Alkanes and Alkenes
- an alkane, or paraffin, is an acyclic saturated hydrocarbon. In other words, an alkane consists of hydrogen and carbon atoms arranged in a tree structure in which all the carbon–carbon bonds are single. Alkanes have the general chemical formula CₙH₂ₙ₊₂.
- an alkene is an unsaturated hydrocarbon that contains at least one carbon–carbon double bond. The words alkene and olefin are often used interchangeably.
- If a compound contains a double bond, its name ends with ene, A number prefix is used to denote the position of the unsaturation
Nucleophiles and Electrophiles
- In organic chemistry reactions happen between an electrophile and a nucleophile
- Nucleophile is a chemical species that donates an electron pair to form a chemical bond in relation to a reaction. All molecules or ions with a free pair of electrons or at least one pi bond can act as nucleophiles. Because nucleophiles donate electrons, they are by definition Lewis bases.
- an electrophile is an electron pair acceptor. Electrophiles are positively charged or neutral species having vacant orbitals that are attracted to an electron rich centre. It participates in a chemical reaction by accepting an electron pair in order to bond to a nucleophile. It can also have a positive charge , a partially positive charge or an empty orbital available.
- A nucleophile has a lone pair, or electron pairs in π-bonds, that attacks an electrophile; an atom deficient in electrons. Since the electrons are what is in movement, and thus “attacks” the electrophile, nucleophilic attacks would be the term used.
Stability of Carbocations
- A carbocation is an ion with a positively charged carbon atom. Among the simplest examples are the methenium CH⁺ ₃, methanium CH⁺ ₅ and vinyl C ₂H⁺ ₃ cations. Occasionally, carbocations that bear more than one positively charged carbon atom are also encountered.
- Alkyl groups are electron donating groups by inductive effect
- Electrophilic addition of an unsymmetrical reagent to an unsymmetrical double bond proceeds in such a way as to involve the most stable carbocation
Addition of Halogens
- The halogens are a group in the periodic table consisting of five chemically related elements: Fluorine, Chlorine, Bromine, Iodine (I), and Astatine. The artificially created element 117 may also be a halogen. In the modern IUPAC nomenclature, this group is known as group 17.
- If a compound contains a triple bond, its name ends with “yne”. A number prefix is used to denote the position of the unsaturation.
- The haloalkanes are a group of chemical compounds derived from alkanes containing one or more halogens. They are a subset of the general class of halocarbons, although the distinction is not often made. Haloalkanes are widely used commercially and, consequently, are known under many chemical and commercial names.
- It is assumed that the stronger the acid, the more stable the conjugate base X. Apart from the H-F all the other acids are strong acids with small differences
- Atoms, ions or molecules that have an electron pair that have an electron pair that may be donated in forming a covalent bond to an electrophile
- It is possible to classify species in order of Nucleophilicity. The most reactive nucleophiles are said to be more nucleophilic than the less reactive.
- For a given element, negatively charged species are more nucleophilic than neutral species
- Nucleophilicity decreases on moving from left to right in a period of the periodic table
- Nucleophilicity increases from top to bottom along a group of the periodic table
- In different solvents the order of nucleophilicity could change slightly
- The degree of substitution on the carbon has a great effect on the SN2
- The reaction rates depend on the concentration of B and the haloalkane
- An elimination reaction is a type of organic reaction in which two substituents are removed from a molecule in either a one or two-step mechanism. The one-step mechanism is known as the E2 reaction, and the two-step mechanism is known as the E1 reaction.
- In chemistry, an alcohol is any organic compound in which the hydroxyl functional group (–OH) is bound to a carbon. The term alcohol originally referred to the primary alcohol ethanol (ethyl alcohol), which is used as a drug and is the main alcohol present inalcoholic beverages.
- Is a primarily electrostatic force of attraction between a hydrogen (H) atom which is covalently bound to a more electronegative atom or group, particularly the second-row elements nitrogen (N), oxygen (O), or fluorine (F)—the hydrogen bond donor (Dn)—and another electronegative atom bearing a lone pair of electrons—the hydrogen bond acceptor (Ac).
- A special type of attractive interaction that exists between an electronegative atom and a hydrogen atom bonded to another electronegative atom.
- The cells of living things are made up of many different sorts of molecules. Two important classes of molecules are nucleic acids and proteins
- Part of these very large molecules are involved in hydrogen bonds with other parts of the same molecules
- Hydrogen bonding plays an important role in determining the three-dimensional secondary structures of proteins
- Hydrogen bonds form between a backbone oxygen and an amide hydrogen to form more frequently either the a-helix or the b-sheet secondary structure of proteins.
Formation of Alkyl Halides
- Alkyl halides (also known as haloalkanes) are compounds in which one or more hydrogen atoms in an alkane have been replaced by halogen atoms (fluorine, chlorine, bromine or iodine).
Elimination of Water
- The elimination of water from an alcohol is called dehydration. Recalling that water is a much better leaving group than hydroxide ion, it is sensible to use acid-catalysis rather than base-catalysis in such reactions.
- Alcohols react with carboxylic acid and carboxylic acid derivatives to give esters as products
- Esters and water are formed when alcohols react with carboxylic acids. This reaction is called esterification, which is a reversible reaction. This type of reaction is called a condensation reaction, which means that water molecules are eliminated during the reaction.
