Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

CHEM compostella > Organic chemistry > Flashcards

Organic chemistry Flashcards

1
Q

functional group of thiol and thioesters

A

-SH
-RC=O-SR’

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

reason between diff in reactivity between alcohols and thiols

A

difference electronegativty between S and O (but both are polar covalent)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

classification of alcohols

A

1ary 2ary 3ary
dependent on number of alkly groups connected on the carbon of the function group OH

!! thiols do not form H bonds but alcohols do

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Reactive properties of the OH group in alcohols and phenols

A
  1. form H bonds
  2. Act as weak bases (protonates to give rise to oxonium ion ROH2+)
  3. Act as weak acids (deprotonated to give rise to alkoxide ion RO-)

!! equilibrium mostly favoured in the basic property, not acidic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

are phenols more or less acidic than alcohols

A

phenols are more acidic

REASON: the phenoxide ion is resonance stabilised

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

dehydration of alcohols

A
  • produces alkene
  • requires H3O+ ions at high temps
  • removes hydroxy group
    -forms a minor and major product (major is the highest degree carbocation)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

how does oxidation of alochols occur biologically?

A

-mediated via NAD+ and NADP+
-a base removes the OH proton and the alkoxide ion transfers a hydride ion (H-) to the coenzyme

!! H- hydride ion = [2e- + H+]

NAD+ + 2e- + 2H+ –> NADH + H+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

alkene to alcohol

A

REAGENTS: water with presence of acid as catalyst

(for unsymmetrical alkenes, OH is added to the carbon having less number of hydrogen atoms)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

oxidation of promary alcohol into aldehyde - selective oxidizing agent

A

PDC (pyridinium chlorochromate) -> controlled but mild so it stops at an aldehyde state of partial oxidation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

1 reaction we need to know for thiols

A

REAGENT: Br2/I2/O2

2R-SH –> R-S-S-R + 2HI
(gas in the hydrogen halogen depending on the one used)

!! S-S is the bond characteristic of the disulfides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

imortance of S-S covalent bonds in the body

A

-can protect cells for oxidative degradation
-eg, glutathionine is oxidised to glutathione disulfide to remove harful oxidants

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

difference bwtween two families of carbonyl groups

A
  1. aldehydes and ketons have R and H groups that CANNOT act as leaving groups in nuc substitution
  2. COOH/COCl/etc have groups that can dettach and undergo nuc substitution

!! hence they have difference reactivities and reactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is the hybridisation of a carbonyl bond

A

C=O so sp2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

nucleophilic substitution of carbonyl compounds

A

NUC SUBSTITUTION: creating a tetrahedral intermediate with sp3 hybridisation

  1. reduction to either a primary or secondary alcohol (LiAlH4, where H- is nuc, in the presence of H+ for protonation)
  2. reduction to a hydroxynitrile (HCN, where CN- is nuc)

!! biologically: to form alcohols the H- ions are donated by the coenzymes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

hemiacetal and acetal formation from carbonyls

A

alcohol ROH molecule uses lone pair of electrons to act as a nucleophile and attack the delta+ carbon of carbonyl

SPONTANEOUS REACTION (equilibrium position is forwards)

WITHOUT ACID: product is an acetal: C of carbonyl is bonded to a OH and an OR’ group

WITH ACID CATALYST: product is a hemiacetal: C of carbonyl bonded to 2OR’ groups

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

carbonyl reacting with an amine

A

PRODUCT: imines R2C=NR
-requires a slightly acidic environment
-can only occur with primary amines (bcos nitrogen is trivalent to be neutral)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is tatutomerism?

