CHM 105 & 106 MO1 UNIT ONE, LECTURE EIGHT/ UNIT TWO, LECTURE ONE 1 CHM 105/106 Program 8: Unit 1 Lecture 8 / Unit 2 Lecture 1 IN THE END OF OUR PREVIOUS LECTURE WE WERE LOOKING AT THE AREA OF CHEMISTRY THAT WE REFER TO AS ORGANIC CHEMISTRY, AND ORGANIC CHEMISTRY IS CHEMISTRY BASED PRIMARILY ON CARBON CONTAINING COMPOUNDS. AND WITHIN THAT GROUP OF ORGANIC CHEMISTRY THE SIMPLEST, I GUESS WE WOULD CALL IT SIMPLEST FROM THE STANDPOINT THAT IT CONTAINS ONLY TWO ELEMENTS, ARE THE CHEMICAL COMPOUNDS CA LLED HYDRO CARBONS. BY THEIR NAME, HYDROCARBONS ARE COMPOUNDS CONTAINING HYDROGEN AND CARBON ONLY, ONLY TWO ELEMENTS IN THERE. WE LOOKED AT ONE GROUP OF THOSE YESTERDAY WHICH WE CALL SATURATED HYDROCARBONS, WHICH HAVE A GENERAL CHEMICAL FORMULA RELATING TO CARBON AND HYDROGEN, CNH2N+2, SO WHATEVER N IS FOR CARBON, FOR INSTANCE IF WE HAD THEN A COMPOUND WHICH HAD, SAY, 10 CARBONS HERE, SO C10, THAT WOULD TELL US THEN THAT THE NUMBER OF HYDROGENS WOULD BE TWO TIMES THAT, 20 PLUS 2. SO THE CHEMICAL FORMULA FOR THE ORGANIC COMPOUND WOULD BE IN THAT CASE. C10H22. WE CALL THIS GROUP THE ALKANES, AS A FAMILY OF ORGANIC COMPOUNDS. WE REFER TO THEM AS THE ALKANES, AND WE LOOKED AT THE FIRST 10 OF THOSE ALKANES YESTERDAY, AND POINTED OUT THAT SOME OF THESE ARE FAIRLY COMMON COMPOUNDS TO US, THINGS THAT WE EXPERIENCE OR UTILIZE ON A FAIRLY COMMON BASIS. THE LATTER ONES ARE THOSE THAT ARE COMPONENTS OF GASOLINE THAT WE USE IN THE AUTOMOBILE. THE FIRST ONE, THE SIMPLEST OF THE ALKANES, METHANE, WE INDICATED WAS A COMPONENT OF NATURAL GAS. PROPANE AND BUTANE OF COURSE ARE TWO OTHER FAIRLY COMMON ALKANE HYDROCARBONS. WE ALSO WENT ON AND TALKED A LITTLE BIT ABOUT THE FACT THAT WHEN YOU HAVE THE FORMULA FOR A HYDROCARBON THAT IT IS POSSIBLE THAT WE CAN PUT THESE TOGETHER, IT IS POSSIBLE THAT WE CAN PUT THESE TOGETHER IN MORE THAN ONE WAY AND ACTUALLY PRODUCE THEN MORE THAN ONE CHEMICAL COMPOUND. MEANING THAT THE COMPOUND SHOULD HAVE SOME DIFFERENT PHYSICA L PROPERTIES – MELTING POINTS, BOILING POINTS, CHEMICAL REACTIVITY, IF THEY IN FACT ARE UNIQUE. AND JUST TO LOOK AT ONE HERE REAL QUICK A GAIN, IF FOR INSTANCE WE HAD A COMPOUND C4H10, CHM 105 & 106 MO1 UNIT ONE, LECTURE EIGHT/ UNIT TWO, LECTURE ONE 2 AND THAT IS AN ALKANE HYDROCARBON, MEETS THE FORMULA 2N, 2 TIMES N PLUS 2 FOR THE HYDROGEN. WE COULD PUT THE 4 CARBONS TOGETHER LIKE SUCH, AND ATTACH THE 10 HYDROGENS, AND AS I INDICATED YESTERDAY, THE CHEMISTRY OF CARBON IS SUCH THAT IT CAN HAVE 4 BONDS, 4 THINGS ATTACHED TO IT. IN OUR STRUCTURAL FORMULA WE SHOW THOSE AS DASHES. WE DON’T NEED TO WORRY ABOUT WHAT A CHEMICAL BOND IS AT THIS POINT, BUT CARBON CAN HAVE 4 THING ESSEN TIALLY ATTACHED TO IT. HYDROGEN CAN HAVE ONLY 1 BOND. AND SO THE ONLY WAY WE CAN HOOK HYDROGENS ON THERE IS WE CAN’T HOOK TWO HYDROGENS TOGETHER AND THEN HAVE ANYTHING LEFT TO