IUPAC Rules for Nomenclature of Organic Compounds with Oxygen, Sulfur, and Functional Grou, Cheat Sheet of Chemistry

Download IUPAC Rules for Nomenclature of Organic Compounds with Oxygen, Sulfur, and Functional Grou and more Cheat Sheet Chemistry in PDF only on Docsity! Prepared by: Corazon D. Sacdalan Chem Dept. COS, TUP-Manila Lecture Notes 2 in Organic Chemistry Lecture BS Food Technology Nomenclature of Organic Compounds Containing Oxygen, Sulfur, and Amino Group IUPAC Rules for Alcohol Nomenclature Alcohol: R-OH functional group : -OH (hydroxy) suffix: ol 1. Select the longest carbon chain that contains the -OH group as the parent alkane and number it from the end that gives -OH the lower number. 2. Start counting at the carbon nearest to -OH. 3. Change the ending of the parent alkane from -e to -ol and use a number to show the position of the -OH group. If the position of the -OH is at C-1, there is no need to write 1. 4. For cyclic alcohols, the carbon bearing the -OH group is considered as C-1. 5. If there more than one -OH present, identify the number where the _OHs are bonded and use the prefix di, tri, etc. 6. Name and number substituents, and list them in alphabetical order Take a look at the following examples. The position of the -OH is at the terminal end and that is your carbon 1. CH3OH CH3CH2OH CH3CH2CH2CH2OH methanol ethanol propanol In the given examples, the position is at the terminal end, and the carbon where the -OH is bonded to the number 1 carbon. If the position of the functional group -OH is not at the terminal end, the carbon in which the -OH is bonded should be listed. Prepared by: Corazon D. Sacdalan Chem Dept. COS, TUP-Manila Ether Ether R-O-R functional group: -OR suffix: alkoxy Ethers are compounds having two alkyl or aryl groups bonded to an oxygen atom Ethers are classified into symmetrical and unsymmetrical ether Symmetrical ether Unsymmetrical ether CH3OCH3 methoxy methane CH3OCH2CH3- methoxy ethane CH3CH2OCH2CH3 – ethoxy ethane CH3CH2CH2OCH2CH3- ethoxy propane Can you see the difference between symmetrical and unsymmetrical ether? IUPAC Rules for Ether Nomenclature In naming ether, the carbon with the shortest carbon chain is the substituent while the carbon with a longer chain is the parent. The suffix of the substituent is oxy, while you name the parent as an alkane. Name first the substituent followed by the parent. Aldehydes and Ketones The functional group of both aldehyde and ketone is carbonyl, -C=O Aldehyde has a general formula of while ketone is IUPAC Rules for Aldehydes and Ketones Nomenclature 1. The IUPAC name of aliphatic aldehydes and ketones are derived from the name of corresponding alkanes, replacing e with -al for aldehyde while -one for ketone 2. For aldehyde, the carbonyl carbon is located at the terminal end and it is always the number one carbon. Prepared by: Corazon D. Sacdalan Chem Dept. COS, TUP-Manila 3. For ketone, the carbonyl group is always in the middle of the molecule; 4. If substituents are present, locate the number where there are bonded. 5. If one of the substituents is -OH, which is the functional group of alcohol, is present in aldehyde and ketone, the carbonyl group will prevail as the functional group, and -OH will be named as hydroxyl. 6. Substituents are listed in alphabetical order. Prepared by: Corazon D. Sacdalan Chem Dept. COS, TUP-Manila benzaldehyde Prepared by: Corazon D. Sacdalan Chem Dept. COS, TUP-Manila 4-bromopentanal The longest C chain is 7, start counting from your right, 2 methyl groups are bonded on C-5 IUPAC name: 5,5-dimethylheptanal these are the 2 ways to write the structural formula of benzaldehyde Esters Esters are derivatives of a carboxylic acid with a general formula of or RCOOR’ Esters comes from the reaction between carboxylic acid and alcohol so it has the IUPAC Rules for Esters Nomenclature 1. The acid part is considered to be the parent and the suffix is -oate, while the alcohol part is the substituent ending in -yl 2. Name first the alcohol part followed by the acid part. Prepared by: Corazon D. Sacdalan Chem Dept. COS, TUP-Manila The acid part has 4 carbon atoms while the alcohol part has 2 IUPAC name: ethylbutanoate carboxylic part and the alcohol part Prepared by: Corazon D. Sacdalan Chem Dept. COS, TUP-Manila Both the acid and alcohol part have 3 carbon atoms IUPAC name: propylpropanoate COCH CH, TUPAC name: ethyl benzoate, from benzoic acid becomes benzoate Amines Amines are the derivatives of ammonia (remember NH3 from General chemistry). Replacing one hydrogen of ammonia with an alkyl group forms an amine with a general formula of R-NH»: IUPAC Rules for Amine Nomenclature 1, Identify the longest carbon chain bonded to the nitrogen atom. Name the parent chain as in alkane and change the -¢-with a suffix -amine. 