Carbonyl Compounds, Lecture notes of Applied Chemistry

Download Carbonyl Compounds and more Lecture notes Applied Chemistry in PDF only on Docsity! 12 March 2020 1 Carbonyl Compounds د دمحم فريح مسهر.م.ا كلية العلوم قسم الكيمياء مادة الكيمياء العضوية لطلبة الصف الثاني 12 March 2020 2 In the 2nd. Semester the following topics will considered: 1- Carbonyl Compounds (Aldehydes & Ketones). 2- Carboxylic Acids. 3- Functional Derivatives of Carboxylic Acids. 4- Carbanion I and II. 5- Amines. 6- Phenols Kinds of carbonyl compounds Two broad classes of compounds contain a carbonyl group: ‘{1) Compounds that have only carbon and hydrogen atoms bonded to the carbonyl group at least 1H ll oC | Ry [FR ~— 2 R groups ketone —e An aldehyde has at least one H atom bonded to the carbonyl group. ~* Akelone has two alkyl or aryl groups bonded to the carbonyl group. 12 March 2020 (2) Compounds that contain an electronegative atom bonded to the carbonyl group i i 1 1 Cc Cc Cc Cc fon) wfc fom) lw carboxylic acid acid chloride ester amide => Each of these compounds contains an electronegative atom (Cl, O, or N) capable of acting as a leaving group. => Acid chlorides, esters, and amides are often called carboxylic acid derivatives, because they canbe syntesed from carbxyle acids arc The table below shows some of the many different kinds of carbonyl compounds 12 March 2020 7 Some Naturally occurring Ketones Used in Perfumes Formulation: 12 March 2020 10 From roses oils (2-Jasmone (with the odor of jasmine) and.a-damascone (odor of roses) All of these ketones can be obtained from natural sources. bp be _ZJasmone_ _a-Damascone_ 12 March 2020 & ketones: ald.between similarityThe Structure: Both aldehydes and ketones contain carbonyl group R, Rˋ = Aliphatic or Aromatic 12 March 2020 12 Nature of the carbonyl group - Carbon bonded to 3 atoms - Sp2 Hybridized -Trigonal planner -Bond Angle 120 12 March 2020 15 - In one important way the C=O & C=C double bonds are very different. - The presence of the high electronegative oxygen make carbonyl more polar. Electrostatic Potential Map 12 March 2020 16 IUPAC (International Union of Pure and Applied Chemistry) 1- Select the longest chain carrying the –CHO group & give the name of the corresponding alkane. 2- Change the suffix –e of the parent alkane to –al 3- Number the chain so that the –CHO group takes no. 1 Nomenclature of Aldehydes 1- According to the IUPAC name: 12 March 2020 17 Common Names for Aldehydes The common names of aldehydes are derived from the names of the corre- sponding carboxyiic acids by replacing -ic acid by -aldehyde. H H | H-C=0 cH,c=0 CH,CH,C=0 CH;CH:;CH me =O Fermaldehyde Acetaldehyde Propionaldehyde a-Butyraldehyde Methanal Ethanal Propanal Butanal Greek letters are used to designate the location of substituents in common names. The carbon adjacent to the CHO group is the & carbon, and so forth down the chain. 