CH4 Flashcards
(93 cards)
1
Q
Carboxylic Acids -> Aldehydes
A
- Reduction
- LiAlH4.
- Reflux in ethoxyethane
2
Q
What is the systematic name of Amides / Carboxylic acid amides?
A
Think of its parents Carboxylic acid, remove oic acid, add amide.
e.g Propanamide
3
Q
What is a primary structure in terms of proteins?
A
This is the sequence of amino acids in the chain.
4
Q
What is the systematic name of Ketones?
A
Ketone ends in -one
e.g propanone
5
Q
Describe the nitration of benzene
A
Reagent : conc. Nitric and sulphuric acid
Conditions: <55c
(if the temp. rises above this then some dintrobenzene can occur giving 1,3-ditrobenzene, a pale yellow solid)
6
Q
What is the systematic name of Acids/Acyl chlorides?
A
Think of its parents carboxylic acid, remove the oic acid and add oyl chloride
e.g Ethanoyl Chloride CH3COCl
7
Q
Define polarisation
A
Unequal electron distribution in a covalent bond.
8
Q
What is meant by refluxing?
A
Evaporation then condensation are occuring and that the condensed material returns to the flask where the reaction is occuring.
tip : If you do not returned to the flask then you could be describing distillation
9
Q
What is the symbol of an Oxidising agent?
A
[O]
10
Q
How do we know that there isn’t an alternating system of C-C and C=C in benzene?
A
It doesn’t decolourise bromine water like an Alkene would
11
Q
Esters -> Alcohols + Carboxylic Acids
A
Hydrolysis
Water
Reflux
12
Q
What is the C-C-C bond angle in benzene?
A
120’
13
Q
Alkene -> Haloalkane
A
Electrophilic addition of HBr
HBr.
Room temp.
Eq.
C2H4(g) + HBr(g) -> C2H5Br(l)
14
Q
Alcohols -> Esters
A
Esterification
Reagent : Carboxylic acid + Strong acid catalyst e.g (conc. H2SO4)
Reflux
15
Q
What does oxidation mean?
A
The removal of hydrogen or the addition of Oxygen.
16
Q
Alcohols -> Halogenoalkanes
A
Bromonation of alcohols
Conc. HBr(aq)
Reflux
17
Q
Alkane -> Haloalkane
A
chlorine radical.
18
Q
Define alkylation
A
Means the substitution of an alkyl group such as methyl CH3 or Ethyl C2H5.
19
Q
What is the systematic name of Carboxylic Acids?
A
ends in -oic acid
e.g methanoic acid HCOOH
20
Q
What is the formula for finding the retardation factor in chromatography?
A
The distance moved by the compound divided by the distance moved by the solvent.
21
Q
What does it mean if a compound is black? In terms of wavelength
A
It means it absorbs all wavelength of light.
22
Q
Describe the delocalised energy of benzene
A
Cyclohexene(6 membered ring with one carbon to carbon double bond) with hydrogen to produce cyclohexane which gives out -120KJmol-1.
Again with cyclohexa-1,3-diene to produce cyclohexane produces -240KJmol-1 If benzene did contain 3 C=C double bonds we would expect -360KJmol-1.
However, the actual value is -208KJmol-1 This figure sugest that benzene does not have a kekulé structure and is more stable than the alternating double,single bond structure. The difference between the expected and found values (152KJmol-1)is called the delocalisation or resonance energy.
23
Q
What is the systematic name of Esters?
A
the alkyl group (from the alcohol) is named first . Then the acid part ends in -oate e.g Methyl propanoate
pointer: beware, very often the structural formula of ester are writen backwards with the acid part written first, the opposite way round to its name
24
Q
What is the affect of racemic mixture of plane polarized light?
A
No net effect due to one isomer rotating plane polarized equally to the other
25
What does it mean for a valid experiment?
If the data obtained from the scientific work is valid then **it is correct for the purpose for which it is needed.**
Factors that should be considered are: Has the data been obtained so that it is accurate? Have the conclusions been made solely on the data obtained? Is the data relevant for the purpose it is being used for?
26
How can the melting temperature be used to tell if the compound is pure or impure?
A pure compound will melt in the temperature given in reference books.
**If impure**, then the compound **will melt at a lower temperature over a range of temperatures** perhaps 5-10'c or more.
