboxylate ion becomes stabilised .
The delocalised ion has equal carbon oxygen single bonds without this delocalisation then carbon double bond oxygen would be present rather than 2 singles which is shorter in length.
64
Explain how the negative charge of a carboxylate ion is distributed.
The carboxylate ion is stabilised by dissociation, with the negative charge (pi charge cloud) shared over the whole carboxylate group.
65
Explain why Chloranoic acid is more acidic than ethanoic acid . And in turn why propanol can acid is less acidic than ethanoic acid.
Alkyl groups have an electron releasing effect wheras electronegative chlorine has an electron withdrawing effect. Attracting electron density away from the carboxylate group makes it less negative and more stable.
66
Give an equation for ethanoic acid with sodium in structural formula.
2CH3COOH +2Na goes into 2CH3COO-NA+ +H2
67
Give an equation for ethanoic acid with sodium hydroxide in structural formula.
CH3COOH +NaOH into CH3COO-Na+ + H2O
68
Give an equation for ethanoic acid with sodium carbonate in structural formula.
2CH3COOH +Na2CO3 goes into 2CH3COO-Na+ +H2O + CO2
69
For the 3 carboxylate salt forming reactions what are the balancing rules in general.
The standard acid plus base reactions won’t need balancing given the base is standard NaOH . The other reactions require a 2 to balance the organic reactant and product.
70
What is the test for the carboxyl functional group ?
Dispite carboxylic acids being weak acids they can liberate CO2 . React with solid sodium carbonate or aqueous sodium hydrogen carbonate both giving effervescence from CO2 gas.
71
Give the two possible reactions that can occur when testing for the carboxylate functional group.
Aqueous NaHCO3 : CH3COOH + NaHCO3 goes into CH3COO-Na+ and water and CO2 all 1 mole no balancing. Same reaction with aqueous sodium carbonate but balance organic product and reactant with 2.
72
Carboxylic acids cant be oxidised further . Give an equation for the exception. Draw the displayed formula for this reaction.
Methanoic acid add [O] goes into H2CO3. Can decompose into CO2.
73
Why can methanoic acid be oxidised?
Since although it is a catboxylic acid it essentially has the structure of an aldehyde group with the R bonded to a H and a double bond O .
74
Describe in very simple terms what esterfication is .
A carboxylic acid will react with an alcohol in the presence of a strong acid catalyst to produce an ester and water.
75
Describe how you would name this Ester- see picture. Structural formula =CH3CH2COOCH3
This Ester is methyl ethanoate (Two words)
76
How from displayed formula can you tell which part has come from the parent alcohole and which part has come from the parent acid in an Ester.
The Ester link will be written as COO. The carbons behind the carbon double bond Oxygen all come from the parent acid . Everything after the COO is parent alcohol . Look for C=O in displayed.
77
What does the parent acid and parent alcohol part of an Ester tell you a loud the name.
Parent Alcohol will give Xyle prefix and the parent Carboxylic acid will give the main base name in the form Xanoate Ester name is 2 words.
78
What is special about the reaction of esterfication.
It is a reversible reaction.
79
Give the displayed formula for the reaction of ethanoic acid plus ethanol
See picture.
80
Explain how Esterfication is done practically.
The reaction is very slow so requires heating under reflux for hours or days with sulphuric acid catalyst Reaction is reversible and so low yield is obtained of Ester. .
81
Give 3 main properties of esters.
1)Perfumes and flavourings 2)Solvents for organic substances like Glue. 3)Plasticisers for polymers
82
Explain why esters have lower boiling points than the carboxylic acids they are derived from.
Esters cant H-Bond to each other and carboxylic acids can.
83
Explain why esters are almost insoluble in water.
Although polar molecules they are unable to H-bond .
84
Explain from what you know about the physical properties of esters why they are used as perfumes.
They are soluble in polar organic substances (not water) , they are volatile so can be sprayed , don’t react with water and have pleasant smells. Also are non toxic.
85
Define hydrolysis. And how it relates to esterfication.
Hydrolysis is the splitting up of a molecule by the addition of water. It is the exact opposite process to esterfication when an ester is hydrolised.
86
What are the two ways that an ester can be hydrolysed . Give the reagents for each one.
1) Acidic Hydrolysis Reagent dilute HCl 2) Basic Hydrolysis Reagent: Dilute NaOH
87
What further process can be done to the reflux mixture in the lab once the ester has been produced and why ?
The Ester will be more volatile than the original carboxylic acid and Alcohol mixture ( equilibrium mixture). So may be distilled off the reaction mixture.