A

KETO/ENOL: constitutinal isomers (tautomers)
-start from original ketone
-removal of a H atom from C of carbonyl bond
-creates a highly negative Carbanion
-this delocalises the electrons and forms C=C bond while the C=O of the carbonyl is broken to C-O
-H attaches to C-O to form C-OH

hence: enols have C=C-OH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what are the conditions for keto-enol tautomerism to be possible (2)

A
  1. hydrogen must be in the alpha position to become deprotonated (ie. adjacent to the C=O of the carbonyl)
  2. must come in contact with a strong base ( to induce deprotonation)
  3. carbonyl has to be in excess otherwise it would just get continuously become deprotonated
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

aldol condensation process

A

1st reaction of kerbs cycle
-a carbonyl is transformed to enol tautomer using a strong base
-enol acts as an electrophile and attacks an aldehyde molecules
-forms C-C covalent bond
-ALDOL: contains both an aldehyde and an alcohol OH functional group

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

are carbanions/carbocations nucleophiles or electrophiles

A

ANION: nucleophiles
CATION: electrophile

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

structure of carboxylic acids

A

-COOH
-Carbon of functional group is sp2 hybridisation
-strongly held by H bonding and so they mainly exist as cyclic dimers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

why are carboxylic acids so reactive

A

the oxygen in the C=O and C-OH bonds pull electrons away from the carbon of the functional group

creates a strong delta positive charge which means that it is a strong electrophile

HENCE: THEY ARE MORE REACTIVE THAN KETONES/ALDEHYDES (bcos they have double the electron pull)

!! H of COOH can also be deprotonated so they can undergo acid base reactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

can carboxylic acids have a basic character?

A

YES - in very acidic conditions

H+ ions can be added on the oxygen of the C=O and becomes C=OH

this is possible because of the stbilisation provided by the resonance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

acid base reactions of carboxylic acids (2)

A
  1. with bases to give salts (eg. with NaOH to form sodium carboxylate COO-Na+)
  2. with water to form the deprotonated ion
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

reactions that convert carboxylic acids into their derivative (6)

A
  1. acid halide: COCl
    addition of H2O
  2. ester: COO
    addition of alcohol with heat and H+ acid catalysis
  3. acid anhydrase: C=OOC=O
    addition of a carboxylic acid with heat and H+ catalysis
  4. amide: CONH
    addition of an amine (can be either primary ot secondary)
  5. thioester: COS
    addition of a thiole with heat and H+ acid catalysis
  6. acyl phosphate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is the type of reactions carboxylic acids undergo to form their derivatives

A

NUC SUBSTITUTION:

OH of COOH acts as the leaving group and the Nuc species attacking the carbonyl C (electrophile) is substituted into the molecule isntead

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

what is the acyl group of a carboxylic acid

A

R-C=O portion of molecule

(ie. everything other than the OH leaving group)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

if in a reaction a water molecule is released when a bond is made, what does this say about the bond?

A

it is weaker and it is prone to hydrolysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

two possibilities for ester hydrolysis

A
  1. acid hydrolysis to form parents alcohol and acid
  2. Saponification: alkali hydrolysis to form parent alcohol and the carboxylATE ION (protonation can then form the acid)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Are amides basic and if yes/no why?

A

NOT BASIC:

the lone pair on the nitrogen can be delocalised over the carbonyl group. Hence the lone pair cannot be used and cannot be donated for protonation

!! this lack of lone pair use also makes them weak nucleophiles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Rank all carboxylic acid derivative in inrcreasing reactivity

A

amide
ester
thioester
anhydrase
acyl chloride

32
Q

use of thioester in biology

A

THIOESTER is more energentic and less stable than a CARBOXYLIC ACID: activation energy of the synthesis of a thioester is lower that the carboxylic acid

!! the body uses thioester CoA which is transformed into a thioester in order to have more probable reactions

33
Q

reduction of carboxylic acids

A

forms primary alcohols
treatment with LiAlH4 (reducing agent) in dry conditions

34
Q

what molecules as monosaccharides and how are they named

A

-polyhydroxyaldehydes (aldoses) OR ketones (ketoses)
-derived from the oxidation of the primary (aldehyde) or secondary (ketone) OH group of a glycerol molecule

NAMING:
1. prefix is the type of molecule (aldo- or keto-)
2. suffix is the chain length

EG. aldotriose is an aldose molecule of 3C length

35
Q

are monosaccharides chiral?

