Pharm. Organic Chemistry I PCD/PCC 102 Course Notes PDF

Pharm.Organic chemistry I PCD/PCC 102 Prof. Dr/ Omaima gaber Prof. Dr/ Ola Rizk Fall 2024-2025  Pharm.Org. Chem I PCD & PCC 102 3 Credit Hours (2Hrs.Lect. 2 Hrs Practical, 1Hr Tutorial) Fall 2024-2025  Course instructors 1-Prof. Dr...

Pharm.Organic chemistry I PCD/PCC 102 Prof. Dr/ Omaima gaber Prof. Dr/ Ola Rizk Fall 2024-2025  Pharm.Org. Chem I PCD & PCC 102 3 Credit Hours (2Hrs.Lect. 2 Hrs Practical, 1Hr Tutorial) Fall 2024-2025  Course instructors 1-Prof. Dr. Omaima Gaber Office Hours: Tuesday 12:30pm - 2:30pm 2-Prof. Dr. Ola Rizk Office Hours: Tuesday 12:30pm - 2:30pm 3- Dr. Mahmoud Ragab Office Hours: Tuesday& Wednesday 12:30pm - 2:30pm  Course aim The prime objective of this course is to provide student with basic knowledge in the field of organic chemistry. The course also aims to enlighten students with the physical and chemical characters of organic compounds their properties, reactions and methods of identification. The course also aims to help the student to acquire skills to give proper nomenclature for organic compounds with special reference to drugs. The course includes practical tuition helping the student to identify organic compounds of different nature.  Student assesment Assessment Methods Schedule (week) Weighing (%) 1. Course work - Weekly - 15 % a- Practical Experiments b- Final Practical Exam - Week 3 & 13 2. Interactive learning, tutorials & - Weekly - 5% assignments 4 quizes - Week 3, 5, 10 & - 5% 11 3. Midterm exam - Week 8 - 15 % 4. Final written - Week 14 & 15 - 50 % 5. Final oral - Week 14 & 15 - 10 % Hydrocarbons  IUPAC nomenclature The IUPAC nomenclature of organic chemistry is a method of naming organic chemical compounds as recommended by the International Union of Pure and Applied Chemistry. IUPAC nomenclature is based on naming a molecule's longest chain of carbons connected by single bonds, whether in a continuous chain or in a ring. All deviations, either multiple bonds or atoms other than carbon and hydrogen, are indicated by prefixes or suffixes according to a specific set of priorities.  Alkanes (Paraffins) General formula: CnH2n+2 number of C atoms name Structure 1 methane CH4 2 ethane CH3CH3 3 n- propane CH3CH2CH3 4 n- butane CH3(CH2)2CH3 5 n-pentane CH3(CH2)3CH3 6 hexane CH3(CH2)4CH3 7 heptane CH3(CH2)5CH3 8 octane CH3(CH2)6CH3 9 nonane CH3(CH2)7CH3 10 decane CH3(CH2)8CH3 -H e.g. methane -H methyl Alkane Alkyl  IUPAC Nomenclature 1- Select the longest chain of hydrocarbons. 2- Number the longest chain from the end nearest to the branch so that side chain would take lowest possible number. 6 5 4 3 2 1 CH3CH2CH2CH2CHCH3 1 2 3 4 5 7 6 5 4 3 6 CH 2CH 7 3 2-Ethylhexane X 2 1 5-Methylheptane X 3-Methylheptane  Cont. IUPAC Nomenclature 3- When two or more substituents are identical, use the prefixes di-, tri-, tetra- etc. 4- When branching first occurs at an equal distance from either end of the parent chain, choose the name that gives the lower number at the first point of difference. CH3 3 7 5 H2 1 4 2 H3C 6 CH C CH3 CH 3 C 5 CH 7 2 H2 6 4 1 CH3 CH3 2,5,6-Trimethylheptane X 2,3,6-Trimethylheptane  Cont. IUPAC Nomenclature When two chains of equal length compete to be parent, choose the chain with the greatest number of substituents CH3 CH3 1 3 7 5 H3C 2 CH 4 CH 6 CH3 CH CH C H2 CH3 CH2CH2CH3 2,3,5-Trimethyl-4-propylheptane (alphabetical) Give the IUPAC name for each of the following compounds 3 CH3 CH3 4 2 1 H3C 2 CH 4 CH 1 3 CH CH CH3 5 Br 6 CH3 CH2CH2CH3 5 6 7 5-bromo-4-ethyl-2,2-dimethylhexane 4-isopropyl-2,3-dimethylheptane Cont. IUPAC Nomenclature  Cont. IUPAC Nomenclature X H3C H3C H3C CH CH CH2 X CH X CH3 H3C H3C sec-butyl isopropyl isobutyl CH3 H3C H3C C X H3C C CH2 X H3C CH3 tert-butyl neopentyl  Physical properties 1- Non polar compounds 2- Insoluble in water 3- Dissolve in organic solvents. 