88
Give the overall equation (structural formula) for the acidic hydrolysis of methyl ethanoate and a brief explanation of how the equation differs to the reactants.
CH3COOCH3 + H2O goes into CH3COOH + CH3OH Here water is added in the actual reaction acid (only catalyst not in actual reaction )however the acid side of it will be the H+ catalyst above the reversible reaction sign.
89
Give the overall structural formula equation for the basic hydrolysis of an Ester with a brief explanation how the equation relates to the reactants.
CH3COOCH3 +NaOH goes into CH3COO- Na+ and CH3OH In this equation the base is included in the reaction. The parent avid reformed reacts with the Na to form a carboxylic acid salt.
90
For both acidic and basic Hydrolysis of esters give the conditions and type of reaction.
Heat under reflux - it is reversible.
91
Give a general word equation for Basic Hydrolysis.
Ester +Base into salt and alcohol.
92
Give a general word equation for acidic hydrolysis of esters.
Ester + water goes into Carboxylic acid and alcohol.
93
What’s a quick way to reform the parent acid alcohol and acid from its ester.
Stick a H on the COO bit to make the acid. Take the rest as being the alcohol.
94
Why is basic hydrolysis preferred to acidic Hydrolysis.
Because it is not reversible so goes to completion giving a better yield of product.
95
Why is the hydrolysis of esters with a base not reversible.
The carboxylate ion from the salt is resistant to attack from weak nucleophiles like Alcoholes so it goes to completion, doesn’t go the other way.
96
Why is the hydrolysis of esters with a base not reversible.
The carboxylate ion from the salt is resistant to attack from weak nucleophiles like Alcohols so it goes to completion, doesn’t go the other way.
97
What actually is a fat or oil?
Fats and oils are simply esters based off of glycerol and long chain fatty(carboxylic) acids. There are referred to as triglycerides as are based on the alcohol glycerol in the ester they make with long (12-14 carbon) chain length carboxylic acids.
98
Describe the structure of a fatty acid.
Tadpole shaped molocule in the form RCOOH where R is a really long hydrocarbon chain.
99
Explain what type of compound glycerol is and give it’s systematic name and draw it’s structure.
An alcohol with 3 OH groups. It’s systematic name is propane-1,2,3- triol. Keep the “e”
100
Explain why vegetable Oils are luiqids and animal fats are solids at room temperature.
Fats have saturated carbon chains so can pack together well. Vegetable oils have unsaturated carbon chains that leads to a mixture of E/Z isomerism and hence pack less well leading to weaker VDW.
101
What are the products of Hydrolysing (reacting with Na or KOH) a fat or oil Ester?
You will get soap (which is a long chain fatty acid salt) and glycerol will always reform when a fat is hydrolysed since the parent alcohol always reforms when an Ester is Hydrolised and a carboxylic acid salt . Nothing different t just glycerol is a wierd looking acid.
102
What Is soap?
Soap is a carboxylic acid salt where the parent acid is a long chain fatty acid. It is made by basic hydrolysis of a fat/oil Ester.
103
Explain how soap causes water to mix with grease.
Soap is a sodium carboxylic acid salt that will dissociate to form Na+ and RCOO- . The long chain fatty acid ion is a tadpole shaped molecule. The kind chain , R, is hydrophobic so will mix with geese whereas the COO- it’s hydrophilic (polar and ionic) and so will mix with water.. This means water and grease can mix and be washed away so the sodium salt can be used as a cleaning agent.
104
What is Biodiesel?
Biodiesel is a mixture methyl ester of long chain carboxylic acids. It is made by reacting oil with methanol with in the presents of a strong acid KOH catalyst.
105
What is Biodiesel?
Biodiesel is a methyl Ester that is made from reacting rape seed oil (a triglycerol Ester) with 3 moles of methanol in the presence of a strong KOH catalyst.
106
How is Biodiesel formed?
By reacting rape seed derived oil (triglycerides)Ester with 3 moles of methanol in the presence of a KOH catalyst.
107
Give the reaction that forms Biodiesel . Including the Catalyst .
Rape seed oil Ester reacts with 3 moles of methanol in the presence of a KOH catalyst. To form glycerol and a methyl Ester which is biodiesel. .
108
Why is Biodiesel considered as being a renewable fuel ?
Since it is made from oils that are derived from crops such as rape seed that grow back annually .
109
What is rape seed oil. And draw it.
It is a triglyceride Ester . An Ester thats parent alcohol is is glycerol, like all oils !
110
What is the general equation that is occurring to form biodiesel in words? Give the specific displayed formula .