3. Number the carbon chain to locate the amine group and any substituents 4. If.an alkyl group is bonded to the nitrogen atom use N instead of a number to. indicate the attachment Prepared by: Corazon D. Sacdalan Chem Dept. COS, TUP-Manila Prepared by: Corazon D. Sacdalan Chem Dept. COS, TUP-Manila 2-methyl groups are attached to N, IUPAC name: N,N-dimethylethanamine In this example, the longest C chain is 3, and N is bonded to C-2, so the correct name is 2-propanamine Amines can also form cyclic, follow the rules in naming an alkane IUPAC name: cyclohexanamine Aniline, an aromatic amine The parent is aniline, add the name of the substituent, it is named as 3- chloroaniline Prepared by: Corazon D. Sacdalan Chem Dept. COS, TUP-Manila ORGANIC CHEMISTRY W/ BIOCHEMISTRY Amides Amides are derivatives of carboxylic acids, derived by combining carboxylic acids with amines. IUPAC Rules for Amine Nomenclature 1. Find the longest chain containing the carbonyl as parent chain and assign the lowest number to Carbonyl carbon 2. Name substituents on nitrogen as N-alkyl. 3. The name of the carboxylic acid is changed from -oic to amide Prepared by: Corazon D. Sacdalan Chem Dept. COS, TUP-Manila This is the general formula of an amide and N can be bonded to H, alkyl or aryl group. The parent chain has only one carbon, from methanoic acid , remove – oic and acid, then add the suffix - amide IUPAC name: methanamide methyl group is bonded to N atom, use N to identify that -CH3 is attached to it IUPAC name: N-methyl ethanamide How to Write the Chemical Formula of Organic Compound? In writing the formula, we have to identify first the functional group, then the parent carbon and the substituents present. For example, for the compound 3- methylpentane It is an alkane, write first 5 C atoms, and at carbon 3 a methyl group is attached, then fill up the carbon atoms with hydrogen, bearing in mind that carbon can only have a maximum of four bonds. Hydrogen is used to fill up the bonds of the carbon. If you were asked to write the formula of 2-hexene, write 6 carbon atoms and place a double bond on C-2, you can start counting either from to the left or to the right and fill each carbon with hydrogen. CH3CH=CHCH2CH2CH3 or CH3CH2CH2CH=CHCH3 Hexanal, this compound contains six carbon atoms and it is an aldehyde since the suffix is -al Write six carbon atoms and write - CHO as its functional group, which is at the terminal end. CH3CH2CH2CH2CH2CHO Prepared by: Corazon D. Sacdalan Chem Dept. COS, TUP-Manila Prepared by: Corazon D. Sacdalan Chem Dept. COS, TUP-Manila Practice Exercise 2 Write the structural formula of the following organic compound 1.3-ethylheptane 2.3-chlorohexane 3.1,3-dibromobenzene 4.2-pentanol 5.ethoxybutane 6.3-fluorooctanal 7.1,2-dichlorocyclohexane 8.3-hydroxybutanoic acid 9.N,N-dimethylbutanamine 10.ethylpentanoate 11.2-butanone 12.pentanethiol 13.N-methylheptanamide 14.2,4-heptadiene 15.2-ethyl-3-hydroxypentanal Prepared by: Corazon D. Sacdalan Chem Dept. COS, TUP-Manila Positional Isomers The position of the functional groups, substituent and double bonds vary or differ from one another. A compound with a molecular formula C4H10O can be an alcohol and ether Here are the isomers of C4H10O as alcohol CH3CH2CH2CH2OH butanol 2- butanol 2-methylpropanol 2-methyl-2-propanol The -OH group is bonded to a different carbon atom, so the position varies, also branching occurs, but still the molecular formula remains the same and they are all alcohol. Also, C4H10O can be represented as CH3OCH2CH2CH3 methoxypropane CH3CH2OCH2CH3 ethoxyethane Prepared by: Corazon D. Sacdalan Chem Dept. COS, TUP-Manila Another example of positional isomers is the compound with a molecular formula of C3H7Br bromopropane 2-bromopropane Functional Isomers In functional isomerism, the organic compound with the same molecular formula but have different functional groups. C3H8O CH3CH2CH2OH CH3CH2OCH3 propanol (alcohol) methoxyethane (ether) C3H6O propanal (aldehyde) 2-propanone (ketone) Prepared by: Corazon D. Sacdalan Chem Dept. COS, TUP-Manila Prepared by: Corazon D. Sacdalan Chem Dept. COS, TUP-Manila