General, Organic, & Biological Chemistry Lecture Notes PDF

General, Organic, & Biological Chemistry: An Interactive Approach First Edition Chapter 19 Amines and Neurotransmitters Copyright © 2023 Pearson Education,...

General, Organic, & Biological Chemistry: An Interactive Approach First Edition Chapter 19 Amines and Neurotransmitters Copyright © 2023 Pearson Education, Inc. All Rights Reserved Learning Objectives 19.1 Identify amines and classify them 1 , 2 , or 3. as 19.2 Describe how intermolecular forces affect boiling points and water solubility of amines. 19.3 Predict and draw the products of acid-base reactions of amines. 19.4 Describe the characteristics of alkaloids and provide examples. 19.5 Describe and provide examples of the general structure and physiological function of neurotransmitters. 19.6 Use the IUPAC system for naming organic compounds to convert from structure to name and from name to structure for amines and ammonium salts. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Think, Pair, Share 19.1 Plants produce a wide array of biologically active compounds, including cocaine, caffeine, and nicotine. What structural similarities do these three molecules share? Do you expect these molecules to be water soluble? Why or why not? How might their solubility affect their ability to be transported through the bloodstream? Copyright © 2023 Pearson Education, Inc. All Rights Reserved Introduction to Amines Amines play essential roles in both basic biology and the treatment of disease. Amines are found in a wide array of medicines and toxins and are important components of the D NA and proteins that make us who we are. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Structure of Amines Amines form when one or more of the hydrogen atoms on the ammonia molecule (NH3 ) is replaced with an alkyl or aromatic group. The basic amine functional group is a nitrogen atom bonded to a combination of hydrogen atoms and carbon groups. The amine functional group is distinct from the amide functional group. Amides contain a nitrogen atom but also contain a carbonyl group. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Three Simple Amines These three amine compounds (identified here by their common names) are found in rotting fish and are responsible for much of its foul odor. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Molecular Shape of Amines Understanding the shape and chemical properties of amines allows us to better predict the functions of these important molecules. An amine nitrogen is surrounded by three atoms and one lone pair of electrons producing a trigonal pyramidal shape with bond angles approximately 109.5. Its polar bonds and bent shape contribute to the overall polarity of the amine functional group. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Classification of Amines A primary (1 ) amine contains a nitrogen atom bonded to one carbon atom or one alkyl group. In a secondary (2 ) amine, the nitrogen is bonded to two carbon atoms or two alkyl groups. A tertiary (3 ) amine contains a nitrogen atom bonded to three carbon atoms or three alkyl groups. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Heterocyclic Amines Compounds that contain atoms other than carbon in the ring are heterocycles. In a heterocyclic amine, the ring contains five or six atoms of which one or two are nitrogen atoms. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Draw to Learn Draw an example of a 1 , 2 , and 3 amine. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Solution Many possible answers. Here is one example for each: 1 amine: 2 amine: 3 amine: Copyright © 2023 Pearson Education, Inc. All Rights Reserved Caffeine Caffeine is a commonly consumed substance that contains amine heterocycles used in cultures around the world. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Amines in the Diet Amines provide essential nutrients and are found in many foods. Vitamin B1 (thiamine), for example, is an essential vitamin found in an array of foods including grains, beans, nuts, and meat. Thiamine deficiency causes beriberi disease. Thiamine is water-soluble and not stored in the body so it must be consumed regularly. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Folic Acid Folic acid occurs naturally in a range of food items. It is particularly important for women who are pregnant to consume enough folic acid; folic acid helps prevent fetuses from developing deformities of the brain or spine. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Amino Acids The proteins in our body are all made up of long chains of amino acids. Each amino acid contains an amino group and a carboxylic acid group. – An NH2 group named as a substituent is called an amino group. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Amines in Medicine Histamines, for example, are signaling molecules released by our immune cells when they recognize a foreign substance. Many allergy sufferers combat histamine symptoms with another amine, diphenhydramine. Albuterol (another drug containing an amine) is a prescription drug used to treat asthma symptoms. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Physical Properties of Amines Primary (1 ) and secondary (2 ) amines, like hydroxyl groups (OH), can form hydrogen bonds with each other. Because 1 and 2 amines hydrogen bond, they have higher boiling points than nonpolar alkanes of similar mass. Alcohols of similar mass have higher boiling points than amines of similar mass. The ability of amine compounds to form hydrogen bonds plays a significant role in the structure of DNA. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Water Solubility of Amines All amines 1 , 2 , and 3  form hydrogen bonds with water. Amines with fewer than six carbon atoms are water soluble. – Large amines are considered water insoluble unless additional polar functional groups are present in the molecule. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Think, Pair, Share 19.2 Rank the following molecules from lowest to highest boiling point. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Solution: Think, Pair, Share 19.2 Boiling points: low C  B  A high Copyright © 2023 Pearson Education, Inc. All Rights Reserved Reactions of Amines Ammonia in the Body: – Bacteria in the gut produce ammonia as they break down protein. – The liver normally converts ammonia into urea. If the liver is not functioning properly, ammonia can build up in the body and cause a coma or death. