29May 2019 by Vincent Summers 1 Comment

What are Oximes and How Are They Useful?

Chemistry
Many with even a casual chemistry acquaintance have heard of such compounds as hydrocarbons, alcohols, ethers, glycols, and so forth. But the majority have probably never heard of oximes. What are oximes? How are they formed? Are they useful? Hydroxylamine Ammonia's chemical formula is NH3. Structurally, it resembles a tripod. If one of its hydrogen atoms is replaced by an hydroxyl group, –OH, the result is hydroxylamine, NH2OH. Two Oxime Varieties Hydroxylamine combines with aldehydes1 or ketones2 to form aldoximes or ketoximes, respectively. These are two subclasses of oxime. For example, hydroxylamine combines with acetaldehyde... CH3–CHO + NH2–OH → CH3–C(H)=N–OH And hydroxylamine combines with dimethylketone... (CH3)2=O + NH2–OH → (CH3)2–C=N–OH Of course there are other synthetic pathways that can be employed to produce oximes. So the question becomes, Do oximes…
Read More
17Nov 2014 by Vincent Summers No Comments

Keto Enol Tautomerism

Chemistry
Is the term keto enol tautomerism familiar to you? If not, give attention to the ensuing discussion. Organic chemistry would be of no value if not for multiple bonds and functional groups.  Such groups impart the reactivity needed to sustain life. One attachment is carbonyl (–C=O). Tautomerism Given the right environment, atoms of a carbonyl group tautomerize. That is, they can exchange a proton (hydrogen). In so doing a π-bond is formed or disappears. The carbonyl or keto form assumes the alkene-alcohol or enol form, or vice versa. For acetone, the two forms are, CH3–(C=O)–CH3 keto form CH2=C(OH)–CH3 enol form See the image above. [sc name="MidArticleAdsense"] Both Aldehydes and Ketones Participate A ketone has its carbonyl carbon atom linked to two other carbon atoms. An aldehyde has its carbonyl carbon…
Read More