A

NO FOR KETONE STRUCTURES

YES FOR ALDEHYDE STRUCTURES (exist as a pair of enantiomers) –> in nature, only one of the enantiomers is present which is the D glyceraldehydes

36
Q

what is the conventional way to draw fisher structure for carbohydrates

A

vertical chain is the longest alkyl chain and the carbonyl group is on the top

37
Q

carbs that we need to know the fisher structure for

A

D-GLUCOSE: an aldose RLRR
D-FRUCTOSE: a ketohexose
LRR
D-GALACTOSE: an aldose RLLR
D-RIBOSE: aldopentose RRR
2DEOXY-D-RIBOSE: aldopentose with same structure as ribose but the O removed at C2

glucose and galactose are C4 epimers

38
Q

what are epimers?

A

monosacharides where we have reversed the configuration of only one carbon cetner

eg. galactose is a C4 epimer of glucose

39
Q

what is the arrangement of monosacharides in water

A

closed CYCLIC rings

REASON: the aldehyde of aldoses combine with the OH groups on the SAME molecule to form hemiacetal formation –> causes the cyclic closure of the molecule

!!! this is a spontaneous process

40
Q

what position does the closed cyclic version of glucose take

A

name: glucopyranose (a/b) formation of intramolecular bond between the COH and the OH at C5

!! cyclisation gives rise to two new isomers at C1 –> alpha glucose with OH DOWN and beta glucose with OH UP –> called teh HAYWORTH structures

41
Q

which type of glucopyranose is more stable? + reason

A

beta is more stable
spontaneous ratio in water of beta:alpha glucose is 2:1

REASON: OH groups in beta glucose is in the equatorial position (least steric hinderence between the OHs)

42
Q

structual properties of the alpha and beta glucopyranoses

A

melting points are almost the same (around 145-150)

optical power is very different: alpha rotates light by a much larger angle (112 vs 18 degress)

43
Q

what is the cyclisation of fructose

A

forms alpha or beta fructofuranose which means it is a 5 point compounds

44
Q

what are anomers

A

the beta and alpha conformations created by the spontaneous cyclisation of monosaccarides

45
Q

what is mutarotation

A

the chain in optical rotation observed when pure alpha or beta anomer is dissolved in water

present due to the free conversion between the alpha to the hemaicetal form and then to the beta form

46
Q

what are reducing sugars + test for them

A

a sugar that can reduce another substance (hence is oxidised itself)

!! fehlins or tollens to test for the aldehyde oxidation
GLUCOSE – oxidised to gluconic acid
!!! quantifiable extent of reducing sugar can be achieved from photospectrometry

47
Q

what is the difference of oxidation of glucose from lab reagents vs in the body?

A
  1. in labs glucose is oxidised to gluconic acid (carboxylic acid group)
  2. in body a specific enzyme interacts and oxidises glucose into glucoronic acid (contains BOTH a carboxylic acid and an aldehyde group)
48
Q

glycoside formation of monossacharides

A

for cyclic monossacharides: reaction with an alchol forms hemiacetal and reaction with a second alcohol forms acetal

!! bond formed is a glycosidic bond and forms at the anomer position of the monossacharide

49
Q

dissacharides and their monomers

A
  1. maltose: 2glucose alpha(1-4)
  2. cellobiose: 2glucose beta(1-4)
  3. sucrose: gluc + fruct (1-2)
    !! not reducing sugar bcos aldehyde group is removed
  4. lactose: gluc + galactose b(1-4)
50
Q

why are dissacharides still reducing sugars

A

postive test with fehlings indicates that they still have an aldehyde group

this is bcos the glycosidic bond is between C1-4 and so the carbonyl bond is not affected

51
Q

O and N linked glycosidic bonds

A

WHEN SUGAR IS BOUND TO RESIDUE (serine or asparagine)

O-linked glycoproteins: covalent bond is between oxygen and the anomeric position - SERINE

N-linked glycoproteins the covalent bond is between nitrogen and the anomeric position - ASPARAGINE

!! the residue is called the aglycon

52
Q

2 types of polyssacharides

A
  1. Homopolysaccharides (one type of monosaccharide)
  2. Heteropolysaccharides (different types of monosaccharides)