27
Aldehydes -\> Carboxylic acid
Oxidation
28
Define conjugation
A **repeating pattern of single and double bonds** between carbon atoms
29
In E,Z-Isomerism, If the groups are on the same side, what type is it?
Z/cis-isomer
30
X-rays shows study that the carbon atoms form what shape in benzene?
Flat hexagon
31
Alcohols -\> Ketones
Oxidation
32
State an importance of a chiral centre?
For the most part, enantiomers have identical physical and chemical properties. Nevertheless, the difference between two enantiomers can have enormous impact, particularly in biological systems, because many important biological molecules are chiral.
In biochemistry, **enzymes can only work if the shape of the molecule is correct.**
33
Alkene -\> Alcohol
Direct **hydration** of **alkenes**
catalyst: Steam + **phosphoric acid**
**High pressure**
34
What the most common type of reaction with benzene?
Electrophilic substitution
35
Define delocalisation
Electron pairs are shared between 3 or more carbon atoms
e.g Benzene
36
What is the systematic name of Amino Acids?
Named after the parent carboxylic acid with **amino added infront.**
e.g 2-Aminopropanoic acid
37
Halogenoalkane -\> Nitriles
**_Nucleophilic Substitution_**
catalyst:** Alcoholic potassium cyanide(aq)**
**Reflux**
38
What is the name of a group or series of group that are responsible for the compound being coloured?
Chromophores
note: a single group is often not able to produce colour in a compound by itself
39
Uses and naming of esters
Uses : \*Esters are fairly unreactive \*Flavourings
Naming: Named from the alcohols and the carboxylic aicd which made them.
CH3OH + CH3COOH-\> CH3COOCH3+ H2O
methanol + ethanoic acid -\> Methyl ethanoate
40
What are enantiomers?
non superimposable mirror image isomers
41
As frequency increases, what happens to the wavelength and energy?
Energy increases,
wavelength decreases
42
Why is there a stronger C-Cl bond in chlorobenzene than an aliphatic C-Cl bond?
This is due to the **non bonding lone pairs overlapping with the ring pi-electron system.**
It is possible to make **phenol from Chlorobenzene but forcing conditions** of temperature and pressure is required around **300'c and increased pressure**.
43
What is the evidence for a ring pi-cloud of electrons in benzene?
Carbon to Carbon bonds are all the same length and that this is **intermediate in size between the length between the double and single bond of carbon**.
44
Define a homologous series.
A family of compounds that have the same **general formula** and contain the same **functional group.**
45
Aldehyde -\> Alcohols
**_Reduction_** of aldehydes
**_Reagent :_** Sodium tetrahydroborate(III) **NaBH4**
**_Conditions;_ Warm in water** or ethanol
Product : **primary alcohols**
**_eq_**
C2H5CHO(l) + 2[H} -\> C3H7OH(l)
46
What is a Chiral centre/carbon atom?
Is a carbon atom that has **4 different groups or atoms bonded to it.**
Beware of questions that ask you to identify chiral centres, **some molecules have more than 1.**
47
What reagent do you use to make an acid chloride?
PCl5 / PCl3
48
Describe Stereoisomerism
They have the **same structural formula** (arrangment of atoms) but **different spacial arrangement** of atoms
49
Tests between aldehyde and ketones
* **_Tollens reagent_** (aldehydes):
Reagent : **ammonical silver nitrate solution**
Observation **: Silver mirror is formed** in the inside of the test tube
**Product** : Silver and carboxylic acid eq. Ag+ + e- -\>Ag
* **_Fehlings solution_** (aldehyde):
Reagent : **solution of copper(II) complex**
Observation : **Red precipitate forms in the blue solution**
**Products** : Copper(I) oxide + Carboxylic acid
e.q Cu2+ + e- -\> Cu+
50
Alcohols -\> Alkenes
**Elimination of water /****Dehydration**
Reagent / Catalyst : **Conc. H2SO4**
Conditions : **Reflux at 180' C**
**_Product :_** Alkene
Eq. C2H5OH(l) -\> CH2 = CH2(g) + H2O(l)
**_Step 1_** protonation of the alcohol using a lone pair on oxygen
**_Step 2_** loss of a water molecule to generate a carbocation
**_Step 3_** loss of a proton (H+) to give the alkene Note : Alcohols with the OH in the middle of a chain can have two ways of losing water.
In Step 3 of the mechanism, a proton can be lost from either side of the carbocation. This gives a mixture of alkenes from unsymmetrical alcohols.
