hi everybody we are starting a brand new chapter today chapter 12 focuses on alcohols from carbonyl compounds and for the first time in a while we're gonna actually start looking at some new reactions as we start now this transition away from substitutions and eliminations and start to get into the chemistry of carbonyl compounds within just a few weeks this is actually a relatively short chapter we should be wrapping this up or the early part of next week and on the slide we see some of the topics we're going to be covering primarily the primary topic in this particular lecture is going to be on the oxidation and reduction chemistry of alcohols and on a future video we're going to be looking at a multi-step synthesis strategy and a new reaction called the grignard reaction so when we start talking about oxidation and reduction reactions this is all about the chemistry of alcohols and their conversion into the carbonyl group which of course is the carbon oxygen double bond so on the slide you see an alcohol in the middle on the right a carbonyl compound could be an aldehyde or a ketone and on the left another carbonyl compound the carboxylic acid so the oxidation of alcohols involves hydrogen or hydrogen's being taken away a hybridization change from sp3 to sp2 and the formation of carbon oxygen double bonds so when the alcohol in the middle is converted to a aldehyde or a ketone that is an example of an oxidation another example is when an alcohol might be converted to a carboxylic acid notice that as the alcohol is oxidized to an aldehyde or a ketone we lose one hydrogen actually we lose two hydrogen's we lose a red hydrogen plus a hydrogen that's on the oxygen and we get a double bond being formed notice what when an alcohol is oxidized to a carboxylic acid we are also losing two hydrogen's and adding a new Oh H group so the opposite direction the opposite chemistry is a reduction reaction and this involves adding hydrogen changing the hybridization from sp2 back to sp3 and at a loss of carbon oxygen double bonds so an aldehyde or ketone being reduced back to an alcohol there's one example notice that hydrogen is now being put back in and a carboxylic acid when that adds hydrogen we can also get back to an alcohol now these are all these are four different types of oxidation and reduction reactions and they all require different types of oxidizing or reducing reagents the strength of those reagents will dictate what which type functional group will either be produced or will undergo reaction there are numerous examples of these types of oxidation and reduction reagents and I'm gonna limit limit our discussion to just a very few of these so at this time we have two simple reagents for oxidizing primary and secondary alcohols excuse me primary or secondary alcohols for a primary alcohol we're gonna use a reagent that's referred to as jordanian chlorochromate here is the structure shown it's got chromium as the as the active metal in this particular oxidizing agent we are simply going to know it as PCC for pyridinium chlorochromate this is specific for the primary alcohol group and primary alcohols are oxidized to aldehydes the aldehyde functional group is a carbonyl that has an alkyl group on to it and it has one hydrogen bond to it secondary alcohols are a little tougher to oxidize we need a reagent that's a little bit stronger so we're going to use chromic acid h2co3 nicely oxidized secondary alkyl Falls to ketones a ketone is a carbonyl group that has two alkyl groups bonded to it now I am a green chemist most of you or many of you know that I do not like using chromium reagents chromium is actually rather hazardous and toxic although these are very effective reagents for oxidizing primary and secondary alcohols you will never see me using these in my research or in our organic chemistry laboratory course there are other reagents that are less commonly known that are quite a bit safer to use so this is the story for primary and secondary alcohols what about a tertiary alcohol the problem with the tertiary alcohol is that there are no hydrogen's bonded to the carbon that contains the O H group so if you even tried oxidizing it you'd end up with a pentavalent carbon carbon with five bonds to it and you guys know how much I love that so that doesn't happen if you do use a really strong oxidizing agent it'll just chew it all the way up to carbon dioxide and that's pretty much useless to us so the only Regents were interested in our PCC for primary alcohols and chromic acid for a secondary alcohol as far as the reduction of simple carbonyl compounds the only reagent you need to know about is sodium borohydride sodium borohydride is a a wonderful reagent it is it is essentially a solid way of storing hydrogen gas which is really cool not very effective for energy storage because it's not it's not it's not particularly stable but more importantly it you don't have a large volume of hydrogen gas being stored per mass or per mole of the reagent but it's great for very simple reductions of organic compounds so if we take our aldehyde as we see on the top in use sodium borohydride that gets reduced back to the primary alcohol if we have ketone sodium borohydride would very nicely reduced that back to a secondary alcohol so now we have a variety of reagents simple reagents that we can use for oxidizing alcohols and for reducing alcohols we'll see a few additional reagents a little bit later on when we get to the chapter on carboxylic acids that is the end of this recording