Rape seed oil + 3CH3OH goes into glycerol and Biodiesel (a methyl Ester )
111
How do you balance both the biodiesel and the sopificaton reaction .
Need to balance with 3 moles of organic product and 3 moles of inorganic reactant.
112
What does classifying Biodiesel as carbon neutral fail to account for?
Ignores land that could be used for food production wasted on rape seed crops. Heating reaction and extraction /processing/ irrigating the crops produces carbon dioxide .
113
How do you know biodiesel is a methyl Ester.
There is a CH3 after the COO which is the bit that comes from the parent alcohol.
114
What is the full ionic equation for the oxidation of ethanal using potassium dichromate .
3CH3CHO+Cr2O72 - + 8H+ goes into 3CH3COOH +4H20 + 2Cr3+
115
What do all acid derivatives have in common , what group ? Draw this
The Acyl group RCOZ , where the Z group determines the acid derivative.
116
Give 3 examples of acid deriritivrs
Acid chlorides , acid anhydrides and esters.
117
Describe , in layman’s terms , the structures of acid chlorides and acid anhydrides.
Acid chlorides are just acids but the OH is replaced by Cl atom. Acid anhydrides are essentially just multiple acid molocules of carboxylic acids that have lost a water between them .
118
What is the general formula of an acid derivative and what part of this general formula will change to give different acid derivatives.
The acid derivative general formula is RCOZ , where the type of acid derivative is dependent on the Z group.
119
For every single acid derivative reaction without fail what is the mechanism used and what is the relation to this and cyanide addition.
It is a nucleophilic addition elimination mechanism, wheras forming hydroxynitriles by cyandide adding to aldehydes and ketones in plain old nucleophilic addition.
120
For all the Acid chloride reactions what rules can you apply to get the corect answers.
Work around forming HCl by loosing a Cl atom from the acid chloride and loosing a H from the other reactant. The combine what is left. The Cl. acts as the Z group in the acid derivative general formula.
121
How can you get the correct answer every time for the reactions of Acid Anhydrides.
You still work around forming HCL but consider the whole OCRO group (the Z group ) to be the chlorine atom.
122
How do the reactions of of acid chlorides and acid anhydrides differ in terms of their bi products.
Acid anhydrides will produce ethanoic acid as a bi-product in all step 1 reactions wheras acid chlorides will produce HCL in all step 1 reactions.
123
What two categories is it possible to caterogize the two reagents that react in nucleophilic addition elimination reactions with acid derivatives into ?
XOH Or XNH2
124
In regards to the nucleophilic addition eliminations that the acid derivatives undergo which of the two types of reactants will go on to react the acid Bi- products in the mixture creating a step 2 reaction and why.
Reagents In the form XNH2 will go on to react with HCl or ethanoic acid depending on if acid chloride or anhydride was used. Forming a salt.
125
What is formed when carboxylate acid Bi- products go on to react with the XNH2 in the mixture and the same question for the HCL produced as a bi product in acid chlorides .
A H is lost from the acid and given to the NH3 and so a carboxylic acid salt with ammonium is formed. For reactions producing HCl as an acid bi product this simply forms amonium chloride.
126
By considering acid derivative reactions as being 2 steps how do you work out the second step and in tern combine the reactions for an overall equation.
The acid looses a H+ and gives it to the original basic reagent. The original basic reagent is now positively charged and so it attracts the one negatively charged what’s left of the acid.
127
Write an equation for ethanoyl chloride and water in words ,structural and displayed formula,.
Ethanoyl chloride + water goes into ethanoic acid and hydrogen chloride. CH3COCl + water goes into CH3COOH +HCl See picture
128
Name and outline a mechanism for the reaction between enanoyl chloride and water .
See picture, should have nucleophile adding in first step and a leaving group and neutralisation of charge value as well as line pair on O reforming a double bond.
129
How should an acid anhydride be written for the purposes of structural formula in R notation.
(RCO)2O
130
Give the reaction of ethanoic anhydride in word , structural and displayed and explain why the product is a little different to usual.
Ethanoic anhydride + water goes into 2 moles of ethanoic acid. (CH3CO)2O + H20 goes to 2CH3COOH The acid doesn’t do the standard step 2 reaction it’s simply after the H has been added to the Z group the OH adding to what’s left forms another ethanoic acid naturally without the need to use 2 moles of water like with 2 step equations.
131
Break down the steps for the reaction between Amonnia and ethanoic anhydride and name an outline a mechanism for the overall reaction.