51
Alcohols -\> Aldehydes
**Oxidation** of primary alcohols. Primary alcohols are easily oxidised to aldehydes
e.g. CH3CH2OH(l) + [O] -\> CH3CHO(l) + H2O(l)
It is essential to **distill** off the aldehyde before it gets oxidised to the acid.
e.g CH3CHO(l)+[O]-\> CH3COOH(l)
52
Explain the resistance of benzene to additional reactions
If addition occured then the stable pi-electron cloud will be lost. Making the compund less stable.
The preferred way for benze to react is the substitution of hydrogen atoms as this will retain the delocalised structure of the molecule.
53
In E,Z-Isomerism, If the groups are on the different side, what type is it?
E/trans-isomer
54
Preparation of phenylamine
Add **HCl and tin** to **nitrobenzene** to **reduce** it to **phenylammonium ions.**
Add **NaOH** to give phenylamine and water.
**Phenylamine** is removed by steam distillation
55
What is the colour change of potassium permanganate?
Purple -\> Colourless
56
What is the systematic name of Amines?
Named after the carbon chain with **amine at the end**
e.g Methyl Amine CH3NH2
57
Halogenation of benzene
C6H5Br**.**
Reagent : **Bromine and benzene**
Catalyst : **Iron(III) Bromide** (halogen carrier) The catalyst causes polarisation of the Br-Br bond.
Conditions : **room temp. out of direct sunlight**.
pointer: Strong sunlight is not possible for the reaction as the **UV may encourage an addition reaction between the benzene and halogen**
58
What is the colour of the product? C6H5N2Cl + C6H5NH2 --\> C6H5-N=N-NH-C6H5 + HCl
Yellow precipitate
59
Halogenalkanes -\> Alcohols
**_Nucleophilic Substitution_**
Reagent : **NaOH(aq)**
Conditions : **Reflux in aq solution** (solvent is important)
Product : Alcohol
Nucleophile : Hydroxide Ion (OH-)
Eq.
C2H5Br(l) + NaOH(aq) -\> C2H5OH(l) + NaBr(aq)
60
What is the process for recrystallisation?
1. Dissolve in minimum volume of hot solvent.
2. Filter hot
3. Allow to cool
4. Filter with cold water to remove soluable impurities
5. Dry the crystalling product
61
What is the process of distillation?
This technique is **used to purify a liquid**. If a mixture of 2 liquids which have close boiliing temperatures need to be seperated then fractional distillation is used. A fractional collum will allow better seperation occur but the distillion fraction may still be impure.
For example, if an ester is made from a carboxylic acid and an alcohol then distilled ester may still contain traces of carboxylic acid and water. The acid is then removed by shaking the ester with an aqeous solution of sodium hydrogen carbonate in a seperating funnel, the result in ester will contain some water and this is removed by using anhydrous calcium chloride.
62
What gives a positive test for both ketones and aldehydes.
**2,4-DNPH** (2,4-Dinitrophenylhydrazine)
Detects the carbonyl group
**Addition-elimination reaction** (nucleophilic addition followed by the elimination of water)
Oberservation : Aromatic carbonyl, an **orange red solid is formed.**
63
What is the test for phenols?
Iron(III) Chloride
observation : purple solution
64
Ketones - \> Alcohols
**Reduction of ketones**
Reagent : Sodium tetrahydridoborate(III) **NaBH4**
Conditions : **Warm in water** / ethanol
Product : **secondary alcohols**
eq
CH3COCH3(l) + 2[H] -\> CH3CH(OH)CH3(l)
65
What does it mean for measurements to be precise?
This is concerned with **measurements that are close to each other.**
66
Nitriles -\> Amines
**Reduction**
Conditions : **Room temperature**
C2H5CN + **4[H]** -\> C2H5CH2NH2
4[H] = reducing agent (**LiAlH4**)
67
What do we call en equimolar(equal) mixture of both optical isomers?
Racemic mixture
68
As carboxylic acids get bigger what happens to their physical properties and why?
As they get **bigger their boiling temperature increases and their solubility decreases.**
This is because of the **increase in the amount of van der waals forces** between the molecules, meaning that **more energy is needed to overcome these forces**, resulting in a higher boiling temperature.
