Spinach The World's Healthiest Foords are health-promoting foods that can change your life. Watch for the launch of our new WHFoods 7-Day Meal Plan on January 23rd! The George Mateljan Foundation is a not-for-profit foundation with no commercial interests or advertising. Our mission is to help you eat and cook the healthiest way for optimal health. Spinach What's New and Beneficial About Spinach Bright, vibrant-looking spinach leaves are not only more appealing to the eye but more nourishing as well. Recent research has shown that spinach leaves that look fully alive and vital have greater concentrations of vitamin C than spinach leaves that are pale in color. The study authors suggest that the greater supply of vitamin C helps protect all of the oxygen-sensitive phytonutrients in the spinach leaves and makes them looking vibrant and alive. Many people are concerned about the nutrient content of delicate vegetables (like baby spinach) when those vegetables are placed in clear plastic containers in grocery store display cases and continuously exposed to artificial lighting. One recent food study has shown that you don't need to worry about the overall status of antioxidants in baby spinach that has been stored and displayed in this way.

In this scientific study, the overall nutrient richness of the baby spinach when exposed to constant light was actually higher than the overall nutrient richness of baby spinach leaves kept in total darkness. The period of time in the study was 9 days, and the spinach was kept at 39°F/4°C (a temperature on the lower end of the scale for most home refrigerators). These findings are good news for anyone purchasing baby spinach in "ready-to-eat" containers. One new category of health-supportive nutrients found in spinach is called "glycoglycerolipids." Glycoclycerolipids are the main fat-related molecules in the membranes of light-sensitive organs in most plants. They're indispensable for the process of photosynthesis carried out by plants. However, recent lab research in laboratory animals has shown that glycoglycerolipids from spinach can help protect the lining of the digestive tract from damage — especially damage related to unwanted inflammation. You can expect to see more studies about this exciting new category of molecules in spinach and its potential health benefits.

In a recent study on the relationship between risk of prostate cancer and vegetable intake — including the vegetables spinach, broccoli, cauliflower, cabbage, Brussels sprouts, mustard greens, turnip greens, collards, and kale — only spinach showed evidence of significant protection against the occurrence of aggressive prostate cancer. ("Aggressive prostate cancer" was defined as stage III or IV prostate cancer with a Gleason score of at least 7. Gleason scores are based on lab studies of prostate tissue and common tumor-related patterns.) The study authors did not speculate about specific substances in spinach that may have been involved in decreased prostate cancer risk. However, we know that certain unique anti-cancer carotenoids—called epoxyxanthophylls — are plentiful in spinach, even though they may not be as effectively absorbed as other carotenoids like beta-carotene and lutein. You can count on seeing future research on neoxanthin and violaxanthin — two anti-cancer epoxyxanthophylls that are found in plentiful amounts in the leaves of spinach. WHFoods Recommendations Among the World's Healthiest vegetables, spinach comes out at the top of our ranking list for nutrient richness.

Rich in vitamins and minerals, it is also concentrated in health-promoting phytonutrients such as carotenoids (beta-carotene, lutein, and zeaxanthin) and flavonoids to provide you with powerful antioxidant protection. Enjoy baby spinach in your favorite salads or make a salad made exclusively of baby spinach. Spinach is one of only three vegetables that we recommend boiling to help reduce its concentration of oxalic acid. We recommend boiling for just 1 minute to minimize loss of nutrients and flavor. For more on the Nutrient-Rich Way of Cooking Spinach, see the How to Enjoy section below. Foods belonging to the chenopod family—including beets, chard, spinach and quinoa—continue to show an increasing number of health benefits not readily available from other food families. The red and yellow betalain pigments found in this food family, their unique epoxyxanthophyll carotenoids, and the special connection between their overall phytonutrients and our nervous system health (including our specialized nervous system organs like the eye) point to the chenopod family of foods as unique in their health value.

While we have yet to see large-scale human studies that point to a recommended minimum intake level for foods from this botanical family, we have seen data on chenopod phytonutrients, and based on this data, we recommend that you include foods from the chenopod family in your diet 1-2 times per week. In the case of a leafy food like spinach, we recommend a serving size of at least 1/2 cup, and even more beneficial, at least one full cup. Spinach, cooked pantothenic acid 5% This chart graphically details the %DV that a serving of Spinach provides for each of the nutrients of which it is a good, very good, or excellent source according to our Food Rating System. Additional information about the amount of these nutrients provided by Spinach can be found in the Food Rating System Chart . A link that takes you to the In-Depth Nutritional Profile for Spinach, featuring information over 80 nutrients, can be found under the Food Rating System Chart.

References Health Benefits We all know that Popeye made himself super strong by eating spinach, but you may be surprised to learn that he may also have been helping to protect himself against inflammatory problems, oxidative stress-related problems, cardiovascular problems, bone problems, and cancers at the same time. Anti-Inflammatory and Anti-Cancer Benefits from Spinach Phytonutrients Even though virtually all vegetables contain a wide variety of phytonutrients—including flavonoids and carotenoids—spinach can claim a special place among vegetables in terms of its phytonutrient content. Researchers have identified more than a dozen different flavonoid compounds in spinach that function as anti-inflammatory and anti-cancer agents. (Some of these substances fall into a technical category of flavonoids known as methylenedioxyflavonol glucuronides.) The anticancer properties of these spinach flavonoids have been sufficiently impressive to prompt researchers to create specialized spinach extracts that could be used in controlled laboratory studies. These spinach extracts have been shown to slow down cell division in human stomach cancer cells (gastric adenocarcinomas), and in studies on laboratory animals, to reduce skin cancers (skin papillomas).

A study on adult women living in New England in the late 1980s also showed intake of spinach to be inversely related to incidence of breast cancer. Excessive inflammation, of course, typically emerges as a risk factor for increased cancer risk. (That's why many anti-inflammatory nutrients can also be shown to have anti-cancer properties.) But even when unrelated to cancer, excessive inflammation has been shown to be less likely following consumption of spinach. Particularly in the digestive tract, reduced inflammation has been associated not only with the flavonoids found in spinach, but also with its carotenoids. Neoxanthin and violaxanthin are two anti-inflammatory epoxyxanthophylls that are found in plentiful amounts in the leaves of spinach. While these unique carotenoids may not be as readily absorbed as carotenoids like beta-carotene or lutein, they still play an important role in regulation of inflammation and are present in unusual amounts in spinach. Decreased risk of aggressive prostate cancer is one health benefit of spinach consumption that should not be overlooked when talking about the anti-cancer properties of spinach.

"Aggressive prostate cancer" is defined as stage III or IV prostate cancer which carries with it a Gleason score of at least 7. (Gleason scores are prostate cancer rating measurements that require lab studies of prostate tissue and evaluation of common tumor-related patterns.) Interestingly, in a recent study that evaluated possible prostate cancer-prevention benefits from a variety of vegetables including spinach, broccoli, cauliflower, cabbage, Brussels sprouts, mustard and turnip greens, collards, and kale — only spinach showed evidence of significant protection against the occurrence of aggressive prostate cancer. Antioxidant Benefits of Spinach Most of the flavonoid and carotenoid nutrients found in spinach that provide anti-inflammatory benefits provide antioxidant benefits as well. Given the fact that spinach is an excellent source of other antioxidant nutrients — including vitamin C, vitamin E, vitamin A (in the form of carotenoids), and manganese —as well as a very good source of the antioxidant zinc and a good source of the antioxidant selenium—it's no wonder that spinach helps lower risk of numerous health problems related to oxidative stress.

