Organic Flashcards
1
Q
מהן התרכובות האנאורגניות?
A
CO carbon monoxide CO2 carbon dioxide CO3 2- carbonate CaC2 calcium carbide HCN hydrogen cyanide CN - cyanide CaCO3 calcium carbonate HCO3 - hydrogen carbonate
וכל מולקולה שלא מכילה C וH
2
Q
למה פחמן מיוחד?
A
- יוצר קשר בודד או כפול או משולש
- אלקטרושליליות 2.5 - מגיב אבל גם לא מגיב
- מסוגל ליצור ארבעה קשרים
3
Q
איזה קשר חזק יותרת פאי או סיגמה?למה?
A
סיגמה בגלל שבפאי יש נוד למרות שיש אוברלאפ בשתי נקודות
4
Q
כמה מעלות יש בין 2 קשרי פאי?
A
90
5
Q
Aromatic definition
A
Fully conjugated and cyclic, floows Huckle’s rule
6
Q
What is Huckle’s rule
A
nr of pie electrons= 4n+2 (n-nr. of rings)
7
Q
What are the three sucategories of aromatic compounds?
A
homo (benzene), hetero (pyridine), fused (naphthalene)
8
Q
What are the three sucategories of aliphatic compounds?
A
saturated (alkanes), unsatureated (alkenes, alkynes)
9
Q
What atoms can participate in the chemical reaction of benzene? What type of chemical reaction is it?
A
SE- SON
10
Q
Increasing bond strength of alkene benzene alkyne alkane
A
alkane
11
Q
Where do carbons always have the same hybridization? which?
A
Alkane (SP3), benzene (SP2)
12
Q
Where do carbons have different hybridizations? which?
A
Alkenes (SP2) except: 1. Only SP2 H2C=CH2 - ethylene
2. Only SP2 (when fully conjugated) H2c=CH-CH=CH2 - like 1,3 butadiene
Alkynes (SP) except: Only SP HC=CH -acetylene
13
Q
Degree of carbon
A
primary- attached to only one carbon
secondary- “ “ two carbons
tertiary- “ “ three “
quaternary- “ “ four “
14
Q
Priorities of naming- alkanes
A
- longest carbon chane
- end closer to abranch gets lowest nr.
- alphabetically
- terminal with more branches
15
Q
What are structural isomers?
A
same molecular formula, differenet connectivity
16
Q
IUPAC
A
international union of pure and applied chemistry
17
Q
Isomers of alkanes
A
4 carbons- (Two) IUPAC- butane, 2-methyl propane
Common- n butane, isobutane
5 carbons- (Three) IUPAC- pentane, 2-methyl butane, 2-di methyl propane
Common- n pentane, iso pentane, neo pentane
6 carbons- (Five) IUPAC- hexane, 2-methyl pentane, 3-methyl pentane, 2 3-di mythyl butane, 2 2-di methyl butane
Common- n hexane, iso hexane, X, X, neohexane
18
Q
Isomers of alkyls
A
3 carbons (Two)- n propyl, iso propyl 4 carbons (Four)- n butyl, sec butyl, tert butyl, iso butyl
19
Q
What does the BP depend on?
A
nr. of branches (less is better)
nr. of carbons (more is better)
surface area (bigger is better)
OH groups (more is better)
20
Q
What are the three chemical reactions?
A
Addition (combination)
Substitution (exchange)
Elimination (decomposition)
21
Q
What are the two mechanisms of reactions? what are thier products?
A
homolysis- radicals
heterolysis- ions (cations or “ium” ending- lewis acid, anions or “ide” ending- lewis base).
22
Q
Alkane reaction example
A
SR halogenation (chlorination)
CH4+nCl2= CH3Cl+1HCL –>chloro methane / methyl chloride
CH2CL2+2HCL –>di-chloro methane
CHCl3+3HCl –>tri-chloro methane / chloroform
CCl4+4HCl –>tetra-chloro methane / carbon tetra chloride *excess\enough/4 moles
(=organic+inorganic)
uses light to occur
This happens in two steps! 1. light activates halogen 2.activated halogen activates alkane 3. alkyl can be radical לשרטט
23
Q
combustion
A
full oxidation organic–>inorganic
CxHy + (X+Y/4)O2 = (Y:2)H2O + (X)CO2
24
Q
What are the two components of gasoline?
