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Organic Chemistry > Lesson 3: Alkenes > Flashcards

Lesson 3: Alkenes Flashcards

1
Q

Types of hydrocarbons

A

Saturated hydrocarbons
Unsaturated hydrocarbons

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2
Q

Do not contain the maximum number of hydrogen atoms.

A

Unsaturated hydrocarbons

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3
Q

Contain carbon-carbon double bonds.

A

Alkenes

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4
Q

General formula of alkenes

A

CsubnHsub2n

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5
Q

In alkenes, molecule is ___________ because the carbon and hydrogen atoms all lie in the same plane.

A

Flat or planar

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6
Q

Hybridization of alkenes

A

Hybrid Orbitals
Molecular Orbitals

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7
Q

Result from combinations of orbitals within a given atom, either prior to or as bonding with another atom takes place.

A

Hybrid Orbitals

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8
Q

Result from combinations of orbitals between atoms as bonding takes place to form molecules.

A

Molecular Orbitals

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9
Q

The sp2 orbitals are arranged in a __________ around the central carbon atom, with bond angles of 120°.

A

Trigonal planar shape

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10
Q

The unhybridized P orbital is ___________ to the plane.

A

Perpendicular

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11
Q

End-on-end overlap of the sp2 orbitals to make a ___________.

A

Sigma bond

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12
Q

Side-to-side overlap of the unhybridized P orbitals to make a __________.

A

Pi-bond

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13
Q

Because of the pi- bond, ___________ is not possible around carbon-carbon double bonds.

A

Free rotation

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14
Q

Since each carbon in the double bond is trigonal planar in shape, the entire ethylene molecule is a ___________, with the atoms separated by bond angles of 120°

A

Flat molecule

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15
Q

In longer Alkyl chains, the additional carbon atoms attached to each other by __________.

A

Single covalent bonds

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16
Q

Each carbon atom is also attached to a sufficient hydrogen atoms to produce a total of __________ about itself.

A

Four single covalent bonds

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17
Q

Existence of isomers that differ in the orientation of their atoms in space.

A

Stereoisomers

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18
Q

An isomers in which the two substituents (the methyl and ethyl groups) are on the same side of the double bond, is called _________.

A

Cis isomer

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19
Q

An isomers with two non hydrogen substituents on opposite sides of the double bond is called ________.

A

Trans isomer

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20
Q

If more than two substituents are attached to the carbon atoms of a double bond, the cis and trans system _____________.

A

Cannot be used

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21
Q

-bisected vertically through the double bond.

A

E-Z system

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22
Q

If the two atoms are in the cis position, the arrangement is ___.

A

Z

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23
Q

Z for German zusammen meaning ________.

A

Together

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24
Q

If the atoms or groups are in the trans position, Tha arrangement is ___.

A

E

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25
Q

E for German entgegen, meaning ________.

A

Opposite

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26
Q

System on which the organic chemists utilize to circumvent problems caused by arbitrary nomenclature.

A

International Union of Pure and Applied chemistry

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27
Q

The suffix for alkene

A

-ene

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28
Q

Rules of the IUPAC system for naming alkenes.

A
  1. Name the parent hydrocarbon.
  2. Number the carbon atoms in the chain.
  3. Write the full name.
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29
Q

A cyclic unsaturated hydrocarbon with one or more carbon-carbon double bonds within the ring system.

A

Cycloalkenes

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30
Q

Alkenes substituents are called __________

A

Alkenyl groups

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31
Q

A noncycli hydrocarbon substituents in which a C-C double bond is present.

A

Alkenyl grouos

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32
Q

Most frequently encountered alkenyl groups:

A

-methylidene(one-carbon)
Common name: methylene
-ethynyl (two-carbon)
Common name: vinyl
-2-propenyl (three-carbon)
Common name: allyl

33
Q

In physical state of alkenes, alkenes are ________ and ________ in nature.

A

Colorless and odorless

34
Q

________ is an exception because it is a colorless gas with a faintly sweet odor.

A

Ethene

35
Q

The first three members of the alkene group are __________.

A

Gaseous in nature

36
Q

The next 14 members of the alkene group are _________.

A

Liquids

37
Q

The remaining alkenes are ________.

A

Solid

38
Q

The alkenes are insoluble in water due to their _________ characteristics.

A

Nonpolar

39
Q

Completely soluble in nonpolar solvents

A

Benzene
Ligroin

40
Q

The boiling points of the compounds increase as the number of ________ into he compound increases.

A

Carbon atoms

41
Q

The boiling point of alkenes and alkanes are ___________.

A

Almost similar

42
Q

The boiling point of straight-chain alkenes is more than ___________ alkenes just as in alkenes.

A

Branched-chain

43
Q

The melting points of these double-bonded compounds depends upon the __________ of the molecules.

A

Positioning

44
Q

The melting point of alkenes is similar to __________.