4- C1-C4 are gases C5-C17 are liquids.. C18 are solids  General methods for preparation A) From compounds containing the same number of carbon atoms: 1) Catalytic reduction of unsaturated hydrocarbons 2) Reduction of ketones 3) Reduction of alkyl halides b) From organomagnesium halides (Grignard reagent): C) From compounds containing lower number of carbon atoms: Wurtz reaction: used for preparation of symmetrical alkanes  The use of hydrogen and metal does not stop the reaction at the formation of alkene and the alkane will be the final product. R R H2 / Ni H2 / Ni R C C R C C R CH2 CH2 R H H 2) From ketones: Zn / HCl / Hg O (Clemmensen reduction) H2 C C R R1 R R1 or NH2NH2 / NaOH (Wolff-Kishner reduction)  RX Zn / HCl RH + ZnXCl e.g. H2 Cl C Zn / HCl H3 C H3 C C CH3 CH3 + ZnCl2 H b) Wurtz reaction: used for preparation of symmetrical alkanes 2 RX + 2 Na RR + 2 NaX    R X   ether   RX + Mg R MgX R1X RR1 + MgX2  Reactions of alkanes Substitution reactions X2 = F2, Cl2, Br2, I2 Conditions: uv light (h) or heat 250-400 ( temperature) mechanism: Free radical Cl2 CH4 + Cl2 CH3Cl + HCl CH2Cl2 + HCl Cl2 Cl2 CCl4 + HCl CHCl3 + HCl mixture of products mechanism: Free radical 1) initiation: hH2O2 Cl Cl 2 Cl. 2) propagation:. a) Cl H CH3 HCl +.CH3.. b) CH3 + Cl Cl CH3Cl + Cl 3) Termination: Cl. + Cl. Cl2.. CH3 + CH3 CH3CH3. CH3 + Cl. CH3Cl.. CCl3 + CCl3 Cl3C-CCl3 (C2Cl6) hexachloroethane Factors affecting rate of halogenation: 1- Type of the halogen 2- ease of abstraction of hydrogen (rate determining step) 3. Stability of the free radical formed  1. Type of the halogen rate of reactivity: F2 > Cl2 > Br2 > I2 Flourination and iodination are difficult to perform in the laboratory (Flourine reacts with alkanes with an explosion while Iodine doesn’t react with alkanes). Chlorination of alkanes is easier than bromination. 2. ease of abstraction of hydrogen (rate determining step) H2 H2 H3C C Cl2 C H3C CH2Cl + CH Cl H3C CH3 h H3C n-propane n-propyl chloride isopropyl chloride minor major H3C H3C H3C Cl2 H3C C Cl + CH CH2Cl CH CH3 H3C h H3C H3C tert-butyl chloride iso-butyl chloride iso-butane major minor ease of abstraction 3ry H > 2ry H > 1ry H 3. Stability of the free radical formed H3C H3C H3C H3C H < < CH H < H3C C H H2C H H3C H3C Increasing rate of reaction towards X2 radicals formed are more stable H3C H3C H 3C.. CH3 <. < CH < H 3C C. CH2 H3C H3C Alkenes (Olefins)  Alkenes (Olefins) Alkenes are hydrocarbons that contain a C=C bond. They have the general formula CnH2n  IUPAC Nomenclature 1- Determine the parent name by selecting the longest continuous carbon chain that contains the double bond and change the ending of the name of the alkane of identical length from –ane to –ene. H2C CH2 ethene propene Common name: ethylene Common name: propylene  Cont. IUPAC Nomenclature 2- The chain is numbered in the direction that gives the doubly bonded carbons the least possible numbers. 5 1 3 4 2 1 2 3 5 4 2-Pentene true 3-Pentene false  Cont. IUPAC Nomenclature 3- If the chain is substituted number to give the substituents the least possible number. 