Our blood vessels, for example, are especially susceptible to damage from oxidative stress, and intake of spinach has been associated with decreased risk of several blood vessel-related problems, including atherosclerosis and high blood pressure. (Interestingly, the blood pressure benefits of spinach may be related not only to its antioxidants, but also to some of its special peptides. Peptides are small pieces of protein, and researchers have discovered several peptides in spinach that can help lower blood pressure by inhibiting an enzyme called angiotensin I-converting enzyme.) Two of the carotenoids that are especially plentiful in spinach — lutein and zeaxanthin — are primary antioxidants in several regions of the eye, including the retina and the macula. Although we haven't seen specific studies on spinach intake and prevention of eye-related problems like macular degeneration, we have seen studies showing that human blood levels of lutein can be increased by consumption of spinach in everyday amounts. We've also seen at least one group of researchers suggesting that spinach has a likely role to play in prevention of eye problems, including age-related macular degeneration. Spinach Helps You Bone Up The wealth of vitamin K provided by spinach is important for maintaining bone health.

Vitamin K1 helps prevent excessive activation of osteoclasts, the cells that break down bone. Additionally, friendly bacteria in our intestines convert vitamin K1 into vitamin K2, which activates osteocalcin, the major non-collagen protein in bone. Osteocalcin anchors calcium molecules inside of the bone. All of these vitamin K-related mechanisms point to the importance of vitamin K-rich foods for bone health, and it is difficult to find vegetables that are richer in vitamin K than spinach. (On our World's Healthiest Foods list, only kale provides more micrograms of vitamin K per cup.) Spinach is also an excellent source of other bone-supportive nutrients including calcium and magnesium. So while spinach probably won't make you super strong the minute you eat it, as it did for Popeye, it will promote your health and vitality in many other ways. It seems like Popeye was pretty smart after all. Description Calorie for calorie, leafy green vegetables like spinach with its delicate texture and jade green color provide more nutrients than any other food. Although spinach is available throughout the year, its season runs from March through May and from September through October when it is the freshest, has the best flavor, and is most readily available.

Spinach belongs to the same family (Amaranthaceae-Chenopodiaceae) as Swiss chard and beets and has the scientific name, Spinacia oleracea. It shares a similar taste profile with these two other vegetables, having the bitterness of beet greens and the slightly salty flavor of Swiss chard. Popeye popularized spinach, but it's too bad he ate it out of a can. Fresh spinach retains the delicacy of texture and green color that is lost when spinach is processed. Raw spinach has a mild, slightly sweet taste that can be refreshing in salads, while its flavor becomes more acidic and robust when it is cooked. There are three different types of spinach generally available. Savoy has crisp, creased curly leaves that have a springy texture. Smooth-leaf has flat, unwrinkled, spade-shaped leaves, while semi-savoy is similar in texture to savoy but is not as crinkled in appearance. Baby spinach is great for use in salads owing to its taste and delicate texture. History Spinach is thought to have originated in ancient Persia (Iran).

Spinach made its way to China in the 7th century when the king of Nepal sent it as a gift to this country. Spinach has a much more recent history in Europe than many other vegetables. It was only brought to that continent in the 11th century, when the Moors introduced it into Spain. In fact, for a while, spinach was known as "the Spanish vegetable" in England. Spinach was the favorite vegetable of Catherine de Medici, a historical figure in the 16th century. When she left her home of Florence, Italy, to marry the king of France, she brought along her own cooks, who could prepare spinach the ways that she especially liked. Since this time, dishes prepared on a bed of spinach are referred to as "a la Florentine." Spinach grows well in temperate climates. Today, the United States and the Netherlands are among the largest commercial producers of spinach. How to Select and Store Choose spinach that has vibrant deep green leaves and stems with no signs of yellowing. The leaves should look fresh and tender, and not be wilted or bruised. Avoid those that have a slimy coating as this is an indication of decay.

At WHFoods, we encourage the purchase of certified organically grown foods, and spinach no exception. Repeated research studies on organic foods as a group show that your likelihood of exposure to contaminants such as pesticides and heavy metals can be greatly reduced through the purchased of certified organic foods, including spinach. In many cases, you may be able to find a local organic grower who sells spinach but has not applied for formal organic certification either through the U.S. Department of Agriculture (USDA) or through a state agency. (Examples of states offering state-certified organic foods include California, New York, Oregon, Vermont, and Washington.) However, if you are shopping in a large supermarket, your most reliable source of organically grown spinach is very likely to be spinach that displays the USDA organic logo. Do not wash spinach before storing as the exposure to water encourages spoilage. Place spinach in a plastic storage bag and wrap the bag tightly around the spinach, squeezing out as much of the air as possible. Place in refrigerator where it will keep fresh for up to 5 days. Here is some background on why we recommend refrigerating spinach.

Whenever food is stored, four basic factors affect its nutrient composition: exposure to air, exposure to light, exposure to heat, and length of time in storage. Vitamin C, vitamin B6, and carotenoids are good examples of nutrients highly susceptible to heat, and for this reason, their loss from food is very likely to be slowed down through refrigeration. Avoid storing cooked spinach as it will not keep very well. Tips for Preparing and Cooking Tips for Preparing Spinach Spinach should be washed very well since the leaves and stems tend to collect sand and soil. Before washing, trim off the roots and separate the leaves. Place the spinach in a large bowl of tepid water and swish the leaves around with your hands as this will allow any dirt to become dislodged. Remove the leaves from the water, empty the bowl, refill with clean water and repeat this process until no dirt remains in the water (usually two to three times will do the trick). Do not leave spinach soaking in the water as water-soluble nutrients will leach into the water. Spinach sold in bags has been pre-washed and only needs to be rinsed.

If you are going to use it in a salad, dry it using a salad spinner or by shaking it in a colander. The Nutrient-Rich Way of Cooking Spinach Spinach is only one of three vegetables we recommend boiling to free up acids and allow them to leach into the boiling water; this brings out a sweeter taste from the spinach. Discard the boiling water after cooking; do not drink it or use it for stock because of its acid content. Quick Boiling—similar to Quick Steaming and Healthy Sauté, our other recommended cooking methods—follows three basic cooking guidelines that are generally associated in food science research with improved nutrient retention. These three guidelines are: (1) minimal necessary heat exposure; (2) minimal necessary cooking duration; (3) minimal necessary food surface contact with cooking liquid. Use a large pot (3 quart) with lots of water and bring to a rapid boil. Add spinach to the boiling water and boil for 1 minute. Begin timing as soon as you place the spinach in the pot if you are using 1 pound or less of spinach. If you are cooking larger quantities of spinach bring the water back to a boil before beginning timing the 1 minute. Do not cover the pot when cooking spinach.

