Module 4: Core Organic AS Flashcards
1
Q
How do Monkeys help in naming alkanes?
A
Monkeys Eat Peanut Butter Politely Hurray is a Mnemonic which gives the initial letters for the first six alkanes: Methane; Ethane; Propane; Butane; Pentane; Hexane.
2
Q
The structural formula of ethanol is …
A
…CH3CH2OH
3
Q
What is the suffix of an aldehyde?
A
-al
4
Q
What happens in Initiation?
e.g in the reaction of an alkene with Bromine
A
- UV radiation provides the energy to break the covalent bond in a bromine molecule
- The bond breaks by homolytic fission
- Radicals are formed
e.g- Br2 → 2Br•
5
Q
What happens in Propagation?
eg. In the reaction of Bromine with Methane
A
- The products of the reaction are made. Note that one reactant is a radical and one product is a radical.
e.g- Br• + CH4 → CH3• + HBr
CH3• + Br2 → CH3Br + Br•
6
Q
What happens in Termination?
eg. In the reaction of Bromine and Methane
A
- Any two radicals can combine
e. g- CH3• + Br• → CH3Br
Br• + Br• → Br2
CH3• + CH3• → CH3CH3
7
Q
Which halogenoalkane produces a white precipitate when hydrolysed in the presence of silver nitrate?
A
Chloroalkane
8
Q
What is the suffix of a carboxylic acid?
A
-oic acid
9
Q
What is the difference between an Alkane and an Alkene?
A
Alkanes are saturated, they only have single bonds. Alkenes are unsaturated and contain C=C double bonds.
10
Q
The molecular formula of ethanol is …
A
… C2H6O
11
Q
what is a saturated hydrocarbon?
A
A hyrdrocarbon which contains single bonds only
12
Q
Which reaction turns an alkane into an alkene?
A
Cracking
13
Q
Define empirical formula
A
The smallest whole-number ratio of elements in a compound
eg: Molecular formula C5H10 has empirical formula CH2
14
Q
What is the prefix for an Iodine containing compound?
A
iodo-
15
Q
Which reaction turns an alkene into an alkane?
A
Hydrogenation
16
Q
Which reaction turns an alkane into a haloalkane?
A
Radical substitution
17
Q
The displayed formula for ethanol is …
A
18
Q
what is an unsaturated hydrocarbon?
A
A hydrocarbon which contains 1 or more carbon-carbon double bonds
19
Q
Which reaction turns an alcohol into a ketone?
A
Oxidation
20
Q
What does it mean if a Hydrocarbon is classed as Aliphatic?
A
The carbon atoms are joined in an Unbranched (straight) or Branched Chain.
21
Q
What does it mean if a Hydrocarbon is classed as Alicyclic?
A
Carbons are joined in Ring (Cyclic) structures.
22
Q
What does it mean if a Hydrocarbon is classed as Aromatic?
A
Some or all of the carbon atoms are found in a Benzene Ring.
23
Q
What is a Suffix and what is it used for?
A
- Added after the stem/name…
E.g. -ol
- Used to indicate different functional groups…
E.g. Alcohols
24
Q
What is a Prefix and what is it used for?
A
- Added before the stem/name…
E.g. Iodo-
- Used to indicate the presence of side chains or functional groups…
E.g. Iodine Halogen (I)
25
What is the Suffix for an **Ester**?
-oate
26
What is the Suffix used when writing the name of specific **Acyl Chloride**s?
-oyl chloride
27
What is the functional group of a **Ketone**?
-C(CO)C-
28
What is the functional group of an **Ester**?
-COOC-
29
What is the functional group of an **Aldehyde**?
-CHO
30
What is the functional group of a **Haloalkane**?
-Cl -Br -I
31
What is the functional group of an **Amine**?
-NH2
32
What if the functional group of a **Nitrile**?
-CN
33
What is an **Isomer**?
Compounds which have the **same** molecular formula but **different** structural formulae.
We can have:
* Positional isomers (eg, branching)
* Functional group isomers (eg alcohol {CH3-CH2-OH} or ether {CH3-O-CH3})
* cis/trans E/Z isomers (involving C=C double bonds)
* Optical isomers (with chiral centres)
34
What effect does **branching** have on the **boiling point** of Alkanes/Isomers?
Decreases the Boiling point.
* Branching leads to poorer packing, so molecules further apart, reducing intermolecular forces
* Longer chains allow more electrons in same chain so more ways for the electrons to arrange themselves unevenly (so bigger instantaneous dipole)
35
what is meant by the term 'reaction mechanisms'?
models that show the movement of electron pairs during a reaction.