Step 1) NH3 + (CH3CO)2O goes into CH3COOH + CH3CONH2 Step 2 NH3+ CH3COOH goes into CH3COO-NH4+ as only product by standard loss of H salt forming reaction. See picture for mechanism.
132
Give the overall word equation for the reaction of ethanoic anhydride with ammonia.
Ethanoic anhydride plus 2 moles of Ammonia make ammonium ethanoate and ethanamide. Note: Is now an amide not amine due to C=O and it’s ammonium salt not ammonia since the ammonia has gained a H from the acid to form the salt.
133
What are the two main Real Life applications of making esters to know in short.
Making Biodiesel by reacting rape seed oil with 3 moles of methanol in the presence of a . in the presents of a strong alkali catalyst to form a mixture of 3 moles of methyl esters (biodiesel and reform glycerol ). Or sopification by the basic hydrolysis of a fat or oil that is originally an Ester with KOH to form a salt that is soap and reform the alcohol as all hydrolysis does which in this case is glycerol.
134
List all the changes In functional groups for the reactions between acid chloride /anhydride and XNH2 compounds . List X for each.
When X is a H atom the new functional group is an amide. When X is an alkyl group the product is an N-substituted amide.
135
List all the changes in functional groups between acid anhydrides / chlorides and XOH compounds list X for each.
When X is a H Atom a carboxylic acid is made. When X is an alkyl group an Ester is formed.
136
Give in words and structural formula the overall reaction that occurs when ammonia reacts with ethanoyl chloride .
Ethanoyl chloride + 2 moles ammonia goes into ethanamide and (No “e”) +ammonium chloride. CH3COCl + 2NH3 goes into CH3CONH2 + NH4+Cl-
137
What is the main product that is produced when an acid chloride or acid anhydride is reacted with a primary amine.
N- substituted Xyl amide IDE not INE
138
Why’s is the reaction using the acid anhydride derivative of a carboxylic acid favoured over using the carboxylic acid itself .
Since it is much faster and it is not a reversible reaction.
139
Explain what the name N-substituted amide means.
Basic origin. N-substituted means that the hydrogen on the N atom of the amine has been substituted for an alkyl group and tells you this has not occurred anywhere else on the molocules. The other reactant will always loose a H and the name just specifies it is on the N. What this means in terms of exam answers. The molecule is now a secondary or tertiary amide (almost always secondary) and so has two or more carbon chains each side of the Nitrogen atom. The smaller alkyl group comes first with an N- before it followed by the bigger alkyl group amide and all this should be one word. N acts like number in positioning a side alkyl chain which must obviously be shorter except the N shows that the position is on the Nitrogen atom rather than the number of a carbon atom like it would usually do.
140
Give the structural and displayed formula for the reaction between ethanoic anhydride and methyl amine. And explain the name.
(CH3CO)2O + 2 moles CH3NH2 goes into CH3CONHCH3 + CH3COO-NH3+CH3 Bit that’s not the Z group will bond with the primary amine that’s lost the H on the N. Suffix comes from alkyl group on the amine hence methyl and the big daddy prefix comes from the original acid derivative reactant. Hence N-substituted methylethanamide. No “e”defo.
141
Give the overal reaction that occurs when ethanoyl chloride reacts with ethanol in words and displayed formula.
Ethanoyl Chloride plus Ethanol goes into ethly ethanoate and Hydrogen chloride. CH3COCl + CH3CH2OH into CH3COOCH2CH3 + HCl
142
How do you know to name an ester that is produced from an alcohol reacting with an acid Chloride.
The length of the alcohol chain makes up the alkyl prefix as always and the acid makes up the suffix anoate part. Only differance is the acid looses a Cl atom rather than an OH.
143
Write the reaction between Ethanoic anhydride and propanol in words then structutal and displayed formula.
Ethanoic Anhydride plus Propanol goes into Propyl ethanoate and Ethanoic acid . (CH3CO)2O + CH3CH2CH2OH into CH3COOCH2CH2CH3 + CH3COOH
144
What do you need to remember when writing an overall equation of an acid derivitive and what needs to be included and left out in the overall equation.
Need to remember the carboxylic acid produced (almost always ethanoic acid) will react with the XH2 compound by the Carboxilic loosing an H from the OH being negetivly charged and the other compound gaines this H and becomes possitivly charged. Include both the main organic product in step 1 and the salt formed in step 2 in the overall equation.
145
What do you need to remember about recations that have 2 steps - any recation with XNH2.
React 2 moles of the XNH2 recatant to acount for both steps.
