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Organic Chemistry 1
به نام خدا
Dr Morteza Mehrdad
University of Guilan, Department of Chemistry,
Rasht, Iran [email protected]
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.
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
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
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 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
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
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
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
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