Chapter 14: Introduction to Organic Chemistry

What is a ketone?

-Monosaccharide made from ketone, -C=O in the middle, general formula is CnH(2n + 1)COCmH(2m + 1), like propanone CH3 COCH3

Use those three to describe Propene?

-an organic compound called propene has the empirical formula CH2. This tells us that it has twice as many hydrogen atoms as carbon atoms in its molecules. -molecular formula The relative molecular mass of propene is 42. We know that its empirical formula is CH2; this CH2 group of atoms has a relative mass of 14, as the relative atomic mass of C = 12 and H = 1. By dividing the relative molecular mass by the relative mass of the empirical formula (42/14 = 3), we see that there must be (3 × CH2) atoms in a propene molecule. So its molecular formula is C3H6. -the structural formula of propene is CH3HC=CH2 (also written as CH3CH=CH2 - but the central H atom does not form a double bond!). This tells us how many hydrogen atoms are bonded to each carbon atom, and that two of the carbon atoms in the molecule are joined by a double bond.

How do you name an organic compound with an alkane and an alkyl?

-by adding -yl to the normal alkane stem, in this case a methyl group. This type of group is called an alkyl group. If there is more than one of the same alkyl side-chain or functional group we indicate how many by inserting di (for two), tri (for three) or tetra (for four) in front of its name. -Note that adjacent numbers in a name have a comma between them, whereas numbers and words are separated by hyphens. -If there is more than one type of alkyl side-chain, they are listed in the name in alphabetical order

What are the types of stereoisomerism?

-cis-trans isomerism -optical isomerism

How do covalent bonds break?

-homolytic fission -heterolytic fission

What are the types of structural isomers?

-position isomerism -functional group isomerism -chain isomerism.

What is a hydrolysis reaction?

A hydrolysis reaction is when one H20 molecule is add to break apart di/polysaccharides. Hydrolysis is the breakdown of a molecule by water. This type of reaction is often speeded up by acid or alkali.

What is a molecular formula?

A molecular formula is the actual number of atoms of each element in a molecule, find this we need to know the relative molecular mass of the compound.

What is a free radical?

A molecule that is unstable and highly reactive because it contains unpaired electrons, the species produced when a bond breaks homolytically.

What is the effect of optical isomers in polarized light?

A pair of optical isomers will rotate the plane of polarised light by equal amounts but in opposite directions. One will rotate polarised light clockwise and the other anticlockwise.

What is an addition reaction?

A reaction in which a reagent adds to the two carbon atoms of a carbon-carbon multiple bond. Involve the formation of a single product from two reactant molecules.

What is an initiation step?

A reaction where a non-radical molecule is split into radicals by absorption of high energy radiation. This type of reaction involves the formation of the free radicals in an initiation step. This requires an input of energy to break a covalent bond, resulting in two free radicals.

What is a propagation step?

A reaction where a radical and a non-radical react to form a radical and a non-radical molecule. The radicals formed can then attack reactant molecules, generating more free radicals. These reactions are called propagation steps. They can be thought of as a chain reaction, which only stops when free radicals react with each other.

What is a termination step?

A reaction where two radicals react to form a non-radical molecule. Two free radicals reacting together will form a molecule, with no free radicals generated. Therefore this is called a termination step.

What is a structural formula?

A structural formula shows the atoms carbon by carbon, with the attached hydrogens and functional groups.

What is a general formula?

An algebraic formula that can describe any member of a family of compounds by substituting a number for n in the general formula you get the molecular formula of a particular compound containing that functional group. Note that this formula assumes there is just one functional group present in the molecule.

What is a halogenoalkane?

An alkane with at least one halogen atom in place of a hydrogen atom, with the general formula of CnH(2n + 1)X (where x is the Halogen). Like Chloromethane CH3Cl.

What is a carbocation?

An organic ion containing a positively charged carbon atom, when the heterolytic fission of a bond can involve a C-X bond, where X is an atom more electronegative than carbon. As the bond breaks, atom takes both the shared electrons, forming an anion. Leaving the alkyl group one electron short, resulting in formation of a positively charged ion.

What is an oxidation reaction?

An oxidation reaction is a reaction in which a molecule looses its electrons. It releases energy. Oxidation is the addition of oxygen atoms to a molecule and/or the removal of hydrogen atoms from a molecule.

What is an aryl group?

Aryl compounds contain at least one benzene ring. A benzene molecule has six carbon atoms arranged in a hexagon, with each carbon atom bonded to one hydrogen atom. Benzene is an arene group that has the general formula of C6H5-

A compound contains the elements carbon, hydrogen and oxygen. Its empirical formula is CH2O and its relative molecular mass is 60. What is the molecular formula of the compound?

C2H6O2

What is an ethyl group?

