Organics Flashcards
1
Q
What is Substitution in relation to chemical reactions of Alkenes?
A
When one H atom is substituted for another atom.
2
Q
What is an Addition reaction of Alkenes?
A
The C=C double bond breaks and small molecules add to the molecule.
Examples:
a) Alkene + H₂ → alkane
b) Alkene + Halogen → haloalkane
c) Unsymmetrical alkene + halogen halide (H’X’) → haloalkane
d) Alkene + water/dilute acid → alcohol
e) Addition Polymerisation
3
Q
What is Markovnikoff’s Rule?
A
If the alkene and the reagent over the arrow are both unsymmetrical, then 2 PRODUCTS will be made in the addition reaction. We call these MAJOR and MINOR products.
Note: Sometimes this rule is referred to as ‘the rich get richer and the poor get poorer’. (Don’t say this in exam it’s not enough).
4
Q
We can turn an __________ into an _________ if DILUTE ACID is used and this might involve MARKOVNIKOFF’S RULE too. This can be shown over the arrow as H₂O/H⁺ or written as dil. H₂SO₄
A
ALKENE
ALCOHOL
5
Q
What is an Oxidation Reaction of an Alkene?
A
Where the alkene GAINS AN OXYGEN ATOM.
6
Q
In an Oxidation Reaction of an Alkene what is the oxidising reagent?
A
PURPLE PERMANGANATE ION, MnO₄⁻
7
Q
What condition is required in an oxidation reaction of an alkene?
A
ACID CONDITIONS (H⁺)
8
Q
What is the product in an oxidation reaction of an alkene?
A
DIOL (ALCOHOL WITH 2 x OH)
9
Q
What colour change is observed in an oxidation reaction of an alkene?
A
PURPLE to COLOURLESS
10
Q
What distinguishing test is used for alkenes?
A
ALKENES will rapidly turn ORANGE BROMINE WATER (BR₂) colourless.
11
Q
What will ALKANES do in ORANGE BROMINE WATER (BR₂)?
A
SLOWLY turn the BR₂ water colourless with UV light.
12
Q
What are the 3 types of Isomers?
A
1) Constitutional/Structural Isomers
2) Cis-Trans Isomers
3) ENANTIOMERS (optical isomers)
13
Q
What is a Constitutional/Structural Isomer?
A
A compound with the SAME molecular formula but different ARRANGEMENT of atoms
14
Q
What is a Cis-Trans Isomer?
A
MUST HAVE A DOUBLE BOND, which can rotate. Each carbon in the double bond must have 2 DIFFERENT GROUPS attached.
15
Q
What is a ENANTIOMER (optical isomer)?
A
Enantiomers are a pair of molecules that are MIRROR IMAGES of each other. They have the same atoms but they are arranged differently in 3D. They MUST have an ASYMMETRIC CARBON ATOM (a carbon bonded to 4 different groups). We call this a CHIRAL carbon.
16
Q
What is a CHIRAL Carbon?
A
A carbon bonded to 4 different groups
17
Q
Optical Isomers have the SAME physical properties (m.p & b.p) and chemical properties except for ONE, what is it?
A
“They will rotate to plane-polarized light in equal but opposite directions.”
18
Q
The Isomer that involves COOH, C, H, NH₂ and R are always shown as ______________. DO NOT draw any bonds at right angles that will be a Not Achieved, show them at _____________ than 90° apart.
A
TETRAHEDRAL
GREATER
19
Q
Many enzymes and amino acids have __________ CARBONS so they can have ___________ ISOMERS OF THEMSELVES.
A
CHIRAL
OPTICAL
20
Q
What does ‘Chiral’ mean?
A
A molecule that cannot be rotated/superimposed on each other.
21
Q
What does ‘AChiral’ mean?
A
A carbon that does not have chirality/molecule.
22
Q
What does ‘S isomer’ mean?
