CHE118A Fun Facts

What nonpolar molecule/compound is in fire extinguishers?

Compressed CO₂

What is the bond angle of NH3 (ammonia)?

107 degrees

What is the bond angle of H20?

104 degress

What is the bond angle of CH4 (methane)

109.5 degrees

How much HCl does the stomach produce each day?

About 2 L per day.

What is the concentration of stomach HCl?

About 0.02 M.

What is the normal pH range of stomach juice?

1.0–2.5.

What does stomach HCl do to proteins?

It denatures/unfolds their natural folded structures.

Why does HCl denature proteins during digestion?

Denaturing the proteins exposes them to attack and breakdown by digestive enzymes.

What protects the stomach wall from its own acid?

gastric mucosa and its mucous secretions insulate the stomach wall from acid attack

What signaling molecule stimulates parietal cells?

Histamine

Which stomach cells secrete HCl?

Parietal cells

Where are HCl-secreting parietal cells located?

gastric glands of the stomach

What acid-reducing medication blocks histamine from reaching pariental cells?

ranitidine

what happens if histamine cannot reach pariental cells?

stomach does not produce stomach acid (less HCl being produced)

What does PPI stand for?

Proton-pump inhibitor

What is an example of a PPI?

Esomeprazole (Nexium)

What do PPIs directly block?

acid-producing proton pump

In which cells do PPIs block proton pumps?

Parietal cells

What is the overall effect of a PPI?

decreases stomach acid production

What are peptic ulcers?

sores in the stomach lining that expose it to an acid attack

What bacterium is associated with peptic ulcers?

Helicobacter pylori (H. pylori)

What is the antibiotic against H. pylori ?

Amoxicillin

Why can stomach acid interfere with H. pylori treatment?

acidic contents of the stomach can cause rapid destruction of the antibiotic

Why is a PPI given with antibiotic therapy?

PPI raises the stomach's pH, allowing the antibiotic to survive longer.

During ulcer treatment, a PPI raises the stomach pH above what value?

above a pH of 4

Why must the antibiotic survive longer in the stomach?

So it can reach H. pylori infection sites deep in the gastric pits of the stomach lining.

Who designs and synthesizes potential drug candidate molecules?

Organic chemists.

Who studies the biochemical and physiological properties of potential drug molecules and helps optimize them?

Pharmacologists.

What field is defined by the partnership between organic chemists and pharmacologists?

Pharmaceutical chemistry.

Pharmaceutical chemistry is a subset of what broader field?

chemical biology

What is chemical biology?

application of chemistry to solve biological problems

Complete the pathway: Histamine → _____ → HCl secretion.

Histamine → activates parietal cells → HCl secretion

PPI pathway

PPI → blocks proton pumps in parietal cells → ↓ HCl production → ↑ stomach pH

Peptic ulcer treatment concept

H. pylori infection → antibiotic treatment + PPI → stomach pH rises → antibiotic survives → reaches infection sites

What does halogens closer to the acid mean?

It means that the molecule has a more stable/delocalized charge

Can molecules still act as an electrophile w/ a closed valence shell?

Yes, if possessing polar bonds which will import the electrophilic charcater; ex: HCl and CH3Cl

What is the general trend for MELTING POINTS of alkanes?

The melting points of straight-chain alkanes generally increase as the molecular weight and carbon chain length increase, driven by stronger London dispersion forces

What is the Zig-Zag Effect and what does it have to do with the trend for the MELTING POINTS of alkanes?

Straight-chain alkanes exhibit an alternating pattern where even-numbered alkanes have higher melting points than their immediate odd-numbered neighbors (e.g., hexane melts higher than pentane or heptane). This occurs because the terminal methyl groups in even-numbered chains pack into a denser, more stable crystal lattice (zig-zag arrangement) compared to odd-numbered chains.

What is petroleum?

mix of several hundreds of hydrocarbons:

• mostly straight chain alkanes

• some branched alkanes

• some aromatic hydrocarbons

Why is the distillation (separation of substances based on differing boiling points) of petroleum significant/important?

allows us to separate petroleum into several different, useful products

After distillation of petroleum (crude oil) the gasoline fraction of crude oil only makes up about:

19%

___ is a mixture of straight, branched, and aromatic hydrocarbons( 5-12 carbons in size)

Gasoline (aka petrol)

How can large alkanes be broken into smaller molecules?

Pyrolysis cracking

After pyrolysis cracking, the yield of gas is ___ rather than ___ w/o pyrolysis cracking (only distillation of petroleum)

47%, 19%

Straight chain alkanes can be converted into branched and aromatic components through…

Reforming and polymerization

What are some sources and use of alkanes

• natural gases

• petrochemicals

• plastics

• solvents

• gas

• kerosene

• jet fuel

• heating oil

• diesel

• lubricating oil

• grease

• wax

• asphalt

• tar

How much energy required to rotate ethane in regards to Newman Projection (60 degrees)?

2.9 kcal/mol

How much energy required to rotate propane in regards to Newman Projection (60 degrees)?

3.2 kcal/mol

How much energy required to rotate butane in regards to Newman Projection (60 degrees)?

3.6 kcal/mol

Lowest energy of the newman projections?

anti, staggered (most stable)

Highest energy of newman projection

eclipsed (least stable)

What types of carbons are the least radically stable?

methyl

What types of carbons are the most radically stable?

tertiary

what is the trend for radical stability from least to most stable?

methyl < primary < secondary < tertiary