5 4 1 Cl 1 3 4 1 2 3 2 3 2 5 4 3- Methyl-1-butene True 1-Chloro-2-pentene true 2-Methyl- 3-butene False 5-Chloro-3-pentene false  Cont. IUPAC Nomenclature 4- Compounds that contain both a double bond and a hydroxyl group use the combined suffix –enol to signify that both functional groups are present. 6 1 3 2 HO 6 4 5 4 2 5 3 1 5-Methyl-4-hexen-1-ol true 2-Methyl-2-hexen-6-ol false  Cont. IUPAC Nomenclature Vinyl, allyl, and isopropenyl are acceptable in the IUPAC system. H2C CH Vinyl H2C H2C CH CH2 C Allyl CH3 Isopropenyl Geometrical Isomerism  Geometrical Isomerism Geometrical Isomerism is noticed in compounds suffering from restricted rotation around double bond. Cis-trans isomers are stereoisomers that are not mirror images, so these are diastereomers. H COOH HOOC H H COOH H COOH cis But-2-ene-1,4-dicarboxylic acid Trans But-2-ene-1,4-dicarboxylic acid (Maleic acid) (Fumaric acid)  Cont. Geometrical Isomerism in Alkenes H H H CH3 C C C C H3C CH3 H3C H cis-2-butene trans-2-butene Geometrical isomers can not exist if either carbon of C=C carries two identical substituents. H3C H H3C H 2-Methylpropene No isomerism  Synthesis of alkenes 1- Dehydrohalogenation of alkyl halides 2- Dehalogenation of vicinal dihalo compounds 3- Dehydration of alcohols 4- Reduction of alkynes  1- Dehydrohalogenation of alkyl halides (-HX) Elimination of X from α C and elimination of H from β carbon Using alcoholic KOH or sodium ethoxide / ethanol H H   alc. KOH /  H C C H R-HC CH2 or NaOC2H5 / C2H5OH /  R X alc. KOH /  CH3CH2CH2Br CH3CH=CH2 Bromopropane propene  Cont. Dehydrohalogenation of alkyl halides    alc. KOH /  H3C H2C CH CH3 Br 2-Bromobutane H3C HC CH CH3 + H3C H2C CH CH2 non terminal alkene terminal alkene (Major) (Minor) Saytzeff alkene Hofmann alkene 2- Dehalogenation of vicinal dihalo compounds (-X2) Means elimination of two halogens from vicinal dihalide using zinc in acetic acid or potassium iodide in acetone. Vicinal dihalide: in which the halogens are on two adjacent carbons. H X Zn / HOAc R HC CH2 C CH2 + ZnX2 or KI / acetone X R H Br + ZnBr2 Zn / HOAc C H3C HC CH2 H3C CH2 Br  3- Dehydration of alcohols (-H2O) Means elimination of water from two neighbouring carbon atoms using sulphuric acid or phosphoric acid. H   H2SO4 /  R H2C CH2 C CH2 + H2O OH or H3PO4 /  R Ease of dehydration: Primary alcohols undergo dehydration to give alkenes H2SO4 / 160 o C H3C CH2 H2C CH2 + H2O OH Ethanol Ethene primary alcohol  Secondary alcohols undergo elimination at lower temperatures than primary alcohols, H H2SO4 / 100 oC H3C HC CH3 C CH2 + H2O OH 2-propanol H3C secondary alcohol propene Tertiary alcohols undergo elimination at much lower temperatures than secondary alcohols. H3C H3C H2SO4 / 80 oC H3C C OH C CH2 + H2O H3C H3C tert. Butanol Butene tertiary alcohol Ease of dehydration: 3° alc. > 2° alc. > 1° alc.  4- Reduction of alkynes (addition of H2) H3C CH3 H2 / Pd H2 / Pd H3C C C CH3 CH3-CH2-CH2-CH3 Syn addition H H 2- Butyne Butane cis-2- butene H3CH2C CH2CH3 H2 / Pd/ CaCO3 (Lindlar,s catalyst) C C Syn addition H H H3CH2C C C CH2CH3 cis-3-Hexene 3-Hexyne Na / NH3 H3CH2C H Anti addition C C H CH2CH3 trans-3-Hexene 2 Na + 2 NH3 2 NaNH2 + H2 Synthesis of alkenes through elimination reactions   alc. KOH /  R H2C CH2 or NaOEt / EtOH /  X (-HX) X Zn / HOAc R HC CH2 R-HC CH2 or KI / acetone X (-X2)   H2SO4 /  R H2C CH2 OH or H3PO4 /  (-H2O)  Synthesis of alkenes Method of Start Elimination of Reagent preparation