!! both can be both linear or branched

53
Q

types of pollyssacharides to know

A
  1. amylose: 1-4 and unbranched
  2. amylopectin: 1-4 and 1-6 and branched (every 20 units)
  3. glycogen: made of amylose and amylopectin, so both 1-4 and 1-6 and branched (every 10 units, so twice as branched as amylopectin)
  4. cellulose
54
Q

function of glycogen

A

storage of glucose , isnt affected by osmotic potential, and high energy density bcos of branching

55
Q

ways of characterising lipids

A
  1. hydrolysable: can be converted into smaller molecules by hydrolysis (waxes/triglycerides/ phospholipids)
56
Q

what compounds are hydrolysable lipids derived from

A

fatty acids

long CH chain with a terminal COOH. longer than 5 carbon atoms

form micelles in water (COOH positioned on the outside)

57
Q

configuration around double bond in natural unsaturated fatty acids

A

cis form

58
Q

MPs of unsaturated and saturated fatty acids comparison

A

saturated: van der waals, higher MP

unsaturated: van der walls but MP is lower bcos of kinks from the double bond - doesnt allow close packing of molecules

59
Q

IUPAC nomenclature of fatty acids

A

number of carbons starting from COOH

eg. 18:1, Delta9

where
18 = number of carbons
1 = number of double bonds
9 = position of the double bond

eg2. 20:5, Delta5,8,11,14,17

60
Q

structure of waxes

A

esters formed from a fatty acids with a long alcohol - condensation reaction which eliminates a water molecule

RCOOR’ functional group
(completely apolar and hydrophobic)

61
Q

structure of triglycerides

A

3 esters made of a molecule of glycerol and 3 fatty acid chains
(condensation reaction) - in the body this condensation can be sequential so it is more common that the 3 alkyl chains are different

CH2(OH)CH(OH)CH2(OH)
glycerol

62
Q

are triglycerides chiral?

A

yes IF the 3 alkyl chains are different - it becomes chiral around the center carbon of the glycerol

63
Q

function of triglycerides

A

chemical compounds used to store energy –> they give the greatest amount of enregy by degraded (than carbs and proteins)

64
Q

fat vs oil

A

fat = saturated lipids, solid at room temperature

oil = unsaturated lipids (C=C), liquid at room temperature

65
Q

hydrolysis of triglycerides

A

ester hydrolysis –> use of water in wither acidic or alkaline (saponification) conditions

OR: enzymes (LIPASES) naturally in the body - independent to the length of the fatty acid chain

66
Q

what is the position of equilibrium for ester formation

A

K is close to 1 so neither side is truly favoured/not favoured

67
Q

glycerophospholipid structure

A

molecule of glycerol with 2 fatty acid chains and phosphatidic acid

!! all 3 bonds are ester bonds

68
Q

isomer def

A

same molecular formula but diff structural formula and or disposition of functional groups

69
Q

what properties do enantiomers have in relation to eachother

A
  1. identical chemical physical properties (MP/BP/density)
  2. diff optical activity (rotate PPL by the same angle in opposite directions)
70
Q

what are meso compounds

A

molecules that look like they should be enantiomers bcos they have flipped chiral center, but are optically inactive bcos of a central line of symmetry

71
Q

consequence on heat of combustion when increasing the alkane length

A

increases

72
Q

heterolytic vs homolytic bond break

A

hetero: electrons are shared asymmetrically, both go to one atom
-> use full arrow

homo: electrons are shared symmetrically, one goes to each original atom –> use half arrow

72
Q

electrophile and nucleophile def

A

electrophile: accept electron pairs (sometimes positive)

nucleophiles: have lone electron pairs to donate (usually negative)

73
Q

trend in strength of nucleophiles

A

increased basicity

compounds with sulfur (HS-/RS-) are stronger than oxygen based compounds (OH-)

negative are stronger than neutral

74
Q

what causes the stability of aromatic compounds

A

orbitals of the carbon atoms are on the same plane, there is a cloud of delocalised electrons.

75
Q

what is the OMP rule for aromatic compound nomenclature

A

O: ortho (1,2 positions)
M: meta (1,3 positions)
P: para (1,4 positions)

76
Q

relationship between classification of amines and their basicity

A

tertiary are the most basic

CHEM compostella (3 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions