Organic Chemistry 1

به نام خدا

Dr Morteza Mehrdad

University of Guilan, Department of Chemistry,

Rasht, Iran m-mehrdad@guilan.ac.ir

1. McMurry, Organic Chemistry, 7th ed., Brooks/Cole,

Monterey CA, 2008. (8th ed.)

2. Morrison and Boyd, Organic Chemistry, 6th ed.,

Benjamin Cummings, CA, 1992.

3. Carey, Organic Chemistry, 6th ed., McGraw-Hill, NY,

2006.

4. Vollhardt and Schore, Organic Chemistry, 4th ed.,W.H.

Freeman, New York, 2002.

5. Streitwieser, Heathcock, and Kosower, Introduction to

Organic Chemistry, 4th ed.; Prentice-Hall, Saddle River,

NJ, 1998.

6. Clayden, Greeves, Warren and Wothers, Organic

Chemistry, Oxford University Press, New York, 2001.

نمره20 :کوئیز

نمره20: نظم و ترتیب و حضور و غیاب

نمره 60: امتحان نیم ترم

نمره100: امتحان آخر ترم

شیمی آلی ویرایش هفتم -جلد اول

دکترعیسی یاوری: ترجمه

1390تهران -نشر نوپردازان

McMurry, John Edward

(Professor Emeritus)

Born July 27, 1942 (age 73)

New York City, United States

Nationality American

Institutions University of California, Santa Cruz,

Cornell University

Alma mater Harvard University A.B. 1964

Columbia University Ph.D. 1967

Doctoral advisor Gilbert Stork

Known for McMurry reaction

book

•Fundamentals of Organic Chemistry, 7th Edition 2011

•Organic Chemistry: With Biological Applications, 2nd

Edition 2011

•Chemistry, 6th Edition. Pearson. 2010

•Fundamentals of General, Organic, and Biological

Chemistry, 6th Edition. Pearson. 2009

•General Chemistry: Atoms First. Pearson. 2009

•The Organic Chemistry of Biological

Pathways. Roberts & Company Publishing. 2005

•Organic Chemistry, 8th Edition. 2012 Cengage

Learning.

Professor Issa Yavari

Tarbiat Modares University

Issa Yavari was born in 1948 in Kermanshah, Iran

and studied chemistry at Pars College, Tehran, where he obtained B.Sc.

and M. Sc.

He received his Ph.D. in the area of Strain-Energy Calculations and

Dynamic NMR Studies of Medium Rings in 1977 from the University of

California, Los Angeles.

After work as Postdoctoral Fellow in the California Institute of Technology

in the field of Application of 15N NMR in Proton-Exchange Studies,

he joined the faculty at the University of Mazandaran, Iran, in 1978.

In 1984 he moved to the Tarbiat Modares University in Tehran.

His research has focused on Quantum-Mechanics Calculations,

Multicomponent Reactions, and Organic Chemistry of Phosphorus and

Sulfur.

11

1 Structure and Bonding

2 Polar Covalent Bonds; Acids and Bases

3 Organic Compounds: Alkanes and Their Stereochemistry

4 Organic Compounds: Cycloalkanes and Their Stereochemistry

5 An Overview of Organic Reactions

6 Alkenes: Structure and Reactivity

7 Alkenes: Reactions and Synthesis

8 Alkynes: An Introduction to Organic Synthesis

9 Stereochemistry

10 Organohalides

11 Reactions of Alkyl Halides: Nucleophilic Substitutions and

Eliminations

ساختار و پیوند

(Structure and Bonding)

Based on McMurry’s Organic Chemistry, 7th edition

1

13

شیمی آلی چیست؟

جانداران زنده از مواد شیمیایی آلی تشکیل شده اند

می سازند... پروتئین هایی که مو، پوست و

DNAمیراث ژنی را کنترل می کند ، غذاها و داروها و....

ساختاری مشابه ترکیبات زیر را دارند: داروي ضد التهاب غير استروئيدي

Many of the materials we use today are made by

chemical synthesis. Most of the new compounds made

today are organic.

15

منشا شیمی آلیoبنیاد شیمی آلی به اواسط سده هیجدهم بازمی گردد.

o استخراج و خالص سازی ترکیبات به دست آمده از گیاهان و جانوران، اغلب

.سخت بود

oترکیبات اغلب به سادگی دستخوش تجزیه می شدند.

oTorben Bergman سوئدی نخستین کسی بود .به تفاوت بین مواد آلی و معدنی اشاره کرد 1770که در

o از آنجاکه ترکیبات آلی از منابع زیستی بدست می آمدند، تصور

”vital force“براین بود که این ترکیبات باید شامل یک نیروی حیاتی .باشند

Torbern Olaf Bergman

16

تصور می شد که ترکیبات آلی برخالف « نیروی حیاتی » براساس نظریه .ترکیبات معدنی قابل تهیه در آزمایشگاه نیستند

شورولChevreul برخالف این مورد، صابون را از چربی 1816در سال ، .حیوانی و قلیا تهیه کرد

وهلرWohler روشی را برای تبدیل نمک معدنی آمونیم 1828درسال ، . سیانات به ماده آلی اوره پیدا کرد

Michel Eugène Chevreul

Friedrich Wöhler

17

،مطالعه ترکیبات کربن استشیمی آلی. ویژه است؟ کربنچرا

99 % میلیون ترکیب شیمیایی، کربن دارند 30از. CAS جواب بسیاری از این پرسش ها را می توان در جدول تناوبی

.مشاهده نمود

4کربن عنصری از گروهA است که می تواند چهار الکترونپیوند کوواالنسی تشکیل 4ظرفیتی را به اشتراک گذاشته و

.دهد

18

19

چرا این فصل؟

:مرور برخی ایده ها از درس شیمی عمومی

اتمها،

پیوندها و وضعیت هندسی مولکولها

20

1.1 Atomic Structure ساختار اتمی

WHAT IS AN ATOM?

o The smallest unit of

an element.

o Consists of a

central nucleus

surrounded by one

or more electrons.

WHAT IS THE NUCLEUS?

o The central part of

an atom.

o Composed of

protons and

neutrons.

o Contains most of an

atom's mass.

WHAT IS A PROTON?

o Positively charged

particle.

o Found within an

atomic nucleus.

WHAT IS A NEUTRON?

o Uncharged particle.

o Found within an

atomic nucleus.

WHAT IS AN ELECTRON?

o Negatively

charged particle.

o Located in shells

that surround an

atom's nucleus.

26

Positively charged nucleus (very dense, protons and neutrons) and small (10-15 m)

Negatively charged electrons are in a cloud (10-10 m) around nucleus

Diameter(atom) is about 2 10-10 m (200 picometers (pm))

[the unit angstrom (Å) is 10-10 m = 100 pm]

3,000,000

27

Atomic Number ( عدد اتمی) and Atomic Mass ( عدد جرمی)

The atomic number (عدد اتمی ) (Z) is The

number of protons in the atom's nucleus

The mass number ( عدد جرمی) (A) is

the number of protons plus neutrons

All the atoms of a given element have

the same atomic number:

Isotopes are atoms of the same element

that have different numbers of neutrons

and therefore different mass numbers

The atomic mass ( جرم اتمی) (atomic weight)

of an element is the weighted average mass

in atomic mass units (amu) of an element’s

naturally occurring isotopes

Timeline

.اتم ها ذرات کروی تو پر هستند: مدل دالتون -1803 مانند ها الکترون که است مثبت بار از خمیری اتم :(کشمشی کیک مدل) تامسون مدل -1897

.دارند قرار آن در کشمش

.دارد نام دار هسته اتم مدل وی پیشنهادی اتمی مدل :راترفورد مدل -1911

و دارند قرار مدار نام به ای دایره های مسیر در ها الکترون :(شمسی منظومه مدل) بور مدل -1913 .چرخند می هسته دور به معینی انرژی با

الکترونها وجود احتمال دهنده نشان :الکترونی ابر مدل -1926 مختلف مناطق در را الکترونها انرژی و الکترونها رفتار که ریاضی مدلی : کوانتمی مکانیک مدل

.کند می بیان هسته اطراف

29

1.2 Atomic Structure: Orbitals

مکانیک کوانتمیQuantum mechanics :

انرژی و احتمال وجود الکترون را توسط یک معادله موج(wave equation) .بیان می کند

تابع موج(Wave function) جواب معادله موج است

اوربیتال هر تابع موج عبارت از یکy است

نمودارy 2 آن را در جایی است که بیشترین احتمال پیداکردن یک الکترون .محدوده بدست می دهد

ابر الکترونی دارای مرز خاصی نیست، اما بیشترین احتمال آنرا در آن محدوده .نشان می دهد

30

Shapes of Atomic Orbitals for

Electrons Four different kinds of orbitals

Denoted s, p, d, and f

s and p orbitals most important in organic and

biological chemistry

s orbitals: spherical, nucleus at center

p orbitals: dumbbell-shaped, nucleus at middle

d orbitals: elongated dumbbell-shaped, nucleus at

center

31

Orbitals and Shells part 1

Orbitals are grouped in shells of increasing size and energy

Different shells contain different numbers and kinds of orbitals

Each orbital can be occupied by two electrons

32

Orbitals and Shells part 2

First shell contains one s orbital, denoted 1s, holds only two electrons

Second shell contains one s orbital (2s) and three p orbitals (2p), eight electrons

Third shell contains an s orbital (3s), three p orbitals (3p), and five d orbitals (3d), 18 electrons

33

p-Orbitals

In each shell there are three perpendicular p

orbitals, px, py, and pz, of equal energy

Lobes of a p orbital are separated by region of

zero electron density, a node ( گره)

34

1.3 Atomic Structure:

Electron Configurations Ground-state electron configuration ( آرایش الکترونی حالت پایه)

(lowest energy arrangement) of an atom

lists orbitals occupied by its electrons. Rules:

1. Lowest-energy orbitals fill first: 1s 2s 2p 3s 3p 4s 3d (Aufbau (“build-up” «بنا کردن» ) principle)

2. Electrons act as if they were spinning around an axis.

Electron spin can have only two orientations, up and down .

Only two electrons can occupy an orbital, and they must be of opposite spin (Pauli exclusion principle اصل طرد پائولی) to have

unique wave equations

3. If two or more empty orbitals of equal energy are available,

electrons occupy each with spins parallel until all orbitals have one electron (Hund's rule قاعده هوند ).

35

1.4 Development of Chemical

Bonding Theory

Kekulé and Couper

independently observed

that carbon always has

four bonds

van't Hoff and Le Bel proposed

that the four bonds of carbon

have specific spatial directions

Atoms

surround

carbon as

corners of a

tetrahedron

Jacobus Henricus

van 't Hoff, Jr.

(1852-1911)

Friedrich August Kekulé

(1829-1896)

Archibald Scott Couper

(1831 -1892)

Joseph Achille Le Bel

(1847-1930)

36

Atoms form bonds because the compound that

results is more stable than the separate atoms

Ionic bonds in salts form as a result of electron

transfers

Organic compounds have

covalent bonds from sharing

electrons (G. N. Lewis, 1916)

Gilbert Newton Lewis

(1875 -1946)

37

Lewis structures (electron dot) show valence

electrons of an atom as dots

Hydrogen has one dot, representing its 1s electron

Carbon has four dots (2s2 2p2)

Kekule structures (line-bond structures) have a line

drawn between two atoms indicating a 2 electron

covalent bond.

Stable molecule results at completed shell, octet

(eight dots) for main-group atoms (two for hydrogen)

38

Atoms with one, two, or three valence electrons form

one, two, or three bonds.