A
8C good- octane\ 2 2 4-tri methyl pentane
7C bad- heptane unbranched
25
What kind of isomers are alkenes and cycloalkanes?
structural isomers
26
In which type of hydrocarbon is the ideal angle equal to 109.5 and how is it called?
What other angles are there?
What is the difference between them called and how does it effect the stability of the molecule?
cycloalkanes
normal angle
abnormal angles- 60, 90, 108, 120
angle strain --> when it increses the molecule will be less stable.
27
What affects the stability of cycloalkanes?
1. angle strain.
| 2. "intramolecular stains" \ "non-bonded interactions" (repulsion between hydrogen atoms).
28
What two conformations are there in alkanes? How can a molecule change between the two?
staggered (stable) --> eclipsed (less stable)
by activation energy
the other way by rotation
29
What are the special conformations in cycloalkane structures?
cyclo pentane: envelope(more stable), half chair(less stable).
cyclo hexane: chair(more stable), chair(less stable).
*only chair has equatorial hydrogens.
30
Which position of hydrogen is most stable?
equatorial rather than axial
31
What is more stable cis or trans, equatorial or axial?
trans, then equatorial
32
ylene
ending of common name of alkenes
33
allene/diene
allene cummulated dienes
| diene- conjugated or isolated dienes
34
what is another name for benzene?
1 3 5-cyclo hexa triene
35
vinyl
the only alkene branch! CH2=CH-
| equals ethene minus 1H
36
CH2=CH-
vinyl, the only alkene branch
| equals ethene minus 1H
37
How many isomers does C4H8 have?
6 overall
cycloalkanes: cyclo butane, methyl cyclo propane
alkenes: 1-butene, iso-butene, cis 2-butene, trans 2-butene
38
How many isomers does C5H10 have?
10 overall
cycloalkanes: cyclopentane, methyl cyclo butane, 1 2-di methyl cyclopropane, 1 1-di methyl cyclopropane, ethyl cyclo propane.
alkenes: 1-pentene, 3-methyl 1-butene, iso- pentene, cis 2-pentene, trans 2-pentene.
39
What effects the stability of alkenes?
1. double bond in the middle is more stable than on the side
| 2. trans more stable than cis
40
Name the types of AE reactions, in which type of molecule do they occur?
alkenes, alkynes, cycloalkanes,aldehydes, ketones.
1. halogination X2 (draw bromination of 1-butene)
2. hydro halogenation HX (adding HI to propene)
3. hydration H2O (hydration of 2-chloro 2-butene)
41
Name the types of AR reactions, in which type of molecule do they occur?
alkenes, alkynes, cycloalkanes.
1. hydrogenation H2 (hydrogenation of ethene)
2. polimerazation (of chloro ethene / vinyl chloride *creates poly vinyl chloride- PVC- plastic)
42
Markovnikov's rule
In AE reactions, hydrogens will tend to attach to the atom with most hydrogens.
43
What is natural rubber made of?
A polimer of isoperene, created in the process of AR of an alkene.
44
What is plastic made of?
A polimer of vinyl chloride, created in the process of AR of an alkene.
45
What is polyisopene?
natural rubber
46
What is poly vinyl chloride?
plastic
47
4 important unsaturated polimers
1. polyisopene- rubber (isolated).
2. b carotene- in carrots (conjugated) 18C.
3. retinal- also called rhod, prostetic in rhodopsin which is a protein in the eyes -aldehyde (conjugated). (b one ion ring + fully conjugated 9 carbon chane with two methyl groups + an aldehyde group) **created from oxidation of precursor.
4. retinol- vitamin A1 -alcohol (conjugated). (b one ion ring + fully conjugated 9 carbon chane with two methyl groups + an alcohol group). **created from reduction of retinal.
48
What is a protein made of?