CH2CH3

What is a nitrile group?

CN- where carbon has a triple bond with nitrogen, the general formula is CnH(2n + 1)CN, like ethanenitrile; CH3CN.

Why do carbon atoms form pi bonds?

Carbon can also form double bonds between its atoms in organic molecules, as well as forming single bonds. A C=C double bond, as found in alkenes such as ethene, is made up of a σ bond and a pi (π) bond.

Why does carbon form single covalent bonds?

Carbon has four valence electrons, by forming single covalent bonds with four other atoms, a carbon atom can gain the electronic configuration of the noble gas neon. These single covalent bonds are known as sigma (σ) bonds.

What is structural isomerism?

Compounds with the same molecular formula but different structural formulae.

What is heterolytic fission?

Covalent bond breaks and both electrons move to one atom. Two oppositely charged ions are formed. The second type of bond breaking involves the 'uneven' breaking of a covalent bond.

On analysis a hydrocarbon was found to contain 0.72 g of carbon and 0.18 g of hydrogen. What is the empirical formula and relative molecular formula of the hydrocarbon?

Find out the ratio of moles, C:H 72/12=0.06, 0.18/1.0=0.18, the simplest whole number ratio is 1:3. So the empirical formula is CH3. And the relative molecular formula is 30 so the molecular formula is C2H6.

What is an ester?

Form when organic acids react with alcohols. Flowers produce esters and esters are used for artificial fruit flavors. General formula is CnH(2n + 1)COOCmH(2m + 1), like ethyl ethanoate; CH3COOC2H5.

What is an optical isomer?

If a molecule contains a carbon atom that is bonded to four different atoms or groups of atoms, it can form two optical isomers. The two different molecules are mirror images of each other and cannot be superimposed. The carbon atom with the four different groups attached is called the chiral centre of the molecule.

How do aryl and alkyl groups bond?

If only one alkyl group is bonded to a benzene ring, we do not have to include a number in the name as all six carbon atoms in the ring are equivalent. With two or more alkyl groups, we need to indicate their positions.

What are possible filling valency of carbons in an aldehyde?

If the valency of carbon is filled with hydrogen the formula is HCHO, if it is filled with a methyl group; the member will be CH3CHO. If it is filled with an ethyl group, the member will be C2H5CHO.

Describe carbocation's positive inductive effect?

In carbocations the more alkyl groups attached to the positively charged carbon, the less the charge density is on the carbon atom with the three covalent bonds. The Organic intermediates formed throughout are energetically more stable when any charge on a species is not concentrated in one place but is spread over several atoms.

How does heterolytic fission work?

In heterolytic fission the more electronegative atom takes both the electrons in the covalent bond. A small curly arrow shows the movement of a pair of electrons.

How is a pi bond formed within a C=C double bond of an alkene?

It is formed above and below the plane of carbon atoms by sideways overlapping of p orbitals. The two lobes that make up the π bond lie above and below the plane of the atoms in an ethene molecule.

Why do the two lobes in c=c overlap sideways?

It maximizes overlap of the p orbitals.

What is polarized light?

Normal light is unpolarised. It can be thought of as fluctuating electric and magnetic fields, vibrating at right angles to each other in every possible direction.

How is polarized light created?

Passing this unpolarised light through a polariser results in polarised light, which vibrates in only one plane.

What is a substitution reaction?

Reaction in which one atom (or group of atoms) replaces another atom (or group) within a molecule. Substitution reactions involve the replacement of one atom, or a group of atoms, by another.

What is stereoisomerism?

Same structural formula but different arrangement of atoms in space, we have compounds whose molecules have the same atoms bonded to each other but with different arrangements of the atoms in space.

What is a skeletal formula?

Shows the simplified organic formula, shown by removing hydrogen atoms from alkyl chains, leaving just a carbon skeleton and associated functional groups. gen, and their bonds, are included in the skeletal formula of an organic molecule.

What is an aldehyde?

Terminal group with a carbon double-bonded to an oxygen. One valency of carbon is free to combine.(R-CO-H). H-C=O. With the general formula of CnH(2n + 1)CHO like ethanal CH3CHO.

What is the structure of c=c bonds?

The carbon atoms involved in the double bond are each surrounded by three pairs of electrons in the σ bonds. These are all in the plane of the molecule and repel each other to give bond angles of about 120°.

How do the carbons form pi bonds?

The carbon atoms involved in the double bond will each form three sigma bonds it is SP2 hybridization. This leaves each carbon atom with one spare outer electron in a 2p orbital, when these two p orbitals overlap they form a pi bond.

How do we name organic compounds?

The class of hydrocarbons called alkanes provide the basis of the naming system. The stem of each name indicates how many carbon atoms are in the longest chain in one molecule of the compound.