Atoms with four or more valence electrons form as

many bonds as they need electrons to fill the s and p

levels of their valence shells to reach a stable octet.

Carbon has four valence electrons (2s2 2p2), forming

four bonds (CH4).

39

Nitrogen has five valence electrons (2s2 2p3) but forms only three bonds (NH3).

Oxygen has six valence electrons (2s2 2p4) but forms two bonds (H2O)

40

Non-bonding electrons

Valence electrons not used in bonding are called

nonbonding electrons, or lone-pair electrons

Nitrogen atom in ammonia (NH3)

Shares six valence electrons in three covalent

bonds and remaining two valence electrons are

nonbonding lone pair

41

نظریه پیوند شیمیایی: ماهیت پیوندهای شیمیایی 1-5

که شوند نزدیک هم به چنان اتم دو که شود می تشکیل هنگامی کوواالنسی پیوند یک همپوشانی دیگر اتم الکترونی تک اوربیتال با آنها از یکی الکترونی تک اوربیتال یک

.نماید

دارد وجود کوواالنسی پیوند بیان برای مدل دو: Valence bond theory (ظرفیتی پیوند نظریه )

Molecular orbital theory ( مولکولی اوربیتال نظریه )

ظرفیتی پیوند نظریه Valence bond theory

به و گیرند می قرار همپوشاننده های اوربیتال در شده جفت صورت به ها الکترون شوند می جذب اتم هردو هسته وسیله

پیوند H–H 1 اوربیتال دو همپوشانی ازsشود می تشکیل هیدروژن الکترونی تک پیوند H–H سیگما پیوند و دارد ای استوانه تقارن sigma (s) bond شود می نامیده.

42

Bond Energy

Reaction 2 H· H2 releases 436 kJ/mol

Product has 436 kJ/mol less energy than two atoms:

H–H has bond strength of 436 kJ/mol or 104 kcal/mol).

(1 kJ = 0.2390 kcal; 1 kcal = 4.184 kJ)

43

Bond Length طول پیوند

هسته بین بهینه فاصله از عبارت بیشترین به منجر که هاست

شود می پایداری نزدیک بسیار هم به ها هسته اگر

هر بار بودن مثبت دلیل به باشند، کنند می دفع را یکدیگر دو،

به قادر باشند، دور هم از اگر

ظرفیتی الکترونهای اشتراک بود نخواهند

44

Using the Valence-Bond Method to Describe a

Molecular Structure Describe the phosphine molecule, PH3 by the valence-bond method.

The predicted H-P-H bond angle is 90o, and the

experimentally measured bond angles are 93o to 94o.

These are in good agreement.

1.6 sp3 Orbitals and the Structure

of Methane

45

bond angles = 109.5°

bond distances = 110 pm

Methane - CH4

Applying simple VB theory results in the following prediction for

methane bonding:

According to this model, the C is bonded to only two H-atoms with

an H-C-H bond of ……?….°.

This is NOT what is observed for methane!

C Hybridisation 1s 2s 2p

z y

z y

z y

z y

z y

1s orbital 2s orbital

2px orbital 2py orbital 2pz orbital

Incre

asin

g

en

erg

y

2s

2p

hybridised orbitals

SP3 orbitals:

Methane

49

Carbon has 4 valence electrons (2s2 2p2)

In CH4, all C–H bonds are identical (tetrahedral)

sp3 hybrid orbitals: s orbital and three p orbitals combine to form four equivalent, unsymmetrical, tetrahedral orbitals (sppp = sp3), Pauling (1931)

Linus Carl Pauling

(1901 –1994)

50

The Structure of Methane

sp3 orbitals on C overlap with 1s orbitals on 4 H atoms to form four identical C-H bonds

Each C–H bond has a strength of 436 kJ/mol and length of 109 pm

Bond angle: each H–C–H is 109.5°, the tetrahedral angle.

