What do alkenes smell like

Plants can synthesize the benzene ring from carbon dioxide, water, and inorganic materials. Animals cannot synthesize it, but they are dependent on certain aromatic compounds for survival and therefore must obtain them from food. Phenylalanine, tyrosine, and tryptophan essential amino acids and vitamins K, B 2 riboflavin , and B 9 folic acid all contain the benzene ring. So far we have examine only aromatic compounds with carbon-containing rings.

However, many cyclic compounds have other elements, like oxygen or nitrogen, in the ring. These compounds, called heterocyclic compounds , will be seen in the biochemistry chapters. For example, diazepam Valium below has nitrogen atoms as part of the aromatic ring system. Briefly identify the important distinctions between a saturated hydrocarbon and an unsaturated hydrocarbon. Briefly identify the important distinctions between an alkene and an alkane.

What are cis-trans geometric isomers? What two types of compounds can exhibit cis-trans isomerism? Classify each compound as saturated or unsaturated. Identify each as an alkane, alkene, alkyne, or aromatic.

Classify each compound as a cis isomer, a trans isomer, or neither. There are no isomers for this molecule. Skills to Develop To differentiate the structure of alkenes and other unsaturated hydrocarbons, like alkynes and aromatics from saturated alkanes.

Recognize that alkenes that can exist as geometric isomers and classify isomers as cis or trans. These are not isomers. Aromatic Compounds Rings of alternating double and single bonds comprise a distinct class, called aromatic hydrocarbons , with unique structures and properties different than regular alkenes.

Biologically Important Compounds with Aromatic Rings Substances containing the benzene ring are common in both animals and plants, although they are more abundant in the latter. Concept Review Exercises Briefly identify the important distinctions between a saturated hydrocarbon and an unsaturated hydrocarbon. Answers Unsaturated hydrocarbons have double or triple bonds and are quite reactive; saturated hydrocarbons have only single bonds and are rather unreactive.

An alkene has a double bond; an alkane has single bonds only. Cis-trans isomers are compounds that have different configurations groups permanently in different places in space because of the presence of a rigid structure in their molecule. Alkenes and cyclic compounds can exhibit cis-trans isomerism. They behave more similarly to alkane structure and lack chemical reactivity.

One of the few types of reactions that a benzene ring will undergo is a substitution reaction. Recall from Chapter 7 that in substitution reactions an atom or group of atoms is replaced by another atom or group of atoms. Halogenation is a common substitution reaction that occurs with benzene ring structures. In the diagram below, notice that the hydgrogen atom is substituted by one of the bromine atoms. A polymer is as different from its monomer as a long strand of spaghetti is from a tiny speck of flour.

For example, polyethylene, the familiar waxy material used to make plastic bags, is made from the monomer ethylene—a gas. Polyethene pellets that are produced in factories can be melted, formed into a giant bubble, and then made into a film that is used in packaging, consumer products, and food services.

There are two general types of polymerization reactions: addition polymerization and condensation polymerization. This section will focus on addition polymerization reactions. For more information about condensation polymerization, see Chapter 10 In addition polymerization, the monomers add to one another in such a way that the polymer contains all the atoms of the starting monomers.

Ethylene molecules are joined together in long chains. The polymerization can be represented by the reaction of a few monomer units:. The bond lines extending at the ends in the formula of the product indicate that the structure extends for many units in each direction. Notice that all the atoms—two carbon atoms and four hydrogen atoms—of each monomer molecule are incorporated into the polymer structure.

Because displays such as the one above are cumbersome, the polymerization is often abbreviated as follows, where n is the number of repeating units:. Structure from: Magmar Many natural materials—such as proteins, cellulose and starch, and complex silicate minerals—are polymers.

Artificial fibers, films, plastics, semisolid resins, and rubbers are also polymers. More than half the compounds produced by the chemical industry are synthetic polymers.

Some common addition polymers are listed in Table 8. Note that all the monomers have carbon-to-carbon double bonds. Many polymers are mundane e. Medical Uses of Polymers An interesting use of polymers is the replacement of diseased, worn out, or missing parts in the body. For example, about a , hip joints and , knees are replaced in US hospitals each year.