Leaving the pot uncovered helps to release more of the acids with the rising steam. Research has shown that the boiling of spinach in large amounts of water helps decrease the oxalic acid content. Remove spinach from pot, press out liquid with a fork, place in a bowl, toss with our Mediterranean Dressing, and top with your favorite optional ingredients. For details see 1-Minute Spinach . How to Enjoy A Few Quick Serving Ideas Add layers of spinach to your next lasagna recipe. Pine nuts are a great addition to cooked spinach. Spinach salads are a classic easy and delicious meal or side dish. WHFoods Recipes That Feature Spinach Oxalates In Spinach - Is Oxalic Acid A Green Smoothie Health Concern? - Incredible Smoothies Oxalates In Spinach – Is Oxalic Acid A Green Smoothie Health Concern? September 9, 2009 Share/Save There I was, enjoying a delicious green smoothie when an article about oxalates in spinach and other leafy greens caught my attention. Is there a hidden danger lurking in my delicious, beloved green smoothie?

Oxalic acid (also referred to as oxalates) are found in many foods and are a controversial subject among nutritionists and health experts. Finding a definitive answer online regarding the potential safety or dangers of this substance can make your head spin (as most cutting-edge nutrition research will). What Is Oxalic Acid? Oxalic acid is a naturally occurring chemical in plants and animals and is also consumed in a variety of different foods such as leafy greens, nuts, seeds, most berries, certain fruits, soy and soy products, meat and dairy products. In large amounts, oxalic acid is poisonous, but toxic levels are not found in foods that we normally eat. The main controversy surrounding oxalic acid in food is whether or not they contribute to the formation of kidney stones. About 80% of the kidney stones formed by adults in the U.S.A. are composed of calcium oxalate. Oxalic acid binds with other minerals such as calcium which form a salt known as an oxalate. Oxalic acid interferes with the absorption of calcium in foods because they bind with it, making it unusable by your body.

Without oxalic acid, foods such as spinach and kale would have a much higher, bio-available calcium content than they do because it is bound up with oxalic acid. These oxalates are usually passed though the urine but in vulnerable individuals, they may crystallize, forming larger stones that cause excruciating pain and require medical attention. What Foods Contain Oxalates? Many foods contain oxalic acid, especially leafy greens such as spinach, kale, chard, parsley, collards and beet greens. Spinach has the highest levels of oxalic acid – 750 milligrams per 100 gram serving. So, should you be concerned about the oxalate content of your spinach green smoothies? Should You Be Concerned? The short answer is “generally, no”. There are a few rare medical conditions such as Primary Hyperoxaluria and Enteric Hyperoxaluria where one would need to restrict their dietary intake of oxalic acid. Also, those who are susceptible and have been treated for calcium-oxalate kidney stones, and therefore at risk of forming them again, should watch their intake of oxalate-containing foods. Otherwise, oxalic acid is not believed to be a health concern for most people.

Keep in mind that your body regularly produces oxalic acid, often synthesizing other substances such as vitamin C into oxalic acid. Whether you eat foods that contain it or not, your body maintains a naturally-occurring level of oxalic acid and regularly produces it whether you consume it in your diet or not. Health Experts Weigh In Most mainstream diet and nutrition experts do agree that oxalic content of foods should not be a concern to healthy individuals. The nutritional benefits of eating oxalate-containing foods such as spinach outweigh the minute risk of forming kidney stones. Dietitians and nutritionists generally do not steer people away from dark, leafy greens because they contain oxalic acid. Some raw food diet experts take the oxalate debate one step further by suggesting that oxalic acid is actually beneficial when consumed from raw, organic greens. They claim that it is the cooking of foods that contain oxalic acid which lead to problems in humans. If You Are Concerned About Oxalates If you have a history of kidney stones or a medical condition that is complicated by the consumption of oxalate-rich foods, you should contact your doctor or health practitioner for advice.

There is some helpful information on the web which lists oxalate levels of many foods which can help you plan your diet should you feel the need to reduce your intake of oxalic acid-containing foods. In general, replacing oxalate-rich greens such as spinach and kale with Romaine lettuce or other lettuces will lower exposure, but also lower overall nutrient density of your smoothies. My Approach To Oxalates In Green Smoothies Since I do not have Hyperoxaluria or any history of kidney stones, I am not going to worry about oxalic acid in my green smoothies. The amount I consume on a daily basis is not toxic. The research that exists does not conclusively point to oxalates as the absolute cause or even a leading contributing factor in the possible formation of kidney stones. What I will do, however, is rotate my greens so that I am not always eating spinach, which contains the highest levels of oxalates. Simply rotating or mixing spinach with lower-level oxalate-containing foods will help even things out and lower my overall exposure. Besides, rotating greens and other foods regularly helps to limit over-consumption of any one nutrient and provides health-promoting variety in the diet.

Do not become obsessed with lowering oxalate exposure though. It’s silly to choose one green over another based on oxalic content if you do not have a preexisting medical condition that should warrant such a choice. Also, isolating one substance in food that may or may not cause a health problem when consumed in excess is a narrow way of looking at health and nutrition. Eating a whole foods diet provides a wide spectrum of nutrients, phytochemicals, vitamins, minerals and trace elements that work together to make a perfect, whole food that nourishes the body. Your body, when given whole food and proper nutrition, works effectively to process the foods you eat, eliminate the substances it doesn’t need and protect itself against disease and other health problems. Enjoy Your Green Smoothies! Green smoothies have a wide range of health benefits , many of these from the potent antioxidants found in spinach, kale, chard, blueberries, strawberries, carrots, oranges, tomatoes and other foods – all of which have oxalic acid. So go ahead and enjoy your green smoothies and the health benefits they provide!

Organic Acids and Bases and Some of Their Derivatives 15.2 Carboxylic Acids: Structures and Names Learning Objectives Name carboxylic acids with common names. Name carboxylic acids according to IUPAC nomenclature. Carboxylic acids occur widely in nature, often combined with alcohols or other functional groups, as in fats, oils, and waxes. They are components of many foods, medicines, and household products ( Figure 15.1 "Carboxylic Acids in the Home" ). Not surprisingly, many of them are best known by common names based on Latin and Greek words that describe their source. What you learn in this chapter about the chemistry of carboxylic acids will help you understand biochemistry ( Chapter 16 "Carbohydrates" through Chapter 20 "Energy Metabolism" ). Figure 15.1 Carboxylic Acids in the Home Carboxylic acids occur in many common household items.

(a) Vinegar contains acetic acid, (b) aspirin is acetylsalicylic acid, (c) vitamin C is ascorbic acid, (d) lemons contain citric acid, and (e) spinach contains oxalic acid. © Thinkstock The simplest carboxylic acid, formic acid (HCOOH), was first obtained by the distillation of ants (Latin formica, meaning “ant”). The bites of some ants inject formic acid, and the stings of wasps and bees contain formic acid (as well as other poisonous materials). The next higher homolog is acetic acid, which is made by fermenting cider and honey in the presence of oxygen. This fermentation produces vinegar, a solution containing 4%–10% acetic acid, plus a number of other compounds that add to its flavor. Acetic acid is probably the most familiar weak acid used in educational and industrial chemistry laboratories. Note Pure acetic acid solidifies at 16.6°C, only slightly below normal room temperature.