Dehydrohalogenation RX -HX Alc.KOH of alkyl halide NaOEt / EtOH Dehalogenation of X - X2 Zn / HOAc Vicinal Dihalide R HC CH2 NaI / Acetone X Dehydration of ROH -H2O H2SO4 /  alcohol Method of Start Addition of Reagent preparation Reduction of alkynes H2 (anti addition) Na / NH3 RC CR H2 (Syn addition) H2 / Lindlar‘s catalyst Reactions of alkenes 1-Addition reactions 2- Oxidation reactions 3-Substitution reactions  Addition reactions Addition of Name of reaction product H2 reduction alkane X2 halogenation vicinal dihalide HX hydrohalogenation Alkyl halide H 2O Direct or indirect hydration Alcohol 1- Hydrogenation of alkenes (reduction reactions): Addition of H2 R R R R H2 / Ni C C H C C H syn addition H H H H Alkane Ni, Pd or Pt could be used as catalysts  2) Halogenation of alkenes (addition of X2) Using Cl2 / CCl4 or Br2 / CCl4 to give vicinal dihalides. It is called electrophilic addition because the reaction is triggered by the addition of an electrophile on the electrons of the double bond. The addition is anti-addition. R R Br R Br2 / CCl4 C C R C C H H H H Br vicinal dibromide  Cont. Halogenation of alkenes (e.g. addition of Br2) Mechanism: Electrophilic addition H H H H - + Br Br R C C R + Br C C   Br R R + Cyclic bromonium intermediate - H H Br Br H R C C R H C C R Br R Br + Nucleophilic attack of Br- Vicinal dibromo compound From opposite side (anti-addition) 3) Hydrohalogenation of alkenes (addition of HX) The decreasing order of the reaction rate: HI > HBr > HCl > HF HBr H2C CH2 H3C CH2Br ethylene Sym. alkene  Addition of HX on unsymmetrical alkene depends on type of reagent Reagent Addition Mechanism HBr or HCl MARKOVNIKOV’S Ionic addition mechanism HBr / H2O2 or Anti - MARKOVNIKOV’S Free radical peroxides addition Mechanism  Markovnikov’s rule Old concept: When an unsymmetrically substituted alkene reacts with a hydrogen halide, the hydrogen adds to the carbon that has the greater number of hydrogen substituents, and the halogen adds to the carbon having fewer hydrogen substituents. Modern concept: In the ionic addition of hydrogen halide to an alkene, protonation of the double bond occurs in the direction that gives the most stable carbocation. Markovnikov’s addition of HX on unsymmetric alkene Unsymmetric alkene Mechanism of Markovnikov’s addition (ionic mechanism): It is an electrophilic addition reaction H3C CH3 H3C CH3 H C + H C Br - Br H3C CH3 H CH3 H CH3 H+ Br- 3o carbocation (more stable) + H CH3 H3C CH3 H3C CH3 2-methylbut-2-ene C H H C H + Br- H CH3 Br CH3 not formed 2o carbocation Markovnikov’s addition of HX on unsymmetric alkene Examples H H C HBr H3C C CH3 H3C CH2 Br 2-Bromopropane CH3 H3C HBr C CH2 CH3 C Br Ether CH3 H3C 2-Methylpropene 2-Bromo-2-methylpropane (100%)  Rearrangement of Carbocations In any reaction that proceed through formation of carbocation, rearrangement could occur to give the most stable one. Stability of carbocations Cont. Rearrangement of Carbocations Cont. Rearrangement of Carbocations  Anti-Markovnikov’s addition of HX to alkenes Anti-Markovnikov’s addition occurs when peroxides (ROOR) are present in the reaction mixture which initiates the free radical mechanism. HBr / H2O2 CH3 - CH = CH2 CH3 - CH2 - CH2Br Anti Markovnikov's  4- Addition of water (direct hydration of alkenes) Occurs by reaction with water in dilute acidic medium. Markovnikov’s rule is followed and rearrangement occurs to give the most stable carbocation. OH H2O/H+ CH3CH2CH = CH2 CH3CH2CH - CH3 