A
Left hand isomer
23
Q
What does ‘R isomer’ mean?
A
Right hand isomer
24
Q
What is an equal mixture of both isomers called?
A
A RESEMIC MIXTURE.
25
Haloalkanes contain halogens from group ___?
17
26
What are Haloalkanes classified as?
1°, 2° or 3° depending on the number of CARBONS bonded to the carbon atom attached to the halogen.
27
In a substitution reaction the halogen functional group is replaced with various '_______'.
GROUPS
28
In an elimination reaction HX (X is a halogen) is ____________ from the molecule and a ______ bond is formed. HOT CONCENTRATED ______________ KOH is required. The product formed is an __________.
REMOVED
DOUBLE
ALCOHOLIC
ALKENE
29
What is Saytzeff's Elimination Rule?
"If there is a CHOICE of C atoms from which the H can be removed to produce 2 different products, then the MAJOR product will be the one formed when the H ATOM IS REMOVED from the C with the LEAST number of H atoms."
For the major product: 'The POOR GET POORER'. (But don't say that in exam).
30
What is the test for an Haloalkane?
Will it float on water, yes or no?
31
What is the suffix for an Alcohol?
-ol
32
What is the attachment group for an alcohol?
OH
33
What can Alcohols be classified as?
Primary (1°)
Secondary (2°)
Tertiary (3°)
34
What is a Primary (1°) alcohol?
The C holding the OH group is itself attached to no other (or 1 other) C.
35
What is a Secondary (2°) alcohol?
The C holding the OH group is itself attached to 2 other C.
36
What is a Tertiary (3°) alcohol?
The C holding the OH group is itself attached to 3 other C.
37
How can you make an alcohol?
By reacting haloalkanes with NaOH₍ₐ𝓆₎ or KOH₍ₐ𝓆₎
38
How do you turn an ALKENE into an ALCOHOL?
By using DILUTE ACID
39
How can DILUTE ACID be shown in symbols?
H₂O/H⁺ or written as dil. H₂SO₄
40
How do ALCOHOLS undergo Elimination reactions?
With WARM CONCENTRATED H₂SO₄
41
What is CONCENTRATED H₂SO₄?
A dehydrating agent that removes WATER (h-OH) from an alcohol.
42
In an alcohol elimination reaction what is formed and made?
A double C=C bond is formed and an ALKENE is made.
43
In an alcohol elimination reaction when does SAYTZEFF'S RULE apply?
When we have a SECONDARY alcohol and it is NOT symmetrical
44
In an alcohol substitution reaction what 3 things do alcohols react with and why?
1) SOCl₂ (thionylchloride) to form CHLOROALKANES.
2) PCl₅ (Phosphorus 5 chloride) to form CHLOROALKANES.
3) CONCENTRATED HCl to form CHLOROALKANES.
45
What are the 3 oxidation reactions of alcohols?
1° alcohols are oxidised to ALDEHYDES. The aldehydes are then oxidised to CARBOXYLIC ACIDS
2° ALCOHOLS ARE OXIDISED TO ketones
3° alcohols CANNOT be oxidised further
So:
1° → aldehyde → carboxylic acid
2° → ketone
3° (cannot be oxidised)
46
What are the 2 catalysts and what colour change occurs for the Oxidation of 1° alcohols (under distillation) and the Oxidation of 2° alcohols (under reflux)?
MnO₄⁻/H⁺
purple → colourless
CrO₇⁻²/H⁺
orange → green
47
What is Distillation?
Distillation is an open system that SEPARATES molecules apart BY BOILING POINTS. Aldehydes have a lower boiling point than carboxylic acids, so aldehydes are evaporated away and collected before a carb
48
What do we use reflux equipment for?
To make a range of organic products (including ketone and Carboxylic acids). We make carboxylic acids this way, because the aldehyde can not escape and is forced to keep oxidizing further.
49
What are the 3 benefits of reflux?
