TASHKENT MEDICAL ACADEMY Department of Bioorganic and Biological Chemistry Bioorganic chemistry FIRST COURSE SUBJECT: Mutual influence of atoms in molecules of organic compounds, and methods of transmission. PAIRING. Aromaticity. Acidic and basic organic compounds. LECTURE №2 LECTURER: PROFESSOR A.D.DZHURAEV

The purpose of the lecture Generate knowledge of electronic effects as the main mode of transmission of mutual influence of atoms and electronic structure of molecules with conjugated bonds as thermodynamically stable systems that are used in the construction of biologically important compounds, as well as build knowledge of acidity and basicity of organic compounds as the most important properties that determine most of the chemical reactions in living organisms.

The Questions of: Types of systems Stability of conjugated systems Types of pairing Aromaticity, the criteria of aromaticity Spatial effects Acidity of organic compounds Most of the organic compounds

Spatial structure of organic compounds (stereoisomers). CONFIGURATION Configuration - This spatial arrangement of atoms or atomic groups WITHOUT possible conformations. EthaneAminoethanol

Conformation Conformation - This different geometric shapes into each other and the resulting atomic groups Spin Around One or more  - Communication. Eclipsed Canted Inhibited

Energy different conformations 0 o 60 o 120 o 180 o 240 o 300 o energy kJ / mol Torsion angle Eclipsed Inhibited canted

Conformation of cyclic compounds "Chair" form "Bath" form "Twist" form

Mutual influence of atoms in the molecule and the way it TRANSMISSION Inductive effect INDUCTIVE EFFECT - mutual influence of atoms SUBMITTED On  - Communication

Mesomeric effect Mesomeric effects - electronic influence vice Submitted On  - Communication.

ELECTRON-DONATING SUBSTITUENTS - DEPUTY SHIFTS THE ELECTRON DENSITY FROM THE SELF. TO TREAT THEM - NR2, - NHR, - NH2, - OH, - OR, - CH3, -I, -BR, -CL, -F ELECTRON-WITHDRAWING SUBSTITUENTS - DEPUTY SHIFTS THE ELECTRON DENSITY TO THE ME. TO TREAT THEM-NO3, -CN, -SO3H, -COOR, -COOH, -CHO Electron-donor and electron-withdrawing substituents

1. CUMULATED SYSTEM  С = С = С = С = С – С = С = С =С  2. ISOLATED SYSTEM  С = С - (СН 2 )N – С = С   3. CONJUGATE SYSTEM  С = С - С = С - С = С - С = С          TYPES OF SYSTEMS

OPEN INTERFACE CIRCUIT СН 2 = СН - СН = СН 2 BUTADIENE - 1,3 CONJUGATE SYSTEMS

Conjugated systems With Closed Circuit CIRCUIT INTERFACE

TYPES OF INTERFACE ,  -pairing - when p - orbitals of all-chain atoms are involved in the formation of  - electron cloud, and the formation of  - communication

TYPES OF INTERFACE р,  - conjugation – when р- orbitals of the heteroatom involved only in education  -electron cloud, but not in education  -communication СН 2 = СН – CI VINYL CHLORIDE

1. THE SYSTEM SHOULD HAVE CLOSED FLAT  - SKELETON 2. ALL ATOMS IN THE CHAIN MUST BE IN SP2-HYBRIDIZATION 3. RULE HUCKEL SYSTEM SHOULD CONTAIN 4 N + 2  ELECTRONS Criteria for aromaticity

BRONSTED ACIDS - ARE NEUTRAL MOLECULES OR IONS, ARE ABLE TO GIVE PROTON (PROTON DONOR). ACIDITY ORGANIC COMPOUNDS А - Н + : В  А- + В – Н Acid basis conjugate conjugate base acid

СН 3 СООН + Н 2 О  СН=СОО- + Н 3 О+ ACETIC ACID BASE ACETATE ION HYDRONIUM ION. (СОПРЯЖЕННОЕ ОСНОВ) (СОПРЯЖЕННАЯ К-ТА) FOR THE REACTION EQUILIBRIUM CONSTANT EQUAL : Equilibrium constant   ΟΗ C ΟΟ НC Η ΟΗ C C Η Κ  

ACIDITY CONSTANT EQUAL VALUE: Р К А = – LG К А acidity constant Product K * [H2O] is constant acidity (Ka)      Н    C C CC KK a *

О - Н ACID CARBOXYLIC ACIDS, ALCOHOLS, PHENOLS S – H ACID THIOLS, THIOETHERS N – H ACID AMIDES, AMINES, IMIDES C – H ACID HYDROCARBONS AND THEIR DERIVATIVES Bronsted acid:

1. ON THE ABILITY OF THE ATOMS ARE BONDED TO HYDROGEN, KEEP YOURSELF IN ELECTRON PAIR AFTER THE DEPARTURE OF THE PROTON (OT ITS ELECTRONEGATIVITY) 2. THE SIZE OF THE ATOM IS BONDED WITH HYDROGEN (ATOMIC POLARIZABILITY) 3. FROM POSSIBLE DELOCALIZATION (REDISTRIBUTION) OF NEGATIVE CHARGE ON THE OTHER ATOMS (ON THE PRESENCE OF CONJUGATED SYSTEMS) 4. ON THE ABILITY OF THE SOLVATED ANION Stability anion depends on the following factors:

С 2 Н 5 ОН = С 2 Н 5 О- + Н+ С 2 Н 5 SН = С 2 Н 5 S- + Н+ С 2 Н 5 SН > С 2 Н 5 ОН acidic compounds

СН– ACID< NH – ACID< OH- ACID<SH- ACID Increasing the power acidity among Bronsted acid CHOH C CH 3 OH C 2 H 5 (CH 3 ) 2 (CH ) 3 3 HCOOH> 3 CH COOH>(CH 3 ) 3 C - COOH

REASONS BRONSTED - THIS NEUTRAL MOLECULES OR IONS, WHICH TAKE PROTON (PROTON ACCEPTOR) REASONS BRONSTED Distinguish between two types of Bronsted Reasons: π- GROUNDS n-GROUNDS (onium )

THESE REASONS TO APPLY - ALKENES, ALKADIENES, ARENA. CENTER OF MAIN, THAT IS THE POINT OF ATTACHMENT OF THE PROTON, IS THE ELECTRONIC π -COMMUNICATIONS. π-ОСНОВАНИЯ

DEPENDING ON THE NATURE OF THE HETEROATOM, THAT IS BY CENTER MAINLY DIFFER: А) AMMONIUM Б) OXONIUM В) SULFONIUM n-GROUNDS (onium )