In the poorly heated laboratories of the late 19th and early 20th centuries in northern North America and Europe, acetic acid often “froze” on the storage shelf. For that reason, pure acetic acid (sometimes called concentrated acetic acid) came to be known as glacial acetic acid, a name that survives to this day. The third homolog, propionic acid (CH3CH2COOH), is seldom encountered in everyday life. The fourth homolog, butyric acid (CH3CH2CH2COOH), is one of the most foul-smelling substances imaginable. It is found in rancid butter and is one of the ingredients of body odor. By recognizing extremely small amounts of this and other chemicals, bloodhounds are able to track fugitives. Models of the first four carboxylic acids are shown in Figure 15.2 "Ball-and-Stick Models of Carboxylic Acids" . Figure 15.2 Ball-and-Stick Models of Carboxylic Acids Carboxylic acids feature a carbon atom doubly bonded to an oxygen atom and also joined to an OH group.

The four acids illustrated here are formic acid (a), acetic acid (b), propionic acid (c), and butyric acid (d). The acid with the carboxyl group attached directly to a benzene ring is called benzoic acid (C6H5COOH). The common names of carboxylic acids use Greek letters (α, β, γ, δ, and so forth), not numbers, to designate the position of substituent groups in acids. These letters refer to the position of the carbon atom in relation to the carboxyl carbon atom. In the nomenclature system of the International Union of Pure and Applied Chemistry (IUPAC), the parent hydrocarbon is the one that corresponds to the longest continuous chain (LCC) containing the carboxyl group. The -e ending of the parent alkane is replaced by the suffix -oic and the word acid. For example, the carboxylic acid derived from pentane is pentanoic acid (CH3CH2CH2CH2COOH). As with aldehydes, the carboxyl carbon atom is counted first; numbers are used to indicate any substituted carbon atoms in the parent chain.

Note Acetic acid can be further oxidized to carbon dioxide and water. Concept Review Exercises Caproic acid (hexanoic acid) can be prepared in an oxidation reaction from what alcohol? what aldehyde? Give the structures of the aldehyde and the carboxylic acid formed by the oxidation of isobutyl alcohol [(CH3)2CHCH2OH]. Answers CH3CH2CH2CH2CH2CHO Key Takeaway Whether in the laboratory or in the body, the oxidation of aldehydes or primary alcohols forms carboxylic acids. Exercises Caprylic acid (octanoic acid) can be prepared in an oxidation reaction from what alcohol? what aldehyde? Give the structures of the aldehyde and the carboxylic acid formed by the oxidation of 1,4-butanediol (HOCH2CH2CH2CH2OH). Answer 15.4 Physical Properties of Carboxylic Acids Learning Objectives Compare the boiling points of carboxylic acids with alcohols of similar molar mass. Compare the solubilities of carboxylic acids in water with the solubilities of comparable alkanes and alcohols in water.

Many carboxylic acids are colorless liquids with disagreeable odors. The carboxylic acids with 5 to 10 carbon atoms all have “goaty” odors (explaining the odor of Limburger cheese). These acids are also produced by the action of skin bacteria on human sebum (skin oils), which accounts for the odor of poorly ventilated locker rooms. The acids with more than 10 carbon atoms are waxlike solids, and their odor diminishes with increasing molar mass and resultant decreasing volatility. Carboxylic acids exhibit strong hydrogen bonding between molecules. They therefore have high boiling points compared to other substances of comparable molar mass. The carboxyl group readily engages in hydrogen bonding with water molecules ( Figure 15.3 "Hydrogen Bonding between an Acetic Acid Molecule and Water Molecules" ). The acids with one to four carbon atoms are completely miscible with water. Solubility decreases as the carbon chain length increases because dipole forces become less important and dispersion forces become more predominant. Hexanoic acid [CH3(CH2)4COOH] is barely soluble in water (about 1.0 g/100 g of water).

Palmitic acid [CH3(CH2)14COOH], with its large nonpolar hydrocarbon component, is essentially insoluble in water. The carboxylic acids generally are soluble in such organic solvents as ethanol, toluene, and diethyl ether. Figure 15.3 Hydrogen Bonding between an Acetic Acid Molecule and Water Molecules Carboxylic acids of low molar mass are quite soluble in water. Table 15.2 "Physical Constants of Carboxylic Acids" lists some physical properties for selected carboxylic acids. The first six are homologs. Notice that the boiling points increase with increasing molar mass, but the melting points show no regular pattern. Table 15.2 Physical Constants of Carboxylic Acids Condensed Structural Formula Which compound has the higher boiling point—CH3CH2CH2OCH2CH3 or CH3CH2CH2COOH? Explain. Which compound has the higher boiling point—CH3CH2CH2CH2CH2OH or CH3CH2CH2COOH? Explain.

Which compound is more soluble in water—CH3COOH or CH3CH2CH2CH3? Explain. Which compound is more soluble in water—CH3CH2COOH or CH3CH2CH2CH2CH2COOH? Explain. Answers CH3CH2CH2COOH because of hydrogen bonding (There is no intermolecular hydrogen bonding with CH3CH2CH2OCH2CH3.) CH3COOH because it engages in hydrogen bonding with water (There is no intermolecular hydrogen bonding with CH3CH2CH2CH3.) 15.5 Chemical Properties of Carboxylic Acids: Ionization and Neutralization Learning Objectives Name the typical reactions that take place with carboxylic acids. Describe how carboxylic acids react with basic compounds. Water-soluble carboxylic acids ionize slightly in water to form moderately acidic solutions. RCOOH Identify the general structure for an ester. Use common names to name esters. Name esters according to the IUPAC system.

Esters have the general formula RCOOR′, where R may be a hydrogen atom, an alkyl group, or an aryl group, and R′ may be an alkyl group or an aryl group but not a hydrogen atom. (If it were hydrogen atom, the compound would be a carboxylic acid.) Figure 15.4 "The Structure of Esters" shows models for two common esters. Figure 15.4 The Structure of Esters Esters feature a carbon-to-oxygen double bond that is also singly bonded to a second oxygen atom, which is then joined to an alkyl or an aryl group. The esters shown here are ethyl acetate (a) and methyl butyrate (b). Esters occur widely in nature. Unlike carboxylic acids, esters generally have pleasant odors and are often responsible for the characteristic fragrances of fruits and flowers. Once a flower or fruit has been chemically analyzed, flavor chemists can attempt to duplicate the natural odor or taste. Both natural and synthetic esters are used in perfumes and as flavoring agents. Note Fats and vegetable oils are esters of long-chain fatty acids and glycerol.

Esters of phosphoric acid are of the utmost importance to life. (For more information about fats/oils and esters, see Chapter 17 "Lipids" , Section 17.2 "Fats and Oils" , and Section 15.10 "Esters of Phosphoric Acid" , respectively.) Names of Esters Although esters are covalent compounds and salts are ionic, esters are named in a manner similar to that used for naming salts. The group name of the alkyl or aryl portion is given first and is followed by the name of the acid portion. In both common and International Union of Pure and Applied Chemistry (IUPAC) nomenclature, the -ic ending of the parent acid is replaced by the suffix -ate ( Table 15.3 "Nomenclature of Esters" ). Table 15.3 Nomenclature of Esters Condensed Structural Formula 15.7 Physical Properties of Esters Learning Objectives Compare the boiling points of esters with alcohols of similar molar mass. Compare the solubilities of esters in water with the solubilities of comparable alkanes and alcohols in water.