1) Increase REACTION RATE (heat causes reactants to have more successful collisions).
2) The lid PREVENTS LOSS of VOLATILE REACTANTS into the atmosphere.
3) INCREASES YIELD (amount) of product made.
50
What is an Aldehyde?
E.g What is its functional group, what does the names end in, what is the condensed formula.
The name aldehyde comes from ALcohol DEHYDrogenated. Functional group is C=O (carbonyl group AND H, at the end of the chain. Names end in -al. Condensed formula -CHO not -COH.
51
What are the physical properties of Aldehydes?
The C=C group is POLAR so intermolecular bonding is fairly strong. So short chain aldehydes are soluble, O in C=O has lone pairs of electrons which can form BONDS with water. Most are pungent smelling liquids.
52
What are Ketones?
e.g Where is the C=O bond, what does the names end in, how are the groups identified.
The C=O bond is IN THE MIDDLE of the molecule. Name ends in -one. Use a number to identify the position of the carbonyl group and side groups.
53
What are the physical properties of Ketones?
The C=O group is POLAR, intermolecular bonding is fairly strong. Short chain ketones are soluble, O in C=O has lone pairs of electrons which can form BONDS with water. Most are sweet smelling liquids.
54
What 3 solutions can be used to oxidize ALDEHYDES into CARBOXYLIC ACIDS?
1) Tollen's reagent
2) Benedicts or Fehlings solution
3) MnO₄⁻/H⁺ or CrO₇⁻²/H⁺
55
What is Tollen's reagent?
The mix contains the [Ag(NH₃)₂]⁺ complex ion. The Ag⁺₍ₐ𝓆₎ IONS are reduced to Ag₍ₛ₎ when the ALDEHYDE is oxidised to a CARBOXYLIC ACID. This produces a 'SILVER MIRROR'.
56
What are the 4 steps to making Tollen's reagent?
1) Take ⁓1mL SILVER NITRATE solution.
2) Add 1 DROP NaOH to form a milky brown ppt. (precipitate)
3) Add AMMONI(A SOLUTION drop by drop until ppt. just disappears
4) Put into clean test tube. Add ORGANIC COMPOUND A (A FEW DROPS) and warm in a beaker of hot water. Then repeat with organic compound B.
57
What is Benedicts/Fehlings Solution?
The mix contains BLUE Cu²⁺₍ₐ𝓆₎ IONS. When the ALDEHYDE is oxidised to the CARBOXYLIC ACID the Cu²⁺ ions are reduced to Cu⁺ IONS. This makes an ORANGE/BRICK RED PRECIPITATE (Cu₂O).
58
What can be used to reduce ALDEHYDES and KETONES into PRIMARY and SECONDARY alcohols respectively when dissolved in water or alcohol?
NaBH₄
59
What are Carboxylic acids?
E.g what does the name end in, what type of acid are they, what is their functional group.
Name ends in -oic acid. They are WEAK acids, COOH is the functional group.
60
What are the physical properties of Carboxylic acids?
Methanoic and Ethanoic acid are SOLUBLE due to HYDROGEN BONDING. Solubility decreases with increasing chain length. Higher m.p & b.p than equivalent hydrocarbons & alcohols due to stronger INTERMOLECULAR BONDING & the formation of dimers; 2 x C.A.'s hydrogen bonded together.
61
How do you make a Carboxylic acid?
By oxidising a 1° acolohol under REFLUX using Cr₂O₇⁻²/H⁺
1° acolohol → alehyde → CARBOXYLIC ACID
62
What is a Neutralisation reactions of Carboxylic acid?
Carboxylic acids are WEAK ACIDS and partially dissociate (break up) in water to produce H₃O⁺ ions. They react slowly because they are weak.
The H₃O⁺ ion causes the pH < 7 and litmus to turn red. We test for Carboxylic acids using blue litmus paper.
63
What 3 things do Acids undergo neutralisation reactions with?