51

1.7 sp3 Orbitals and the Structure

of Ethane Two C’s bond to each other by s overlap of an sp3

orbital from each

Three sp3 orbitals on each C overlap with H 1s orbitals to form six C–H bonds

C–H bond strength in ethane 423 kJ/mol

C–C bond is 154 pm long and strength is 376 kJ/mol

All bond angles of ethane are tetrahedral

Ethane:

CH3-CH3

53

1.8 sp2 Orbitals and the Structure

of Ethylene sp2 hybrid orbitals: 2s orbital combines with two 2p

orbitals, giving 3 orbitals (spp = sp2). This results in a double bond.

sp2 orbitals are in a plane with120° angles

Remaining p orbital is perpendicular to the plane

Incre

asin

g

energ

y

2s

2p

hybridised orbitals

single unhybridised

2p orbital

SP2 orbitals:

Ethylene

56

Bonds From sp2 Hybrid Orbitals

Two sp2-hybridized orbitals overlap to form a s bond

p orbitals overlap side-to-side to formation a pi () bond

sp2–sp2 s bond and 2p–2p bond result in sharing four electrons and formation of C-C double bond

Electrons in the s bond are centered between nuclei

Electrons in the bond occupy regions are on either side of a line between nuclei

57

Structure of Ethylene

H atoms form s bonds with four sp2 orbitals

H–C–H and H–C–C bond angles of about 120°

C–C double bond in ethylene shorter and stronger than single bond in ethane

Ethylene C=C bond length 134 pm (C–C 154 pm)

58

1.9 sp Orbitals and the Structure of

Acetylene

C-C a triple bond sharing six electrons

Carbon 2s orbital hybridizes with a single p orbital giving two sp hybrids

two p orbitals remain unchanged

sp orbitals are linear, 180° apart on x-axis

Two p orbitals are perpendicular on the y-axis and the z-axis

Acetylene

C2H2

One s-bond

& two -bonds

61

Orbitals of Acetylene

Two sp hybrid orbitals from each C form sp–sp s bond

pz orbitals from each C form a pz–pz bond by sideways overlap and py orbitals overlap similarly

62

Bonding in Acetylene

Sharing of six electrons forms C C

Two sp orbitals form s bonds with hydrogens

Double and Triple Bonds

65

66

1.10 Hybridization of Nitrogen and

Oxygen

Elements other than C can have hybridized orbitals

H–N–H bond angle in ammonia (NH3) 107.3°

C-N-H bond angle is 110.3 °

N’s orbitals (sppp) hybridize to form four sp3 orbitals

One sp3 orbital is occupied by two nonbonding

electrons, and three sp3 orbitals have one electron

each, forming bonds to H and CH3.

67

1.11 Molecular Orbital Theory

A molecular orbital (MO): where electrons are most likely to be found (specific energy and general shape) in a molecule

Additive combination ترکیب جمعی (bonding) MO is lower in

energy

Subtractive combination تفریقی ترکیب (antibonding) MO is

higher energy

68

Molecular Orbitals in Ethylene

The bonding MO is from combining p orbital lobes

with the same algebraic sign

The antibonding MO is from combining lobes with

opposite signs

Only bonding MO is occupied

69

1.12 Drawing Structures

Drawing every bond in organic molecule can

become tedious.

Several shorthand methods have been

developed to write structures.

Condensed structures don’t have C-H or C-C

single bonds shown. They are understood.

e.g. (ساختارهای متراکم)

70

3 General Rules:

1) Carbon atoms aren’t usually shown. Instead a

carbon atom is assumed to be at each intersection

of two lines (bonds) and at the end of each line.

اتم های کربن معموال نشان داده نمی شوند( 1

2) Hydrogen atoms bonded to carbon aren’t shown.

اتم های هیدروژن متصل به کربن نشان داده نمی شوند( 2

3) Atoms other than carbon and hydrogen are shown

(See table 1.3).

سایر اتم ها نشان داده می شوند( 3

71

72

Journal of Chemical Education, 1988, 65, 1036.