1 Start ee here. | tT By 6 vy H a3 | 12 March 2020  Here, as with the carboxylic acids, we notice that C-2 of the IUPAC name corre: sponds to alpha of the common name, uh fronkeo cnc CH;,CH,CH,CHC=0 CH,;CH,CHCH,C=0 CH,CHCH,CH,C=0 H; t H; H; a-Methylvaleraldehyde \ p-Methylvaleraldehyde Tsocaproaldehyde 2-Methylpentanal 3-Methylpentanal y-Methylvaleraldehyde 4Methylpentanal 1 H Ono onOpeo asOieo OES” COhardec Benzaldehyde p-Tolualdehyde (O}eis-0 p-Nitrobenzaldehyde Salicylaldehyde (Phenylethanal) (o-Hydroxybenzaldehyde) 12 March 2020  + In the IUPAC system all ketones are identified by the suffix -one. {1} Find the longest chain containing the carbonyl group, and change the.-e ending of the parent alkane to the suffix -one, ‘{2] Number the carbon chain to give the carbonyl carbon the lower number. Apply all of the other usual rules of nomenclature, | notice the new rules for nomenclature | rl qt 1 | {I | | CHagHaGCHagHeGHs — GHaGH—CHGHAECHs © GHagHaG CHa CHs 3-Hexanone 4-Hexen-2-one 2,4-Hexanedione (New: Hexan-3-one) (New: Hex-4-en-2-one) (New: Hexane-2,4-dione) YY 12 March 2020 (The suffix -phenone indicates that the acyl group is attached to a benzene ring.) Ops Oyaae OO _— a Benzophenone NO, ) of )--O) O 3-Nitro-4'-methylbenzophenone Yo 12 March 2020  ™* When it's necessary to refer to the R-C=0 as a substituent, the name acyl (a-sil) group is used and the name ending -)! is attached. Thus, -COCH) is an acety! group, CHO is a formy! group, -COAr is an aroy! group, and ~COCcHs is a benzoyl group, 0 O oO 0 | I ll aS Hac7 yoo Cy * An acyl group Acetyl Formyl Benzoyl HO.c oO SOsH cr Oo 2-Methanoylbenzoic acid 4-Ethanoylbenzenesulfonic acid (o-formylbenzoic acid) (p-acetylbenzenesulfonic acid) If other functional groups are present and the doubly bonded oxygen is con. sidered a substituent on a parent chain, the prefix oxo. is used, For example; Oo O il il CH2aCH»CH»CCH»sCH 3-Oxohexanal Sea CHC ere 12 March 2020 3- The lower aldehydes and ketones are soluble in water because of H-bonding with water. They are all soluble in organic solvents 12 March 2020 30 Solubility 4- Formaldehyde is gas (b.p. = -25 and is use either as aqueous solution (formalin) or as one of its solid polymers - paraformaldehyde (-CH2O-)n - Trioxane (CH2O)3 12 March 2020 31 Metaformaldehyde Acetaldehyde (b.p. =20) is often generated from its higher boiling trimer by heating with acid: 12 March 2020 32 * Jautomers are constitutional isomers that differ in the location of a double bond and a hydrogen atom. Two tautomers are in equilibrium with each other. ==> Intemal alkynes undergo hydration with concentrated acid, whereas terminal alkynes require the presence of an additional Hg”* catalyst—usually HgSO,—to yield methyl ketones by Mar. kovnikov addition of H,0, H OH H oO HzO \ / “yf a CH;—-C=C-CH,; ——> C=C =~ CH-C-C H»SO, fi o% \ CHa CH, H CH, enol | ketones H OH H HzO \ / | -P oo H—C=C—CHg3 iSO, et —_— = CG. Hgso, | H __CHg ess a enol methyl ketone Markovnikov addition of HO H adds to the terminal C. 1- Oxidation of 1° Alcohols , using K2Cr2O7 or Na2Cr2O7 with H2SO4, or PCC in CH2Cl2 at room temp. or I(ᴠ)-containing Dess-Martin periodinane in CH2Cl2 solvent PCC in CH2Cl2 Distillation from reaction mixture 12 March 2020 36 Primary alcohol " {0} {0} gC ae Cc ee RG ~H R” ~H H An aldehyde Secondary alcohol OH 0 ~ aK RH aR R’ A ketone Tertiary alcohol m {0} Cc ——> RT RY No reaction A carboxylic acid rv 12 March 2020 B- Hydration of Dihalogen Compounds Gem-Dihalides: So using either Cl2 or CrO₃/ Acetic anhydride 12 March 2020 40 3- Reduction of Acid Chlorides and Esters: A- Reduction of acid chlorides 12 March 2020 41 Examples: I n Reduotion of goid chlorides CH:CH; strong reducing agent 0 I i. Cl [1] LiAIH, (2) 40 IHILIAHIOC( CH [2] H,0 mild reducing agent CH,CH,CHLOH 0 I a CHyCH; “H the reduction of an acid chloride, Cl’ comes off as the leaving group. £Y 12 March 2020 5- Ozonolysis of alkene, gives Ald. & Ketones 12 March 2020 45 The following examples illustrate the results for each type of alkene carbon, 0 0 A gen La (2) Me,S MH 2-Methyl-2-butene Acetone Acetaldehyde (1.0, cH, 780 My Aye + A, (2) Ques 3-Methyl-1-butene lsobutyraldehyde Formaldehyde 12 March 2020 Preparation of Ketones: 1- Oxidation of 2° Alcohols 2° Alcohols oxidized to give ketones Using Cu and Air at 300°C : Industrial الخ....طالء، بالستك، ادويه، مفرقعات، والمطهرات 12 March 2020 47 2- Friedel-Crafts Acylation -O R—Co + ArH —ASb_, R-C_ar + HCI or other cl Lewis acid Acid chloride Ketone n-Pentyl phenyl ketone No rearrangement of n-penty! group <O)coci + <O) AS ©; + HCl Benzoyl! chloride ¥ ort Benzophenone (Phenyl ketone) (CH3CO),0 + <O) A. CH —C + CH3;COOH Acetic anhydride i Acetophenone (Methyl phenyl! ketone) 12 March 202!  The most likely mechanism for Friedel-Crafts acylation is analogous to the carbonium ion mechanism for Friedel-Crafts alkylation (Sec. 11.10), and involves the following steps: (1) RCOCI + AIC —» RC=O + AICI” ® o A (2) ArH +RC=O —> Ar COR o * (3) An + AIC" —> Ar-C-R + HCl + AICI; COR In planning the synthesis of diary! ketones, ArCOAr’, it is particularly important to select the right combination of ArCOCI and Ar'H. In the prepara- tion of m>nitrobenzophenone, for example, the nitro group can be present in the acid chloride but not in the ring undergoing substitution, since as a strongly deactivating group it prevents the Friedel-Crafts reaction (Sec. 12.8). 12 March 2020  -— © ON Benzene (O>-¢4O) oO ON OoN 4 m-Nitrobenzophenone O) coc, os O) COOH m-Nitrobenzoyl m-Nitrobenzoic acid chloride |s NO,, H,SO, Oper BeA- O)coos Toluene Benzoic acid No reaction A. O2n(O) + (O)coa Nitrobenzene Benzoyl chloride 12 March 2020  0 [1] (CHg)pCuLi 0 C : C CH,CH; “CI (2]H,0 CH;CH; “CH; % The reaction is generally carried out at —78 °C in ether solution, and yields are often excellent. For example, manicone, a substance secreted by male ants to coordinate ant pairing and mating, has been synthesized by reaction of lith- ium diethylcopper with (£)-2,4-dimethyl-2-hexenoyl chloride. Formone i | Cc (CH3CHp}2CuLi C. LC e: aVr'2 Zanes Ether, 7c” CHaCH2GH” °G" "CHaCHs — CHy CH c CHgCHCH™ Sc 2,4-Dimethyl-2-hexenoyl 4,6-Dimethy!-4-octen-3-one chloride (manicone, 92%) % Note that the diorganocopper reaction occurs only with acid chlorides. Car- boxylic acids, esters, acid anhydrides, and amides do not react with lithium diorganocopper reagents. 90 12 March 2020 4- Addition of water to Acetylenes: 12 March 2020 56 5- Acetoacetic ester synthesis of Ketones: 12 March 2020 57