A

Alkanes

45
Q

___________ molecules have a lower melting point than ________ as the molecules are packed in a U-bending shape.

A

Cis-isomers, trans isomers

46
Q

Alkenes are weakly _______ just like alkanes

A

Polar

47
Q

Alkenes are slightly more ________ than alkanes due to the presence of double bonds.

A

Reactive

48
Q

The pi electrons which make up the double bonds can easily be removed or added as they are __________ held.

A

Weakly

49
Q

Naturally occurring alkenes

A

Ethene
Pheromone
Terpenes

50
Q

Produced naturally by all higher plants from the amino acid methionine and is a plant growth regulator.

A

Ethene

51
Q

Compound used by insects (and some animals) to transmit a message to other members of the same species.

A

Pheromones

52
Q

Organic compounds whose carbon skeleton is composed of two or more 5-carbon isoprene structural units.

A

Terpenes

53
Q

Other example of Alkenes

A

Propylene
B-carotene
ą-pinene

54
Q

Produced primarily as a by-product of petroleum refining and of ethylene production by steam cracking of hydrocarbon feedstocks.

A

Propylene

55
Q

The orange pigment that gives carrots their color. It is an important dietary source of vitamin A and is thought to offer some protection against certain types of cancer.

A

B-carotene

56
Q

An organic compound of the terpene class. It is found in the oils of many species of many coniferous trees, notably the pine.

A

ą-Pinene

57
Q

Alkenes are generally prepared through ____________, in which two atoms on adjacent carbon atoms are removed, resulting in the formation of a double bond.

A

B elimination reactions

58
Q

Alkenes can be prepared by 3 methods

A

Dehydration of alcohols
Dehydrohalogenation of Alkyl halides
Dehalogenation of alkenes

59
Q

A molecule of water is eliminated from an alcohol molecule by heating the alcohol in the presence of a strong mineral acid.

A

Dehydration reactions

60
Q

The mechanism of dehydration reaction

A
  1. Protonation of the alcohol
  2. Dissociation of the oxonium ion.
  3. Deprotonation of the carbocations.
61
Q

-Involves in the loss of a hydrogen and a halide from an Alkyl halide (RX).
-normally accomplished by reacting the Alkyl halide with a strong base, such as sodium ethoxide.

A

Dehydrohalogenation of Alkyl halides

62
Q

Mechanisms of Dehydrohalogenation of Alkyl halides

A
  1. A strong base removes a slightly acidic hydrogen proton from the Alkyl halide via and acid-base reaction.
  2. The electrons from the broken hydrogen-carbon bond attracted toward the slightly positive carbon atom attached to the chlorine atom.
63
Q

Main reasons for the reactivity of alkenes.

A

Weak bond
Electron density

64
Q

Pi bond is a __________, unlike sigma bond that isn’t easily break.

A

Weak bond

65
Q

Alkene attract electrons

A

Electron density

66
Q

The most characteristic reaction of alkenes

A

Addition to carbon-carbon double bond

67
Q

Addition reaction of alkenes

A

Markovnikov’s rule
Regioselective reaction

68
Q

In the addition of HX or H20 to an alkene, hydrogen adds to the carbon of the double bond having the greater number of hydrogen.

A

Markovnikov’s rule

69
Q

A reaction in which one direction of bond forming or bond breaking occurs in preferences to all other directions.

A

Regioselective reaction

70
Q

Alkenes that have double bonded carbon atoms bearing the same ligands

A

Symmetrical alkenes

71
Q

Alkenes that have double bond carbon atoms bearing different ligands.

A

Unsymmetrical alkenes

72
Q

Reaction of alkenes: Addition

A

A. Addition of hydrogen halides
B. Addition of water
C. Addition of bromine and chlorine
D. Hydroxylaction (oxidation)
E. Hyrogenation

73
Q

Formation process of monomers by repeated addition reactions of many unsaturated alkene molecules.

A

Addition polymerization

74
Q

________ is a method of oxidatively cleaving alkenes or alkynes using ozone (O3).

A

Ozonolysis

75
Q

This reaction is often used to identify the structure of unknown alkenes, by breaking them down into smaller, more identifiable species.

A

Oxidative cleavage of alkenes

76
Q

Applications and uses of alkenes

A

-polyethylene hip replacement.
-shatterproof acrylic plexiglass
-PVC piping for drains.

77
Q

Commercial use of ethylene;

A

Ripening of climacteric fruits
-bananas
-tomatoes
-avocadoes
-mangoes
-papayas
-persimmons
-honeydew melons

78
Q

Applications of alkenes

A

-ripening fruits and vegetables.
-1-octene for lemon oil
-Ocatadecene (C18H36) found in fish liver.
-Butadiene in coffee.
-lycopene and carotene give the attractive red, orange, and yellow colors to fruits and vegetables.

Organic Chemistry (4 decks)

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