Figure 5 shows dehydration synthesis of glucose binding together to form maltose and a water molecule. Table 2 summarizes macromolecules and some of their functions.
Figure 5. In this dehydration synthesis reaction, two molecules of glucose are linked together to form maltose. In the process, a water molecule is formed. Which of the following is the name for molecules whose structures are nonsuperimposable mirror images? Two molecules containing the same types and numbers of atoms but different bonding sequences are called enantiomers. Skip to main content. Microbial Biochemistry. Search for:. Organic Molecules Learning Objectives Identify common elements and structures found in organic molecules Explain the concept of isomerism Identify examples of functional groups Describe the role of functional groups in synthesizing polymers.
Clinical Focus: Cristina, Part 1 Cristina is a year-old student who visited her doctor, complaining about an itchy skin rash. What kinds of substances would you expect to find in a moisturizing cream? What physical or chemical properties of these substances would help alleviate itching and inflammation of the skin?
Think about It Describe the most abundant elements in nature. What are the differences between organic and inorganic molecules? Think about It We say that life is carbon based. What makes carbon so suitable to be part of all the macromolecules of living organisms? Think about It What is the byproduct of a dehydration synthesis reaction? Key Concepts and Summary The most abundant elements in cells are hydrogen, carbon, oxygen, nitrogen, phosphorus, and sulfur.
Life is carbon based. Each carbon atom can bind to another one producing a carbon skeleton that can be straight, branched, or ring shaped. The same numbers and types of atoms may bond together in different ways to yield different molecules called isomers. Isomers may differ in the bonding sequence of their atoms structural isomers or in the spatial arrangement of atoms whose bonding sequences are the same stereoisomers , and their physical and chemical properties may vary slightly or drastically.
Functional groups confer specific chemical properties to molecules bearing them. Common functional groups in biomolecules are hydroxyl, methyl, carbonyl, carboxyl, amino, phosphate, and sulfhydryl. Macromolecules are polymers assembled from individual units, the monomers , which bind together like building blocks.
Many biologically significant macromolecules are formed by dehydration synthesis , a process in which monomers bind together by combining their functional groups and generating water molecules as byproducts. Multiple Choice Which of these elements is not a micronutrient?
C carbon is not a micronutrient. Show Answer Answer d. Enantiomers are molecules whose structures are nonsuperimposable mirror images. Show Answer True. Show Answer False. Think about It Why are carbon, nitrogen, oxygen, and hydrogen the most abundant elements in living matter and, therefore, considered macronutrients? Identify the functional group in each of the depicted structural formulas. The structural formula shown corresponds to penicillin G, a narrow-spectrum antibiotic that is given intravenously or intramuscularly as a treatment for several bacterial diseases.
The antibiotic is produced by fungi of the genus Penicillium. Identify three major functional groups in this molecule that each comprise two simpler functional groups. Name the two simpler functional groups composing each of the major functional groups identified in a. It can also be used as a fuel in diesel engines. Ethyl methyl ether Methoxyethane 3D Download 3D Ethyl methyl ether , or methoxyethane , is a colorless gas at room temperature, having a boiling point of 7.
Like dimethyl ether, it is fairly water soluble. Diethyl ether Ethoxyethane 3D Download 3D Diethyl ether , or ethoxyethane , or just plain ether , is a colorless liquid at room temperature, having a boiling point of Unlike dimethyl ether and ethyl methyl ether, it is only slightly soluble in water, with 6. Diethyl ether has a strong, somewhat sweet, odor, and the vapor can cause drowsiness or unconsciousness.
Since it has such a low boiling point less than human body temperature , it evaporates easily, and the fumes can quickly become overwhelming. Diethyl ether is also extremely flammable, especially in the vapor form. Diethyl ether was first synthesized by the German physician Valerius Cordus in , who obtained it by distilling a mixture of ethanol and sulfuric acid "oil of vitriol" ; he named the substance "oil of sweet vitriol.