HOOK THE CARBON, SO IF A HYDROGEN IS HOOKED TO A CARBON IT IS USED UP THEN ALL OF ITS ABILITY TO BOND. WELL WE COULD DO IT THAT WAY, OR WE COULD A LSO HOOK 3 CARBONS LIKE THIS AGAIN WITH THE HYDROGENS ATTACHED, AND THEN THE 4TH CARBON WE COULD PUT HERE AND ATTACH HYDROGENS, AND IF WE LOOK WE SHOULD HAVE AGAIN 4 CARBONS AND 10 HYDROGENS SURROUNDING IT. AND THES E ARE TWO DIFFERENT CHEMICAL COMPOUNDS WHICH WE REFER TO THEN AS ISOMERS, STRUCTURAL ISOMERS OF THE SAME CHEMICAL FORMULA, BOTH OF THESE ARE C4H10, BOTH OF THESE ARE ALKANES, SATURATED HYDROCARBONS, BUT THEY ARE TWO DISTINCT CHEMICAL COMPOUNDS. AND THE NAMING RULES USED IN ORGANIC CHEMISTRY ARE CALLED THE IUPAC RULES . WHICH REFER TO IN THE TEXT, BUT WE’RE NOT GOING TO SPEND ANY APPRECIABLE TIME AS WE GO THROUGH THE COURSE WORRYING ABOUT APPLYING IUPAC RULES. WE’LL LEARN A FEW BASIC NAMES OF THE ORGANICS AND USE THEM AS SUCH, BUT THE IUPAC RULE IS TO NAME THE LONGEST CARBON CHAIN AS THE BASIC NAME AND THEN TO TELL WHAT OTHER THINGS MIGHT BE PRESENT IN THE MOLECULE. IN THIS CASE, THE LONGEST CONTINUOUS CHAIN IS FOUR. THIS COMPOUND IS MERELY CALLED BUTANE. THAT’S ALL WE HAVE TO SAY. THE ENDING, I DIDN’T MENTION THIS IN THE PREVIOUS LECTURE, BUT THE ENDING OF ALL ALKANES IS A-N-E, THAT’S KIND OF A WAY WE CAN GET AN IDEA WHEN WE SEE A NAME AS TO WHAT TYPE OF CHEMICAL COMPOUND, WHAT TYPE OF ORGANIC COMPOUND IT IS. THIS ONE HAS 3 CARBONS IN A ROW. NO MATTER WHICH WAY YOU GO, THE LONGEST CONTINUOUS CHAIN WOULD BE 3, AND SO THE BASE NAME IS PROPANE. AGAIN NOTICE IT ENDS IN A-N-E. BUT THIS TIME WE HAVE THIS LITTLE GROUP CHM 105 & 106 MO1 UNIT ONE, LECTURE EIGHT/ UNIT TWO, LECTURE ONE 3 HANGING RIGHT HERE AND SO WE HAVE TO TELL IT IT’S THERE. IN THE DETAILED IUPAC SYSTEM WE NUMBER THE CARBONS AND WE TELL WHAT CARBON THE GROUP IS ATTACHED. SO IF WE WERE TO DO THAT AND CALL THIS CARBON 1 AND THIS ONE 2 AND THIS ONE 3, WE COULD THEN CALL THIS 2, TO TELL THAT ON THE SECOND CARBON OF THE PROPANE THERE’S SOMETHING ATTACHED, AND THEN WE WOULD SA Y WHAT’S ATTACHED? METHYL. THIS IS THE NAME, METHYL IS THE NAME FOR THIS LITTLE CH3 GROUP HANGING ON THERE AND WE WOULD CALL THAT THEN 2-METHYL PROPANE, AND THOSE ARE THE SAME RULES THAT WE WOULD USE NO MATTER HOW COMPLI CATED THE MOLECULE M IGHT BECOME. ALRIGHT, SO THE MAIN THING THAT WE’RE LOOKING AT HERE, THE MAIN THING THAT I WANT TO STRESS IS THE FACT THAT WE HAVE SO MANY DIFFERENT WAYS OF PUTTING TOGETHER THESE CARBON HYDROGEN STRUCTURES. AS I MENTIONED YESTERDAY, BY THE TIM E WE GET TO C10, C10H22 HAS ABOUT 70 DIFFERENT UNIQUE WAYS OF HOOKING IN TOGETHER. 