1-Butene 2-Butanol sec. alcohol CH3 CH3 H2SO4/ H2O C = CH2 CH3 C CH3 CH3 or dil. H2SO4 OH 2-Methyl-1-propene Tert-Butyl Alcohol  Rearrangement of Carbocations During addition of water rearrangement could occur to give the most stable carbocation either by hydride or methide shift. H3C + CH3 H CH3 H2O / H CH CH CH2 HO C C CH3 + H3C CH CH CH3 hydride shift H3C CH3 H OH Major product Minor product 3-methyl-1-butene 2-methylbutan-2-ol 3-methylbutan-2-ol CH3 OH CH3 OH H2SO4 / H2O CH3 C CH CH2 CH3 C CH CH3 + CH 3 C CH CH3 methide shift CH3 CH3 CH3 CH3 major minor 3,3-dimethylbut-1-ene 2,3-dimethylbutan-2-ol 3,3-dimethylbutan-2-ol  H2 / Ni Preparation & Addition R CH2 CH3 syn addition reactions of alkenes Br Br2 / CCl4 R CH CH2 Br vicinal dibromide   alc. KOH /  OH Br2 / H2O R H2 C CH2 R CH CH2 Br or NaOEt / EtOH /  X (-HX) Bromohydrin Br X HBr Zn / HOAc R CH CH3 R HC CH2 R-HC CH2 or KI / acetone Markovnikov’s addition X (-X2) HBr R CH2 CH2 Br   H2O2 H2SO4 /  Anti-Markovnikov’s addition R H2 C CH2 OH OH or H3PO4 /  H2O/H + (-H2O) R CH CH3 1)BH3 / ether R CH2 CH2OH 2)H2O2 /NaOH primary alcohol  2- Oxidation of alkenes Reaction reagent Product Hydroxylation with Cold, dil. KMnO4 / H2O cis diol mild oxidizing agent Or OsO4 / H2O2 Epoxidation followed 1) RCOOOH Trans diol by Hydrolysis of 2) H2O / H+ or H2O / OH- epoxide in acidic or alkaline medium Oxidative cleavage of 1) Hot basic KMnO4 Acids alkenes 2) H+ Ozone / Zn / H2O Aldehydes or ketones Ozone / H2O2 Acids and ketones  A) Oxidation with mild oxidizing agent (syn hydroxylation) Using cold / dil KMnO4 or OsO4 / H2O2 The alkene is oxidized to vicinal diol (glycols) OH OH Cold KMnO4 / H2O CH3CH CH2 CH3CH CH2 or OsO4 / H2O2 1,2-Propanediol Propene (Propylene glycol)  B) Epoxidation of alkenes (anti-hydroxylation) Alkenes undergo epoxidation with peroxy acid to epoxides (oxiranes). This epoxide could be hydrolyzed in acidic or alkaline medium to give trans diol O O OH H 2 O / H+ C C + C C C C C R OOH alkene peroxyacid epoxide OH Trans diol O O H3C CH H2C CH2 CH2 ethylene oxide propylene oxide  C) Oxidative Cleavage of Alkenes 1- Using hot basic permanganate solutions. O O 1) KMnO4 / OH- / H2O / heat + R1 RCH CHR1 R C C 2) H+ OH OH 1) KMnO4 / OH- / H2O / heat C2H5COOH + CO2 C2H5CH=CH2 butene 2) H+ propionic acid Terminal alkenes form CO2 as a product 3-Substitution reactions of alkenes  3-Substitution reactions of alkenes When the reaction of alkenes with Br2 is carried out at high temperature, substitution reaction occurs at the α carbon by free radial mechanism.  H3C H BrH2C H Br2 / 500 oC C C C C Substitution reaction H H (Free radical mechanism) H H Whereas when the reaction is carried out using Br2 in non polar solvents at room temperature, addition to the double bond occurs using ionic mechanism. H3C H H3 C Br Br2 / CCl4 / RT C C H C C H Addition reaction (ionic mechanism) Br H H H Therefore, It is a temperature dependant reaction Alkynes  Alkynes Hydrocarbons that have triple bonds General formula CnH2n-2 IUPAC Nomenclature: HC CH Ethyne or acetylene CH C CH2 CH CH2 ane yne 1-Penten-4-yne CH C CH CH CH3 3-Penten-1-yne  IUPAC Nomenclature H3C H3C C CH2C CH H3C 4,4-Dimethyl-1-pentyne  Synthesis of alkynes 1-From other alkynes having lower number of carbon atoms: liq. NH3 HC CH + NaNH2 HC CNa sodium acetylide     HC CNa + R1X HC CR1 + NaX primary alkyl halide Dialkylation of acetylene can be achieved by carrying out the sequence twic  2- By elimination reactions: Alkynes may be prepared by a double dehydrohalogenation of dihaloalkanes either vicinal or geminal using alcoholic KOH or Na / liquid NH3. Geminal dihalide in which both halogens are on the same carbon. CH2 CH2 H2C alc. KOH /  HC Na / liq NH3 Br HC CH Br Br vic- dibromide vinyl bromide 1,2-dibromoethane 2 Na / liq NH3 CH3CHCl2 HC CH gem- dihalide ethylidene chloride  Cont. By elimination reactions: Alkynes may be also prepared by a double dehalogenation of tetrahalogenated compounds using Zn / acetic acid or NaI / acetone. Br Br Zn / HOAc R C C R Zn / HOAc R C C R R C C R or NaI / acetone or NaI / acetone Br Br Br Br tetrahalogenated compound  Reactions of alkynes 1. Hydrogenation H2 / Pd/ CaCO3 R R (Lindlar,s catalyst) C C Syn addition H H (Z)-alkene H2 / Pd RCH=CHR R C C R ? H2 / Pd R H Na / NH3 RCH2-CH2R C C Anti addition Alkane H R (E)-alkene 2. Halogenation R Br Br Br Br2 Br2 R C C R C C R C C R CCl4 / RT CCl4 / RT Br R Br Br  3. Addition of hydrogen halide Hydrogen halides add to alkynes to form alkenyl halides. Addition follows Markovnikov’s rule to produce geminal dihalides. H H Br H HBr HBr H C C H C C H C C H Br H Br H Vinyl bromide ethylidene Markovnikov,s addition bromide R H Br H HBr HBr R C C H C C R C C H Br H Br H  Cont. Addition of hydrogen halide If the addition occurs in presence of peroxides, it will follow anti- Markovnikov’s rule to produce vicinal dihalides. H H Br Br HBr HBr H C C H C C H C C H H2O2 H2O2 Br H H H  4- Addition of water (direct hydration) Hydration of an alkyne yields an alcohol called an enol. Enols rapidly isomerizes to aldehydes or ketones (keto–enol tautomerism). Hydration follows Markovnikov’s rule. Terminal alkynes yield methyl substituted ketones. R H R H dil. H2SO4 C C R C C H + H2O C CH HgSO4 / 60 °C O H O H H enol Vinyl alcohol derivative Ketone Keto-enol tautomerism H3C dil. H2SO4 H3C C C H + H2O C CH3 HgSO4 / 60 °C O  5- Diels-Alder reaction: Alkynes can be used as dienophiles in Diels–Alder reactions to prepare cyclohexane compounds with two isolated double bonds. H CH2 C H + C CH2 R R 6- Ozonolysis: Carboxylic acids are produced when alkynes are subjected to ozonolysis O 1 R R1 R R1 R R H2O H2O2 RC CR1 + O3 C C C C C OH + HO C O O O O O O ozonide diketone  Reactions due to acidity of hydrogens 1- Reaction with ammoniacal silver nitrate: Used for detection of terminal alkynes from non-terminal alkynes and alkenes that will not give that reaction _ + HC CH + Ag(NH3)2OH HC CAg AgC CAg Silver acetylide white ppt 2- Alkylation reactions: liq. NH3 HC CNa + NH3 HC CH + NaNH2 sodium acetylide     HC CNa + R1X HC CR1 + NaX primary alkyl halide  Synthesis of alkynes Br Br Zn / HOAc H C C H H C C H or NaI / acetone Br Br Br Br Zn / HOAc tetrahalogenated compound or NaI / acetone NaNH2 2 Na / liq NH3 / liq NH3 R1X CH3CHCl2 HC CH HC CNa HC CR1 gem- dihalide sodium acetylide ethylidene chloride H2 Na / liq NH3 C Na / liq NH3 H2C Br CH2 HC Br Br vic- dibromide 1,2-dibromoethane vinyl bromide  Reactions of alkynes +- Br2 R Br Br2 Br Br Ag(NH3)2OH C C RC CH R C C Ag R C C R CCl4 / RT Br R CCl4 / RT Br Br R H2O / dil. H2SO4 C CH3 R H Br H HgSO4 / 60 °C O HBr C C HBr R C C R methyl Ketone Br R Br H R Br H C C H R H Br Br HBr HBr Br2 Br R C C R C C R H2O2 H2O2 CCl4 / RT Br R H H alc. KOH or 2 Na / Liq NH3 R , O3 / H2O R R1 R Lindlar s C OH + HO C C C R C C R catalyst H2O2 O O H H (Z)-alkene CH2 R R H Na / NH3 CH2 C C H R R (E)-alkene H2 / Pd H2 / Pd RCH=CHR RCH2-CH2R Alkane