Holoprotein:
1. prosthetic group- non protein
2. apoprotein- only protein
49
hemoglobin protein
prosthetic- heme
apoprotein- globin (2 alpha, 2 beta)
conected by a binding site
50
rhodopsin protein
prosthetic- rhod \ retinal (b one ion ring + fully conjugated 9 carbon chane with two methyl groups + an aldehyde group)
apoprotein- opsin (ring, lys-basic charged NH3+
connected to the oxygen of an aldehyde in the prosthetic group by schiff base linkage C=N (dehydration)
51
Vitamins- fat soluble and water soluble
fat soluble: DEAK
D3- bones E-antioxidant A1-vision K1-blood clotting
water soluble: CB
C- "askorbic acid" immune
B- "niacin" / "nicotin acid" B1-thiamine B2-riboflavin B6-pyridoxal B7-biotin B9-pholic acid B12-coblamin
52
acetylene, way of prodduction, uses
common name of alkyne H-C---C-H
CaO (lime) + 3C (coke/coal) --> CaC2 (inorganic) + CO(inorganic
CaC2 + H2O --> C2H2 + Ca(OH)2
OR
by partial oxidation of CH4
used for lightning, welding
**combustion of acetylene is very exothermic
53
H-C---C-H
acetylene
54
Which molecules have equal BP if they have similar masses?
alkynes and alkanes
55
Are alkanes or alkynes more acidic? why?
alkyne (SP) rather than alkane (SP3) becuse alkynes have more S characteristics, and therefore it will be easier to extract hydrogens.
56
sextet nr.
nr of pie electrons in Huckle's rule
57
hoe many lone pairs of electron do the following atoms have? SON
S, O- 2
| N- 1
58
What are the three famous non aromatic cyclic molecules?
piperidine, indene, pyrolidine
59
What is the name of benzene as a branch?
phenyl
60
How many isomers are there for a benzene with two branches?
Three (o,p,m)
61
How many isomers are there for a benzene with three branches?
Three (123, 124, 135)
62
How many isomers are there for a benzene with four branches?
Three (234 ,235, 246)
63
List the ortho-para directors. How is the precentage divided between them?
The seven ortho-para directors:
R-N-R, H-N-R, X(halogen), OH, R(alkyl), R-O(alkoxy), NH2(amino).
*All activating except from X
ortho-63%
para-34%
64
List the meta directors.In which reactions do they exist? How much is the precentage?
The five meta directors in reactions of benzene:
COOH(carboxylic acid),CHO(aldehyde), CN-(cyanide), NO2(nitrogen dioxide), SO3H(sulfonic acid).
*All activating
93%
65
Increasing speed of types of directors
meta deactivating
66
What are the five benzene reactions? What are their mechanisms?
Always SE
1. Halogenation
2. Alkylation
3. Acylation
4. Nitration
5. Sulfonation
67
IUPAC and common naming of halogen containing compounds
IUPAC halo+alkane
| common alkyl+halide
68
What are the three types of halogen containing compounds?
1. alkyl halide (attached to a SP3 hyberdized carbon)
2. vinyl halide (attached to a SP2 hyberdized carbon)
3. aryl halide (attached to a SP2 hyberdized carbon in an aromatic ring)
69
Degree of halogen containing compounds, their stability
Is determined by the number of carbons that the carbon which is attached to a halogen is attached to.
1 degrees is the least stable while 3degrees is the most stable.
70
How are the following compounds called:
1. Halogen attached to a SP3 hyberdized carbon
2. Halogen attached to a SP2 hyberdized carbon
3. Halogen attached to a SP2 hyberdized carbon in an aromatic ring
1. alkyl halide
2. vinyl halide
3. aryl halide
71
What are the reactions and their mechanisms in halogen containing compounds?
nucleuphilic substitotion:
SN1- 1 reactant, 2 steps (slow)-more stable
SN2- 2 reactants, 1 step (fast)-less stable
72
Which has a higher BP- alkyl halide or alkane?why?
Alkyl halide because its polar (dipole-dipole), alkane has only london forces.
73
What is ethyl chloride used for?
local anesthetic
74
What is used as a local anesthetic?
ethyl chloride
75
list and draw the three inhalation anesthetics
1. chloroform CHCl3
2. halothane 3HC-O-CH3
3. enflurane C2H5-O-CH3
76
what is chloroform used for?
inhalation anesthetic CHCl3
77
what is halothane used for?
inhalation anesthetic 3HC-O-CH3
78
what is enflurane used for?
inhalation anesthetic C2H5OCH3
79
What is carbon tetrachloride used as?What does it damage? What does it cause?
CCl4
1. refrigirant
2. fire extinguisher
3. dry cleaning solvent
Damages liver, kidneys and nervous system.
Coma, death.
80
What is DDT used for? How is it called?Draw it.
