Aliphatic, Alicyclic & Aromatic Hydrocarbons PDF

02 /1 2 /2 0 2 4 Describe the physical and chemical properties of aliphatic and aromatic hydrocarbons and aliphatic...

02 /1 2 /2 0 2 4 Describe the physical and chemical properties of aliphatic and aromatic hydrocarbons and aliphatic ALIPHATIC, ALICYCLIC & hydrocarbons. AROMATIC HYDROCARBONS SLIDESMANIA.COM Discuss the pharmaceutical importance of aliphatic Edison C. Santiago, RPh, RChT, MSc cand hydrocarbons a n d aromatic hydrocarbons SLIDESMANIA.COM 1 2 3 ALIPHATIC HYDROCARBON ALIPHATIC HYDROCARBON Saturated hydrocarbons A n aliphatic compound or aliphatic hydrocarbon is an - Saturated hydrocarbon contains ma i nl y of alkanes which organic c o m p o u n d contai ning h ydrogen a nd ca r bon atoms that are usually linked together in chains that are straight. are op en chai n hydrocarbons conta ini ng carbon-carbon ALIPHATIC & ALICYCLIC The te r m Aliphatic has be e n derived f r om the Greek wor d single bond. - These c o m p o u n ds are inert in nature a nd do n ot readily HYDROCARBONS “Aleiphar” which translates to “fat”. react with acid, bases or other reagents. SLIDESMANIA.COM SLIDESMANIA.COM SLIDESMANIA.COM Unsaturated hydrocarbons Three types of aliphatic hydrocarbons: - Unsaturated hydrocarbons are alkenes a nd alkynes which Alkanes are aliphatic hydrocarbons with only single covalent bonds. have one carbon-ca rbon doubl e b o n d a nd one carbon- Alkenes are hydrocarbons that conta in at least one C–C ca r bon triple b on d respectively. 1 - They are mor e reactive tha n saturated hydrocarbons, a nd doubl e b ond Alkynes are hydrocarbons that conta in a C–C triple bond. they usually fewer hydr ogen a toms can be seen in bond with ca r bon atoms. 4 5 6  02 /1 2 /2 0 2 4 ALKANES PROPERTIES OF ALKANES Colourless REACTION OF ALKANES Less dense than water Alkanes, also called paraffins, are a class of Non-polar molecules so they are soluble in non-polar solvents than in COMBUSTION polar solvents - Alkanes b u r n in the presence of oxygen, a highly exothermic hydrocarbons that are fully saturated with Insoluble in water hydrogen. They contain n o double or triple oxidation-reducti on reaction that produces carbon dioxide and Lipophilic bonds in their carbon skeletons a n d have the water. As a consequence, alkanes are excellent fuels. As ↑ M W, ↑ B P a n d M P m a x i m u m n u m b e r of carbon to hydrogen As ↑ branching, ↓ B P covalent bonds. SLIDESMANIA.COM SLIDESMANIA.COM SLIDESMANIA.COM Alkanes have the general formula CnH2n+2. Example: Examples: Alkanes are n a m e d with the suffix “-ane” ➔ Methane is the principal com p on e n t of natural gas. following the hydrocarbon prefixes. ➔ Butane used in cam p i n g stoves an d lighters. ➔ Kerosene, diesel oil, an d fuel oil are primarily mixtures of alkanes Methane: The chemical structure of with higher molecular masses. methane, a simple alkane. neopentane boils at 9.5°C isopentane boils at 27.85 °C pentane boils at 36.1 °C ➔ The m ai n source of these liquid alkane fuels is crude oil, a co m p l e x mixture that is separated by fractional distillation. 7 8 9 REACTION OF ALKANES ALKENES REACTION OF ALKANES - Alkenes are hydrocarbons that contain one or mor e doubl e bonds. HALOGENATION - Wi t h the addition of a halogen gas an d energy, alkanes c an be - Alkenes have the general formula CnH2n. n=4 C4H8 halogenated with the reactivity of the halogens. - Alkanes are n a m e d with the suffix “-ene” following the - Substitution reaction - Ch e m i cal reaction where an at om or hydr ocarbon prefixes. functional g r ou p of a molecule is replaced by another at om or THERMAL CRACKING functional group. - Thermal cracki ng is typically per for me d at high SLIDESMANIA.COM SLIDESMANIA.COM SLIDESMANIA.COM Examples: temperatures, and often in the presence of a catalyst. - The comple x alkanes wi th high molecular weigh ts that are f ound in crude oil are frequently br oke n into smaller, more useful alkanes by thermal cracking; alkenes a nd hydr oge n gas are also pr oduce d by u si ng this method. 