It becomes less solable because the **polar acid (COOH) group is becoming a smaller part of the molecule.**
69
Explain why E,Z-isomerism occurs
One end of a double bond cannot rotate relative to the other end.
Beware, it is wrong to say because the double bonds cannot rotate.
70
Alkene -\> Dibromoalkane
**Electrophilic addition** of Bromine
Reagent : **Br (dissolved in CCl4)**
Conditions : **Room temp.**
Eq.
C2H4(g) + Br2(l) -\> CH2BrCHBr(l) which is 1,2- dibromoethane
71
Define bond energy
The energy needed to break a covalent bond into its consituent atoms (gas phase)
The higher the value the stronger the bond(s).
72
What is the iodoform test used for and how is it carried out?
Test for **CH3C=O** group e.g. propanone.
Also compounds containing **CH3CH(OH)** group as this is oxidised to the CH3=O group during the reaction. This means that ethanol and propan-2-ol also react in this way but not propan-1-ol.
When reacted with an **_alkaline (NaOH) solution of iodine a yellow precipitate of triodomethane (iodoform),_** CHI3 is formed
73
Halogenoalkanes -\> Amines
Nucleophilic Substitution
React halogenoalkane with an excess of **ammonia,** dissolved in ethanol.
74
What causes the colour of objects in terms of light being absorbed?
The colour that was see is the colour that is not being absorbed
75
Halogenoalkanes -\> Alkenes
**_Elimination_**
Reagent **:** **Alcoholic NaOH**
Conditions : **Reflux** in alcoholic solution
Product : Alkene Mechanism
Eq. C3H7Br + NaOH(alc) -\> C3H6 + H2O + NaBr
With unsymetrical Halogenoalkanes a mixture of products may be formed.
76
What is a tertiary structure?
This describes the overall 3 dimentional shape of the protein molecule.
77
What considerations should you take with a new product?
Include health and safety in its manufacture, and its transport.
The availability of the starting materials, Costs, Markets for the product
78
What's the difference the addition of cyanide to a carbonyl group and one without a carbonyl group?
With a carbonyl group you use **HCN**
Without a carbonyl group you use KCN
79
Alkene -\> Polymers
**Polymerisation**
**_Conditions :_** Ziegler Natta
**_Catalyst:_** AlCl3
**_Low density polymerisation :_** 200' celcius 2000 atmospheres
**_High density polymerisation :_** 60' celcius low pressure
80
Alkylation of benzene
Often called a **friedel-crafts reaction.**
Catalyst **:** **AlCl3**
Reaction carried out is similar to halogenation of benzene but for example chloromethane is used in place of bromine (CH3Cl)
81
How is the pi-cloud of decolocalised electrons around the ring formed in benzene?
p-orbitals overlapping
82
What is the useful product that you get when naphthalen-2-ol has a coupling reaction with benzenediazonium chloride.
An **insoluble red dye.**
83
Alkene -\> Alkane
**_Hydrogenation_**
Reagent **: hydrogen**
Conditions : **Ni Catalyst** - finely divided
Product : Alkane
Eq. C2H4(g) + H2(g) -\> C2H6(g) ethane
**_Use:_** Margerine manufacture
84
What do enantiomers do to plane polarized light?
They rotate the plane of polarised light, left or right, equally
e.g 5' to left, 5' to the right
85
What does it mean if a compound is white/colourless? In terms of wavelength being absorbed?
Many organic compounds absorb UV light but our eyes cannot detect them so we see it as white or colourless
86
Other than potassium dichromate with aqeous sulphuric acid, what is another oxidising agent?
potassium permanganate, aqeous sulphuric acid
87
What is the colour change of acidified potassium dichromate in the oxidation of primary and secondary alcohols?
**Orange -\> Green**
88
Nitriles -\> Carboxylic Acids
_**Hydrolysis** _
Conditions : **Reflux with boiling water**
**_Eq._** C2H5CN + 2H2O -\> C2H5COOH + NH3
89
What is a secondary structure?
This describes the amino acid chains coiled in a double helix are used in hydrogen bonding, electrostatic attraction and s-s bridges (di sulphide bonds)
90
What is the systematic name of Aldehydes?
Aldehyde ends in an -al e.g Ethanal
91
What does it mean for measurements to be accurate?
This means they are **close to the accepted values**
92
in blue light, a compound appears black because...
**it absorbs the blue light**
93
what is meant by the term electrophile
(An ion that is) **an electron pair acceptor**
