How do functional groups define classes of organic compounds, and what are the main organic reactions?
Organic reactions and functional groups: identify organic classes from their functional groups using Table R, and recognize the main organic reactions such as combustion, substitution, addition, esterification and polymerization.
A focused Regents Chemistry answer on functional groups and organic reactions: identifying alcohols, acids, esters and other classes from Table R, and recognizing combustion, substitution, addition, esterification, saponification, fermentation and polymerization.
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What this topic is asking
The Core Curriculum asks you to identify classes of organic compounds from their functional groups (using Table R) and to recognize the main organic reactions: combustion, substitution, addition, esterification, saponification, fermentation and polymerization. The Regents tests both reading Table R and naming a reaction type, usually in Part A and Part B-2.
Functional groups and Table R
Table R lists the functional groups with their general formulas and the class they define. The ones you must recognize include the hydroxyl group (alcohols), the carboxyl group (organic acids), the ester linkage (esters), the ether linkage (ethers), and the groups for aldehydes, ketones, amines, amides and halides. To classify a compound, find its functional group on Table R.
The main organic reactions
Three more appear on the Regents. Saponification is the reaction of a fat or oil with a base to produce soap. Fermentation converts sugar (glucose) into ethanol and carbon dioxide, often using yeast. Polymerization joins many small monomer molecules into a long-chain polymer (for example many ethene molecules forming polyethylene).
Recognizing a reaction type
The clue is usually in what the reactants and products are:
- Hydrocarbon oxygen is combustion.
- An atom swapped onto a saturated chain is substitution.
- A double or triple bond becoming single by adding atoms is addition.
- Acid alcohol ester water is esterification.
- Sugar ethanol is fermentation.
- Many small units joining into one large molecule is polymerization.
Try this
Q1. Identify the class of an organic compound that contains an group on a carbon chain. [1 point]
- Cue. An alcohol (the hydroxyl functional group, from Table R).
Q2. Name the organic reaction in which small monomers join to form a long-chain molecule. [1 point]
- Cue. Polymerization.
Exam-style practice questions
Practice questions written in the style of NYSED exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
Regents (Part A style)1 marksWhich type of organic reaction produces an ester from an alcohol and an organic acid? (1) substitution (2) addition (3) esterification (4) saponificationShow worked answer →
A 1-point Part A item on organic reaction types. The answer is (3) esterification.
Esterification is the reaction of an organic acid with an alcohol to produce an ester and water. Substitution replaces an atom (typically a hydrogen on an alkane with a halogen); addition adds atoms across a double or triple bond; saponification is the reaction of a fat with a base to make soap. Only esterification fits "alcohol plus organic acid".
Markers reward identifying esterification as the alcohol-plus-acid reaction that forms an ester.
Regents (Part B-2 style)3 marksUsing Table R, identify the class of organic compound represented by each functional group. (a) a compound containing on a carbon chain; (b) a compound containing ; (c) state the reaction type when an alkene reacts with hydrogen to form an alkane.Show worked answer →
A 3-point constructed-response item using the Table R functional groups.
(a) (1 point): a compound with a hydroxyl group on a carbon chain is an alcohol.
(b) (1 point): a compound with a carboxyl group is an organic acid (carboxylic acid).
(c) Reaction type (1 point): adding hydrogen across the double bond of an alkene to form an alkane is an addition reaction.
Markers reward identifying the alcohol and organic-acid classes from their Table R functional groups, and naming the addition reaction across the double bond.
Related dot points
- Organic chemistry and hydrocarbons: classify alkanes, alkenes and alkynes using their general formulas, and name simple hydrocarbons using Table P and Table Q.
A focused Regents Chemistry answer on organic chemistry and hydrocarbons: why carbon forms so many compounds, the alkane, alkene and alkyne homologous series with their general formulas, isomers, and naming using the Table P and Table Q reference data.
- Types of chemical reactions: classify reactions as synthesis, decomposition, single replacement, double replacement or combustion, and use Table J and Table F to predict whether a reaction occurs.
A focused Regents Chemistry answer on classifying reactions as synthesis, decomposition, single replacement, double replacement or combustion, and using the Table J activity series and Table F solubility guidelines to predict products and precipitates.
- Oxidation numbers and redox reactions: assign oxidation numbers using the standard rules, and identify oxidation, reduction, and the oxidizing and reducing agents in a reaction.
A focused Regents Chemistry answer on oxidation numbers and redox: the rules for assigning oxidation states, the meaning of oxidation (loss of electrons) and reduction (gain of electrons), and how to identify the oxidizing and reducing agents.
- Types of chemical bonds: distinguish ionic, covalent and metallic bonding in terms of electron transfer or sharing, and relate bond type to the elements involved.
A focused Regents Chemistry answer on ionic, covalent and metallic bonding: how electrons are transferred or shared, why bonds form to reach stability, the role of energy, and how to predict bond type from the elements involved.
- Nuclear chemistry: identify alpha, beta, positron and gamma radiation, balance nuclear equations, and use half-life with the Table T relationship and Table O data.
A focused Regents Chemistry answer on nuclear chemistry: the types of radiation and their symbols, balancing nuclear equations by conserving mass number and atomic number, half-life calculations, and the difference between fission and fusion.
Sources & how we know this
- Physical Setting/Chemistry Core Curriculum — New York State Education Department (2002)
- Reference Tables for Physical Setting/Chemistry, 2011 Edition — New York State Education Department (2011)