Its use as an anesthetic was first demonstrated publicly by Crawford W. Long on March 30, There was a long and bitter priority dispute between William T. Morton, Charles T. Jackson, and Horace Wells, who also made public demonstrations of the use of ether in the s, but Long's work is now generally recognized to have been the first. Ether was widely used in surgical procedures until the mid 20th century, when it was replaced by nonflammable anesthetics such as halothane , which also reduced post-surgical nausea.
Diethyl ether is commonly used in chemistry labs as a solvent. It is unreactive towards most oxidizing and reducing agents, doesn't react with acids or bases, and dissolves a wide variety of compounds.
It is particularly useful in the Grignard reaction , in which organomagnesium compounds called Grignard reagents react with compounds containing carbon-oxygen double bonds, thus producing new carbon-carbon bonds.
These reactions require extremely dry conditions, because any water which is present will react with the Grignard reagent. Ether is fairly easy to obtain in a very dry form, either by purchasing it directly from a chemical supply company, or by distilling it from sodium. In addition, the lone pairs on the oxygen atoms in the ether can complex with the magnesium atoms in the Grignard reagent, stabilizing the reagent somewhat. There are a number of hazards associated with the use of diethyl ether.
It is extremely flammable, it evaporates very easily, and its vapor is more dense than air. It is a standing rule in organic chemistry labs among those who want to remain standing that when diethyl ether is being used, no open flames are allowed , since a Bunsen burner can light ether vapor which has evaporated from a container some distance away.
For a demonstration of this, see the Demonstrations page on the Ether Trough. Another hazard associated with diethyl ether is its ability to form peroxides upon standing; ether peroxides are dangerously unstable, and old bottles of ether that have been sitting around for a long time are a potential explosion hazard.
In addition, heating ethers can also cause the formation of peroxides, especially towards the end of a distillation when a large amount of heat is being passed through a decreasing amount of liquid. For this reason, it is a standing rule in chemistry labs that ethers should never be distilled to dryness. The Ether Bunny Ethylene oxide 3D Download 3D Ethylene oxide , or oxacyclopropane the oxa prefix indicates replacement of a carbon with an oxygen in a cyclic compound , and oxirane , is the simplest of the cyclic ethers.
Compounds which contain two carbon atoms and one oxygen atom in a ring are also known as epoxides. Ethylene oxide is synthesized industrial by the reaction of ethylene with oxygen; this reaction is carried out at high pressures with a silver catalyst to produce ethylene oxide in high yields. Ethylene oxide is used in the production of ethylene glycol , and is also used to sterilize medical equipment.
It is also an important reagent in organic synthesis. It is fairly soluble in water, with 4. MTBE has been used as an octane-boosting additive for gasoline, but this use is becoming less common because of concerns about the contamination of drinking water resulting from the leakage of MTBE-laced gasoline from underground storage tanks.
Because MTBE is more soluble in water than the hydrocarbon components of gasoline, it tends to be the component that dissolves first in groundwater. Tetrahydrofuran THF 3D Download 3D Tetrahydrofuran , or oxacyclopentane, is a common organic solvent especially in Grignard reactions , often used in place of diethyl ether because of its much lower volatility and flammability.
It is derived from the aromatic molecule furan , by catalytic hydrogenation, in which two hydrogen molecules or four hydrogen atoms, hence "tetrahydro" are added to the two double bonds in furan, turning them into single bonds. There are two isomers of pyran, which differ in the positions of the double bonds, as shown above.
The pyran structure is found in the cyclic form of many sugar molecules, where it is usually referred to as a pyranose ring. Like diethyl ether and THF, it is a good solvent for the Grignard reaction. Like many small cyclic ethers, it is miscible with water.
Dibenzo- para -dioxin 3D Download 3D The molecule shown above, dibenzo- para -dioxin , is the parent compound of a group of molecules called the dioxins , which contain two benzene rings links by ether bridges, and containing chlorine atoms on the benzene rings polychlorinated dibenzodioxins, PCDDs. Dioxins are produced in the burning of coal, metal smelting, diesel trucks, the burning of treated wood, cigarette smoke, and as side products of the reactions used to synthesize some herbicides.