36
what is homolytic fission?
homolytic fission occurs when a covalent bond breaks and each electron goes to a different bonded atom. This generates two highly reactive neutral species called Radicals.
37
What is a haloalkane's reagents and observations?
* Silver nitrate, ethanol and water
* **White precipitate-** indicates chloro-
* **Cream precipitate-** indicates bromo-
* **Yellow precipitate-** indicates iodo-
38
what do the curly arrows show in a reaction mechanism?
the flow of electron pairs during a reaction mechanism
39
what are radicals?
species with one of more unpaired electrons
40
what is heterolytic fission?
when a covalent bond breaks and both electrons go to one of the bonded atoms, this results in a positive ion (cation) and a negative ion (anion) being formed
X + Y ----\> X+ + Y-
41
Name the reaction route for Alkanes to Haloalkanes
Radical substitution
42
Draw curly arrows to show the mechanism of nucleophilic substitution.
43
what is covalent bond fission?
a covalent bond is a strong electrostatic attraction between a shared pair of electrons and the nucleus of the bonded atoms, during the first stage of a chemical reaction , activation energy causes the covalent bonds to break, this is described as undergoing fission.
44
Name the reaction route for Alkenes to Alcohols
Hydration
45
Name the reaction route for Alkenes to Haloalkanes
Halogenation
46
Name the reaction route for Alcohols to Aldehydes
Oxidation
47
Name the reaction route for Alcohols to Alkenes
Dehydration
48
what is covalent bond formation?
when two radicals or two oppositely charged ions collide, a new bond is formed.
49
Name the reaction route for Alkanes to Alkenes
Cracking
50
What is redistillation?
The purification of a liquid by performing multiple distillations.
For example, when ethanol is made by fermentation, distillation is used to remove the ethanol from the mixture of water, yeast and any remaining sugar. This distillate is usually distilled again to purify the ethanol further.
51
What is E/Z isomerism?
A type of stereoisomerism.
An organic molecule must have a C=C double bond and both carbon atoms must be attached to different groups.
52
state and explain the three stages of radical substitution
1) **_initiation_**- the formation of the radicals
2) **_Propagation_**- two repeated steps that build up the desired product in a side reaction
3) **_Termination_**- two radicals collide and make a stable product
53
what is an electrophile?
is an **electron-pair acceptor**
54
What is Cis-Trans Isomerism?
A special type of E/Z isomerism where two substituents on each carbon atom are the same.
In this case, the E isomer is also a trans isomer and the Z isomer is also a cis isomer.
However the Trans isomer is not necessarily an E isomer, and the Cis isomer is not necessarily a Z isomer.
55
what is an electrophillic addition reaction of alkenes?
two or more molecules become bonded to make one product. for alkenes the pi bond breaks and a small molecule is added across the two carbon atoms to make a staurated organic product
56
Describe an aromatic hydrocarbon
**They have a 6-carbon ring with molecular formula C6H6.**
This structure is stable because the elctrons are shared across all the carbon atoms. This part of a molecule is rarely involved in chemical reactions and is often represented using a skeletal formula.
57
what is an alkene?
a homologous series of **unsaturated** hydrocarbons
58
what is hyrdogenation?
an additon reaction in which hydrogen is added across a carbon- carbon **Double** bond
59
what is halogenation?
an addition reaction where a halogen is added across carbon-carbon **Double** bonds, the alkene becomes **saturated** and a **dihaloalkane** is produced
60
What is a nucleophilic substitution?
A reaction where an atom or group of atoms is exchanged for a nucleophile. The nucleophile is attracted to the partial positive charge on the carbon atom and donates its lone pair of electrons to form a new covalent bond.
61
what is hydration?
an addition reaction between a **gaseous alkene** and **steam**- it is used in industry to make **alcohols**, the conditions involve **high temperatures** and **high pressures** with a **_phosphoric acid_** catalyst
62
In infrared radiation, every bond vibrates at its own frequency. The amount of vibration depends on:
* The bond strength
* The bond length
* The mass of each atom involved in the bond
63
what is an alkane?
a homologous series of **saturated** hydrocarbons
64
State and explain the boiling point of alcohols as the chain length increases
**The boiling point increases.**
This is because as the molecules get longer, there are more surface area contacts and so stronger induced dipole-dipole intermolecular forces. This results in more energy being needed to overcome these attractive forces, and therefore a higher boiling point.
65
What happens to the solubility of alcohols as the chain length increases?
**The solubility of the alcohol decreases.**
This is because the aliphatic chain can't form hydrogen bonds and this becomes the larger part of the molecule.
66
Define the term: displayed formula
Shows the structure, bonding and relative positions of atoms in a molecule.