Ester molecules are polar but have no hydrogen atom attached directly to an oxygen atom. They are therefore incapable of engaging in intermolecular hydrogen bonding with one another and thus have considerably lower boiling points than their isomeric carboxylic acids counterparts. Because ester molecules can engage in hydrogen bonding with water molecules, however, esters of low molar mass are somewhat soluble in water. Borderline solubility occurs in those molecules that have three to five carbon atoms. Table 15.4 "Physical Properties of Some Esters" lists the physical properties of some common esters. Note Esters are common solvents. Ethyl acetate is used to extract organic solutes from aqueous solutions—for example, to remove caffeine from coffee. It also is used to remove nail polish and paint. Cellulose nitrate is dissolved in ethyl acetate and butyl acetate to form lacquers. The solvent evaporates as the lacquer “dries,” leaving a thin film on the surface. High boiling esters are used as softeners (plasticizers) for brittle plastics.

Table 15.4 Physical Properties of Some Esters Condensed Structural Formula CH3CH2CH2COOH because there is intermolecular hydrogen bonding (There is no intermolecular hydrogen bonding in CH3CH2COOCH3.) 15.8 Preparation of Esters Learning Objective Identify and describe the substances from which most esters are prepared. Some esters can be prepared by esterification The formation of an ester from a carboxylic acid and an alcohol., a reaction in which a carboxylic acid and an alcohol, heated in the presence of a mineral acid catalyst, form an ester and water: The reaction is reversible. As a specific example of an esterification reaction, butyl acetate can be made from acetic acid and 1-butanol. A Closer Look: Condensation Polymers A commercially important esterification reaction is condensation polymerization, in which a reaction occurs between a dicarboxylic acid and a dihydric alcohol (diol), with the elimination of water. Such a reaction yields an ester that contains a free (unreacted) carboxyl group at one end and a free alcohol group at the other end.

Further condensation reactions then occur, producing polyester polymers. The most important polyester, polyethylene terephthalate (PET), is made from terephthalic acid and ethylene glycol monomers: Polyester molecules make excellent fibers and are used in many fabrics. A knitted polyester tube, which is biologically inert, can be used in surgery to repair or replace diseased sections of blood vessels. PET is used to make bottles for soda pop and other beverages. It is also formed into films called Mylar. When magnetically coated, Mylar tape is used in audio- and videocassettes. Synthetic arteries can be made from PET, polytetrafluoroethylene, and other polymers. Concept Review Exercises Describe the typical reaction that takes place with esters. Identify the products of an acidic hydrolysis of an ester. Identify the products of a basic hydrolysis of an ester. Esters are neutral compounds, unlike the acids from which they are formed. In typical reactions, the alkoxy (OR′) group of an ester is replaced by another group.

One such reaction is hydrolysis The reaction of a substance with water., literally “splitting with water.” The hydrolysis of esters is catalyzed by either an acid or a base. Acidic hydrolysis is simply the reverse of esterification. The ester is heated with a large excess of water containing a strong-acid catalyst. Like esterification, the reaction is reversible and does not go to completion. As a specific example, butyl acetate and water react to form acetic acid and 1-butanol. The reaction is reversible and does not go to completion. Example 7 Write an equation for the acidic hydrolysis of ethyl butyrate (CH3CH2CH2COOCH2CH3) and name the products. Solution Remember that in acidic hydrolysis, water (HOH) splits the ester bond. The H of HOH joins to the oxygen atom in the OR part of the original ester, and the OH of HOH joins to the carbonyl carbon atom: The products are butyric acid (butanoic acid) and ethanol. Skill-Building Exercise Write an equation for the acidic hydrolysis of methyl butanoate and name the products.

When a base (such as sodium hydroxide [NaOH] or potassium hydroxide [KOH]) is used to hydrolyze an ester, the products are a carboxylate salt and an alcohol. Because soaps are prepared by the alkaline hydrolysis of fats and oils, alkaline hydrolysis of esters is called saponification The hydrolysis of fats and oils in the presence of a base to make soap. (Latin sapon, meaning “soap,” and facere, meaning “to make”). In a saponification reaction, the base is a reactant, not simply a catalyst. The reaction goes to completion: As a specific example, ethyl acetate and NaOH react to form sodium acetate and ethanol: Example 8 15.10 Esters of Phosphoric Acid Learning Objectives Describe phosphate esters. Understand why phosphate esters are important in living cells. Just as carboxylic acids do, inorganic acids such as nitric acid (HNO3), sulfuric acid (H2SO4), and phosphoric acid (H3PO4) also form esters. The esters of phosphoric acid are especially important in biochemistry.

A phosphoric acid molecule can form a monoalkyl, a dialkyl, or a trialkyl ester by reaction with one, two, or three molecules of an alcohol. Esters of pyrophosphoric acid and triphosphoric acid are also important in biochemistry. Esters of these acids are present in every plant and animal cell. They are biochemical intermediates in the transformation of food into usable energy. The bonds between phosphate units in adenosine triphosphate (ATP) are called phosphoanhydride bonds. These are high-energy bonds that store energy from the metabolism of foods. Hydrolysis of ATP releases energy as it is needed for biochemical processes (for instance, for muscle contraction). Phosphate esters are also important structural constituents of phospholipids and nucleic acids. (For more information about phospholipids and nucleic acids, see Chapter 17 "Lipids" , Section 17.3 "Membranes and Membrane Lipids" , and Chapter 19 "Nucleic Acids" , respectively.) Note The explosive nitroglycerin (glyceryl trinitrate) is an ester formed from glycerol and nitric acid.

It is used in medicine to relieve chest pain in heart disease. Concept Review Exercise 15.11 Amines: Structures and Names Learning Objectives Identify the general structure for an amine. Identify the functional group for amines. Determine the structural feature that classifies amines as primary, secondary, or tertiary. Use nomenclature systems to name amines. Amines are classified according to the number of carbon atoms bonded directly to the nitrogen atom. A primary (1°) amine A compound that has only one alkyl or aryl group on the nitrogen atom. has one alkyl (or aryl) group on the nitrogen atom, a secondary (2°) amine A compound that has two alkyl or aryl groups on the nitrogen atom. has two, and a tertiary (3°) amine A compound that has three alkyl or aryl groups on the nitrogen atom. has three ( Figure 15.5 "The Structure of Amines Compared to Water, an Alcohol, and an Ether" ).