- Alcohol oxidation is very important in organic synthesis
Redox Reactions and Enzymes
- Redox is a type of chemical reaction in which the oxidation states of atoms are changed. Redox reactions are characterized by the transfer of electrons between chemical species, most often with one species undergoing oxidation while another species undergoes reduction.
- Biochemical reactions in living organisms are essentially transfers of energy. Often they occur together, linked in a chain, in what are referred to as oxidation/reduction reactions
- In oxidation/ reduction reactions, one chemical is oxidized and its electrons are passed to another chemical. Such coupled reactions are referred to as redox reactions.
- Important metabolic processes such as glycolysis, Kreb’s cycle and electron transport phosphorylation involve the transfer of electrons by redox reactions
- Enzymes are proteins that accelerate chemical reactions in living organisms
- Device for estimating blood alcohol content (BAC) from a breath sample
- Newer breathalyzer use spectroscopic analysis of the breath trapped in the sample cell and measure and analyze the alcohol contained in it
Aromatic Compounds and Eas
- Aromatic compounds must have a cyclic cloud of delocalized p electrons above and below the plane of the ring
- The characteristic of aromatic compounds are the following: high degree of unsaturation, give substitution rather than addition reactions
- High stability
- Planar structure
Biologically Relevant Examples
- Folic acid, Pteroyl- L- glutamic acid, vitamin Bc are necessary for the production and maintenance of new cells.
- The adjective aromatic is used by organic chemists in a rather different way than is normally applied
- It has origins in the observation that certain natural substances such as cinnamon bark, wintergreen leaves, vanilla beans and anise seeds contained fragrant compounds having common but unexpected properties.
- Such compounds have a very low C to H ratio and therefore it was hypothesized that they might contain double bonds
- Benzene is an organic chemical compound with the chemical formula C₆H₆. The benzene molecule is composed of six carbon atoms joined in a ring with one hydrogen atom attached to each. As it contains only carbon and hydrogen atoms, benzene is classed as a hydrocarbon.
- Aromatic compounds must have a cyclic cloud of delocalized p electrons above and below the plane of the ring
Electrophilic Aromatic Substitution
- Electrophilic aromatic substitution is an organic reaction in which an atom that is attached to an aromatic system is replaced by an electrophile.
- The reaction involves a substitution started by an electrophilic species
- a carbonyl group is a functional group composed of a carbon atom double-bonded to an oxygen atom: C=O. It is common to several classes of organic compounds, as part of many larger functional groups. A compound containing a carbonyl group is often referred to as a carbonyl compound.
- The ending for a ketone is-one; a keto group is numbered to give the carbonyl group the lowest number
Reactivity of Carbonyls
- The ability of the carbonyl O to accommodate a negative charge determines the main chemistry of the group by providing a site for nucleophilic attack at the C
- The main reaction is Nucleophilic Addition, the carbonyl behaves as an electrophile
- Aldehydes are more reactive
- nucleophilic addition reaction is an addition reaction where a chemical compound with an electron-deficient or electrophilic double or triple bond, a π bond, reacts with electron-rich reactant, termed a nucleophile, with disappearance of the double bond and creation of two new single, or σ, bonds.
- The reactions are involved in the biological synthesis of compounds in the metabolism of every living organism, and are used by chemists in academia and industries such as pharmaceuticals to prepare newest complex organic chemicals, and so are central to organic chemistry.
- The chemistry of carbohydrates most closely resembles that of alcohol, aldehyde, and ketone functional groups. As a result, the modern definition of a CARBOHYDRATE is that the compounds are polyhydroxy aldehydes or ketones.
- Oxidation is the loss of electrons during a reaction by a molecule, atom or ion. Oxidation occurs when the oxidation state of a molecule, atom or ion is increased. The opposite process is called reduction, which occurs when there is a gain of electrons or the oxidation state of an atom, molecule, or ion decreases.
- Aldehydes are very readily oxidized; ketones with difficulty
- A carboxylic acid is an organic compound that contains a carboxyl group. The general formula of a carboxylic acid is R–COOH, with R referring to the rest of the molecule. Carboxylic acids occur widely. Important examples include the amino acids and acetic acid.
Structure and Acidity
- The inductive effect: The acidity of a carboxylic acid can increase if electrowithdrawing atoms or groups are attached to it
General Formula and structure
- In organic and inorganic chemistry, nucleophilic substitution is a fundamental class of reactions in which an electron rich nucleophile selectively bonds with or attacks the positive or partially positive charge of an atom or a group of atoms to replace a leaving group; the positive or partially positive atom is referred to as an electrophile. The whole molecular entity of which the electrophile and the leaving group are part is usually called the substrate. The nucleophile essentially attempts to replace the leaving group as the primary substituent in the reaction itself, as a part of another molecule.
- Hydrolysis is any chemical reaction in which a molecule of water ruptures one or more chemical bonds. The term is used broadly for substitution, elimination, and fragmentation reactions in which water is the nucleophile.
- the chemical breakdown of a compound due to reaction with water.
- Esters instead can’t be formed from amides
- An amide, also known as an acid amide, is a compound with the functional group RₙEₓNR′₂. Most common are carboxamides, but many other important types of amides are known, including phosphoramides and sulfonamides. The term amide refers both to classes of compounds and to the functional group within those compounds.
- In living cells, amide formation is catalyzed by enzymes. Proteins are polyamides; they are formed by joining amino acids into long chains.