Enter the structural features of your organic molecule to generate its IUPAC name.
Your IUPAC name will appear here.
Understanding IUPAC Naming for Organic Compounds
The International Union of Pure and Applied Chemistry (IUPAC) provides a systematic nomenclature for organic compounds, ensuring a unique name for every distinct chemical structure. This system is crucial for clear communication among chemists worldwide. The IUPAC naming convention follows a set of rules that consider the parent hydrocarbon chain, functional groups, and substituents.
Core Principles of IUPAC Naming:
Parent Chain Identification: The first step is to identify the longest continuous carbon chain in the molecule. This chain forms the basis of the parent name. For example, a chain of six carbons is called "hexane."
Functional Group Suffix: The principal functional group (the one with the highest priority according to IUPAC rules) determines the suffix of the parent name. For instance, an alcohol (-OH) adds "-ol" to the parent alkane name (e.g., hexanol). A carboxylic acid (-COOH) adds "-oic acid" (e.g., hexanoic acid).
Numbering the Chain: The carbon chain is numbered to give the lowest possible numbers to the principal functional group. If there's no principal functional group, then substituents get the lowest numbers.
Identifying and Locating Substituents: Any groups attached to the parent chain that are not part of the main chain or the principal functional group are called substituents or branches. These are named using prefixes like "methyl" (CH₃), "ethyl" (C₂H₅), "chloro" (Cl), "bromo" (Br), etc. Their positions on the parent chain are indicated by numbers.
Alphabetical Order: When multiple different substituents are present, they are listed in alphabetical order in the name, regardless of their position numbers. Prefixes like 'di-', 'tri-', 'tetra-' used to indicate multiple identical substituents are ignored for alphabetization.
Multiple Bonds: Alkenes (C=C) and alkynes (C≡C) are named by changing the ending of the parent alkane name to "-ene" or "-yne," respectively. The position of the multiple bond is indicated by numbering the carbons involved.
Complex Structures: For cyclic compounds, the prefix "cyclo-" is added to the parent alkane name.
How This Calculator Works:
This calculator simplifies the process by asking for key structural information:
Longest Carbon Chain Length: Determines the base name (meth-, eth-, prop-, but-, pent-, hex-, etc.).
Primary Functional Group: Specifies the suffix (-ol, -al, -one, -oic acid, -amine, etc.) and influences numbering priority.
Position of Primary Functional Group: Indicates where the main functional group is attached, crucial for clarity.
Substituents/Branches: Lists any side chains or groups attached (e.g., methyl, ethyl, halogens).
Positions of Substituents: Specifies the carbon number where each substituent is attached.
Double/Triple Bonds: Identifies the presence and location of unsaturation.
The calculator combines these elements according to IUPAC rules, generating a systematic name. Note that this calculator provides a simplified approach and may not cover every complex scenario or exception in advanced organic nomenclature.
The calculator would combine these to suggest "3-ethylhex-4-en-2-one".