2 10 11 12  02 /1 2 /2 0 2 4 REACTIONS OF ALKENES REACTIONS OF ALKENES PHYSICAL PROPERTIES OF ALKENES Hydrogenation (Addition Reaction) - O n e bonds in doubl e b o n d is broken. Halogenation - Ea ch of the ca r bon a t o m in the b o n d ca n the n attach - A ddi tion of halogens Colorless gas (Et, Prop, But) another a t o m or gr oup while r ema i ning joined to each Li quid (Pent, Hex, Hept) other by a single bond. SLIDESMANIA.COM SLIDESMANIA.COM SLIDESMANIA.COM Solid (15 ca r bon above) Hydration De nse tha n water - A ddi tion reaction be twe en alkene a nd water to form Insoluble in water alcohol. Boi li ng point a nd me lti ng poin t very similar to the alkanes 13 14 15 ALICYCLIC HYDROCARBONS ALKYNES PHARMACEUTICAL USES OF - their n a m e attributed to their r e se mblance to aliphatic ALICYCLIC HYDROCARBONS - Alkynes are Unsaturated hydrocarbons that contains a c o m p o u n ds in their properties. carbon-ca rbon triple bond. - c o m p o u n d that is both aliphatic - Alkynes have the general formula CnH2n-2. a nd cyclic. SLIDESMANIA.COM SLIDESMANIA.COM SLIDESMANIA.COM - Alkanes are n a m e d wi th the suffix “-yne” following the - they have no specific a r oma C yclopropane a nd cycl obutane are gases a nd have be e n hydr ocarbon prefixes. - stability de pends on the used as anesthetics. che mica l structure of the Cycloparaffins a nd cycloalkenes are also ocular and de r mal Properties of Alkynes: compound irritants, they defat the skin. They are also skin sensitizers; N o n polar due to slightly solubility in polar solvents. - Exampl es of this category: their sensitizing activity increases wi th the n u m b e r of Insoluble in water a nd polar solvents. cyclopropane, cyclobutane, 3 doubl e bonds. Have slightly hi gher boiling poi nt tha n alkanes a nd cyclopentane, cyclohexane, etc. alkenes. 16 17 18  02 /1 2 /2 0 2 4 PROPERTIES OF AROMATIC HYDROCARBONS - The aromatic hydrocarbons are unsaturated hydrocarbons which have one or mor e planar six-ca r bon rings called A r oma tic c o m p o u n ds are generally nonpolar and AROMATIC HYDROCARBONS be nze ne rings, to which hydr oge n a toms are attached. i mmisci bl e with water. As they are often unreactive, they are useful as solvents for Examples: SLIDESMANIA.COM SLIDESMANIA.COM SLIDESMANIA.COM other nonpolar compounds. These c o m p o u n d s exhibit aromaticity The ratio of car bon a toms to hydr oge n a toms is relatively hi gh in these types of molecules. W h e n burnt, the a r omatic hydrocarbons display a strong a nd sooty flame whi ch is yellow. benzene 19 20 21 Huckel’s Rule: 4n +2 Rule and Aromaticity Huckel’s Rule: 4n +2 Rule and Aromaticity Aromatic Substitution Reactions Huckel’s Rule is used in order to estimate the aromatic qualities of any - These reactions involve the r eplacement of one substituent planar ring-shaped molecule in the field of organic chemistry. - the aromaticity of the be nze ne mol e cul e is established on the ring of a n aromatic hydrocarbon, c o m m o n l y a since it obeys the Hu ckel rule. hydr ogen atom, by a different substituent group. Characteristics: 1. It m u s t b e cyclic SLIDESMANIA.COM SLIDESMANIA.COM SLIDESMANIA.COM 2 Every a t o m in the ring m u s t b e conjugated benzene 3. The molecules m u s t b e flat Aromatic substitution: Example of an aromatic substitution reaction. 4 - Oth er examples of aromatic c o m p o u n ds that compl y with The double b o n d attacks the NO2 cation, then a proton (hydrogen cation) is lost to rearomatize the system. Huckel’s Rule incl ude pyrrole, pyridine, a nd furan. 22 23 24  02 /1 2 /2 0 2 4 The green p i g m e n t found in plants, m o r e c o m m o n l y k n o w n as chlorophyll, consists of aromatic hydrocarbons a n d is very important in the process of Coupling Reactions food production in plants. The nucleic acids a n d a m i n o acids in the h u m a n body also consist of these - C oupl ing reactions are reactions involving a me tal catalyst aromatic hydrocarbons. that ca n result in the formation of a carbon-ca rbon bon d be twe e n two radicals. Methylbenzene w h i c h is an aromatic hydrocarbon is used as a solvent in m o d e l glues THANK YOU! Naphthalene is an important i t e m in the production of mothballs Hydrogenation For the synthesis of drugs, dyes, a n d explosives, an aryl hydrocarbon k n own A N Y QUESTIONS? SLIDESMANIA.COM SLIDESMANIA.COM SLIDESMANIA.COM as Phenanthrene is used - The hydr oge nation reactions involving arenes generally Trinitrotoluene or TNT is a very important aromatic hydrocarbon which is lead to the formation of saturated rings. widely used for explosive purposes. Plastic industry a n d petrochemical industries m a k e use of aromatic hydrocarbons extensively. 25 26 27 5