1) Bases
2) Metals
3) Carbonates
64
Acid + Base → salt + _____
H₂O
So:
Acid + Base → salt + H₂O
65
Acid + Metal → salt + _____________ ______
Hydrogen Gas
So:
Acid + Metal → salt + Hydrogen Gas
66
Acid + Carbonate → salt + _________ + _________ ____________
Water + Carbon dioxide
So:
Acid + Carbonate → salt + Water + Carbon dioxide
67
What happens in an Acid + Chlorinating agent reaction?
Carboxylic acids react with a 'CHLORINATING AGENT' such as SOCl₂ OR PCl₅ to turn into an ACID CHLORIDE.
68
How do you test for a carboxylic acid?
Add BLUE litmus paper. If its a carboxylic acid it will TURN RED.
69
What are Acid Chlorides?
E.g what do the names end in, what is the functional group.
Name ends in -oyl chloride. Functional group is COCl
70
What are the physical properties of Acid Chlorides?
They are pungent, FUMING LIQUIDS at room temp. They have lower m.p and b.p than alcohols + carboxylic acids as there are NO hydrogen bonds. Acid Chlorides are VERY REACTIVE because there are strong dipoles created within the molecule.
71
What happens in an Acid Chloride + Water reaction?
Acid chlorides undergo violent, exothermic reactions with WATER to form a CARBOXYLIC ACID and HCl. A steamy Gas is seen, this is HCl₍ᵍ₎dissolving in moist air to form hydrochloric acid.
72
What happens in an Acid Chloride + Ammonia reaction?
Acid chlorides react NH₃ to make AMIDES.
73
What happens in an Acid Chloride + Alcohol → Ester reaction?
Acid chlorides react with alcohols to make an ESTER. This is an EFFICIENT way of making an ester, no catalyst is needed. Esters have a pleasant, sweet smell.
74
How do you test for an Acid Chloride?
Add WATER, if its an Acid Chloride there will be a VIOLENT, STEAMY reaction.
2) Add BROMINE Water if its an Acid Chloride there will be a VIOLENT, reaction.
3) Add Cr₂O₇²⁻/H⁺ if its an Acid Chloride there will be a VIOLENT, STEAMY reaction.
75
How are ESTERS made?
From an ALCOHOL and a CARBOXYLIC ACID (OR ACID CHLORIDE) joining together.
76
What is the Ester functional group?
COO
77
How do you name an Ester?
By splitting the molecule between the C=O/C-O bond.
You name the alcohol part with -yl and name the carboxylic part with
-oate.
78
What are the physical properties of Esters?
Esters are sweet/fruity smelling. THEY ARE NOT SOLUBLE (except methylmethanoate) they float on water. Cannot hydrogen bond so lower B.P and M.P than alcohol or carboxylic acid.
79
How do you make an Ester (Esterification)?
By using an ALCOHOL & ACID CHLORIDE this needs no catalyst. You can also make an ester using ALCOHOL & CARBOXYLIC ACID. This needs the catalyst CONC. H₂SO₄ (which removes WATER) and HEAT. The reaction is usually done under REFLUX.
80
How do you test for an Ester?
Pour in to a beaker of WATER, it will float as a layer on top. Smell it, it will smell sweet.
81
What happens in an Ester Hydrolysis reaction with an ACID?
HYDROLYSIS means to break a bond using water. hydro=water, lysis=to cut. Under ACIDIC conditions (H₂O/H⁺) the ester reacts with water and is split back into the CARBOXYLIC ACID and ALCOHOL again (it is the reverse of esterification).
82
What happens in an Ester Hydrolysis reaction with a BASE?
Under BASIC conditions the ester reacts with water and is split into the CARBOXYLIC SALT and ALCOHOL again.
83
What happens in an Ester Hydrolysis reaction with AMMONIA?
Hydrolysis of Esters using AMMONIA is slow. It produces an AMIDE and an ALCOHOL.