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Acid-Base Reactions Ammonia (NH3 ) functions as a base by accepting a proton (H ) from water to produce the ammonium ion and hydroxide ion (OH ). Amines 1 , 2 , and 3  can also react as above, accepting a proton to produce ammonium ions in dynamic equilibria. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Ammonium Salts Amines also react with acids to form water-soluble ammonium salts. Ammonium salts are much more soluble in water than the corresponding unprotonated amine. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Let’s Practice 19.1 What product or products are formed when an amine reacts with an acid such as HCl? A) a ketone and the hydroxide ion B) a hemiacetal C) an ammonium salt D) an acetal and the hydroxide ion E) a primary alcohol and ammonia Copyright © 2023 Pearson Education, Inc. All Rights Reserved Solution: Let’s Practice 19.1 C) an ammonium salt (R-NH3 Br )   Copyright © 2023 Pearson Education, Inc. All Rights Reserved Alkaloids: Plant Amines Plants produce thousands of molecules that are classified as alkaloids– naturally occurring amines derived from plant sources. The alkaloid ephedrine, from the ephedra plant, was widely marketed as a nutritional supplement until the high-profile death of pitcher Steve Bechler in 2004. In addition to containing an amine functional group, alkaloids often have complex structures and are biologically active once they enter the human body. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Famous Alkaloids Cocaine is an alkaloid produced by the coca plant. Caffeine is an alkaloid produced by the coffee plant. Nicotine is an alkaloid produced by the tobacco plant. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Think, Pair, Share 19.3 Caffeine is an alkaloid most of us are familiar with. Identify two different chemical characteristics of the caffeine molecule. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Solution: Think, Pair, Share 19.3 Any two of: Amide, 3 amine, alkene Copyright © 2023 Pearson Education, Inc. All Rights Reserved Neurotransmitters In our brains, 86 billion specialized nerve cells called neurons process and transmit information. Neurons contain distinct parts, including a cell body, an axon, and dendrites. Neurons communicate by sending messages from one neuron to the next. There are gaps between neurons, called synapses. To relay a message across the synapse, a neuron releases a neurotransmitter. The neurotransmitter crosses the synapse and binds to a receptor, relaying a signal to the target cell. Many neurotransmitters are amines. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Amine Neurotransmitters Key neurotransmitters and their functions: Table 19.1 Key Neurotransmitters and their Functions. Neurotransmitter Function Made in the Blank body from: Dopamine a natural stimulant that increases tyrosine The structure of dopamine. A benzene ring is in a vertical orientation with C 1 occupying the topmost vertex. The ring contains alternating double bonds between C 1 and C 2, C 3 and C 4, and C 5 and C 6. C 5 pleasurable feelings; regulates muscle movement, cognition, sleep, and mood and C 6 are each single bonded to O H. C 2 is single bonded to C 1 of a 2-carbon alkane chain depicted as a line structure using 1 line. C 2 of the alkane chain is single bonded to N H 2 on the upper right. Norepinephrine plays a role in sleep, attention, focus, and tyrosine The structure of norepinephrine. A benzene ring is in a vertical orientation with C 1 occupying the topmost vertex. The ring contains alternating double bonds between C 1 and C 2, C 3 and C 4, and C 5 and C 6. C 5 and C 6 are each single bonded to O H. C 2 is single bonded to C 1 of a 2-carbon alkane chain depicted as a line structure using 1 line. C 1 of the alkane chain is wedge bonded to O H above. C 2 of the alkane chain is single bonded to N H 2 on the upper right. alertness Epinephrine plays an important role in fight-or-flight tyrosine (adrenaline) response by increasing blood flow to muscles, heart rate, and blood sugar levels The structure of epinephrine. A benzene ring is in a vertical orientation with C 1 occupying the topmost vertex. The ring contains alternating double bonds between C 1 and C 2, C 3 and C 4, and C 5 and C 6. C 5 and C 6 are each single bonded to O H. C 2 is single bonded to C 1 of a 1 N and 3 C heteronuclear alkane chain depicted as a line structure using 3 zigzag lines. In the alkane chain, N bound to H occupies the third position. C 1 of the alkane chain is wedge bonded to O H above. Serotonin facilitates relaxation, deep sleep, rational tryptophan The structure of serotonin. A benzene ring is in a vertical orientation with C 1 occupying the topmost vertex. The ring contains alternating double bonds between C 1 and C 2, C 3 and C 4, and C 5 and C 6. C 6 is single bonded to O H. The ring is fused to a 5-membered heterocyclic pentagonal ring in a horizontal orientation consisting of 1 N and 4 C atoms. In the pentagonal ring, N bound to H occupies the first position which is the bottom right vertex. The two rings are fused to each other such that C 2 and C 3 of the benzene ring are the C 2 and C 1 of the pentagonal ring, respectively. In the pentagonal ring, a double bond is present between C 3 and C 4. C 3 of the pentagonal ring is single bonded to C 1 of a 2- carbon alkane chain depicted as a line structure using 1 line. C 2 of the alkane chain is single bonded to N H 2 on the upper right. thinking, mood, learning, and memory Acetylcholine regulates muscle activation, learning, and acetyl-Co-A, The structure of acetylcholine. A 1 O, 1 N, and 5 C heteronuclear alkane chain is depicted as a line structure using 6 zigzag lines. O occupies the third position and N occupies the sixth position. C 2 is double bonded to O above. N is single bonded to C H 3 on the upper right and C H 3 on the upper left, each in the form of a line. short-term memory choline Copyright © 2023 Pearson Education, Inc. All Rights Reserved Copyright This work is protected by United States copyright laws and is provided solely for the use of instructors in teaching their courses and assessing student learning. Dissemination or sale of any part of this work (including on the World Wide Web) will destroy the integrity of the work and is not permitted. The work and materials from it should never be made available to students except by instructors using the accompanying text in their classes. All recipients of this work are expected to abide by these restrictions and to honor the intended pedagogical purposes and the needs of other instructors who rely on these materials. Copyright © 2023 Pearson Education, Inc. All Rights Reserved