Figure 15.5 The Structure of Amines Compared to Water, an Alcohol, and an Ether Note To classify alcohols, we look at the number of carbon atoms bonded to the carbon atom bearing the OH group, not the oxygen atom itself. Thus, although isopropylamine looks similar to isopropyl alcohol, the former is a primary amine, while the latter is a secondary alcohol. The common names for simple aliphatic amines consist of an alphabetic list of alkyl groups attached to the nitrogen atom, followed by the suffix -amine. (Systematic names are often used by some chemists.) The amino group An NH2 unit. (NH2) is named as a substituent in more complicated amines, such as those that incorporate other functional groups or in which the alkyl groups cannot be simply named. Example 9 Draw the structure for 2-amino-3-methylpentane. Solution Always start with the parent compound: draw the pentane chain. Then attach a methyl group at the third carbon atom and an amino group at the second carbon atom. Skill-Building Exercise Draw the structure for 2-amino-3-ethyl-1-chloroheptane.

Ammonium (NH4+) ions, in which one or more hydrogen atoms are replaced with alkyl groups, are named in a manner analogous to that used for simple amines. The alkyl groups are named as substituents, and the parent species is regarded as the NH4+ ion. For example, CH3NH3+ is the methylammonium ion. The ion formed from aniline (C6H5NH3+) is called the anilinium ion. Example 14 15.12 Physical Properties of Amines Learning Objectives Explain why the boiling points of primary and secondary amines are higher than those of alkanes or ethers of similar molar mass but are lower than those of alcohols. Compare the boiling points of tertiary amines with alcohols, alkanes, and ethers of similar molar mass. Compare the solubilities in water of amines of five or fewer carbon atoms with the solubilities of comparable alkanes and alcohols in water.

Primary and secondary amines have hydrogen atoms bonded to an nitrogen atom and are therefore capable of hydrogen bonding (part (a) of Figure 15.6 "Hydrogen Bonding" ), although not as strongly as alcohol molecules (which have hydrogen atoms bonded to an oxygen atom, which is more electronegative than nitrogen). These amines boil at higher temperatures than alkanes but at lower temperatures than alcohols of comparable molar mass. For example, compare the boiling point of methylamine (CH3NH2; −6°C) with those of ethane (CH3CH3; −89°C) and methanol (CH3OH; 65°C). Tertiary amines have no hydrogen atom bonded to the nitrogen atom and so cannot participate in intermolecular hydrogen bonding. They have boiling points comparable to those of ethers ( Table 15.5 "Physical Properties of Some Amines and Comparable Oxygen-Containing Compounds" ). Figure 15.6 Hydrogen Bonding (a) Amine molecules are associated through hydrogen bonding. (b) An amine molecule can form a hydrogen bond with water molecules.

Table 15.5 Physical Properties of Some Amines and Comparable Oxygen-Containing Compounds Name 91 0.25 All three classes of amines can engage in hydrogen bonding with water (part (b) of Figure 15.6 "Hydrogen Bonding" ). Amines of low molar mass are quite soluble in water; the borderline of solubility in water is at five or six carbon atoms. To Your Health: Amines in Death and Life Amines have “interesting” odors. The simple ones smell very much like ammonia. Higher aliphatic amines smell like decaying fish. Or perhaps we should put it the other way around: Decaying fish give off odorous amines. The stench of rotting fish is due in part to two diamines: putrescine and cadaverine. They arise from the decarboxylation of ornithine and lysine, respectively, amino acids that are found in animal cells.

(For more information about lysine, see Chapter 18 "Amino Acids, Proteins, and Enzymes" , Section 18.1 "Properties of Amino Acids" .) Aromatic amines generally are quite toxic. They are readily absorbed through the skin, and workers must exercise caution when handling these compounds. Several aromatic amines, including β-naphthylamine, are potent carcinogens. Concept Review Exercises Which compound of each pair has the higher boiling point? Explain. butylamine or butyl alcohol Which compound is more soluble in water—CH3CH2CH3 or CH3CH2NH2? Explain. Which compound is more soluble in water—CH3CH2CH2NH2 or CH3CH2CH2CH2CH2CH2NH2? Explain.

Answers butylamine because the N–H bonds can engage in hydrogen bonding; pentane cannot engage in hydrogen bonding CH3CH2CH2CH2CH2NH2 because it has a greater molar mass than CH3NH2 CH3CH2NH2 because amines can engage in hydrogen bonding with water; alkanes cannot engage in hydrogen bonding 15.13 Amines as Bases Name the typical reactions that take place with amines. Describe heterocyclic amines. Recall that ammonia (NH3) acts as a base because the nitrogen atom has a lone pair of electrons that can accept a proton. Amines also have a lone electron pair on their nitrogen atoms and can accept a proton from water to form substituted ammonium (NH4+) ions and hydroxide (OH−) ions: As a specific example, methylamine reacts with water to form the methylammonium ion and the OH− ion. Nearly all amines, including those that are not very soluble in water, will react with strong acids to form salts soluble in water. Amine salts are named like other salts: the name of the cation is followed by the name of the anion.

Example 15 15.14 Amides: Structures and Names Learning Objectives Identify the general structure for an amide. Identify the functional group for an amide. Names amides with common names. Name amides according to the IUPAC system. The amide functional group has an nitrogen atom attached to a carbonyl carbon atom. If the two remaining bonds on the nitrogen atom are attached to hydrogen atoms, the compound is a simple amide. If one or both of the two remaining bonds on the atom are attached to alkyl or aryl groups, the compound is a substituted amide. Note The carbonyl carbon-to-nitrogen bond is called an amide linkage. This bond is quite stable and is found in the repeating units of protein molecules, where it is called a peptide linkage. (For more about peptide linkages, see Chapter 18 "Amino Acids, Proteins, and Enzymes" , Section 18.3 "Peptides" .) Simple amides are named as derivatives of carboxylic acids.

The -ic ending of the common name or the -oic ending of the International Union of Pure and Applied Chemistry (IUPAC) name of the carboxylic acid is replaced with the suffix -amide. Example 16 15.15 Physical Properties of Amides Learning Objectives Compare the boiling points of amides with alcohols of similar molar mass. Compare the solubilities in water of amides of five or fewer carbon atoms with the solubilities of comparable alkanes and alcohols in water. With the exception of formamide (HCONH2), which is a liquid, all simple amides are solids ( Table 15.6 "Physical Constants of Some Unsubstituted Amides" ). The lower members of the series are soluble in water, with borderline solubility occurring in those that have five or six carbon atoms. Like the esters, solutions of amides in water usually are neutral—neither acidic nor basic. Table 15.6 Physical Constants of Some Unsubstituted Amides Condensed Structural Formula 290 slightly soluble The amides generally have high boiling points and melting points.

These characteristics and their solubility in water result from the polar nature of the amide group and hydrogen bonding ( Figure 15.7 "Hydrogen Bonding in Amides" ). (Similar hydrogen bonding plays a critical role in determining the structure and properties of proteins, deoxyribonucleic acid [DNA], ribonucleic acid [RNA], and other giant molecules so important to life processes. See Chapter 19 "Nucleic Acids" .) Figure 15.7 Hydrogen Bonding in Amides Amide molecules can engage in hydrogen bonding with water molecules (a). Those amides with a hydrogen atom on the nitrogen atom can also engage in hydrogen bonding (b). Both hydrogen bonding networks extend in all directions. Concept Review Exercises Which compound has the higher boiling point—butyramide (CH3CH2CH2CONH2) or ethyl acetate (CH3COOCH2CH3)? Explain. Which compound has the higher boiling point—butyramide or dimethylacetamide [CH3CON(CH3)2]? Explain.