The artificial ball-and-socket hip joints are made of a special steel the ball and plastic the socket. People crippled by arthritis or injuries gain freedom of movement and relief from pain. Patients with heart and circulatory problems can be helped by replacing worn out heart valves with parts based on synthetic polymers.

These are only a few of the many biomedical uses of polymers. The hip is much like a ball-and-socket joint, and total hip replacements mimic this with a metal ball that fits in a plastic cup. What is a monomer? What is a polymer? How do polymer molecules differ from the molecules we have discussed in earlier sections of this chapter?

What is addition polymerization? What structural feature usually characterizes molecules used as monomers in addition polymerization? Monomers are small molecules that can be assembled into giant molecules referred to as polymers, which are much larger than the molecules we discussed earlier in this chapter. In addition polymerization, the monomers add to one another in such a way that the polymer contains all the atoms of the starting monomers.

C H Cl Write the condensed structural formula of the monomer from which Saran is formed. To ensure that you understand the material in this chapter, you should review the meanings of the bold terms in the following summary and ask yourself how they relate to the topics in the chapter. Any hydrocarbon containing either a double or triple bond is an unsaturated hydrocarbon. Alkenes have a carbon-to-carbon double bond. The general formula for alkenes with one double bond is C n H 2 n.

Alkenes can be straight chain, branched chain, or cyclic. Simple alkenes often have common names, but all alkenes can be named by the system of the International Union of Pure and Applied Chemistry and have the ending -ene. Cis-trans isomers or geometric isomers are characterized by molecules that differ only in their configuration around a rigid part of the structure, such as a carbon—to-carbon double bond or a ring.

The molecule having two identical or closely related atoms or groups on the same side is the cis isomer ; the one having the two groups on opposite sides is the trans isomer. The physical properties of alkenes are quite similar to those of alkanes.

Like other hydrocarbons, alkenes are insoluble in water but soluble in organic solvents. More reactive than alkanes, alkenes undergo A ddition Reactions across the double bond. There are four types of addition reactions: Hydrogenation which involves adding H 2 across the double bond, Hydrohalogenation which involves adding hydrogen and a halogen Cl, Br, or I across the double bond, Halogenation which involves adding two halogen atoms Cl, Br, or I across the double bond, and Hydration which involves adding water as H and -OH across the double bond.

Alkenes also undergo addition polymerization , molecules joining together to form long-chain molecules. The reactant units are monomers , and the product is a polymer.

Alkenes can also be involved in Rearrangement Reactions that convert one compound into a related isomer. Rearranging cis to trans isomers are common rearrangement reactions. Elimination Reactions can regenerate alkene structures by the removal of water or dehydration of alkanes. Alkynes have a carbon-to-carbon triple bond. The properties of alkynes are quite similar to those of alkenes. They are named much like alkenes but with the ending — yne. Aromatic compounds contain a cyclic hydrocarbon, benzene C 6 H 6 with alternating double-bonds.

Due to resonance structures, the aromatic ring is extremely stable and does not undergo the typical reactions expected of alkenes. The electrons that might be fixed in three double bonds are instead delocalized over all six carbon atoms. The main reaction aromatic compounds will undergo are substitution reactions. A polycyclic aromatic hydrocarbon PAH has fused benzene rings sharing a common side. Give the molecular formula for each compound.

Describe a physiological effect of some PAHs. What are some of the hazards associated with the use of benzene?

What is wrong with each name? Following are line-angle formulas for three compounds. Draw the uncondensed structure for each. Text for this chapter has been adapted from the creative commons resources listed below, unless otherwise noted in the text. Please click here to download: CH Chapter 8 PDF file This text is published under creative commons licensing, for referencing and adaptation, please click here.

Opening Essay 8. Back to the Top 8. Mathematically, this can be indicated by the following general formulas: In an alkene, the double bond is shared by the two carbon atoms and does not involve the hydrogen atoms, although the condensed formula does not make this point obvious, ie the condensed formula for ethene is CH 2 CH 2.

