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Regents Chemistry Organic Chemistry Review

For the organic chemistry topic on the Regents Chemistry exam, we will use the following three tables from the Reference Table.























Table Q shows three homologues series of hydrocarbons: alkanes, alkenes and alkynes.


Alkanes have all single bonds and are considered saturated. Alkenes have a double bond. Alkynes have a triple bond. Alkenes and alkynes are considered unsaturated because they have double and triple bonds.


The general formulas for each type of hydrocarbon is given in the table as well. For example, the general formula for an alkene is CnH2n. If we want to know the formula for an alkene containing 5 carbons, we can calculate the number of hydrogens by doing 5*2 = 10, C5H10.

What is the formula for an alkane containing 5 carbons? C5H2*5+2 = C5H12





Table P shows the prefix for the number of carbons in a chain. For example, the name of an alkane containing three carbons must be propane.



















Table R presents classes of organic compounds, functional groups, and examples with names.

Some of the questions on the Regents exam ask to recognize a functional group.


We can also be asked to name a compound with a specific functional group. For this type of question, we need to look at the example of the name for the specific functional group. For example, if a molecule has an OH functional group, its name should end in "ol" (the example in the chart is 1-propanol).












Organic Reactions


Addition: You will recognize an addition reaction by seeing alkene (CnH2n) + X2 (X can be Cl, Br, I or F) on the reactant side.

Example: C3H6 + Cl2 → C3H6Cl2


Substitution: You will recognize substitution by seeing alkane ( CnH2n+2) + X2 (X can be Cl, Br, I or F) on the reactant side.

Example: C4H10 + Cl2 → C4H9Cl + HCl


Esterification: alcohol + organic acid ---> ester + water


Fermentation: In this reaction Glucose is on the reactant side and ethanol and carbon dioxide are on the product side. An enzyme such as zymase is used to speed up the reaction.

C6H12O6 ----> 2C2H5OH + 2CO2


Saponification: This reaction produces soap.

Fat + strong base ---> soap + glycerol


Polymerization: small identical molecules come together to make one big molecule.


Naming Hydrocarbons:


1. Find the longest continuous carbon chain (parent chain). Use Table P for the prefix. If your molecule has all single bonds, it is an alkane and will end in "ane".

If your molecule has a double bond, it will end in "ene." We need to specify to which carbon the double bond is attached by putting a number in front of the name. For example, 2 pentene means the double bond is attached to the second carbon.

If your molecule has a triple bond, it will end in "yne." We need to put a number for the triple bond as well.


2. Number the carbons in your parent chain starting with the carbon closest to the first substituent.


3. Name substituents with a number in front, representing the carbon it is connected to. For hydrocarbon substituents, the name will end in "yl." For example, 3-methyl is a CH3 group attached to the third carbon on the parent chain. For halogens, the name ends in "o": Br-bromo, Cl - chloro, I -iodo.


4. First put the name of substituents in alphabetical order followed by the name of the parent chain.


Example: 2,3-dimethylhexane


Facts to memorize

  1. Carbon is an element that is present in all organic molecules. It can form rings and chains.

  2. Isomers are molecules with the same molecular formula but different structure.



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