146
What temperature can the acid chloride reactions be done under.
Room temp since they are very reactive.
147
Give the reaction of propanoyl chloride reacting with ethanol in words and structural formula.
Propanoyl Chloride + ethanol goes into ethyl propanoate and HCl. CH3CH2COCl+ CH3CH2OH goes into CH3CH2COOCH2CH3 + HCl
148
Why is the reaction of an acid chloride a prefered method than reacting an alcohol with a carboxylic acid.
It is a reaction that will go to completion unlike the equilibrium that is established in the alcohol with carboxylic acid method. This means you also get a higher yield of ester. The acid chloride method is also much faster since the other method takes hours and days. No catalyst is needed for the acid chloride method and it can be done at room temp since they are so reactive.
149
What is a downside to forming an ester using an acid chloride reacting with an alcohol rather than using its parent acid.
HCl is a more harmfull bi product gas.
150
What conditions should the reaction of an acid chloride with an alcohol be done under and why.
Done under reflux and dry so the acid chloride doesnt react with water to produce Poisonous steamy fumes of HCl.
151
What is observed when ethanoyl chloride reacts with Water.
White steamy fumes of HCl gas. Cl combines with H as always.
152
What is observed when ethanoyl chloride reacts with ammonia.
White smoke of Ammonium Chloride.
153
Name the organic product produced when Ethanoyl Chloride reacts with Ammonia in the first step. And explain why NH4Cl is produced in the overall reaction not HCl.
The Organic product will be ethanamide. No "e" since the ns dont clash. The HCl that is always produced in step 1 will react with the NH3 in the mixture since it is basic. So thats what it actualy end up being
154
Define a Phenol.
A phenol is a Benzene ring with only an OH attcahed to it.
155
How can you figure the products of a reaction of a phenol and a carboxylic acid derivitive.
Exactly the same process following the form HCL method and as it is an XOH reactant there is no step 2.
156
Draw a molocule of phenol and give its structural formula.
Structural formula is C6H5OH
157
Give the strucural and displayed formula for when a molocule of Phenol reacts with an acid Chloride or anhydride of the main product produced and give the clasification of this molocule.
CH3COO-Benzene ring This compound is called phenol ethanoate. It is Ester of phenol and is hence and ester.
158
Dispite the reaction of a phenol and C.A.D not being all that important how is it similar and hence important for understanding the reaction to make asprin.
Asprin is made from 2-hydroxybenzoic acid which contains a Phenol group. In the reaction the Phenol group is turned into an ester by reacting it with the reactive athanoic anhydride. The H is lost from the OH on the Phenol and the reactants combine as normal to produce an ester and ethanoic acid. The molocule reacted is esentally the same but it has a COOH group on the benzene ring. This remains unchanged so when the asprin ester forms, the benzene ring keeps this COOH goup on in the ester. Other than this the reaction is the same to any Phenol reaction.
159
Give the common and systematic name of the reactants used in the reaction to make asprin. Draw both.
2-Hydroxybenzoic acid and ethanoic anhydride. (2-Hydroxybenzoic acid is also known as saicylic.)
160
Give steps 5 and 6 for the purification of an organic solid ( specifically making Asprin) .
5) Wash the crystals- with distilled water. This will remove soluble impurities 6)Dry the crystals between aborbant paper.
161
Draw out a Butchner flask.
See picture.
162
What would a way of testing the degree of purity of a sample.
Determin the melting point or melting range of a sample. A very pure substance will have a sharp melting point that is at the same value for that substance that is quoted in a data book.
Impure will me;t over a range nelow the quoted value.
163
What will happen to the melting point of a sample if impurities are present (including the solvent from the recrystalisation process).
The melting point will be lowered and the sample will melt over a range of several degrees Celcius.
164
How can the melting point of a sample be measured .
Melting point can be measured by an electronic melting point machine or by using a practical set up where the capilary tube is strapped to a thermometer imersed in some heating oil. In both cases some of the sample is put into the capilary tube. The tube is heated up and is heated slowly near the melting point.
165
What set of atoms ,acting as the Z group, are lost when acid anhydrides undergo nuclephilic addition elimination reactions.
Everything downwards from the carbon single bond oxygen. So for ethanoic anhyydride the "Z" that is lost in order to form "HCl" will be CH3COO. Esentially to know what to go for to be lost from an acid anhydride molocule just form the acid for that many carbons by taking the Z group as being something that needs only a H atom to form the given acid as always. The rest combines to form an ester or whatever it is.
166
Draw the aparatus that would be used to determin the melting point of a sample and state what prpoperties the heating oil must have in order for it to work and suggest where a degree of error could occur.
