Chemical Reactions Flashcards

1
Q

Synthesis

A

A + B -> AB

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2
Q

Decomposition

A

AB -> A + B

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3
Q

Single replacement

A

AB + C -> AC + B

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4
Q

Double replacement

A

AB + CD -> AC + BD

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5
Q

Homolysis

A

A:B -> A. + B.
Produces radicals

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6
Q

Heterolysis

A

A:B -> A+ + :B-
Produces ions

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7
Q

What direction do curly arrows represent the movement of electrons?

A

Site of high electron density to site of low electron density.
sigma- to sigma+

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8
Q

What do full arrows represent?

A

Movement of a pair of electrons.

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9
Q

What do half arrows represent?

A

Movement of one electrons.

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10
Q

Where do heterolytic reactions almost always occur at?

A

Polar covalent bonds

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11
Q

Where do heterolytic reactions almost always occur at?

A

Polar covalent bonds

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12
Q

What do heterolytic reactions make?

A

Often assisted by the formation of a new bond to another molecule.
Y + AB -> YA + B

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13
Q

What are the 5 key reaction mechanisms?

A
  • Sn1 Substitution reaction
  • Sn2 Substitution reaction
  • Addition reactions
  • Elimination reactions
  • Free radical chain reactions
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14
Q

What is a nucleophilic substitution reaction?

A

Replacement of one functional group/atom with another negatively charged functional group/atom.

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15
Q

What is a nucleophile?

A

A chemical species that forms bonds by donating an electron pair.

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16
Q

Draw the mechanism for a nucleophilic reaction

A

Slide 11 on week 4 of BIOS4006
A = nucleophile
Y = leaving group

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17
Q

What is a Sn1 and Sn2 reaction?

A

Nucleophilic substitution reaction (double replacement)

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18
Q

What is a Sn1 example reaction?

A

Reaction between a TERTIARY alkyl halide and NAOH - a 2 step reaction.

19
Q

What is a Sn2 example reaction?

A

Reaction between a PRIMARY alkyl halide and NAOH - a 1 step reaction.

20
Q

What is the difference between Sn1 and Sn2 reactions?

A

Sn1 = unimolecular
Sn2 = bimolecular

21
Q

Give an example of a photochemical free radical chain reaction.

A

Alkyl halide made from a hydrocarbon and halogen gas.
CH4 + Cl2 -> CH3Cl + HCl

22
Q

Describe the steps for a free radical chain reaction.

A

Initiation
Propagation
Chain termination
(check slides 23+24)

23
Q

What is a addition reaction.

A

2 or more molecules combine to make a larger molecule.

24
Q

What is an electrophilic addition reaction.

A

A reaction between an electrophile and nucleophile, adding to double or triple bonds.

25
Q

What is an electrophile?

A

An atom/molecule that forms bonds with another atom/molecule by accepting an electron pair.

26
Q

What is an carbocation?

A

Ion with a positively charged C atom

27
Q

What is step A in the first step of electrophilic addition?

A

+ charge on electrophile is attracted to electron denstiy in double bond.

28
Q

What is step B in the first step of electrophilic addition?

A
  • As electrophile approaches double bond (of C=C)
  • Electrons in A-B bond are repelled towards B
29
Q

What is step C in the first step of electrophilic addition?

A
  • Double bond breaks, and A binds to C (forming carbocation)
  • The two electrons in A-B bond move to B, forming B- ion
30
Q

What is step A in the second step of electrophilic addition?

A

B- ion acts as a nucleophile and attacks carbocation.

31
Q

What is step B in the second step of electrophilic addition?

A
  • The lone pair of electrons on the B- ion are attracted towards the + charged C in carbocation
  • Causing B to bond to it
32
Q

What are the two mechanistic types for elimination reaction?

A

E1 - 2 step involving an intermediate carbocation

E2 - 1 step

33
Q

What is hydrolysis?

A

Involves adding water to one large molecule to break it into multiple smaller molecules.

34
Q

What is a condensation reaction?

A

2 or more molecules combine to form a larger molecule, with simultaneous loss of a small molecule (e.g. water).

Term usually reserved for reactions where new C-C bond is formed.

35
Q

What is esterification?

A

Process of combining an organic acid with an alcohol to form an ester + water.

acid + alcohol -> ester + water

36
Q

OIL RIG

A

Oxidation Is Loss
Reduction Is Gain

37
Q

What is the oxidation state?

A

The number of charges an atom would have in a molecle/ion if electrons were transferred completely.

38
Q

What is the oxidation number of uncombined elements?

A

0

39
Q

What is the oxidation number of oxygen (in most compunds)?

A

-2

Exception: In peroxides it is -1.

40
Q

What is the oxidation number of hydrogen (in most compounds)?

A

+1

Exception:
H combined with a metal of lower electronegativity.

41
Q

What is the oxidation number of halogens?

A

-1

42
Q

What is the oxidation number of groups 1,2 and 3?

A

+1, +2 and +3

43
Q

What is the oxidation number of carbon?

A

Vary between +4 to -4.