See entry below. Dioxins are fat-soluble, and can accumulate in the bodies of those who come into contact with them. Many of the dioxins are toxic and carcinogenic, especially those in which chlorine atoms are substituted at the b -positions three carbons away from the oxygen atoms on the benzene rings, rather than the a -positions two carbons away from the oxygens.
It was present as a contaminant in Agent Orange, a herbicide used to clear jungle foliage during the Vietnam War.
Agent Orange itself was a mixture of 2,4-dichlorophenoxyacetic acid 2,4-D and 2,4,5-trichlorophenoxyacetic acid 2,4,5-T ; TCDD was produced during the synthesis of these compounds, and was present in the mixture that was used during the war.
Anisole 3D Download 3D Anethole , or methoxybenzene, has a smell similar to that of oil of aniseed see entry for anethole below , and is used in perfumes. In this case the change of the stereochemistry causes a drastic change in the perceived scent. Aldehydes and ketones are known for their sweet and sometimes pungent odors. The odor from vanilla extract comes from the molecule vanillin.
Likewise, benzaldehyde provides a strong scent of almonds. Because of their pleasant fragrances aldehyde and ketone containing molecules are often found in perfumes. However, not all of the fragrances are pleasing. In particular, 2-Heptanone provides part of the sharp scent from blue cheese and R -Muscone is part of the musky smell from the Himalayan musk deer.
Lastly, ketones show up in many important hormones such as progesterone a female sex hormone and testosterone a male sex hormone. Notice how subtle differences in structure can cause drastic changes in biological activity. The ketone functionality also shows up in the anti-inflammatory steroid, Cortisone.
Ketones are formed in the human body as a by-product of lipid metabolism. Acetone is also produced as a breakdown product of acetoacetic acid. Acetone can then be excreted from the body through the urine or as a volatile product through the lungs. Normally, ketones are not released into the bloodstream in appreciable amounts. Instead, ketones that are produced during lipid metabolism inside cells are usually fully oxidized and broken down to carbon dioxide and water.
This is because glucose is the primary energy source for the body, especially for the brain. Glucose is released in controlled amounts into the bloodstream by the liver, where it travels throughout the body to provide energy. For the brain, this is the primary energy source, as the blood-brain barrier blocks the transport of large lipid molecules.
However, during times of starvation, when glucose is unavailable, or in certain disease states where glucose metabolism is disregulated, like uncontrolled diabetes mellitus, the ketone concentrations within blood rises to higher levels to provide an alternative energy source for the brain. Ketoacidosis can be a life threatening event. Ketones can be easily detected, as acetone is excreted in the urine. In severe cases, the odor of acetone can also be noted on the breath.
Carboxylic Acids can be easily recognized as they have a carbonyl carbon that is also linked directly to an alcohol functional group. So the carbonyl carbon is also attached directly to an alcohol. In the ester functional group, the carbonyl carbon is also directly attached as part of an ether functional group. Carboxylic acids are organic compounds which incorporate a carboxyl functional group, CO 2 H.
The name carboxyl comes from the fact that a carbonyl and a hydroxyl group are attached to the same carbon. Carboxylic acids are named such because they can donate a hydrogen to produce a carboxylate ion. The factors which affect the acidity of carboxylic acids will be discussed later. An ester is an organic compound that is a derivative of a carboxylic acid in which the hydrogen atom of the hydroxyl group has been replaced with an alkyl group.
The general formula for an ester is shown below. The R group can either be a hydrogen or a carbon chain. The steps for naming esters along with two examples are shown below. Carboxylic acids can form hydrogen bond dimers which increases their boiling points above that of alcohols of similar size Table 9.
Small esters have boiling points which are lower than those of aldehydes and ketones with similar mass Table 9. Esters, like aldehydes and ketones, are polar molecules. Thus, their boiling points are higher than ethers and lower than aldehydes and ketones of similar size. Low molecular weight carboxylic acids tend to be liquids at room temperature, whereas larger molecules form waxy solids. Carboxylic acids that range in carbon chain length from 12 carbons are typically called fatty acids, as they are commonly found in fats and oils.