See picture for aparatus. A degree of error could occur if thermometer is not at the same temperature as the actual sample in the capilary tube.
167
Give the structural formula of Propanoic Anhydride and give the reaction it undergeos in structural formula with methanol. Describe what acts as the Z group here.
(CH3CO)2O + CH3OH goes into CH3CH2COOCH3 CH3CH2COOH ( note propanoic acid needs to be formed as a bi product here not ethanoic acid) The Z group is still everything conded to the carbonyl carbon apart from the R group behind it. Since the general fromula of an acid anhydride is given by RCOZ , Z just becomes the longer 3 carbon chain and the single bond O that still only needs to combine with one H from the other reatant to produce its acid in this case propanoic.
168
Name , without explanation , all 6 steps for the Purification by recrystalisation of an Organic solid.
Disolve in Hot solvent. Hot filter through fluted filter paper quicky. Place beaker in ice bath to cool it down and recrystalise. Suction Filter with a Butchner flask to seperate out impurities. Wash the crystals with distiled water and then dry the crystals between absorbant paper.
169
Draw both ethanoic anhydride and propanoic anhydride out in a linear fassion.
See picture.
170
Draw in skeletal formula a molocule of methyl 2-methylpropanoate.
See picture.
171
Draw a molocule of ethyl 3-methyl Butanoate in skeletal formula.
See picture.
172
GIve one similarity and two differences in the processes that form soap and biodiesel.
One similarity is in both cases oil and fatty acid triglycerides are reacted with 3 moles of another reagent to form 3 moles of the desired organic product they are both 3 balance reactions that reform glycerol in the products. Two differences Biodiesel is reacted with 3 moles of methanol to form a methyl ester as biodieses in the presence of a KOH catalyst. Wheras the triglyceride is hydrolysed by 3 moles of NaOH or KOH to form a sodium or pottasium carboxilic acid salt tadpole molocule that acts as soap.
173
Give three uses of Glycerol. Explain why glycerol is very soluble.
It is used in many pharmacutical and cosmetic preperations since it atracts water and prevents ointments drying out. It is a solvent in many medicines and in food industry. It is used as a placticicer. It is so soluble do to the three OH groups present so redily forms H-bonds with water.
174
What happens with plasticicers over time.
Over time placticicers will leak away leaving the plastic brittle and inflexible.
175
(CH3)2CHOH was reacted with (CH3CO)2O give the structural formula of the producs and name the main organic product stating how you did so.
CH3CO2CH(CH3)2 and CH3CO2H Split up the acid and alcohol parts as usual and then add in any substitients to the part of the name it concerns as methyl or ethyl etc. The longest chain must include the O from the ester link in essence. Hence the name of this ester is 1-Methylethyl ethanoate. Remember it can sound rediculous as miss said and you disnt remember the longest chain numbers carbons both ways from the ester link and has to include that carbon so cant loop round.
176
Where do you number carbons from in an ester.
The ester link is carbon 1 in both directions moving away increasing respectivly.
177
Name and outline a mechanism for reacting (CH3)2CHOH with CHCOCL
See picture .
178
Name and outline a mechanism for reacting. (CH3)2CHOH with CHCOCL
See picture .
179
The student purified the crude solid product , N-phenylethanamide by recrystalisation outline the method the student should use for this recrystalisation.
Dissolve the product in the minimum volume of water / solvent (in a boiling tube / beaker) If dissolving is not mentioned, CE = 0 / 4 1 Hot water / solvent Steps must be in a logical order to score all 4 marks 1 Allow the solution to cool and allow crystals to form. 1 Filter off the pure product under reduced pressure / using a Buchner funnel and side arm flask Ignore source of vacuum for filtration (electric pump.)
180
State two practical reasons why the percentage yield of a recrystalisation process may not be 100 percent.
Any two from: Product left in the beaker or glassware Sample was still wet Sample lost during recrystallisation. Do not allow “sample lost” without clarification
181
Give a reason other than the harmfull poison HCl gas produced that may lead ethanoic anhydride to be a prefered reagent to ethanoyl chloride dispite ethonoyl chloride having a slower rate of reaction.
An identified hazard of ethanoyl chloride E.g. “Violent reaction”, “harmful”, “reacts violently with water” Do not allow “toxic”, “irritant” (unless linked with HCl gas).