Insecticide "Dichloro Diphenyl Trichloro ethane"
81
What is used as an insecticide?
DDT "Dichloro Diphenyl Trichloro ethane".
82
What are cfc's? How are they called?What are the used for?
```
Choloro-Fluoro carbons "Freons"
used as:
1. refrigarent
2. air conditioning
3. airosols
```
83
hat are the 8 famous halogen containing compounds?
1. ethyl chloride (local anesthetic)
2. inhalation anesthetics: chloroform, halothane and enflurane
3. carbon tetrachloride
4. natural hormones: T3 T4
5. Dichloro Diphenyl Trichloro ethane (insecticide)
6. Freons/cfc's "Choloro-Fluoro carbons"
7. teflone
8. PVC
84
What are T3and T4?What are they called?
thyroid gland produced hormones "thyroxine" and "tri iodothyroxine"
85
IUPAC and common naming for alochols
IUPAC- #C + di\tri...ol
| common- alkyl + alcohol
86
Wood alcohol
methanol
toxic!
15ml--> blindness
30ml-->death
87
common alcohol
ethanol
| 600ml-->death
88
rubbing alcohol
propanol
89
Preparation of alcohol
1. fermentation
2. hydration of alkene-->alcohol
3. hydrolysis of alkyl halide-->alcohol+strong acid
4. reduction of an aldehyde or carboxylic acid or ketone-->a primary alcohol!
90
Reactions of alcohols
1. dehydration
* of 1 alcohol-->alkene
* of 2 akcohols-->ether
2. esterification
* alcohol+organic acid-->ester+water
* alcohol+inorganic acid-->alkyl halide+water
3.oxidation
primary alcohol: goes through mild oxidation and becomes aldehyde.
aldehyde goes through oxidation and becomes carboxylic acid
secondary alcohol:goes through oxidation and becomes a ketone
tertiary alcohol: no reaction!
91
increasing BP: Alcohols water alkane ether
alkane, ether, alcohol, water (london, dipole , 3H, 4H)
92
Solubility of organic compounds
Are soluble in organic solvent, and also in water if they are able to make H bonding (but depends on the carbon chain).
93
What does the solubility depend on? + statement
nr. of carbons (less is better)
nr. of OH groups (more is better) same with BP
nr. of branches (more is better)
All first six orgnic compounds are souluble in water (first three to infinity, then it decreases), from there on they are not soluble because the carbon chane is too long and hydrophobic.
94
Are alcohol and water acids or bases?
weak acids, alcohol is slightly less acidic becuse it has a larger PKa value of 15.5
95
alkoxy
ethers
alkyl + oxygen (negatively charged)
created fhrough hydrolysis of alcohol alongside with H3O+
96
Phenols
Ar-OH NOT alcohols!
| *most are solid at RT
97
Increasing BP and solubility in water: cyclohexanol, phenol, hexanol
Explain.
hexanol
98
phenoxy
phenyl + oxygen (negatively charged)
| created fhrough hydrolysis of phenol alongside with H3O+ - was once used to brush teeth
99
Which is more acidic- alcohol or phenol?
phenol because it has a lower PKa value of 10
100
Oxidation of phenols creates.... which are.....
quinones,not aromatic
101
Which is more stable: phenoxy ion or cyclohexoxy ion? Why?
phenoxy ion because of delocalized electrons (like moving target).
102
Types of ethers
1. ether (aliphatic)
2. cyclic ether (O in a ring / connecting a ring and something else / connecting two rings)
3. epoxide (3 member ring)
103
Naming ethers
IUPAC- alkoxy + alkane
| common- alkyl + alkyl + ether
104
What will be able to replace a halogen in a halogen containing compound?