function generateIUPACName() {
var chainLength = parseInt(document.getElementById("chainLength").value);
var functionalGroupInput = document.getElementById("functionalGroup").value.trim().toLowerCase();
var functionalGroupPosition = parseInt(document.getElementById("functionalGroupPosition").value);
var branchesInput = document.getElementById("branches").value.trim().toLowerCase();
var branchPositionsInput = document.getElementById("branchPositions").value.trim();
var doubleBondsInput = document.getElementById("doubleBonds").value.trim().toLowerCase();
var resultElement = document.getElementById("result");
resultElement.style.color = '#333'; // Reset color
// Basic validation
if (isNaN(chainLength) || chainLength 0 && functionalGroupPosition !== 1) {
resultElement.textContent = "Error: Carboxylic acid functional group is always at position 1.";
return;
}
if (functionalGroupInput.includes('-cho') && functionalGroupPosition > 0 && functionalGroupPosition !== 1) {
resultElement.textContent = "Error: Aldehyde functional group is always at position 1.";
return;
}
if (functionalGroupPosition > chainLength) {
resultElement.textContent = "Error: Functional group position cannot exceed chain length.";
return;
}
var parentChain = getParentChain(chainLength);
var suffix = getSuffix(functionalGroupInput);
var prefixOrder = []; // Store [position, branch_name]
// Process branches
if (branchesInput) {
var branches = branchesInput.split(',').map(function(item) { return item.trim(); });
var positions = branchPositionsInput.split(',').map(function(item) { return item.trim(); });
if (branches.length !== positions.length) {
resultElement.textContent = "Error: Number of branch positions must match number of branches.";
return;
}
for (var i = 0; i < branches.length; i++) {
var pos = parseInt(positions[i]);
var branch = branches[i];
if (isNaN(pos) || pos chainLength) {
resultElement.textContent = "Error: Invalid position for branch '" + branch + "'.";
return;
}
prefixOrder.push({ pos: pos, name: branch });
}
}
// Process double/triple bonds
var bondInfo = [];
if (doubleBondsInput) {
var bonds = doubleBondsInput.split(',');
for (var i = 0; i < bonds.length; i++) {
var bondStr = bonds[i].trim();
var match = bondStr.match(/(c=c|c≡c)\s+at\s+(\d+)/);
if (match) {
var type = match[1];
var pos = parseInt(match[2]);
if (isNaN(pos) || pos chainLength) {
resultElement.textContent = "Error: Invalid position for bond '" + bondStr + "'.";
return;
}
bondInfo.push({ pos: pos, type: type });
} else {
resultElement.textContent = "Error: Invalid double/triple bond format. Use 'C=C at X' or 'C≡C at X'.";
return;
}
}
}
// Sort branches and bonds by position
prefixOrder.sort(function(a, b) { return a.pos – b.pos; });
bondInfo.sort(function(a, b) { return a.pos – b.pos; });
// Construct the name
var fullName = "";
var prefixes = "";
var currentPos = -1;
var branchCounts = {};
// Add substituents
for (var i = 0; i < prefixOrder.length; i++) {
var item = prefixOrder[i];
if (item.pos !== currentPos && currentPos !== -1) {
// Handle multiple substituents at the same position if needed,
// but current simple structure assumes one branch per position for simplicity
}
currentPos = item.pos;
if (!branchCounts[item.name]) branchCounts[item.name] = 0;
branchCounts[item.name]++;
}
var sortedBranchNames = Object.keys(branchCounts).sort();
var sortedPrefixes = [];
for (var i = 0; i 1) {
prefixStr = getMultiplierPrefix(count) + name;
}
// Find all positions for this branch name
var positionsForBranch = [];
for(var j=0; j 1) {
// This logic needs refinement to correctly handle multiple identical branches at the *same* position
// For now, we will list the position multiple times if identical branches are at different positions.
}
// Simplified approach: Add each branch and its position individually first
finalPrefixList.push(pos + '-' + name);
}
// Remove duplicates and sort
finalPrefixList = finalPrefixList.filter((item, index) => finalPrefixList.indexOf(item) === index);
finalPrefixList.sort(function(a, b) {
var posA = parseInt(a.split('-')[0]);
var posB = parseInt(b.split('-')[0]);
if (posA !== posB) return posA – posB;
return a.localeCompare(b); // Alphabetical for same position
});
// Rebuild prefixes string correctly
var prefixString = "";
var tempPrefixes = {}; // { 'methyl': { positions: [2], count: 1 }, 'ethyl': { positions: [3], count: 1 } }
for(var i=0; i 1){
countPrefix = getMultiplierPrefix(data.count);
}
parts.push(posStr + '-' + countPrefix + name);
}
prefixString = parts.join('-') + '-';
// Add double/triple bonds to name construction
var bondString = "";
if (bondInfo.length > 0) {
var bondParts = [];
for (var i = 0; i 0) {
lowestNumber = Math.min(lowestNumber, functionalGroupPosition);
}
for(var i=0; i 0 ? bondInfo[0].pos : ";
var bondSuffix = ";
if(bondInfo.length === 1){
bondSuffix = mainBondPos + (bondInfo[0].type === 'c=c' ? 'en' : 'yn');
} else if (bondInfo.length > 1) {
// For multiple bonds, it gets complex (e.g., hexa-1,3-diene)
// Simplified: just list all positions before 'diene'/'diyne'
var positions = bondInfo.map(b => b.pos).sort((a,b) => a-b);
bondSuffix = positions.join(',') + (bondInfo[0].type === 'c=c' ? 'diene' : 'diyne'); // Assumes all bonds are same type for simplicity
}
// The parent chain name structure needs to accommodate this.