Thus, until you become more familiar the language of organic chemistry, it is often most useful to draw out line or partially-condensed structures, as shown below: Back to the Top 8. Looking Closer: Environmental Note Alkenes occur widely in nature. Concept Review Exercises Briefly describe the physical properties of alkenes. Answers Alkenes have physical properties low boiling points, insoluble in water quite similar to those of their corresponding alkanes.

Key Takeaway The physical properties of alkenes are much like those of the alkanes: their boiling points increase with increasing molar mass, and they are insoluble in water. Exercises Without referring to a table or other reference, predict which member of each pair has the higher boiling point. Answer 1-pentene 3-nonene. Concept Review Exercises Briefly identify the important distinctions between a saturated hydrocarbon and an unsaturated hydrocarbon.

Answers Unsaturated hydrocarbons have double or triple bonds and are quite reactive; saturated hydrocarbons have only single bonds and are rather unreactive. Key Takeaway Alkenes are hydrocarbons with a carbon-to-carbon double bond. Back to the Top. Note Acetylene is used in oxyacetylene torches for cutting and welding metals. Concept Review Exercises Briefly identify the important differences between an alkene and an alkyne. Answers Alkenes have double bonds; alkynes have triple bonds.

Key Takeaway Alkynes are hydrocarbons with carbon-to-carbon triple bonds and properties much like those of alkenes. Exercises Draw the structure for each compound. Name each alkyne. Concept Review Exercises How do the typical reactions of benzene differ from those of the alkenes? Answers Benzene is rather unreactive toward addition reactions compared to an alkene. Recognizing Aromatic Compounds Which compounds are aromatic?

Skill-Building Exercise Which compounds are aromatic? Key Takeaway Aromatic hydrocarbons appear to be unsaturated, but they have a special type of bonding and do not undergo addition reactions. Back to the Top Polycyclic Aromatic Hydrocarbons Some common aromatic hydrocarbons consist of fused benzene rings—rings that share a common side.

Biologically Important Compounds with Benzene Rings Substances containing the benzene ring are common in both animals and plants, although they are more abundant in the latter. Note So far we have studied only aromatic compounds with carbon-containing rings. Worked Example Which compounds can exist as cis-trans geometric isomers? Skill-Building Exercise Which compounds can exist as cis-trans isomers? Concept Review Exercises What are cis-trans geometric isomers? Answers Cis-trans isomers are compounds that have different configurations groups permanently in different places in space because of the presence of a rigid structure in their molecule.

Like Liked by 1 person. I am doing a work about chemistry of smell for students. Try making esters. Good luck! Got me thinking… These beautiful charts are only relevant to human nasal perception. Do they key on one compound or a standard of multiple compounds acting in concert?

Thanks for the charts. Olfactory perceptions are subjective. Most people, however, will agree on the smells in the posters. Thanks for visiting. I love this poster and I printed a large version in my office. Looking at it today, I thought that in the box for benzene-enal, you could actually put cinnamic aldehyde, which is an important flavor and fragrance compounds that is missing form the chart and it is not far flung to look at it as the enal of benzene.

Ooh, I love this chart. My father was a chemist but had a poor sense of smell. I am not a chemist but am fascinated by the chemistry and physiology of smell. When I smell something stinky, I get really curious about what makes it so unpleasant. What does a pinacate beetle smell like insulin, apparently and why is it so distinctive yet impossible for me to describe to others? Why does body odor specifically armpits not disturb me as much as air freshener or Febreeze?

Thanks for the chart. As already pointed out by Greg E and Uncle Al , numerous hydrocarbons without any heteroatom-based functional groups do show characteristic smells.

More pleasant smells are found in the group of monoterpenes , i. A sufficiently conjugated system is far from being colourless, take lycopene 9 , the deep red coloured dye in tomatoes as an example.

Adamantane smells of camphor. Sign up to join this community. The best answers are voted up and rise to the top.

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