Which compound is more soluble in water—acetamide (CH3CONH2) or 1-butene (CH2=CHCH2CH3)? Explain. Which compound is more soluble in water—CH3CONHCH3 or 2-methylbutane [CH3CH(CH3)CH2CH3)]? Explain. Answers butyramide because the nitrogen-to-hydrogen (N–H) and the carbon-to-oxygen double (C=O) bonds can engage in hydrogen bonding; ethyl acetate cannot engage in hydrogen bonding acetamide because the N–H and C=O bonds can engage in hydrogen bonding with water; 1-butene cannot engage in hydrogen bonding with water 15.16 Formation of Amides Learning Objective Describe the preparation procedure for amides. The addition of ammonia (NH3) to a carboxylic acid forms an amide, but the reaction is very slow in the laboratory at room temperature. Water molecules are split out, and a bond is formed between the nitrogen atom and the carbonyl carbon atom. In living cells, amide formation is catalyzed by enzymes.

Proteins are polyamides; they are formed by joining amino acids into long chains. In proteins, the amide functional group is called a peptide bond. (For more information about proteins, see Chapter 18 "Amino Acids, Proteins, and Enzymes" , Section 18.4 "Proteins" .) Polyamides Just as the reaction of a diol and a diacid forms a polyester ( Section 15.8 "Preparation of Esters" ), the reaction of a diacid and a diamine yields a polyamide A condensation polymer in which the monomer units are joined by an amide linkage.. The two difunctional monomers often employed are adipic acid and 1,6-hexanediamine. The monomers condense by splitting out water to form a new product, which is still difunctional and thus can react further to yield a polyamide polymer. Some polyamides are known as nylons. Nylons are among the most widely used synthetic fibers—for example, they are used in ropes, sails, carpets, clothing, tires, brushes, and parachutes.

They also can be molded into blocks for use in electrical equipment, gears, bearings, and valves. Concept Review Exercises Write the condensed structural formulas and give names of the two compounds from which butanamide (CH3CH2CH2CONH2) is formed. Write the condensed structural formulas and names of the two compounds from which CH3CH2CH2CH2CH2CONHCH2CH2CH3 is formed. Answers CH3CH2CH2CH2COOH (pentanoic acid) and NH3 (ammonia) 15.17 Chemical Properties of Amides: Hydrolysis Learning Objective Identify the typical reaction that amides undergo. Generally, amides resist hydrolysis in plain water, even after prolonged heating. In the presence of added acid or base, however, hydrolysis proceeds at a moderate rate. In living cells, amide hydrolysis is catalyzed by enzymes. Amide hydrolysis is illustrated in the following example: Note Hydrolysis of an amide in acid solution actually gives a carboxylic acid and the salt of ammonia or an amine (the ammonia or amine initially formed is neutralized by the acid).

Basic hydrolysis gives a salt of the carboxylic acid and ammonia or an amine. Example 17 15.18 End-of-Chapter Material Chapter Summary To ensure that you understand the material in this chapter, you should review the meanings of the following bold terms in the summary and ask yourself how they relate to the topics in the chapter. A carboxylic acid (RCOOH) contains the functional group COOH, called the carboxyl group, which has an OH group attached to a carbonyl carbon atom. An ester (RCOOR′) has an OR′ group attached to a carbonyl carbon atom. An amine is derived from ammonia (NH3), with one, two, or all three of the hydrogen atoms of NH3 replaced by an alkyl (or an aryl) group. The amide functional group has a carbonyl group joined to a nitrogen atom from NH3 or an amine. There are many familiar carboxylic acids.

The R group may be a hydrogen atom (as in formic acid, HCOOH), an alkyl group (as in acetic acid, CH2COOH), or an aryl group (as in benzoic acid, C6H5COOH). The location of substituents along the carbon chain is indicated by a Greek letter (for common names) or a number (for names from the International Union of Pure and Applied Chemistry). A carboxylic acid is formed by the oxidation of an aldehyde with the same number of carbon atoms. Because aldehydes are formed from primary alcohols, these alcohols are also a starting material for carboxylic acids. Carboxylic acids have strong, often disagreeable, odors. They are highly polar molecules and readily engage in hydrogen bonding, so they have relatively high boiling points. Carboxylic acids are weak acids. They react with bases to form salts and with carbonates and bicarbonates to form carbon dioxide gas and the salt of the acid. Esters are pleasant-smelling compounds that are responsible for the fragrances of flowers and fruits.

They have lower boiling points than comparable carboxylic acids because, even though ester molecules are somewhat polar, they cannot engage in hydrogen bonding. However, with water, esters can engage in hydrogen bonding; consequently, the low molar mass esters are soluble in water. Esters can be synthesized by esterification, in which a carboxylic acid and an alcohol are combined under acidic conditions. Esters are neutral compounds that undergo hydrolysis, a reaction with water. Under acidic conditions, hydrolysis is essentially the reverse of esterification. When carried out under basic conditions, the process is called saponification. Inorganic acids also react with alcohols to form esters. Some of the most important esters in biochemistry are those formed from phosphoric acid. Amines are nitrogen-containing organic molecules derived from ammonia (NH3). A primary (1°) amine (RNH2) has one organic group bonded to the nitrogen atom, a secondary (2°) amine (R2NH) has two organic groups bonded to the nitrogen atom, and a tertiary (3°) amine (R3N) has three organic groups bonded to the nitrogen atom.

Amines are basic compounds that react with strong acids to produce ammonium (NH4+) salts. A cyclic compound in which the ring contains one or more noncarbon atoms is called a heterocyclic compound. There are many heterocyclic amines, including many physiologically important ones. Alkaloids are heterocyclic amines found in many plants. Caffeine, nicotine, and cocaine are familiar alkaloids. Organic compounds containing a carbonyl group bonded to a nitrogen atom are amides, and the carbon-to-nitrogen bond is an amide linkage (or a peptide linkage). Most amides are colorless and odorless, and the lighter ones are soluble in water. Because they are polar molecules, amides have comparatively high boiling points and melting points. Amides are synthesized from carboxylic acids and NH3 or amines. Amides are neutral compounds. They resist hydrolysis in water, but acids, bases, and enzymes catalyze the reaction. Additional Exercises Of the families of organic compounds discussed in this chapter, which are known for their typically unpleasant odors? Which for their characteristically pleasant aromas? What is esterification of a carboxylic acid?

How does it differ from neutralization? Like alcohols, phenols form esters with carboxylic acids. The hydrocarbon group from phenol is called phenyl. Draw the structure of phenyl acetate. Describe the hydrogen bonding in carboxylic acids, both acid-acid and acid-water. How does this influence their physical properties? Which compound is more soluble in water—benzoic acid or sodium benzoate? Explain. Dicarboxylic acids have two carboxyl groups and are named with the ending -dioic acid. Give the equation for the reaction of 1,5-pentanedioic acid (HOOCCH2CH2CH2COOH; common name, glutaric acid) with each of the following: 1 mol of NaOH 2 mol of NaOH Without consulting tables, arrange the following compounds in order of increasing boiling point: butyl alcohol, methyl acetate, pentane, and propionic acid. From which alcohol might each acid be prepared via oxidation with acidic dichromate?