A less electronegative halogen
105
what is the product of beta elimination of a haloalkane?
alkene
106
enol
OH from branch connected to any end of the double bond in the main chain
107
which is more stable: primary or tertiary alcohol?
tertiary alcohol
108
What can chlorofluoro carbns cfc's cause
ozone layer deplition (turns into oxygen).
| 2O3 + Cl --> 3O2 + Cl
109
What can increase the acidity of a phenols?
a negative inducting ion: COOH, CHO, C=O, NO2, OH, X (high EN)
110
What can increase the bacisity of a phenols?
a positive inducting ion: H or alkyl group (low EN)
111
What do positive and negative inducting ions do?
change the PH by effecting the OH group in a phenol
112
How are epoxides produced?
by adding O2 to alkenes or benzenes
113
preparation of ether
1. dehydration of two alcohols
| 2. adding alkyl halide to alcohol
114
uses of ether
1. as anesthetic (diethyl ether- a volitile liquid)
| 2. as organic solvent
115
increasing solubility: ether, alcohol
ether (2H)
116
is ether an acid or a base?
it is a weak base
117
reactions of ethers
1. ether + strong acid --> dialkoxonium chloride
2. opening apoxide ring with water--> ethylene glycol
3. ether + O2 + light --> peroxides (toxic) *That is why we must keep diethyl ether in dark bottles and exclude oxygen.
118
biological significance of epoxides
1. amino acid synthesis (thyrosin)
2. natural hormone synthesis (T3 T4)
3. antibiotic ionophores (monancin, nonactin, crown ether, cryptands)
4. long chain of epoxides is toxic (okadiac acid)
5. can activate carcinogenic substances (causes cancer)
119
into what groups can we divide sulfor containing compounds?
Inorganic:
H2S hydrogen sulfide
H2SO3 sulforous acid
H2SO4 sulfuric acid
organic:
R-S-H thiol "mercaptan"
R-S-R' thio ether "sulfide"
R-SOOH sulfinic acid
R-OSR sulfoxide
R-O-SOOR sulfite ester
R-SOO-OH sulfonic acid
S-SOO-O-R sulfone
R-O-SOO-O-R sulfateester
120
reactions of halo alkanes
1. hydrolysis (+H2O-->alcohol + strong acid)
2. basic hydrolysis (+ NaOH--> alcohol + strong base)
3. + ammonia NH3--> primary amine + strong acid)
4. +alcohol--> ether + strong acid)
5. +hydrogen sulfide SH2--> thiol + strong acid)
6. +thiol--> thio ether + strong acid)
7. +halogen--> haloalkane + strong acid)
121
Beta elimination of halo-alkane turns it into?
An alkene
122
IUPAC and common naming of thiols
IUPAC: alkane + thiol
Common: mercapto + alkane OR alkyl + mercaptan
123
Reactions of thiols
Mild oxydaion --> disulfide + H2O
| With alkyl halide --> Sulfide + strong acid
124
How many H bonds does thiol make in water?
None
125
Increasing acidity of thiol alcohol and phenol
Thiol (pKa=8.5) > phenol (pKa=10) > alcohol pKa=15.5)
126
Naming sulfides
alkyl + alkyl + sulfide
127
This O= is called...and it is the functional group of
Keto group.
| ketone, aldehyde, quinone.
128
Aldehyde naming
IUPAC: #C + al (enal..)
Common: form\acet\propion... + aldehyde (only in alkanes!)
129
What is the last carbon in the chain called?
Omega carbon
130
Ketone naming
IUPAC: #C + nr. + one/dione
common: alkyl + alkyl + ketone
131
How many H bonds does aldehyde make in water?
Two.
132
Is aldehyde an acid or a base?
A weak base
133
Who is more basic aldehyde or ether?
aldehyde
134
To what group does the ugly older daughter and younger pretty doughter refer to? explain.
Aldehyde's reactivity. It prefers to react in basic solutions so that addition will be first made between the positively charged carbon (ugly sister) and a nucleophile. Only then will an electrophile react with the negatively charged oxygen. This way the yield is greater.
135
Reactions of aldehydes and ketones
hydration --> unstable diol (chloral is an exception because it produces hydrated chloral which is stable).
sodium cyanide NaCN --> cyanohydrin
alcohol --> hemiacetal (when reacted with aldehyde)
--> hemiketal (when reacted with ketone)
primary amine --> schiff base
condensation?