182
Given a student carrying out a recrytalisation of an organic solid process explain why the following would be done : The minimum quantity of hot water was used:
To ensure the hot solution would be saturated / crystals would form on cooling
183
Given a student carrying out a recrytalisation of an organic solid process explain why the following would be done : The flask was left to cool before crystals were filtered off:
Yield lower if warm / solubility higher if warm
184
Given a student carrying out a recrytalisation of an organic solid process explain why the following would be done : The crystals were compressed in the funnel:
Air passes through the sample not just round it Allow better drying but not water squeezed out
185
Given a student carrying out a recrytalisation of an organic solid process explain why the following would be done : A little cold water was poured through the crystals:
To wash away soluble impurities.
186
Explain how a simple laboratory process can be carried out to show that a recrystalised product is a pure sample of a particular substance.
Key parts to consider are pure and particular substance. Hence : Measure the melting point 1 Use of melting point apparatus or oil bath 1 Sharp melting point / melting point matches data source value. Note melting point and not boiling point and the aparatus would be a thermometer strapped to a capilary tube containing the sample.
187
Suggest the impurity that is most likely to cause a deviation in the melting point (lower it) after the recrystalisation purification process and also state how a more acurate value for the melting point in light of this could be obtained and possible errors is the melting point aparatus itself.
Impurity would be water. Press the sample of crystals between filter papers Allow give the sample time to dry in air If the theromometer is not at the same temperature as the sample in the capilary tube.
188
Define saturated solution.
A saturated solution is a solution that contains the maximum amount of solute that can be disolved.
189
For the reaction of CH3CH2COCl with ammonia, name and outline the mechanism and name the organic product.
propanamide (Ignore -1- ) penalise other numbers penalise propaneamide and N-propanamide
190
What is the difference between the way amines and amides are named .
Amines are named with the prefix Xyle eg methylamine. Amides are named with the prefix Xan eg propanamide. neither feel the need to include an "e" mid name.
191
What is the difference between the way amines and amides are named .
Amines are named with the prefix Xyle eg methylamine. Amides are named with the prefix Xan eg propanamide. neither feel the need to include an "e" mid name.
192
Suggest one reason why chlorobenzene (C6H5Cl) does not react with ammonia under normal conditions.
electron rich ring or benzene or pi cloud repels nucleophile/ammonia Allow • C–Cl bond is short/stronger than in haloalkane • C–Cl is less polar than in haloalkane • resonance stabilisation between ring and Cl
193
Do you keep the the e in when naming glycerol IUPAC name ?
Yes
194
State two practical reasons why the percentage yield of a recrystalisation process may not be 100 percent.
Any two from: Product left in the beaker or glassware Sample was still wet Sample lost during recrystallisation/ stays in solution after recrystalisation. Sample lost when filtering Do not allow “sample lost” without clarification
195
(ii) Describe the experimental conditions and the practical method used to ensure that the acid is obtained in a high yield. Draw a diagram of the assembled apparatus you would use. From propan-1-ol
Excess acidified potassium dichromate(VI) 1 Reflux (for some time). In the diagram credit should be given for • a vertical condenser Lose M3 and M4 for a distillation apparatus. 1 • an apparatus which would clearly work Do not allow this mark for a flask drawn on its own. Penalise diagrams where the apparatus is sealed
196
Given a student carrying out a recrytalisation of an organic solid process explain why the following would be done : The minimum quantity of hot water was used:
To ensure the hot solution would be saturated / crystals would form on cooling.
197
Given a student carrying out a recrytalisation of an organic solid process explain why the following would be done : The flask was left to cool before crystals were filtered off:
Yield lower if warm / solubility higher if warm.
198
Given a student carrying out a recrytalisation of an organic solid process explain why the following would be done : The crystals were compressed in the funnel:
Air passes through the sample not just round it Allow better drying but not water squeezed out This is in regards to removing the filtrate under reduced pressure using a butchner flask.
199
What is the main visual difference between a nucleophilic addition mechanism and a nucleophilic addition elimination mechanism. Comment on what happens to the carbonyl group in each.
Nucleophilic addition has a second lot of external attack from the hydrogen ion after the "standard step". The carbonyl group is lost for an OH group.
Nucleophilic addition elimination consists of the standard step of course. From here you get this wierd lazerus type internal transformation , this is where the leaving Z group is lost and so is the active hydrogen. There is no external influence to make this happem , the carbionyl reforms and overall stays in tact.
200
Give two types of nucleophilic addition reactions and state what they all have in common. State the nucleophile and reagents for the reactions you have mentioned.
First type is Reduction of ketones or aldehydes.
Sodium borohydride in ageous solution. H+ comes from the water in in the aqeous solution (solvent).