67
Define the term: Structural formula
Shows the arrangement of atoms in the most simple way
CH3CH2CH3 for propane
68
What are the three steps of free-radical subsitution.
1) Initiation
2) Propagation
3) Termination
69
What is the **second** propogation step of the chlorination of methane to form chloromethane?
70
In **propagation** is the number of radicals on each side of the arrow in a reaction the same or different?
Same, generally in propagation there is one radical on both sides.
71
If an alkane reacts with a halogen, which of the following products can form?
Hydrogen halide
Halogenoalkane
Hydrogen
Halogen
Hydrocarbon with longer chain than orignal alkane
If an alkane reacts with a halogen, which of the following products can form?
Hydrogen halide - This happens when X(radical) reacts with alkane
Halogenoalkane - This happens when alkyl radical reacts with X2
Hydrogen - This will Never **_Never_** ***NEVER*** happern
Halogen -This can happen as a termination: X(radical + X(radical --\> X2
Hydrocarbon with longer chain than orignal alkane - This can happen as a termination: alkyl radical + alkyl radical --\> longer chain alkane
72
Are there any radicals left after termination?
No
73
Define the term: Homologous series
A family of organic compounds with **similar chemical properties** and the **succesive members differ by the addition of a -CH2- group.**
74
Define the term: Functional Group
A part of a molecule that is largely responsible for it properties. eg. the -OH group on an alcohol
75
What is an electrophile? A nucleophile?
Electrophile: An electron pair **acceptor** eg. Br2
Nucleophile: An electron pair **donater** eg OH-
76
What is a Stereoisomer?
A molecule with the same stuctural formula but a different arrangement of atoms in space around the molecule.
77
What are the conditions needed for Halogenation?
A Halogen at room temperature
78
What are the conditions needed for Hydrogenation?
Hydrogen, A nickel catalyst at 423K+ (60oC+)
79
What are the conditions needed for the reaction of a Hydrogen Halide and an Alkene?
A **Gaseous** Hydrogen Halide at room temperature. If they are both gases they can be mixed, if liquid then one is bubbled through the other.
80
What are the conditions needed for the Hydration of an alkene?
Steam and a Phosphoric acid catalyst.
81
What type of alcohol and what conditions are needed to oxidise the alcohol into an aldehyde?
A **Primary** alcohol. Low heat under **reflux** with acidified **Potassium dichromate.** (K2Cr2O7)(Can be any group 1 element dichromate but is normally Na or K)
82
What type of alcohol and what conditions are needed to oxidise an alcohol into a Carboxylic acid?
A **Primary** alcohol, high heat, under reflux with acidified K2Cr2O7. Then it is distilled.
83
What type of alcohol and what conditions are needed to oxidise an alcohol into a ketone?
A **Secondary** alcohol. Heat under reflux with acidified K2Cr2O7.
84
Which alcohols do not undergo Oxidation reactions?
Tertiary alcohols
85
What reaction produces an alkene from an alcohol? What conditions are needed for this reaction?
**Dehydration.**
Heating under reflux with acidified K2Cr2O7 using an acid catalyst, either H2SO4 or H3PO4.
86
What conditions are needed for the substitution reactions of alcohols to form haloalkanes?
Heating under reflux with a Sodium Halide and Sulfuric Acid.
87
What type of bond is formed between C-C and C-H? What forms this bond?
A Sigma σ covalent bond.
The σ bond is the result of an overlap of two orbitals
88
What are the bond angles around a Carbon atom covalently bonded to 4 other atoms?
109.5°
89
How does chain length affect boiling points of alkanes? Why?
As chain length increases, so does boiling point. This is because the larger molecules have a **larger surface area** so there is **more surface contact** and **stronger London forces/induced dipole-dipole interactions** form which require **more energy to overcome**. Plus if a molecule is larger, the **electrons are more likely to distribute unevenly** and cause a (stronger) dipole which will induce a dipole in neighbouring molecules which will require more energy to overcome.
90
What is a formula for working out the complete combustion of alkane?
CxHy + (x+(y/4))O2→xCO2 + (y/2)H2O
91
What is the bond angle around a carbon atom in a double bond?
120º
92
How is a double bond formed?
A sigma bond is formed, then a pi (π) bond is formed.
93
What forms a pi bond? Where is the electron density?
The sideways overlap of two p-orbitals.
The electron density is concentrated above and below the bond.
94
Which has a higher boiling point: Ethane or Ethanol?
Why?
Ethanol, because hydrogen bonds can form between the H atom from one molecule and the O of another. Hydrogen bonds are stronger than the weaker London Forces between alkanes so require more energy to overcome.