Comparable to other oxygen containing molecules, the short-chain carboxylic acids tend to be soluble in water, due to their ability to form hydrogen bonds. As the carbon chain length increases, the solubility of the carboxylic acid in water goes down.
Esters can also hydrogen bond with water, although not as efficiently as carboxylic acids, and thus they are slightly less soluble in water than carboxylic acids of similar size. Carboxylic acids typically have in unpleasant, pungent and even rancid odors.
The smell of vinegar, for example, is due to ethanoic acid also known as acetic acid. The odor of gyms and unwashed socks is largely caused by butanoic acid, and hexanoic acid is responsible for the strong odor of limburger cheese.
Due to their acidic nature, carboxylic acids also have a sour taste as noted for vinegar and the citric acid found in many fruits. Esters, on the otherhand, have enjoyable aromas and are responsible for the aroma of many fruits and flowers. Esters can also have fruity flavors. Carboxylic acids and esters are common in nature and are used for a multitude of purposes.
For example, ants in the Formicidae family use the simplest carboxylic acid, formic acid, as both a chemical defense and as an attack to subdue prey Figure 9. Acetic acid also gives sourdough bread its sharp taste and accounts for the sour flavors in wine. Citric acid is found in many fruits and accounts for their sour flavor.
Other carboxylic acids such as PABA and glycolic acid are used in the cosmetic industry. PABA which is produced by plants, fungi, and bacteria is a common component of food and is related in structure to the vitamin folate.
In PABA was patented as one of the first compounds used in the manufacture of sunscreen. However, its use has fallen out of favor since the mids due to concerns that it may increase cellular UV damage, as well as contribute to allergies. In food processing it is used as a preservative and in the skin care industry it is used most often as a chemical peel to reduce facial scarring by acne. A Formic acid is the defense toxin used by ants in the Formicidae family. The photo on the left shows various flavors of vinegar at a market in France.
Photo by Georges Seguin C Citric acid is a common component of fruit, providing a sour taste. It was patented in for its use in sunscreen products.
However, due to safety concerns and allergic response, the use of PABA has been discontinued for this purpose. Suncreen photo provided by HYanWong E Glycolic acid is commonly used in cosmetics as a chemical peel used to reduce scarring by acne. Glycolic study provided by Jaishree Sharad. Esters are readily synthesized and naturally abundant contributing to the flavors and aromas in many fruits and flowers.
For example, the ester, methyl salicylate is also known as the oil of wintergreen Figure 9. The fruity aroma of pineapples, pears and strawberries are caused by esters, as well as the sweet aroma of rum. Esters also make up the bulk of animal fats and vegetable oils as triglycerides.
The formation of lipids and fats will be described in more detail in Chapter Alcohol functional groups can be involved in several different types of reactions. In this section, we will discuss two major types of reactions. The first are the dehydration reactions and the second are the oxidation reactions. Alcohols can also be involved in addition and substitution reactions with other functional groups like aldehydes, ketones, and carboxylic acids.
These types of reactions will be discussed in more detail within the aldehyde and ketone, and carboxylic acid sections. In chapter 8, we learned that alcohols can be formed from the hydration of alkenes during addition reactions. We also learned that the opposite reaction can also occur. Alcohols can be removed or eliminated from molecules through the process of dehydration or the removal of water.
The result of the elimination reaction is the creation of an alkene and a molecule of water. Elimination reactions that occur with more complex molecules can result in more than one possible product. In these cases, the alkene will form at the more substituted position at the carbon that has more carbon atoms and less hydrogen atoms attached to it.
For example, in the reaction below, the alcohol is not symmetrical. Thus, there are two possible products of the elimination reaction, option 1 and option 2. In option 1, the alkene is formed with the carbon that has the fewest hydrogens attached, whereas in option 2 the alkene is formed with the carbon that has the most hydrogens attached.
Thus, option 1 will be the major product of the reaction and option 2 will be the minor product. Alcohol elimination reactions using small 1 o alcohols can also be used to produce ethers.
To produce an ether rather than the alkene, the temperature of the reaction must be reduced and the reaction must be done with excess alcohol in the reaction mixture. For example:. In this reaction alcohol has to be used in excess and the temperature has to be maintained around K. If alcohol is not used in excess or the temperature is higher, the alcohol will preferably undergo dehydration to yield alkene.