70 DIFFERENT NAMES, 70 DIFFERENT COMPOUNDS, ALL WITH THE SAME CHEMICAL FORMULA. SO CHEMICAL FORMULAS TELL US WHAT AND HOW MUCH OF EACH ARE THERE, STRUCTURAL FORMULAS TELL US HOW THEY’RE HOOKED TOGETHER, AND IF WE HAVE MORE THA N ONE WAY WE CAN HOOK THEM TOGETHER, THOSE ARE REFERRED TO AS ISOMERS. NOW ONE OTHER TYPE OF HYDROCARBON THAT FALLS INTO THIS SAME GENERAL CATEGORY ARE THE CYCLOALKANES. NOTICE THAT WE STILL HAVE THIS NAME ALKANES, BUT THE CYCLO PART. THE NORMAL ALKANES A RE CHAINS, LONG CHAINS, THINGS CAN BE BRANCHED OFF OF THOSE CHAINS, BUT AS W E SEE THEY’RE JUST HOOKED TOGETHER, BUT CYCLOALKANES NOW BY THE TERM WOULD BE CYCLIC, OR IN OTHER WORDS WE’RE GOING TO HOOK THINGS TOGETHER. LET’S TAKE BUTANE FOR A SECOND. THIS IS THE WAY WE WOULD NORMALLY PICTURE BUTANE, 4 CARBONS INA ROW LIKE THIS. IF WE WERE TO TAKE THE TWO END CARBONS, THIS WAS ONE CARBON AND AN END, THIS WAS THE OTHER ONE. IF WE WERE TO BEND THEM AROUND WE CAN ACTUALLY HOOK THEM TOGETHER LIKE SUCH AND WE WILL STILL HAVE HYDROGENS ON HERE. SO WE END UP WITH SORT OF A SQUARE LOOKING SHAPE. NOW THE NAMING FOR THIS IS STILL THAT IT’S A BUTANE, BECAUSE IT HAS 4 CARBONS, AND THAT WOULD BE THE RULE WE WOULD APPLY, BUT OBVIOUSLY THIS ISN’T THE SAME BUTANE AS WHAT WE SAW JUST A MOMENT AGO WHERE THE 4 WERE INA ROW. CHM 105 & 106 MO1 UNIT ONE, LECTURE EIGHT/ UNIT TWO, LECTURE ONE 4 AS A MATTER OF FACT, IT DOESN’T HAVE THE SAME CHEMICAL FORMULA BECAUSE HERE THIS HAS A CHEMICAL FORMULA OF C4H8. THIS IS NOT, THIS IS NOT AN ISOM ER OF THE PREVIOUS CHEMICAL FORMULA. THE PREVIOUS CHEMICAL FORMULA WAS C4H10. THIS IS A NEW COMPOUND, NEW CHEMICAL FORMULA. BUT HOW ARE WE GOING TO SHOW THIS NOW NOT BEING THE SAME AS THE OTHER BUTANE? WE USE THE PREFIX “CYCLO.” SO THIS WOULD BE CALLED CYCLOBUTANE, WHICH TELLS THE READER THAT 4 CARBONS, BUT THE END CARBONS ARE HOOKED BACK TOGETHER TO MAKE IT INTO A CYCLING MATERIAL. AND THE TEXT SHOWS A COUPLE OF CYCLIC COMPOUNDS. ONE THAT IS SOMEWHAT OF INTEREST, LET’S LOOK AT THIS INE RIGHT HERE WHICH HAS 3 CARBONS ON IT AND EACH OF THESE CARBONS WOULD HAVE A COUPLE OF HYDROGENS ATTACHED, LIKE SUCH. THIS IS CALLED CYCLO, AND THE NAME FOR 3 CARBONS WAS PROPANE, SO CYCLOPROPANE. CYCLOPROPANE IS AN ANESTHETIC. IT WAS USED FOR MANY YEARS IN PLACE OF ETHER BECAUSE OF SOME OF THE ILL-EFFECTS THAT ETHER HAS – AFTER-EFFECTS, NAUSEA, ETC, AND SO ETHER WAS REPLACED FOR SOME TIM E WITH A CHEMICAL CALLED CYCLOPROPANE. THE ONLY PROBLEM IS CYCLOPROPANE IS VERY REACTIVE AND SO NECESSARY PRECAUTIONS HAD TO BE TAKEN. YOU COULDN’T HAVE ANY STATIC ELECTRICITY, THINGS HAD TO BE PROPERLY ELECTRICALLY GROUNDED, THE CLOTHING WORN IN FOR AN OPERATING ROOM HAD TO BE CAREFUL THAT IT WASN’T CLOTHING…YOU WOULDN’T WEAR INA WOOL SUIT, WHICH COULD PICK UP STATIC ELECTRICITY. SO CYCLOPROPANE THEN WAS USED AS AN ANESTHETIC. OKAY? NOW, MOST OF THE, HERE WE GO, MOST OF THE HYDROCARBONS OF COURSE ARE OBTAINED FROM OUR PET ROLEUM SUPPLY. AND IF YOU TRAVEL ACROSS TEXAS, OKLAHOMA, EVEN PARTS OF MISSOURI, OHIO, YOU MAY SEE IN THE FIELDS ALONG THE ROAD THESE PUMPS.