// E.g., Hex + bondSuffix + suffix
// Or, if functional group has priority, it dictates numbering.
// Complex logic needed here for correct numbering and combining:
// For now, we'll create a simplified structure.
// If a functional group is present and dictates numbering, the bonds might be referred to differently.
// Let's try to build the structure: prefix + parentChain + bondSuffix + suffix
}
var finalName = "";
var baseName = parentChain;
// Priority order: Carboxylic Acid > Aldehyde > Ketone > Alcohol > Amine > Alkene/Alkyne > Alkane
// Numbering should give lowest numbers to highest priority group.
// This calculator simplifies by allowing explicit position inputs.
// Simplified name construction:
// Prefixes (sorted by position, then alpha) + Parent Chain + (optional bond position/type) + Suffix
var middlePart = "";
if (bondString) {
// Determine the position for the bond suffix. It's usually the lowest position of the multiple bond.
var lowestBondPos = bondInfo.length > 0 ? bondInfo[0].pos : ";
var bondTypeSuffix = ";
if (bondInfo.length === 1) {
bondTypeSuffix = lowestBondPos + (bondInfo[0].type === 'c=c' ? 'en' : 'yn');
} else if (bondInfo.length > 1) {
// Simplified handling for multiple bonds
var positions = bondInfo.map(b => b.pos).sort((a, b) => a – b);
// Check if all bonds are the same type
var allAlkenes = bondInfo.every(b => b.type === 'c=c');
var allAlkynes = bondInfo.every(b => b.type === 'c≡c');
if (allAlkenes) {
bondTypeSuffix = positions.join(',') + 'diene'; // Simplified for two double bonds
} else if (allAlkynes) {
bondTypeSuffix = positions.join(',') + 'diyne'; // Simplified for two triple bonds
} else {
// Mixed bonds – very complex, requires advanced logic
bondTypeSuffix = positions.join(',') + 'dyne/diene'; // Placeholder
}
}
// Decide where bond suffix goes relative to functional group
// Generally, higher priority groups dictate numbering.
// If functional group is a ketone/alcohol/etc., and a double bond is present,
// the numbering is chosen to give the functional group the lowest number.
// The double bond position is then indicated.
// Example: Hex-4-en-2-one (ketone at 2, alkene starts at 4)
// For simplicity, let's try to insert the bond information logically.
// If the functional group position is specified and is NOT 1, use it.
// Otherwise, use the lowest bond position.
var effectivePositionForMiddle = lowestBondPos; // Default to lowest bond position
if (functionalGroupPosition && functionalGroupPosition > 0 && functionalGroupPosition !== 1) {
// If functional group has a position (and isn't carboxylic acid/aldehyde), use it.
// Check priority: if functional group priority is higher than alkene/alkyne.
// For simplicity here, if specified, we use the functional group position.
effectivePositionForMiddle = functionalGroupPosition;
}
middlePart = effectivePositionForMiddle + bondTypeSuffix;
}
// Construct the full name parts
var nameParts = [];
// Add prefixes first
if (prefixString) {
nameParts.push(prefixString);
}
// Add parent chain and middle part (bonds)
var chainAndBondPart = baseName;
if (middlePart) {
// Need to decide if baseName comes before or after bond info.
// Example: Hex-4-en-2-one. 'Hex' is base, '4en' is bond, '2one' is suffix.
// Example: Pent-1-en. 'Pent' is base, '1en' is bond.
chainAndBondPart = baseName + middlePart;
}
nameParts.push(chainAndBondPart);
// Add suffix
if (suffix) {
nameParts.push(suffix);
}
finalName = nameParts.join(");
// Refinement needed for accurate ordering and combining of parts based on IUPAC rules.
// The current logic is a simplification.