CH3CH2COOH HOOCH2COOH (CH3)2CHCH2COOH The distinctive aroma and flavor of oranges are due in part to octyl acetate, an ester formed from 1-octanol (octyl alcohol) and acetic acid. Write the condensed structural formula for octyl acetate. A lactone is a cyclic ester. What product is formed in following reaction? A lactam is a cyclic amide. What product is formed in the following reaction? Draw the structures for the eight isomeric amines that have the molecular formula C4H11N. Give each a common name and classify it as primary, secondary, or tertiary. Draw the structures for the five isomeric amines that have the molecular formula C7H9N and contain a benzene ring. Classify each compound as primary, secondary, or tertiary. Cocaine is usually used in the form of the salt cocaine hydrochloride and sniffed up the nose. Some prefer to ingest their cocaine by smoking it (mixed with tobacco, for example). Before smoking, the cocaine hydrochloride must be converted back to the free base (that is, to the molecular form).

Explain the choice of dosage form for each route of administration. Draw the structures all the isomeric amides that have the molecular formula C4H9NO. An ester with the molecular formula C6H12O2 was hydrolyzed in aqueous acid to yield an acid Y and an alcohol Z. Oxidation of the alcohol with potassium dichromate (K2Cr2O7) gave the identical acid Y. What is the condensed structural formula of the ester? The neutralization of 125 mL of a 0.400 M NaOH solution requires 5.10 g of a monocarboxylic acid. Draw all the possible structures for the acid. If 3.00 g of acetic acid reacts with excess methanol, how many grams of methyl acetate are formed? How many milliliters of a 0.100 M barium hydroxide solution are required to neutralize 0.500 g of dichloroacetic acid?

Answers unpleasant: carboxylic acids; pleasant: esters sodium benzoate because it is ionic and forms ion-dipole forces with water; benzoic acid can engage in hydrogen bonding only with water pentane < methyl acetate < butyl alcohol < propionic acid CH3COOCH2CH2CH2CH2CH2CH2CH2CH3 Oxalic acid | definition of oxalic acid by Medical dictionary Oxalic acid | definition of oxalic acid by Medical dictionary Related to oxalic acid: oxalic acid poisoning oxalic acid [ok-sal´ik] a poisonous dicarboxylic acid found in various fruits and vegetables, and formed in the metabolism of ascorbic acid and ethylene glycol . While it is not usually a problem with normal diets, it is seen in high concentrations in certain ornamental plants (such as Diffenbachia), as well as in some bleaches and antirust products. Persons or animals that chew on the plants or otherwise consume the chemical can be poisoned. Oxalic acid is highly toxic and if ingested vomiting should not be induced. If the person is at home, a poison control center and emergency services should be contacted immediately.

The acid can be neutralized by administration of calcium by either the oral or the intravenous route. High urinary oxalate concentrations may cause deposition of kidney stones and other urinary calculi . ox·al·ic ac·id (ok-sal'ik as'id), An acid found in many plants and vegetables, particularly in buckwheat (family Polygoniaceae) and Oxalis (family Oxalidaceae); used as a hemostatic in veterinary medicine, but toxic in elevated levels when ingested by humans; also used in the removal of ink and other stains, and as a general reducing agent; salts of oxalic acid are found in renal calculi; accumulates in cases of primary hyperoxaluria. oxalic acid /ox·al·ic ac·id/ (ok-sal´ik) a dicarboxylic acid occurring in various fruits and vegetables and as a metabolic product of glyoxylic or ascorbic acid; it is not metabolized but is excreted in the urine. Excess may lead to formation of calcium oxalate calculi in the kidney.

oxalic acid (H2C2O4) [oksal′ik] a member of a family of dibasic acids found in many common plants, such as buckwheat, wood sorrel, and rhubarb. It is an important reagent and is used in bleaching and drying. Poisonous if ingested, oxalic acid is used in veterinary medicine as a hemostatic. In dietary intake of foods containing oxalic acid, the substance binds with calcium and is sometimes found in renal calculi and the urine of patients with hyperoxaluria. Also called ethanedioic acid . ox·al·ic ac·id (ok-sal'ik as'id) An acid found in many plants and vegetables; used as a hemostatic in veterinary medicine, but toxic when ingested by humans; also used in the removal of ink and other stains, and as a general reducing agent; salts of oxalic acid are found in renal calculi; accumulates in cases of primary hyperoxaluria.

ox·al·ic ac·id (ok-sal'ik as'id) Acid found in many plants and vegetables; toxic in elevated levels when ingested by humans; also used in the removal of ink and other stains, and as a general reducing agent. oxalic acid a poisonous, dibasic acid found in various fruits and vegetables, and formed in the metabolism of ascorbic acid. In plants the acid is present in the form of oxalate . The commercial acid is highly toxic and if ingested should be neutralized by the administration of lime water (calcium hydroxide solution) or other convenient source of calcium, which reacts with the acid to form insoluble calcium oxalate. oxalic acid test papers used to detect indole production in an indole test. How to Make Oxalic Acid | eHow How to Make Oxalic Acid  Email Save Oxalic acid (H2C2O4) is a relatively strong organic acid and is a common reducing agent in organic chemistry. There are a number of methods for preparing oxalic acid from nitric acid, and one important difference among them is the amount of oxalic acid that is produced from a given amount of nitric acid.

Oxalic acid can be prepared in a laboratory with nothing more than sugar and nitric acid, although a small amount of vanadium pentoxide will act as a catalyst and allow the reaction to proceed much more swiftly. Things You'll Need Filter paper Large container to hold boiling water Place the sugar in the flat-bottomed flask and add the nitric acid. Heat the flask in a bath of boiling water. The sugar will dissolve in a vigorous reaction that produces an extremely large amount of nitric acid fumes. Remove the flask from the water bath as soon as the reaction begins to produce the fumes, and place it on a surface that will not conduct heat. After the reaction subsides in about 15 minutes, pour the still-hot solution into an evaporating basin. Evaporate the solution with mild heat from a Bunsen burner for about 15 minutes until it reaches a volume of about 20 mL, then add about 40 mL of water. Evaporate the solution down to about 20 mL again, and thoroughly cool the solution in an ice-water bath. Allow the rapidly forming crystals of oxalic acid to complete their crystallization in about 10 minutes.

Filter the remaining solution through filter paper, and add the crystals to a small amount of hot water. Allow the oxalic acid to recrystallize, which should take about 20 minutes. Dry the crystals by pressing them between pads of drying paper or with a desiccator. Don't use an ordinary oven since this could cause the oxalic acid to decrystallize. This preparation should yield about 7 g of oxalic acid. Tips & Warnings This method will produce a large amount of nitric acid fumes and must be performed under a fume hood with adequate ventilation.

Question: Also found in Spinach and similar plants, which organic acid is the primary acid found in Rhubarb leaves?
Answer: OXALIC ACID