CE 10224A - Science for CE (Organic Chemistry) Flashcards Preview

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Flashcards in CE 10224A - Science for CE (Organic Chemistry) Deck (79)
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1

What are stereoisomers?

Molecules with the same molecular formula and order of atoms bound together but differ in their 3-D spatial orientation.

Same molecular and structural formula but different arrangement in space

2

What are olefins?

Alkenes

3

What are alkynes?

Compounds with C-C triple bonds

4

What are aromatics?

Compounds containing a benzene ring

5

What are properties of aromatics?

They contain a benzene ring - electrons are delocalised across the ring.

Most have a pleasant smell

Addition reactions are possible (however the ring is very stable)

Common naming of aromatic rings is to label from the first substituted carbon then use subsequent numbering
Traditional naming system uses ortho-, meta- and para- prefixes

6

What are the properties of: short chain alkanes, long chain alkanes, aromatics, alkenes and branched components?

Short chain alkanes:
- poor energy content
- excellent low temp’ properties
- very volatile
- good lubricant

Long chain alkanes:
- greatest energy content
- poor low temp’ properties
- poor volatility
- poor lubricant

Aromatics:
- poor energy content
- good low temp properties if short chain
- poor volatility
- good lubricant

Alkenes:
- good energy content
- good low temp properties
- good volatility
- poor lubricant

Branched components:
- lower energy content than straight chain
- greatest low temp properties
- poor volatility
- poor lubrication

7

What is acetone?
What’s its formula?

A ketone, also known as propanone
Formula: CH3COCH3

8

What is acetaldehyde?
What’s its formula?

An aldehyde, also known as ethanal
Formula: CH3CHO

9

What is formic acid?
What’s its formula?

A carboxylic acid, also known as methanoic acid
Formula: HCOOH

10

What’s acetic acid?

A carboxylic acid also known as ethanoic acid
Formula: CH3COOH

11

What is ethyl acetate?
What’s its formula?

An ester, also known as ethyl ethanoate

12

What is ether/diethyl ether?

An ether, also known as ethoxyethane
Formula: C2H5OC2H5

13

What’s benzene?

A hydrocarbon (aromatic) with formula C6H6.

14

What is toluene?
What’s its formula?

Aromatic hydrocarbon, methyl benzene
C6H5CH3

15

What is phenol?
What’s its formula?

Aromatic hydrocarbon with formula C6H5OH

16

What is pyridine?
What’s its formula?

Heteroaromatic compound (azine)
Formula: C5H5N

17

What is THF?
What’s its formula?

Heterocyclic compound, TetraHydroFuran
Formula: C4H8O

18

What is DMF?
What’s its formula?

Dimethylformaldehyde
Formula: (CH3)2NCHO

19

What is DMSO?
What’s its formula?

Dimethylsulfoxide
Formula: (CH3)2SO

20

What is formaldehyde?
What’s its formula?

An aldehyde, also known as methanal
Formula: CH20

21

What are the 4 main analytical techniques used to determine organic structures?

NMR

X-ray crystallography

FT-IR (fourier transform infra-red)

Mass spectroscopy

22

What's x-ray crystallography?

What are its limitations?

An analytical technique which can be used to determine structures of crystalline solids.

The technique works by firing X-rays at a structure.
The X-rays will interact with the electron cloud around atoms and diffract.
By assessing how the X-rays have diffracted and the pattern they produce we can determine the structure of a compound.


Limitations:
- Only works on crystalline solids
- Can't see H atoms
- Expensive and time consuming

23

How does NMR work?

Nuclei are held in a powerful magnetic field.
If the nuclei have the correct spin state, and can align with the magnetic field then they can be detected by NMR.

A radiowave at set frequency is used to excite the target atoms from a low energy state to a high one
As the nuclei relaxes back to its ground state it emits radiowaves, this can be detected and gives the information needed.

24

What does a carbon C13 spectra suggest?
(left to right)

200-150ppm: Unsaturated C next to O atom e.g. C=O

150-100ppm: Unsaturated C atoms e.g. C=C

100-50ppm: Saturated C atoms next to O e.g. RO-CH3

50-0ppm: saturated C atoms e.g. R-CH3

25

What's mass spectroscopy?

Tool that gives the molecular weight of a compound, which works by measuring the mass of a charged compound.

The sample is volatised and ionised.
This is then sent as a beam of charged ions through a magnetic field which separates based on mass:charge ratio.
This then flows to the detector.

26

What's FT-IR?
(infra-red)

Analytical technique can be used to assess functional groups.
All bonds vibrate and move. When moving these will absorb infra-red radiation.
We can pass radiation at different wavelengths through a sample and measure what is absorbed and what frequencies are not.
Stronger bonds vibrate faster (absorb more energy) as do lighter atoms.

27

What aspects can stabilise charged species?

Steric bulk around the charge (many atoms around the charged atom/ion which prevents it reacting easily

Electronic effects - groups can donate or remove electronic charge

28

What do EWG and EDG represent (electronic effects)?

EWG - electron withdrawing groups (have negative induction effect

EDG - electron donating groups (have positive induction effect)

29

What is indicative of leaving groups?

pKa

The lower the pKa the better the leaving group is.
This is also a good indication of the strength of a Nucleophile (in reverse) with large pKa meaning a stronger nucleophile.

30

What is epoxidation?

Any reaction that converts a compound (especially an alkene) into an epoxide.

An epoxide is an organic compound containing a three-membered ring consisting of an oxygen atom and 2 carbon atoms.