// Let's try a more structured approach for the final assembly:
var finalCompoundName = "";
var prefixesString = "";
// Assemble prefixes part
var prefixList = [];
for(var key in tempPrefixes){
var data = tempPrefixes[key];
data.positions.sort((a,b)=> a-b);
var posStr = data.positions.join(',');
var prefixToAdd = "";
if (data.count > 1){
prefixToAdd = getMultiplierPrefix(data.count) + key;
} else {
prefixToAdd = key;
}
prefixList.push({pos: data.positions[0], name: posStr + '-' + prefixToAdd}); // Use first position for sorting
}
prefixList.sort(function(a,b){
if(a.pos !== b.pos) return a.pos – b.pos;
return a.name.localeCompare(b.name);
});
prefixesString = prefixList.map(item => item.name).join('-') + '-';
// Assemble the middle part (parent chain + bonds)
var mainChainName = parentChain;
var bondPart = "";
if(bondInfo.length > 0){
var bondPositions = bondInfo.map(b => b.pos).sort((a,b) => a-b);
var bondType = bondInfo[0].type; // Assuming all same type for simplicity
var bondSuffix = "";
if(bondInfo.length === 1){
bondSuffix = bondPositions[0] + (bondType === 'c=c' ? 'en' : 'yn');
} else {
// Simplified multiple bonds
var allAlkenes = bondInfo.every(b => b.type === 'c=c');
var allAlkynes = bondInfo.every(b => b.type === 'c≡c');
if (allAlkenes) bondSuffix = bondPositions.join(',') + 'diene';
else if (allAlkynes) bondSuffix = bondPositions.join(',') + 'diyne';
else bondSuffix = bondPositions.join(',') + 'dyne/diene'; // Mixed
}
// Place bond suffix correctly. Usually before the suffix if functional group is lower priority.
// If functional group is higher priority, numbering is dictated by FG.
// Example: hex-4-en-2-ol. Numbering based on -OH. Alkene starts at 4.
// Example: hex-1-en-3-one. Numbering based on -one. Alkene starts at 1.
// Let's assume functional group dictates numbering if present and has priority.
// If functional group position is specified:
if(functionalGroupPosition && functionalGroupPosition > 0 && !['carboxylic acid', '-cho'].includes(functionalGroupInput) ){
// Use functional group position for overall numbering.
// The bond suffix position is determined relative to this numbering.
bondPart = bondSuffix; // This might need adjustment based on FG position.
} else {
// Use lowest bond position if no high priority FG or FG is at end.
bondPart = bondSuffix;
}
mainChainName = parentChain + bondPart; // e.g., hexen, hexyn
}
// Assemble the final name
// Order: Prefixes + ParentChain + Bonds + Functional Group Suffix
// If bonds are present, and functional group is high priority (like ketone),
// the bond position might be inserted *before* the functional group suffix.
// Example: hex-4-en-2-one
var finalSuffix = "";
if (suffix) {
// Decide if functional group position needs to be explicit.
// If it's not at C1 (like alcohol, ketone, amine), its position is needed.
var FG_Pos_Str = "";
if (functionalGroupPosition && functionalGroupPosition > 0 && !['carboxylic acid', '-cho'].includes(functionalGroupInput)) {
FG_Pos_Str = functionalGroupPosition;
} else if (functionalGroupInput.includes('carboxylic acid') || functionalGroupInput.includes('-cho')) {
FG_Pos_Str = "1"; // Implicitly 1
}
finalSuffix = FG_Pos_Str + suffix;
}
// Combine parts – careful ordering is key
finalCompoundName = prefixesString + mainChainName + finalSuffix;
// Cleanup double hyphens and leading/trailing hyphens
finalCompoundName = finalCompoundName.replace(/–/g, '-');
if (finalCompoundName.startsWith('-')) finalCompoundName = finalCompoundName.substring(1);
if (finalCompoundName.endsWith('-')) finalCompoundName = finalCompoundName.substring(0, finalCompoundName.length – 1);
// Special cases / Simplifications:
// – If it's just an alkane with no substituents or functional groups.