136
Use of hydrated chloral
sleeping inducer
137
stability of ketone enol and cyclic-enol
enol
138
Preparation of primary amine
alkyl halide + amonia
139
Preparation of secondary amine
alkyl halide + primary amine
140
Preparation of tertiary amine
alkyl halide + secondary amine
141
Preparation of quatentary amine
alkyl halide + tertiary amine
142
How many H bonds is each amine capable of doing?
primary 3
secondary 2
tertiary 0
quatentary 0
143
Increasing BP of amines
3
144
Increasing solubility of amines
3
145
Increasing basicity of amines
quatentary is not included because it is a weak acid
2 > 1 > 3 > ammonia
*aliphatic is more basic than aromatic
146
Increasing stability of amines
2 > 1 > 3 > ammonia
147
reactions of amines
1/2/3 amine + HX --> 4 a
primary amine + HNO2 (nitrous acid) -->alcohol + water + N2
secondary amine + HNO2 (nitrous acid) -->nitroso amine + water
tertiary amine --> no reaction!
aromatic amine + HNO2 (nitrous acid) + HCl --> diazonium chloride + water
148
Tyrosine is a key structure in..
Dopa, dopamine, norepinnephrin, epinephrin --> all are neurotransmitters.
149
Tryptophan is a key structure in..
serotonin (happyness) and melatonin (day/night cycle) --> both are neurotransmitters.
150
Histadine is a key structure in..
Histamine (alergy)
151
O
||
R-C-
acyl group
152
What is the connection between malic acid and butenedioic acid?
We get butenedioic acid if we remove the hydroxy group from malic acid and a double bond forms instead.
153
naming of mono acids
IUPAC: #C + oic acid
Common: formic/acetic/propionic/butyric/valeric/caproic + acid
154
naming of di acids
IUPAC: #C + dioic acid
Common: oxalic/malonic/succinic/glutaric/adipic + acid
155
naming of tri acids
di acid with functional groups,one will always be a carboxy group
156
What is the connection between maleic acid and fumaric acid?
They are the cis and trans structures of butenedioic acid, respectively.
157
Is malic acid toxic?
No. it is maleic.
158
Describe what happens in the elimination-addition reaction of a tri acid
citric acid --> (eliminotion of water) = aconitic acid
| aconitic acid --> (addition of water) = isocitric acid
159
3HC-COO-
acetate ion
160
acyl+halogen is
acyl halide
161
acyl+organic acid is
aceto acid
162
Preparation of acids
oxydation of an aldehyde/toluene/alkene
| two HARD 2-step reactions with NaCN
163
How many H bonds does a carboxylic acid do?
Four
164
Acid reactions
R-COOH + HX --> acyl halide + water
R-COOH + R-COOH --> acid anhydride + water
R-COOH + R-OH --> ester + water
R-COOH + ammonia --> primary amide + water
R-COOH + primary amine --> secondary amide + water
R-COOH + secondary amine --> tertiary amide + water
decarboxylation of R-COOH --> alkane
Beta oxidation in two steps --> beta keto acid (ketone body)
*decarboxylation of beta keto acid --> ketone (ketone body)
*reduction of beta keto acid --> beta hydroxy acid (ketone body)
165
What are the three ketone bodies?
beta keto acid, ketone (acetone), beta hydroxy acid
166
How can we know if an amino acid is a part of a protein or not? Give an example for each.
It is a part of a protein if the amino group is attached to the alpha carbon, example- all amino acids
if not, it is not a protein like in the case of GABA " gamma amino butyric acid", which is an inhibitor of neurotransmitters.
167
Lactone
cyclic ester
comes from hydroxy acid (dehydration)
*beta lactone does not exist
168
Lactide
cyclic ester (two ester bonds)
comes from two lactic acids (dehydration)
*has cis and trans forms
169
Laktam
cyclic amide
comes from amino valeric acid (dehydration)
*beta laktam exists but is not very stable (in penicillin)
170
Reactions of acyl halide
acyl halide + water --> R-COOH + HX
O
||
acyl halide + Na-O-C-R --> anhydride + NaX
acyl halide + R-OH --> ester + HX
acyl halide + ammonia --> primary amide + HX
171
Creating anhydride (monoacid)
two identical mono acids (dehydration) *not a ring
OR
two different mono acids (dehydration) *not a ring
OR
di acid like succinic acid (dehydration) --> succinic anhydride *ring
172
which form is more stable chair or boat?
In cyclo hexanes the chair conformation is more stable
173
which form is more stable half chair or envelope?
In cyclo pentanes the envelope conformation is more stable
174
which conformation is the only one containing equatorial ?
chair in cyclo hexanes
175
reaction of tertiary amine
no reaction!
176
Which acid is stronger- formic or acetic? Why?
formic because of the positive inductive effect of the CH3 in acetic acid
