CHEM1112 Lecture Notes - Lecture 10: Nucleophile, Methyl Group, Protic Solvent

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19 May 2018

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Identify and name organic halogen compounds

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Primary - halogen on end of chain

Secondary - Carbon connected to halogen has 2 chains

Tertiary - carbon connected to halogen has 3 chains

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10.1

Monday, 28 August 2017

10:23 PM

10. Organic halogen compounds Page 1

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Predict the products of the elimination of alkyl halides, using Zaitsev's rule, and give the reagents required to

perform this reaction

Direct substitution mechanism

SN2 (substitution -

nucleophilic -

second - order)

2 = because rate

depends on 2 things

(n/e phile)

Has transition state

Reaction rate proportional to

concentrations of both nucleophile

and electrophile

e.g. if you double concentration of

nucleophile or electrophile -> rate

will double

Increasing conc means rate is more

likely to occur

Since both starting materials

involved in transition state, and

there is only one step, reaction

rate proportional to concs of both

starting materials

Steps

Nucleophile tends to have neg

charge

Nucleophile substitutes with

leading group

2 - because rate depends on conc

of substrate and nucleophile

Tertiary alkyl halides react so

slowly that they are unreactive

towards an SN2 mechanism

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Screen clipping taken: 28/08/2017 10:43 PM

Screen clipping taken: 2/10/2017 12:23 PM

SN1 (substitution -

nucleophilic - first

order)

(1 = because rate

only depends on 1

thing, starting

materials)

Reaction rate proportional to

concs of organohalide/starting

material only

Reaction rate proportional to

formation of carbocation

Larger hill = formation of

carbocation (getting rid of Br-)

Loss of leading group

Nucleophilic attack

(nucleophile attacks

electrophile), nucleophile

substitutes for leading group

Steps

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10.2 - elim and sub (Wk 4)

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10:24 PM

10. Organic halogen compounds Page 2

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Screen clipping taken: 28/08/2017 10:47 PM

TS = transition state

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If neutral nucleophile

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Primary secondary, tertiary alkyl halides

1 = primary carbocation (1 alkyl group attached to it)

2 = secondary

3 = tertiary (most stable)

10. Organic halogen compounds Page 3

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Document Summary

Secondary - carbon connected to halogen has 2 chains. Tertiary - carbon connected to halogen has 3 chains. Screen clipping taken: 28/08/2017 10:46 pm: organic halogen compounds page 1. Predict the products of the elimination of alkyl halides, using zaitsev"s rule, and give the reagents required to perform this reaction. Sn2 (substitution - nucleophilic - second - order) 2 = because rate depends on 2 things (n/e phile) Reaction rate proportional to concentrations of both nucleophile and electrophile e. g. if you double concentration of nucleophile or electrophile -> rate will double. Increasing conc means rate is more likely to occur. Since both starting materials involved in transition state, and there is only one step, reaction rate proportional to concs of both starting materials. 2 - because rate depends on conc of substrate and nucleophile. Tertiary alkyl halides react so slowly that they are unreactive towards an sn2 mechanism.

Related Questions

1.Structural isomer refers to organic compound that have the same molecular formula but different structure (bonding pattern is different). This problem is designed to guide you to explore structure isomer.

(a)Go ahead and write Lewis structure for butane (C₄H₁₀). You may draw four C atoms connect straight as like in train.

(b)In the above structure, four C atoms are connected straight in a line. If you move one C atom to the side (like 3 C atoms in a line, one connected to the middle C atom), after you supply all the H atoms to make all the C atoms saturated with 4-bonds each. Will the molecular formula for your structure drawn be different from butane?

( c) Structures you obtained in (a) and (b) are an example of structural isomers. What kind of name we can give to structure in (b) so we can differentiate it from structure in (a)?

2.Alkane is the basic building block of organic compound. We often write alkane chain as a group R. On this basic chain, we can add different functional group, like âOH for alcohol, -COOH for carboxylic acid.

(a)Methanol refers to CH₃OH. Ethanol refers to CH₃CH₂OH. Draw the Lewis structure for these two compounds.

(b) If you have a straight alkane chain, where does âOH group can be attached? How do you name it so you can know where âOH group is attached?

3. Give the Lewis structure for CH₃COOH. Give its systematic name and common name.

4. Ester refers to two alkane chains connected through a single O atom. Write the Lewis structure for this simplest kind of ester: CH₃OCH₃. Find its name and some common use.

5. Benzene molecular formula is C₆H₆. The six carbon atoms are connected to form a ring (hexagon). Draw the Lewis structure for C₆H₆. Do you think the six bond lengths between C-C atoms should be same or not according to your drawn Lewis structure?