if (!branchesInput && !functionalGroupInput && !doubleBondsInput) {
finalCompoundName = parentChain;
}
// – If it's an alcohol, and the OH is at C1, the '1' might be omitted (e.g., ethanol, not ethan-1-ol).
if (finalCompoundName.endsWith('-1ol')) {
finalCompoundName = finalCompoundName.substring(0, finalCompoundName.length – 2) + 'ol';
}
// – If it's an aldehyde, it's always at C1, so '-1al' is redundant.
if (finalCompoundName.endsWith('-1al')) {
finalCompoundName = finalCompoundName.substring(0, finalCompoundName.length – 2) + 'al';
}
// – If it's a ketone and the position is not specified but implied at C2 for short chains.
// This calculator relies on explicit input for position.
// Final check for empty strings and formatting
finalCompoundName = finalCompoundName.replace(/–/g, '-'); // Ensure no double hyphens
// Remove trailing hyphen if it results from concatenation
if (finalCompoundName.endsWith('-')) {
finalCompoundName = finalCompoundName.slice(0, -1);
}
// Handle case where there are no prefixes or bonds, just parent + suffix
if (finalCompoundName.includes(parentChain) && finalCompoundName.startsWith(parentChain) && !prefixesString && !bondPart) {
// If the name starts with the parent chain and there were no prefixes or bonds, it's likely correct as is.
} else if (finalCompoundName.startsWith(parentChain) && prefixesString && !bondPart) {
// Example: methylhexane. Prefixes should be first.
}
// A more robust assembly:
var orderedParts = [];
var collectedPrefixes = []; // Store {pos: number, name: string}
var collectedBonds = []; // Store {pos: number, type: string}
// Populate collected prefixes
for(var i=0; i CHO > C=O > OH > NH2 > C=C > C≡C
var fgPriority = getFunctionalGroupPriority(functionalGroupInput);
var lowestBondPos = collectedBonds.length > 0 ? collectedBonds[0].pos : chainLength + 1;
var FGPos = functionalGroupPosition && functionalGroupPosition > 0 ? functionalGroupPosition : chainLength + 1;
// If FG is carboxylic acid or aldehyde, numbering starts at 1.
if (functionalGroupInput.includes('carboxylic acid') || functionalGroupInput.includes('-cho')) {
FGPos = 1;
}
var numberToUse = Math.min(FGPos, lowestBondPos);
var numberingScheme = "";
// Construct the name based on numbering
var prefixPartStr = "";
var tempPrefixMap = {}; // { name: { positions: [], count: 0 } }
for(var i=0; i<collectedPrefixes.length; i++){
var p = collectedPrefixes[i];
if(!tempPrefixMap[p.name]){
tempPrefixMap[p.name] = {positions: [], count: 0};
}
tempPrefixMap[p.name].positions.push(p.pos);
tempPrefixMap[p.name].count++;
}
var sortedPrefixNames = Object.keys(tempPrefixMap).sort();
var prefixStrings = [];
for(var i=0; i a-b);
var posStr = data.positions.join(',');
var prefix = data.count > 1 ? getMultiplierPrefix(data.count) + name : name;
prefixStrings.push(posStr + '-' + prefix);
}
prefixPartStr = prefixStrings.join('-') + '-';
var chainPart = parentChain;
var bondPartStr = "";
if (collectedBonds.length > 0) {
var bondPositions = collectedBonds.map(b => b.pos).sort((a,b) => a-b);
var bondType = collectedBonds[0].type; // Assume same type for simplicity
var bondSuffix = "";
if (collectedBonds.length === 1) {
bondSuffix = bondPositions[0] + (bondType === 'c=c' ? 'en' : 'yn');
} else {
// Simplified handling for multiple bonds
var allAlkenes = collectedBonds.every(b => b.type === 'c=c');
var allAlkynes = collectedBonds.every(b => b.type === 'c≡c');
if (allAlkenes) bondSuffix = bondPositions.join(',') + 'diene';
else if (allAlkynes) bondSuffix = bondPositions.join(',') + 'diyne';
else bondSuffix = bondPositions.join(',') + 'dyne/diene'; // Mixed
}
// Place bond suffix relative to chain. It goes between parent chain and FG suffix usually.