84
What are the 2 steps in making Soap?
1) ESTERIFICATION: MAKING ESTER LINKS.
Take fatty acids (carboxylic acids) and link them onto propan-1,2,3-triol (glycerol) using CONC. H₂SO₄ this creates 'TRIglycerides'.
2) ESTER HYDROLYSIS WITH A BASE.
BREAK the Ester links using a base, NaOH. The 'fatty acids' cleaved off are the SOAP.
85
What is soap?
The SODIUM SALT of a CARBOXYLIC ACID.
86
What are Amides?
E.g what is the functional group, what does the name end in.
Functional group is CONH₂. Names end in -amide.
(If there are other groups attached to the N then prefix with 'N' rather than the number.)
87
What happens in the reaction of ACID CHLORIDE + AMMONIA?
ACID CHLORIDES react with AMMONIA to form an AMIDE & AMMONIUM CHLORIDE (2 x NH₃ molecules are needed).
88
What happens when Hydrolysis (breaking up) is done using an ACID?
Amides react with ACID to make carboxylic acid and ammonium ions.
89
What happens when Hydrolysis (breaking up) is done using an BASE?
Amides react with BASES to make carboxylate ions and ammonia.
90
What are the 3 types of Polymers?
1) Addition Polymers
2) Condensation Polymers: Polyesters
3) Condensation Polymers: Polyamides
91
What happens in the process of Addition Polymerisation?
"The Monomer" has a double bond "the conditions" Heat, pressure and a catalyst are used for the double bond to be broken in the "repeating unit". "A section of Polymer" shows 4 repeating units linked up.
92
What does 'Poly' mean in relation to Polyesters?
Many
93
What does 'Ester' mean in relation to Polyesters?
Ester links
94
What are Polyesters (condensation polymer)?
Polyesters are polymers that form when many ALCOHOLS link up with many CARBOXYLIC ACIDS (byproduct= H₂O) OR ACID CHLORIDES (byproduct= HCl).
95
What are condensation polymers?
Each monomer must have 2 functional groups. They are called condensation polymers because a SMALL MOLECULE of H₂O or HCl is ejected when each link is made. Heat and a catalyst is needed.
96
What does hydrolysing a polyester (breaking the bond) mean?
An ester bond can be hydrolysed (cleaved) by reacting with either an ACID or a BASE.
97
If you cleave an ester link with an ______ you remake the alcohol and ____________ ACID ("if you add an acid you make an acid".)
ACID
CARBOXYLIC
98
If you cleave an ester link with an _______ you remake the alcohol and a _____________ SALT.
BASE
CARBOXYLATE
99
What are Polyamides (condensation polymer)?
Molecules with repeating AMIDE LINKS (CONH).
An AMIDE LINK and a PEPTIDE LINK are the same thing.
100
When do Polyamides (condensation polymers) form?
When an AMINE group links up with a CARBOXYLIC ACID group (or ACID CHLORIDE) on a neighbouring molecule. It also releases H₂O OR HCl.
101
How can a polyamide be hydrolysed (breaking the bond)?
A POLYAMIDE can be hydrolysed (cleaved) by reacting with either an ACID or a BASE.
102
What are the 2 rules for hydrolysing a polyamide?
1) If you cleave an amide link with an ACID you remake the CARBOXYLIC ACID and a NH₃⁺ group.
2) If you cleave the amide link with a BASE you remake the NH₂ group and form a CARBOXYLATE SALT.
(ONLY 1 functional group will return to the original form in either case).
103
What are amino acid's roles in polypeptides?
Amino acids are molecules with an AMINO and CARBOXYLIC ACID group. POLYPEPTIDES are based on repeating AMINO ACID units. Amino acids (except glycine) have 4 different groups bonded to a chiral carbon (asymmetric) therefore they can form optical isomers.
104
What can 2 amino acids form when joined via a condensation reaction?
a dipeptide.