The dehydration of secondary and tertiary alcohols to get corresponding ethers is unsuccessful as alkenes are formed too easily in these reactions. Some alcohols can also undergo oxidation reactions. Remember in redox reactions, the component of the reaction that is being oxidized is losing electrons LEO while the molecule receiving the electrons is being reduced GER.
In organic reactions, the flow of the electrons usually follows the flow of the hydrogen atoms. Thus, the molecule losing hydrogens is typically also losing electrons and is the oxidized component.
The molecule gaining electrons is being reduced. For alcohols, both primary and secondary alcohols can be oxidized. Tertiary alcohols, on the other hand, cannot be oxidized. In many oxidation reactions the oxidizing agent is shown above the reaction arrow as [O]. The oxidizing agent can be a metal or another organic molecule. In the reaction, the oxidizing agent is the molecule that is reduced or accepts the electrons.
In alcohol oxidation reactions, the hydrogen from the alcohol and a hydrogen that is attached to the carbon that has the alcohol attached, along with their electrons, are removed from the molecule by the oxidizing agent. Removal of the hydrogens and their electrons results in the formation of a carbonyl functional group.
In the case of a primary alcohol, the result is the formation of an aldehyde. In the case of a secondary alcohol, the result is the formation of a ketone. Note that for a tertiary alcohol, that the carbon attached to the alcohol functional group does not have a hydrogen atom attached to it. Thus, it cannot undergo oxidation. When a tertiary alcohol is exposed to an oxidizing agent, no reaction will occur. Notice that for the primary alcohol that undergoes oxidation, that it still retains a hydrogen atom that is attached to the carbonyl carbon in the newly formed aldehyde.
This molecule can undergo a secondary oxidation reaction with an oxidizing agent and water, to add another oxygen atom and remove the carbonyl hydrogen atom. This results in the formation of a carboxylic acid. Methanol is quite poisonous to humans. Ingestion of as little as 15 mL of methanol can cause blindness, and 30 mL 1 oz can cause death.
However, the usual fatal dose is to mL. Formaldehyde reacts rapidly with the components of cells, coagulating proteins in much the same way that cooking coagulates an egg. This property of formaldehyde accounts for much of the toxicity of methanol. Organic and biochemical equations are frequently written showing only the organic reactants and products.
In this way, we focus attention on the organic starting material and product, rather than on balancing complicated equations. Ethanol is oxidized in the liver to acetaldehyde:. The acetaldehyde is in turn oxidized to acetic acid HC 2 H 3 O 2 , a normal constituent of cells, which is then oxidized to carbon dioxide and water.
Even so, ethanol is potentially toxic to humans. The rapid ingestion of 1 pt about mL of pure ethanol would kill most people, and acute ethanol poisoning kills several hundred people each year—often those engaged in some sort of drinking contest. Ethanol freely crosses into the brain, where it depresses the respiratory control center, resulting in failure of the respiratory muscles in the lungs and hence suffocation.
Ethanol is believed to act on nerve cell membranes, causing a diminution in speech, thought, cognition, and judgment. It has a high vapor pressure, and its rapid evaporation from the skin produces a cooling effect. It is toxic when ingested but, compared to methanol, is less readily absorbed through the skin.
Write an equation for the oxidation of each alcohol. Use [O] above the arrow to indicate an oxidizing agent. The first step is to recognize the class of each alcohol as primary, secondary, or tertiary. This alcohol has the OH group on a carbon atom that is attached to only one other carbon atom, so it is a primary alcohol.
Oxidation forms first an aldehyde and further oxidation forms a carboxylic acid. This alcohol has the OH group on a carbon atom that is attached to three other carbon atoms, so it is a tertiary alcohol. No reaction occurs. This alcohol has the OH group on a carbon atom that is attached to two other carbon atoms, so it is a secondary alcohol; oxidation gives a ketone. In this section, we will discuss the primary reactions of aldehydes and ketones. These include oxidation and reduction reactions, and combination reactions with alcohols.
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