Second type is the production of 2-hydroxynitriles .
KCN followed by the addition of dilute HCL , HCL is what provides the H+ for the second step.
201
State the scenario where you would find a nucleophilic addition elimination reaction (there is only one) and state also the possible nucleophiles this could include.
The only scenario in the whole sylabus where this happens is during acylation.
The adding of an acyl group to any of the following nucleophiles:
Primary Amine , Ammonia , alcohol , water.
202
Name and outline a mechanism for the production of propan-1-ol , give a reagent and needed condition ton produce the nucleophile that should also be named.
203
Name and outline a mechanism for the hydrolysis of ethanoyl chloride. What fact should you recall in terms of hydrolysis about acid anhydrides.
Ethanoyl chloride as an acylating agent is more vulnerable to hydrolysis ( acid chlorides will more readily react with water).
204
Why is acylation called that , in other words what is acylated.
Draw the acyl group and give the general equation for acylation.
Beaucse the nucleophile is acylated. The nucleophile gains an acyl group.
205
Describe in your own words what happens in terms of the mechanism for a nucleophilic addition reaction.
NSv n;
206
Describe in your own words what happens during a nucleophilic addition elimination reaction.
A nucleophile attack the carbonyl carbon as the standard step where the carbonyl bond is broke into a single leaving a lone pair on the oxygen. This is "the standard step".
A provided H+ ion will then bond on.
There is so leaving group, only one product , and the CO double bond is traded for an OH bond.
207
What three factors effect how readily an acylation reaction occurs and which two of said factors are connected.
1) The magnitude of the Delta plus charge on the carbonyl carbon. This is in turn dependent on the elctron withdrawing or releasing effect of the Z group.
2) How easily the Z group can be lost.
3) How good the nucleophile is.
1 and 2 are linked since the more elecronegatice electron withrawing leaving Z groups tend to be good leaving groups since they will form stable negative ions , like Cl.
208
What makes one nucleophile better than another and list the best to worst nucleophiles for acylation reactions.
Good nucleophiles are those that easily donate electrons more easily. Charged nucleophiles are better than neutural ones and less electronegative atoms are better than those which are not since can more easily donate electrons as cling onto them less tightly.
209
For acylation reactions explain why the nucleophile needs to lose a hydrogen and give the name of this special hydrogen atom.
All nucleophiles for acylation are neutural and so need to form neutural products. The atom with the lone pair gets a possitive charge when it gives up both of the elctrons it was a having to hold before to form a bond.
By gaining an electron from the homolytic bond breaking with the active hydrogen (a hydrogen not with another hydrogen) this neutralises the charge on the nucleophile atom.
210
Give in layman's terms the principle behind purification by recrystallisation at a molecular level.
Unwanted ions will get trapped inside a lattice when it forms resulting in an impure solid lattice. To combat this is disolved and so the impurities float around in solution in low concentrations and when the lattice reforms less of the unwanted ions are trapped in the lattice.
211
Draw and label the apparatus you would use for suction filtration and give the main two parts that make this up.
212
What is the principle behind suction filtration , and why is this favourable to gravity filtration.
The rubber tubing attached to the side arm creats a reduced pressure , so the presusre gradient forces the filtrate (unwanted luiqid) through the the filter paper.
213
For purification by recrystallisation , what in an ideal world would be the optimal relationship between solvent and impurity. Refer to temperature and note this is different to the relationship of the solvent and the required product.
Impurity is insioluble at the cooled room temperature so there isnt any opertunity for it to precipitate along with the disired product , would be even better if it the impurity was insoluble even at the higher temperature so only the required product didolved.
214
What can be done if a crystal is slow to form.
Need to kick start crystallisation by creating a surface for then ions to coordinate themselves around. Can either add a seed crystal or you can just scratch the side of the beaker with the stiring rod. In both cases this will create a surface that the crystal can coordinate itself around.
215
There is some work on drug activity and also some on melting point analysis so check if that's already in there.
nsvjha
216
How and why will melting point differ if there is some impurity left over from the solvent on the solid product after purification by recrystallisation.
1) The melting point will be LOWER , this can include luiqid solvent from a recrystalisation process.
2) The sample will melt over a range of several degrees celcius.
217
Name and outline a mechanism for the production of the compound 2-hydroxypropanenitrile, state where everything in the mechanism comes from.
Nucleophilic addition mechanism.
218
To do , asprin actual organic reaction , maybe other arene based ones , phenol , picture of the melting point aparatus equiptment. Drug selling and extra points on thalidamide.
Last tiny bit.
