Write structural formulas for compounds that meet the following descriptions: (a) An alkene, C6

Write structural formulas for compounds that meet the...

Key Concepts

Alkenes

Alkenes are hydrocarbons that feature at least one carbon-carbon double bond. The presence of the double bond not only introduces a degree of unsaturation into the molecule but also influences aspects of reactivity, physical properties, and stereochemistry. Understanding alkenes is fundamental in organic chemistry for predicting reaction outcomes and for the structural determination of molecules.

Structural Formulas

A structural formula depicts the specific arrangement of atoms within a molecule, including the connectivity and positioning of bonds. In organic chemistry, structural formulas are essential tools that help visualize and distinguish between different isomers, enabling chemists to understand and predict the behavior of compounds in various reactions.

Cis-Trans (Geometric) Isomerism

Cis-trans isomerism, also known as geometric isomerism, occurs when the substituents around a double bond or a ring are arranged differently in space. This phenomenon depends on having different groups on each of the double-bonded carbons, and it results in isomers with distinct physical and chemical properties even though they share the same molecular formula.

Aromatic Compounds

Aromatic compounds are characterized by having a ring of atoms with delocalized pi electrons, following Huckel's rule. This delocalization provides significant stability and affects the electronic and chemical properties of the molecule. The benzene ring is the prototypical aromatic system and serves as a key building block for many complex organic structures.

Transcript

00:01 Okay, problem 56, we are writing structural formulas for these molecules that they described for us.

00:11 So there's a lot of different answers for these kind of problems, so i'm going to come up with one, but if it's not the same as the one you came up with, it doesn't mean it's wrong.

00:21 So these descriptions have many other isomers that could come with it.

00:28 So i'll just write what i have in mind and um we'll go from there okay so starting with part a part a says um we want an alken with five carbons alken with five carbons okay so that's exactly what i'm going to do here for part a i will write my five carbons okay one two three four five okay and i want a double bond somewhere and i don't know i just want to put it here on the very first carbon okay so now that we have that i actually need to rewrite that now that we have this double bond on the first carbon right we could fill up the rest of the bonds with hydrogens okay so this bond would have ch2 right could handle four bonds in the same oh not actually not the same the second carbon could only handle one hydrogen because it has three bonds before that okay so then we have ch2 ch2 and ch3 okay so that's that's the structure that i came up with for part b and again that double bond could be anywhere else in this structure so that's just where i wanted to put it part b okay part b we got an alkyne with four carbons so i want to start with having four carbons right one two three four okay so i have four carbons and we have an alkyne we have an alkyne meaning we have three um three bonds or a triple bond we have a triple bond somewhere and i'm just deciding to put that again on the first carbon okay so um now that we have that triple bond let's go ahead and fill it out with hydrogens right this first first carbon can handle one more hydrogen plus those three bonds gives it a total of four bonds the second carbon is saturated with four bonds so we could leave it alone so i'll just write the next carbon right next to it right and then we have this carbon which could handle two more hydrogens and finally we have ch3 at the end.

03:12 Okay.

03:13 So that's what i came up with with part b.

03:16 Again, if yours doesn't look like this, it doesn't mean it's wrong...

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