chainPart = parentChain + bondSuffix;
}
var fgPartStr = "";
if (suffix) {
var fgPos = functionalGroupPosition ? functionalGroupPosition : 1; // Default to 1 if not specified but implied
if (functionalGroupInput.includes('carboxylic acid') || functionalGroupInput.includes('-cho')) {
fgPos = 1;
}
if (fgPos > 0 && fgPos <= chainLength) { // Only add position if valid and needed
fgPartStr = fgPos + suffix;
} else {
fgPartStr = suffix; // For cases like ethanol where position 1 is implied/omitted
}
}
finalCompoundName = prefixPartStr + chainPart + fgPartStr;
// Final cleanup
finalCompoundName = finalCompoundName.replace(/–/g, '-').replace(/-\./g, '.').replace(/\.\-/g, '.');
if (finalCompoundName.startsWith('-')) finalCompoundName = finalCompoundName.substring(1);
if (finalCompoundName.endsWith('-')) finalCompoundName = finalCompoundName.substring(0, finalCompoundName.length – 1);
// Handle simple alkanes
if (!branchesInput && !functionalGroupInput && !doubleBondsInput) {
finalCompoundName = parentChain;
}
// Handle omission of '1' for terminal groups when it's standard
if (finalCompoundName.endsWith('-1ol')) finalCompoundName = finalCompoundName.slice(0, -2) + 'ol';
if (finalCompoundName.endsWith('-1al')) finalCompoundName = finalCompoundName.slice(0, -2) + 'al';
if (finalCompoundName.endsWith('-1amine')) finalCompoundName = finalCompoundName.slice(0, -6) + 'amine'; // Simplified, IUPAC prefers amino- prefix unless it's the only FG.
// If only double bond at pos 1, e.g. pent-1-en, the 1 is often kept.
// One last check for logical consistency, e.g. ensuring prefix positions are valid
if(finalCompoundName.includes('nan-') || finalCompoundName.includes('nan') && finalCompoundName.length = 1 && length prefixes.length) {
// For lengths beyond dodecane, IUPAC uses a numerical prefix followed by 'ane'
return length.toString(); // Example: 13 becomes 13
}
return "";
}
function getSuffix(functionalGroup) {
if (!functionalGroup) return "";
if (functionalGroup.includes("carboxylic acid") || functionalGroup.includes("-cooh")) return "oic acid";
if (functionalGroup.includes("-oh")) return "ol";
if (functionalGroup.includes("-cho")) return "al";
if (functionalGroup.includes("-c=o") || functionalGroup.includes("-one")) return "one";
if (functionalGroup.includes("-nh2") || functionalGroup.includes("-amine")) return "amine"; // IUPAC prefers amino- prefix unless it's the main FG.
if (functionalGroup.includes("c=c") || functionalGroup.includes("ene")) return "ene"; // Typically part of chain name, not suffix
if (functionalGroup.includes("c≡c") || functionalGroup.includes("yne")) return "yne"; // Typically part of chain name, not suffix
return ""; // Default or unrecognized
}
function getMultiplierPrefix(count) {
if (count === 2) return "di";
if (count === 3) return "tri";
if (count === 4) return "tetra";
if (count === 5) return "penta";
if (count === 6) return "hexa";
if (count === 7) return "hepta";
if (count === 8) return "octa";
if (count === 9) return "nona";
if (count === 10) return "deca";
return ""; // For counts > 10, standard IUPAC might use numerical prefixes
}
function getFunctionalGroupPriority(functionalGroup) {
if (!functionalGroup) return 0;
if (functionalGroup.includes("carboxylic acid") || functionalGroup.includes("-cooh")) return 10;
if (functionalGroup.includes("-cho")) return 9;
if (functionalGroup.includes("-c=o") || functionalGroup.includes("-one")) return 8;
if (functionalGroup.includes("-oh")) return 7;
if (functionalGroup.includes("-nh2") || functionalGroup.includes("-amine")) return 6;
// Alkenes/Alkynes have lower priority for suffix naming but influence numbering.
return 0; // Default / lowest priority
}