What do we mean by positive inductive effect?

The electrons away from themselves. We say that the electron-donating nature of alkyl groups has a A positive inductive effect on adjacent groups.

How is the electrostatic forces between the sigma bonds?

The four bonding pairs of electrons around each carbon atom repel each other. They position themselves in a tetrahedral arrangement to get as far apart from each other as possible. The tetrahedral bond angle is 109.5°

How are chains written using functional groups?

The position of side-chains or functional groups is indicated by numbering the carbon atoms in the longest chain. The numbering starts at the end that produces the lowest possible numbers in the name.

What is an empirical formula?

The simplest whole number ratio of atoms of each element in a compound

What is position isomerism?

There is a free rotation about the C-C single bonds, it is the position of the functional group that varies in each isomer, eg C3H6Br2. No different chemical properties.

Why are these two stereoisomers different?

They have different arrangements of the atoms in space so they are different compounds with different physical properties and some different chemical properties, e.g. differing rates for the same reaction.

What is a sigma bond?

Two atomic orbitals combined to form a molecular orbital that is symmetrical around the axis connecting two atomic nuclei.

What is cis-trans isomerism?

Two of the groups are the same attached to the C=C. Unlike a C C single bond, there is no free rotation about a C=C double bond. This results in the possibility of a different type of isomerism in unsaturated organic compounds. Whenever we have unsaturated compounds with the structures, we can have this cis-trans type of isomerism.

Why do we use numbering systems?

We also use the numbering system where necessary to indicate the position of the functional group in a molecule. For some functional groups no number is needed because the group can only be positioned at the end of a chain.

What is Functional group Isomerism?

When isomers have different functional groups to each other. For example, given the molecular formula C3H8O we can draw both an alcohol and an ether. These two isomers have different functional groups and so have very different chemical properties.

What is chain isomerism?

When the hydrocarbon chain is arranged differently (such as branching). They differ in the structure of their carbon 'skeleton'. For example, butane and methylpropane are chain isomers, both with the molecular formula of C4H10.

What is an elimination reaction?

When the leaving group and a proton on an adjacent carbon both leave to form a double bond. Elimination reactions result in the removal of a small molecule from a larger one.

What is homolytic fission?

Where each bonding atom receives one electrons from the shared pair, forming two radicals. Both the atoms at each end of the bond leave with one electron from the pair that formed the covalent bond.

What is a hydrocarbon?

a compound made of hydrogen and carbon atoms

What is a functional group?

a group of atoms responsible for the characteristic reactions of a particular compound. Different classes of compounds have different functional groups. Eg: The functional group in an alkene is the C=C double bond. The functional group in a carboxylic acid is the —COOH group.

what is an alkene?

a hydrocarbon with a carbon-carbon double bond, the general formula is CnH2n. Eg: Ethene.

What is a carboxylic acid?

any compound containing a carbonyl with a hydroxyl substituent on the carbonyl carbon. Like CnH(2n + 1)COOH. Eg: ethanoic acid; CH3COOH.

What is an amine?

any organic compound that contains a basic nitrogen atom, the general formula is CnH(2n + 1)NH2, like methylamine; CH3NH2

Describe the structure 1,2-dibromoethene?

both the Br atoms remain fixed on the same side of the C=C double bond

What is a methyl group?

carbon bonded to 3 hydrogens CH3

Where is the pair of electrons in a sigma bond?

found in a region of space (described as a lobe) between the nuclei of the two atoms sharing the electrons. The electrostatic attraction between the negatively charged electrons and the two positively charged nuclei bonds the atoms to each other.

Name the first ten alkanes

methane CH4, ethane C2H6, propane C3H8, butane C4H10, pentane C5H12 , hexane C6H14, heptane C7H16, octane C8H18, nonane C9H20, decane C10H22

What is an alcohol?

organic compound with a hydroxyl group attached to one of its carbon atoms, the general formula is CnH(2n + 1)OH, for example methanol CH3OH.

What does nucleophile mean?

species that can act as a donor of a pair of electrons.

What does electrophile mean?

species that can act as an acceptor of a pair of electrons in an organic mechanism.

Explain the representation?

the 'wedge' bond is sticking out of the plane of the paper and the 'dashed-line' bond is sticking into the plane of the paper.

Describe trans-1,2-dibromoethene?

the Br atoms are positioned across the C=C double bond. (Remember that the prefix 'trans-' means across.)

What is a reduction reaction?

the removal of oxygen from a substance and or the addition of hydrogens or electrons to a substance. Reduction is the chemical opposite of oxidation.

How is carbocation's electronegativity?

when carbocations are formed as intermediates in reactions, the tertiary carbocation is most likely to form as its positive charge is, in effect, 'smeared' over the C+ atom and the three carbon atoms it is bonded to.